A novel contrast agent with rare earth-doped up-conversion luminescence and Gd-DTPA magnetic resonance properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu Qing; Wei Daixu; Cheng Jiejun

2012-08-15

The magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF{sub 4}:Yb, Er were successfully synthesized by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF{sub 4}:Yb, Er nanoparticles through EDC/NHS coupling chemistry. The as-prepared products were characterized by powder X-ray diffraction, transmission electron microscopy, dynamic light scattering, energy dispersive X-ray analysis, and fourier transform infrared spectrometry. The room-temperature upconversion luminescent spectra and T{sub 1}-weighted maps of the obtained nanoparticles were carried out by 980 nm NIR light excitation and a 3T MR imaging scanner, respectively. The results indicated that the as-synthesized multifunctional nanoparticles with small size, highly solubility in water, and bothmore » high MR relaxivities and upconversion luminescence may have potential usage for MR imaging in future. - Graphical abstract: We have synthesized magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF4:Yb, Er by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF4:Yb, Er nanoparticles through EDC/NHS coupling chemistry. Highlights: Black-Right-Pointing-Pointer A novel magnetic-luminescent multifunctional nanoparticles are synthesized. Black-Right-Pointing-Pointer The nanoparticles are highly efficient for luminescence and T{sub 1}-weighted MR imaging. Black-Right-Pointing-Pointer The nanoparticles are small in size and highly solubility in water. Black-Right-Pointing-Pointer The nanoparticles hold great potential usage for future biomedical engineering.« less

Sub-10 nm lanthanide doped BaLuF{sub 5} nanocrystals: Shape controllable synthesis, tunable multicolor emission and enhanced near-infrared upconversion luminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, Ling; Lu, Wei; Wang, Haibo

2015-04-15

Highlights: • Sub-10 nm cubic phase BaLuF{sub 5} nanocrystals were synthesized by a hydrothermal method for the first time. • Tunable multicolor from yellow to yellow-green was achieved by controlling Gd{sup 3+} content in BaLuF{sub 5}:Yb/Er system. • Intense near-infrared upconversion luminescence in BaLuF{sub 5}:Gd/Yb/Tm nanocrystal. • The enhancement near-infrared luminescence can be realized by adjusting the content of Gd{sup 3+} in BaLuF{sub 5}:Gd/Yb/Tm system. - Abstract: In this study, sub-10 nm BaLuF{sub 5} nanocrystals with cubic phase structure were synthesized by a solvothermal method using oleic acid as the stabilizing agent. The as-prepared BaLuF{sub 5} nanocrystals were characterized bymore » transmission electron microscopy (TEM), X-ray diffraction (XRD), and analyzed by the upconversion (UC) spectra. The TEM results reveal that these samples present high uniformity. Compared with Gd-free samples, the size of BaLuF{sub 5}:Yb/Er doped with 10% Gd{sup 3+} decreased to 5.6 nm. In addition, BaLuF{sub 5}:Yb/Tm/Gd upconversion nanoparticles (UCNPs) presented efficient near-infrared (NIR)-NIR UC luminescence. Therefore, it is expected that these ultra-small BaLuF{sub 5} nanocrystals with well-controlled shape, size, and UC emission have potential applications in biomedical imaging fields.« less

Folic acid-functionalized up-conversion nanoparticles: toxicity studies in vivo and in vitro and targeted imaging applications

NASA Astrophysics Data System (ADS)

Sun, Lining; Wei, Zuwu; Chen, Haige; Liu, Jinliang; Guo, Jianjian; Cao, Ming; Wen, Tieqiao; Shi, Liyi

2014-07-01

Folate receptors (FRs) are overexpressed on a variety of human cancer cells and tissues, including cancers of the breast, ovaries, endometrium, and brain. This over-expression of FRs can be used to target folate-linked imaging specifically to FR-expressing tumors. Fluorescence is emerging as a powerful new modality for molecular imaging in both the diagnosis and treatment of disease. Combining innovative molecular biology and chemistry, we prepared three kinds of folate-targeted up-conversion nanoparticles as imaging agents (UCNC-FA: UCNC-Er-FA, UCNC-Tm-FA, and UCNC-Er,Tm-FA). In vivo and in vitro toxicity studies showed that these nanoparticles have both good biocompatibility and low toxicity. Moreover, the up-conversion luminescence imaging indicated that they have good targeting to HeLa cells and can therefore serve as potential fluorescent contrast agents.Folate receptors (FRs) are overexpressed on a variety of human cancer cells and tissues, including cancers of the breast, ovaries, endometrium, and brain. This over-expression of FRs can be used to target folate-linked imaging specifically to FR-expressing tumors. Fluorescence is emerging as a powerful new modality for molecular imaging in both the diagnosis and treatment of disease. Combining innovative molecular biology and chemistry, we prepared three kinds of folate-targeted up-conversion nanoparticles as imaging agents (UCNC-FA: UCNC-Er-FA, UCNC-Tm-FA, and UCNC-Er,Tm-FA). In vivo and in vitro toxicity studies showed that these nanoparticles have both good biocompatibility and low toxicity. Moreover, the up-conversion luminescence imaging indicated that they have good targeting to HeLa cells and can therefore serve as potential fluorescent contrast agents. Electronic supplementary information (ESI) available: Up-conversion luminescence spectra of UCNC-Er and UCNC-Er-FA, UCNC-Tm and UCNC-Tm-FA. Confocal luminescence imaging data collected as a series along the Z optical axis. See DOI: 10.1039/c4nr02312a

Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

NASA Astrophysics Data System (ADS)

Liu, Pei; Cheng, Wenjing; Yao, Yunhua; Xu, Cheng; Zheng, Ye; Deng, Lianzhong; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

2017-11-01

Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

Intense blue up-conversion luminescence in Tm 3+/Yb 3+ codoped oxyfluoride glass-ceramics containing β-PbF 2 nanocrystals

NASA Astrophysics Data System (ADS)

Zhang, Junjie; Duan, Zhongchao; He, Dongbing; Dai, Shixun; Zhang, Liyan; Hu, Lili

2005-12-01

Up-conversion luminescence properties of a Tm 3+/Yb 3+ codoped oxyfluoride glass-ceramics under 980 nm excitation are investigated. Intense blue emission centered at 476 nm, corresponding to 1G 4 → 3H 6 transitions of Tm 3+ was simultaneously observed in the transparent oxyfluoride glass ceramics at room temperature. The intensity of the blue up-conversion luminescence in a 1 mol% YbF 3-containing glass-ceramic was found to be about 40 times stronger than that in the precursor oxyfluoride glass. The reason for the intense Tm 3+ up-conversion luminescence in the oxyfluoride glass-ceramics is discussed. The dependence of up-conversion intensities on excitation power and possible up-conversion mechanism are also evaluated.

Intense blue up-conversion luminescence in Tm3+/Yb3+ codoped oxyfluoride glass-ceramics containing beta-PbF2 nanocrystals.

PubMed

Zhang, Junjie; Duan, Zhongchao; He, Dongbing; Dai, Shixun; Zhang, Liyan; Hu, Lili

2005-12-01

Up-conversion luminescence properties of a Tm3+/Yb3+ codoped oxyfluoride glass-ceramics under 980 nm excitation are investigated. Intense blue emission centered at 476 nm, corresponding to 1G4-->3H6 transitions of Tm3+ was simultaneously observed in the transparent oxyfluoride glass ceramics at room temperature. The intensity of the blue up-conversion luminescence in a 1 mol% YbF3-containing glass-ceramic was found to be about 40 times stronger than that in the precursor oxyfluoride glass. The reason for the intense Tm3+ up-conversion luminescence in the oxyfluoride glass-ceramics is discussed. The dependence of up-conversion intensities on excitation power and possible up-conversion mechanism are also evaluated.

Rare-earth doped transparent nano-glass-ceramics: a new generation of photonic integrated devices

NASA Astrophysics Data System (ADS)

Rodríguez-Armas, Vicente Daniel; Tikhomirov, Victor K.; Méndez-Ramos, Jorge; Yanes, Angel C.; Del-Castillo, Javier; Furniss, David; Seddon, Angela B.

2007-05-01

We report on optical properties and prospect applications on rare-earth doped oxyfluoride precursor glass and ensuing nano-glass-ceramics. We find out the spectral optical gain of the nano-glass-ceramics and show that its flatness and breadth are advantageous as compared to contemporary used erbium doped optical amplifiers. We present the possibility of flat gain cross-section erbium doped waveguide amplifiers as short 'chip', all-optical, devices capable of dense wavelength division multiplexing, including the potential for direct writing of these devices inside bulk glasses for three-dimensional photonic integration. We carried out a comparative study of the up-conversion luminescence in Er 3+-doped and Yb 3+-Er 3+-Tm 3+ co-doped samples, which indicates that these materials can be used as green/red tuneable up-conversion phosphors and white light simulation respectively. Observed changes in the spectra of the up-conversion luminescence provide a tool for tuning the colour opening the way for producing 3-dimensional optical recording.

New nanoplatforms based on UCNPs linking with polyhedral oligomeric silsesquioxane (POSS) for multimodal bioimaging

NASA Astrophysics Data System (ADS)

Ge, Xiaoqian; Dong, Liang; Sun, Lining; Song, Zhengmei; Wei, Ruoyan; Shi, Liyi; Chen, Haige

2015-04-01

A new and facile method was used to transfer upconversion luminescent nanoparticles from hydrophobic to hydrophilic using polyhedral oligomeric silsesquioxane (POSS) linking on the surface of upconversion nanoparticles. In comparison with the unmodified upconversion nanoparticles, the POSS modified upconversion nanoplatforms [POSS-UCNPs(Er), POSS-UCNPs(Tm)] displayed good monodispersion in water and exhibited good water-solubility, while their particle size did not change substantially. Due to the low cytotoxicity and good biocompatibility as determined by methyl thiazolyl tetrazolium (MTT) assay and histology and hematology analysis, the POSS modified upconversion nanoplatforms were successfully applied to upconversion luminescence imaging of living cells in vitro and nude mouse in vivo (upon excitation at 980 nm). In addition, the doped Gd3+ ion endows the POSS-UCNPs with effective T1 signal enhancement and the POSS-UCNPs were successfully applied to in vivo magnetic resonance imaging (MRI) for a Kunming mouse, which makes them potential MRI positive-contrast agents. More importantly, the corner organic groups of POSS can be easily modified, resulting in kinds of POSS-UCNPs with many potential applications. Therefore, the method and results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications.A new and facile method was used to transfer upconversion luminescent nanoparticles from hydrophobic to hydrophilic using polyhedral oligomeric silsesquioxane (POSS) linking on the surface of upconversion nanoparticles. In comparison with the unmodified upconversion nanoparticles, the POSS modified upconversion nanoplatforms [POSS-UCNPs(Er), POSS-UCNPs(Tm)] displayed good monodispersion in water and exhibited good water-solubility, while their particle size did not change substantially. Due to the low cytotoxicity and good biocompatibility as determined by methyl thiazolyl tetrazolium (MTT) assay and histology and hematology analysis, the POSS modified upconversion nanoplatforms were successfully applied to upconversion luminescence imaging of living cells in vitro and nude mouse in vivo (upon excitation at 980 nm). In addition, the doped Gd3+ ion endows the POSS-UCNPs with effective T1 signal enhancement and the POSS-UCNPs were successfully applied to in vivo magnetic resonance imaging (MRI) for a Kunming mouse, which makes them potential MRI positive-contrast agents. More importantly, the corner organic groups of POSS can be easily modified, resulting in kinds of POSS-UCNPs with many potential applications. Therefore, the method and results may provide more exciting opportunities for multimodal bioimaging and multifunctional applications. Electronic supplementary information (ESI) available: Schematic illustration of the formation of POSS-UCNPs. TEM images of NaYF4:Yb,Tm and NaYF4:Yb,Tm@NaGdF4 nanoparticles in cyclohexane; the TEM image of POSS-UCNPs(Tm) in water. DLS of POSS-UCNPs(Tm) in water. The energy dispersive X-ray (EDX) spectrum of POSS-UCNPs(Er). XPS of POSS-UCNPs(Er); XPS of Si element. UCL spectra of POSS-UCNPs(Er) in physiology saline as a function of time. UCL spectra of NaYF4:Yb,Tm@NaGdF4 [UCNPs(Tm)] and POSS-UCNPs(Tm), excited with a 980 nm laser (100 mW cm-2). In vivo UCL imaging of Kunming mice after intravenous injection with POSS-UCNPs(Tm) at different time points. See DOI: 10.1039/c5nr00950b

Upconversion luminescent logic gates and turn-on sensing of glutathione based on two-photon excited quantum dots conjugated with dopamine.

PubMed

Gui, Rijun; Jin, Hui; Liu, Xifeng; Wang, Zonghua; Zhang, Feifei; Xia, Jianfei; Yang, Min; Bi, Sai

2014-12-07

Under the two-photon excitation, upconversion luminescent "INHIBIT" and "OR" logic gates of water-dispersed CdTe quantum dots (QDs) were constituted by conjugating the QDs with dopamine. This facilitated the development of a novel QDs-based upconversion luminescent probe for efficient turn-on sensing of glutathione.

The role of Nb in intensity increase of Er ion upconversion luminescence in zirconia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smits, K., E-mail: smits@cfi.lu.lv; Sarakovskis, A.; Grigorjeva, L.

2014-06-07

It is found that Nb co-doping increases the luminescence and upconversion luminescence intensity in rare earth doped zirconia. Er and Yb-doped nanocrystalline samples with or without Nb co-doping were prepared by sol-gel method and thermally annealed to check for the impact of phase transition on luminescence properties. Phase composition and grain sizes were examined by X-ray diffraction; the morphology was checked by scanning- and high-resolution transmission electron microscopes. Both steady-state and time-resolved luminescence were studied. Comparison of samples with different oxygen vacancy concentrations and different Nb concentrations confirmed the known assumption that oxygen vacancies are the main agents for tetragonalmore » or cubic phase stabilization. The oxygen vacancies quench the upconversion luminescence; however, they also prevent agglomeration of rare-earth ions and/or displacement of rare-earth ions to grain surfaces. It is found that co-doping with Nb ions significantly (>20 times) increases upconversion luminescence intensity. Hence, ZrO{sub 2}:Er:Yb:Nb nanocrystals may show promise for upconversion applications.« less

Up-conversion in an Er-containing nanocomposite and microlasers based on it

NASA Astrophysics Data System (ADS)

Sobeshchuk, N. O.; Denisyuk, I. Yu.

2017-06-01

The results of an investigation of three-dimensional polymer microcavities doped with inorganic luminescent particles are presented. Microlasers in the form of rectangular parallelepipeds were fabricated based on the SU8 2025 photoresist by means of compact UV lithography. Luminescent particles containing erbium oxide were obtained by low-temperature synthesis of the corresponding chlorides in a nonaqueous medium. The obtained spectra confirm the presence of a narrowband laser radiation exhibiting a Stokes shift.

Temperature sensing of adipose tissue heating with the luminescent upconversion nanoparticles as nanothermometer: in vitro study

NASA Astrophysics Data System (ADS)

Yanina, I. Yu.; Volkova, E. K.; Zaharevich, A. M.; Konyukhova, J. G.; Kochubey, V. I.; Tuchin, V. V.

2017-03-01

The luminescence spectra of upconversion nanoparticles (UCNPs) imbedded in fat tissue were measured in a wide temperature range, from room to human body and further to hyperthermic temperatures. The two types of synthesized UCNP [NaYF4:Yb3+, Er3+] specimens, namely, powdered as-is and embedded into polymer film, were used. The results show that the luminescence of UCNPs placed under the adipose tissue layer is reasonably good sensitive to temperature change and reflects phase transitions of lipids in tissue cells. The most likely, multiple phase transitions are associated with the different components of fat cells such as phospholipids of cell membrane and lipids of fat droplets. In the course of fat cell heating, lipids of fat droplet first transit from a crystalline form to a liquid crystal form and then to a liquid form, which is characterized by much less scattering. The phase transitions of lipids were observed as the changes of the slope of the temperature dependence of UCNP luminescence intensity. The obtained results confirm a high sensitivity of the luminescent UCNPs to the temperature variations within tissues and show a strong potential for providing a controllable tissue thermolysis.

Effect of various surfactants on changes in the emission color chromaticity in upconversion YVO4: Yb3+, Er3+ nanoparticles

NASA Astrophysics Data System (ADS)

Woźny, Przemysław; Szczeszak, Agata; Lis, Stefan

2018-02-01

YVO4: Yb3+,Er3+ upconverting nanocrystals were synthesized via a hydrothermal method using different compounds as surfactants. Structure and morphology of the nanocrystals were investigated by X-ray diffraction and transmission electron microscopy. Tetragonal crystal structure of the nanocrystals appeared irrespective of the type of surfactant used. The average crystallite size was estimated by TEM images. The obtained products were composed of small nanoparticles, in the size range of 10-60 nm, depending on the surfactant used. The morphology of the nanoparticles was also regulated by the type of surfactant. Spectroscopic analysis of the materials obtained was carried out by measuring the emission and excitation spectra and the intensity of luminescence as a function of laser energy and luminescence decays. The nanocrystals prepared exhibited a green upconversion emission attributed to the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+, under NIR (985 nm) pulse laser irradiation, and their emission lifetimes were in the range 3.84-4.90 μs. On the basis of the spectroscopic investigation, the upconversion mechanism was proposed and chromaticity coordinates were calculated. Surfactants were found to influence on chromaticity of luminescence.

Cooperative upconversion luminescence in Tb{sup 3+}:Yb{sup 3+} co-doped Y{sub 2}SiO{sub 5} powders prepared by combustion synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br; Vieira, Simone A.; Guimarães, Renato B.

2014-03-15

Frequency upconversion (UC) luminescence via cooperative energy transfer (CET) process between pairs of Yb{sup 3+} and Tb{sup 3+} ions was investigated in Tb{sup 3+}:Yb{sup 3+}:Y{sub 2}SiO{sub 5} crystalline ceramic powders prepared by combustion synthesis. Surface morphology and structure of the powders were investigated by scanning electronic microscopy and X-ray powder diffraction. Photoluminescence experiments were performed in Tb{sup 3+}-singly doped samples using ultraviolet light (λ=255 nm) and in Tb{sup 3+}:Yb{sup 3+} co-doped samples using a near-infrared (NIR) diode laser (λ=975 nm). Upon excitation with the NIR diode laser, UC luminescence with an intense emission band centered at ∼549 nm, corresponding tomore » the 4f intraband {sup 5}D{sub 4}→{sup 7}F{sub 5} transition of Tb{sup 3+}, along with less intense emission bands at ∼490, ∼590 and ∼620 nm, corresponding to other {sup 5}D{sub 4}→{sup 7}F{sub J} transitions, was detected. The CET rate was estimated by analyzing the dynamics of UC luminescence with rate equations model of the electronic populations. -- Graphical Abstract: Left: Cooperative upconversion luminescence spectra of three powder samples prepared by combustion synthesis. Right: The SEM image of the powder showing that it consists of agglomerated flake-like shaped particles of various sizes. Full scale bar is 20 μm. Highlights: • Yttrium orthosilicate (Y{sub 2}SiO{sub 5}) powders were prepared by combustion synthesis. • Cooperative upconversion is observed for the first time in Tb{sup 3+}–Yb{sup 3+} doped Y{sub 2}SiO{sub 5}. • Energy transfer and back-transfer rates between Tb{sup 3+} and Yb{sup 3+} pairs were estimated.« less

Growth and optical properties of Pr,Yb-codoped KY 3F 10 fluoride single crystals for up-conversion visible luminescence

NASA Astrophysics Data System (ADS)

Kim, Kyoung Jin; Jouini, Anis; Yoshikawa, Akira; Simura, Rayko; Boulon, Georges; Fukuda, Tsuguo

2007-02-01

We investigate different ways to realize laser emission from (Pr 3+) 3P J=0,1,2 levels by pump sources other than the common argon and excimer-dye laser. The use of infrared (IR) laser diodes in combination with intra- and inter-ionic energy transfer processes (up-conversion) could be an efficient solution towards laser oscillation. Pr 3+,Yb 3+-codoped KY 3F 10 (Pr, Yb:KYF) single crystals were successfully grown by the micro-pulling-down (μ-PD) method. The crystals were transparent with a slightly greenish color, 2.0-2.5 mm in diameter, 20-30 mm in length and free from visible inclusions and cracks. Effective segregation coefficients of Pr and Yb in KYF were studied by means of absorption and chemical analysis. Strong visible emission via selective IR pumping with λ=975 nm and up-conversion excitation were obtained in Pr, Yb:KYF at room temperature (RT). Luminescence measurements have been carried out and the decay kinetics of the Pr 3+ visible emissions was investigated by room temperature time-resolved spectra.

Highly efficient saturated visible up-conversion photoluminescent Y 2 O 3 :Er 3+ microspheres pumped with a 1.55 μm laser diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Jinbo; Wu, Lili; Zhang, Chuanjiang

2017-01-01

Highly efficient saturation up-conversion (UC) luminescent Y2O3:Er3+ microspheres have been successfully prepared via a hydrothermal-homogeneous precipitation method. Bright visible luminescence can be clearly seen with a 1.55 mu m laser diode excitation power as low as similar to 0.03 W cm(-2). The up-conversion (UC) emission spectra indicate that the strongest red emission with a peak situated at similar to 660 nm originated from the I-4(9/2) -> I-4(15/2) transition of Er3+. The peaks situated at similar to 520 and 550 nm can be assigned to the transition from H-2(11/2)/S-4(3/2) state to the ground state of Er3+. The high efficient saturation up-conversionmore » emission is related to the highly crystalline structure. These results indicate a new way to enhance UC radiation in rare-earth ion-doped materials prepared using a hydrothermal-homogeneous precipitation method.« less

An Nd3+-sensitized upconversion nanophosphor modified with a cyanine dye for the ratiometric upconversion luminescence bioimaging of hypochlorite

NASA Astrophysics Data System (ADS)

Zou, Xianmei; Liu, Yi; Zhu, Xingjun; Chen, Min; Yao, Liming; Feng, Wei; Li, Fuyou

2015-02-01

Excessive or misplaced production of ClO- in living systems is usually associated with many human diseases. Therefore, it is of great importance to develop an effective and sensitive method to detect ClO- in living systems. Herein, we designed an 808 nm excited upconversion luminescence nanosystem, composed of the Nd3+-sensitized core-shell upconversion nanophosphor NaYF4:30%Yb,1%Nd,0.5%Er@NaYF4:20%Nd, which serves as an energy donor, and the ClO--responsive cyanine dye hCy3, which acts as an energy acceptor, for ratiometric upconversion luminescence (UCL) monitoring of ClO-. The detection limit of ClO- for this nanoprobe in aqueous solution is 27 ppb and the nanoprobe was successfully used to detect the ClO- in the living cells by ratiometric upconversion luminescence. Importantly, the nanoprobe realized the detection of ClO- in a mouse model of arthritis, which produced an excess of ROS, under 808 nm irradiation in vivo. The excitation laser efficiently reduced the heating effect, compared to the commonly used 980 nm laser for upconversion systems.Excessive or misplaced production of ClO- in living systems is usually associated with many human diseases. Therefore, it is of great importance to develop an effective and sensitive method to detect ClO- in living systems. Herein, we designed an 808 nm excited upconversion luminescence nanosystem, composed of the Nd3+-sensitized core-shell upconversion nanophosphor NaYF4:30%Yb,1%Nd,0.5%Er@NaYF4:20%Nd, which serves as an energy donor, and the ClO--responsive cyanine dye hCy3, which acts as an energy acceptor, for ratiometric upconversion luminescence (UCL) monitoring of ClO-. The detection limit of ClO- for this nanoprobe in aqueous solution is 27 ppb and the nanoprobe was successfully used to detect the ClO- in the living cells by ratiometric upconversion luminescence. Importantly, the nanoprobe realized the detection of ClO- in a mouse model of arthritis, which produced an excess of ROS, under 808 nm irradiation in vivo. The excitation laser efficiently reduced the heating effect, compared to the commonly used 980 nm laser for upconversion systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06407k

Current Advances in Lanthanide‐Doped Upconversion Nanostructures for Detection and Bioapplication

PubMed Central

Chen, Cailing

2016-01-01

Along with the development of science and technology, lanthanide‐doped upconversion nanostructures as a new type of materials have taken their place in the field of nanomaterials. Upconversion luminescence is a nonlinear optical phenomenon, which absorbs two or more photons and emits one photon. Compared with traditional luminescence materials, upconversion nanostructures have many advantages, such as weak background interference, long lifetime, low excitation energy, and strong tissue penetration. These interesting nanostructures can be applied in anticounterfeit, solar cell, detection, bioimaging, therapy, and so on. This review is focused on the current advances in lanthanide‐doped upconversion nanostructures, covering not only basic luminescence mechanism, synthesis, and modification methods but also the design and fabrication of upconversion nanostructures, like core–shell nanoparticles or nanocomposites. At last, this review emphasizes the application of upconversion nanostructure in detection and bioimaging and therapy. Learning more about the advances of upconversion nanostructures can help us better exploit their excellent performance and use them in practice. PMID:27840794

Preparation of ZnO nanoparticles showing upconversion luminescence through simple chemical method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anjana, R.; Subha, P. P.; Markose, Kurias K.

2016-05-23

Upconversion luminescence is an interesting area while considering its applications in a vast variety of fields. Rare earth ions like erbium is the most studied and efficient candidate for achieving upconversion. Erbium and ytterbium co-doped ZnO nanoparticles were prepared through co-precipitation method. A strong red emission has been obtained while exciting with 980 nm laser. Dependence of luminescence emission colour on ytterbium concentration has been studied.

Upconversion microparticles as time-resolved luminescent probes for multiphoton microscopy: desired signal extraction from the streaking effect

NASA Astrophysics Data System (ADS)

Pominova, Daria V.; Ryabova, Anastasia V.; Grachev, Pavel V.; Romanishkin, Igor D.; Kuznetsov, Sergei V.; Rozhnova, Julia A.; Yasyrkina, Daria S.; Fedorov, Pavel P.; Loschenov, Victor B.

2016-09-01

The great interest in upconversion nanoparticles exists due to their high efficiency under multiphoton excitation. However, when these particles are used in scanning microscopy, the upconversion luminescence causes a streaking effect due to the long lifetime. This article describes a method of upconversion microparticle luminescence lifetime determination with help of modified Lucy-Richardson deconvolution of laser scanning microscope (LSM) image obtained under near-IR excitation using nondescanned detectors. Determination of the upconversion luminescence intensity and the decay time of separate microparticles was done by intensity profile along the image fast scan axis approximation. We studied upconversion submicroparticles based on fluoride hosts doped with Yb3+-Er3+ and Yb3+-Tm3+ rare earth ion pairs, and the characteristic decay times were 0.1 to 1.5 ms. We also compared the results of LSM measurements with the photon counting method results; the spread of values was about 13% and was associated with the approximation error. Data obtained from live cells showed the possibility of distinguishing the position of upconversion submicroparticles inside and outside the cells by the difference of their lifetime. The proposed technique allows using the upconversion microparticles without shells as probes for the presence of OH- ions and CO2 molecules.

[Up-conversion luminescent materials of Y2O3: RE(RE=Er or Er/Yb) prepared by sol-gel combustion synthesis].

PubMed

Han, Peng-de; Zhang, Le; Huang, Xiao-gu; Wang, Li-xi; Zhang, Qi-tu

2010-11-01

Y2O3 powders doped with rare-earth ions were synthesized by sol-gel combustion synthesis. Effects of different calcinating temperatures, Er+ doping concentration and Yb3+ doping concentration were investigated. It was shown that the single well crystallized Y2O3 powders could be obtained at 800 degrees C; as the calcinating temperature increased, the crystallinity and upconversion luminescence intensity were higher; the particle size was uniform around 1 microm at 900 degrees C; when Er3+ doping concentration was 1 mol%, the green upconversion luminescence intensity reached the maximum, but for red upconversion luminescence, when Er3+ doping concentration was 4 mol%, its luminescence intensity reached the maximum; as the ratio of Yb3+ to Er3+ was 4:1, the green emission intensity reached the maximum, while the red emission intensity was always increasing as Yb3+ doping concentration increased.

Comparison of temperature sensing of the luminescent upconversion and ZnCdS nanoparticles

NASA Astrophysics Data System (ADS)

Yanina, I. Yu.; Volkova, E. K.; Sagaidachnaya, E. A.; Konyukhova, J. G.; Kochubey, V. I.; Tuchin, V. V.

2018-02-01

The luminescence spectra of upconversion nanoparticles (UCNPs) and ZnCdS nanoparticles (ZnCdSNPs) were measured and analyzed in a wide temperature range: from room to human body and further to a hyperthermic temperature resulting in tissue morphology change. The results show that the luminescence signal of UCNPs and ZnCdSNPs placed within the tissue is reasonably good sensitive to temperature change and accompanied by phase transitions of lipid structures of adipose tissue. The most likely that the multiple phase transitions are associated with the different components of fat cells, such as phospholipids of cell membrane and lipids of fat droplets. In the course of fat cell heating, lipids of fat droplet first transit from a crystalline form to a liquid crystal form and then to a liquid form, which is characterized by much less scattering. The results of phase transitions of lipids were observed as the changes in the slope of the temperature dependence of the intensity of luminescence of the film with nanoparticles embedded into tissue. The obtained results confirm a high sensitivity of the luminescent UCNPs and ZnCdSNPs to the temperature variations within thin tissue samples and show a strong potential for the controllable tissue thermolysis.

Co-operative energy transfer in Yb3+-Er3+ co-doped SrGdxOy upconverting phosphor

NASA Astrophysics Data System (ADS)

Kumar, Ashwini; Pathak, Trilok K.; Dhoble, S. J.; . Terblans, J. J.; Swart, H. C.

2018-04-01

Upconversion nanoparticles (UCNPs) have shown considerable interest in many fields; however, low upconversion efficiency of UCNPs is still the most severe limitation of their applications. Yb3+ and Er3+ co-doped SrGd4O7/Gd2O3(SGO) upconversion (UC) phosphors were synthesized by a modified co-precipitation process. The UC properties were investigated by direct excitation with a 980 nm laser. It was observed that the as prepared materials showed relatively strong green emission, while upon the incorporation of the Er3+ ion, there was an increase in the upconversion luminescence intensity for the red component. The effect of different doping concentration of Er3+on the emission spectra and X-ray diffraction patterns of the UC materials have also been studied. The luminescence lifetimes and Commission Internationale de L'Eclairage coordinates for these as prepared samples were determined to understand the energy transfer (ET) mechanisms occurring between Yb3+ and Er3+ in the SGO host matrix. The UC luminescence intensity as a function of laser pump power was monitored and it was confirmed that the UC process in SGO:Yb3+/Er3+is a two-photon absorption process. The findings reported here are expected to provide a better approach for understanding of the ET mechanisms in the oxide based Yb3+/Er3+ co-doped UC phosphors. This study might be helpful in precisely defined applications where optical transitions are essential criterion and this can be easily achieved by smart tuning of the emission properties of Yb3+/Er3+ co-doped UC phosphors.

Anti-Stokes Luminescence in High Quality Quantum Wells

NASA Astrophysics Data System (ADS)

Vinattieri, A.; Bogani, F.; Miotto, A.; Ceccherini, S.

1997-11-01

We present a detailed investigation of the anti-Stokes (AS) luminescence which originates from exciton recombination when below gap excitation is used, in a set of high quality quantum well structures. We observe strong excitonic resonances in the AS signal as measured from photoluminescence and photoluminescence excitation spectra. We demonstrate that neither the electromagnetic coupling between the wells nor the morphological disorder can explain this up-conversion effect. Time-resolved luminescence data after ps excitation and fs correlation spectroscopy results provide clear evidence of the occurrence of a two-step absorption which is assisted by the exciton population resonantly excited by the first photon.

Plasmon enhanced upconversion luminescence of NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites for cell imaging.

PubMed

Yuan, Peiyan; Lee, Yih Hong; Gnanasammandhan, Muthu Kumara; Guan, Zhenping; Zhang, Yong; Xu, Qing-Hua

2012-08-21

NaYF(4):Yb,Er@SiO(2)@Ag core-shell nanocomposites were prepared to investigate metal-enhanced upconversion luminescence. Two sizes (15 and 30 nm) of Ag nanoparticles were used. The emission intensity of the upconversion nanocrystals was found to be strongly modulated by the presence of Ag nanoparticles (NPs) on the outer shell layer of the nanocomposites. The extent of modulation depended on the separation distance between Ag NPs and upconversion nanocrystals. The optimum upconversion luminescence enhancement was observed at a separation distance of 10 nm for Ag NPs with two different sizes (15 and 30 nm). A maximum upconversion luminescence enhancement of 14.4-fold was observed when 15 nm Ag nanoparticles were used and 10.8-fold was observed when 30 nm Ag NPs were used. The separation distance dependent emission intensity is ascribed to the competition between energy transfer and enhanced radiative decay rates. The biocompatibility of the nanocomposites was significantly improved by surface modification with DNA. The biological imaging capabilities of these nanocomposites were demonstrated using B16F0 cells.

Luminescence of Er/Yb and Tm/Yb doped FAp nanoparticles and ceramics

NASA Astrophysics Data System (ADS)

Grigorjeva, L.; Smits, K.; Millers, D.; Jankoviča, Dz

2015-03-01

The nanoparticles of hydroxiapatite and fluorapatite doped with Er/Yb and Tm/Yb were synthesized and characterized by FTIR, XRD, SEM and TEM methods. The results of up-conversion luminescence studies were presented for the samples as prepared, annealed at 500°C and at 900-1000 °C. At annealing above 800°C the ceramic state was formed. It is shown that fluorapatite host is more appropriate than hydroxiapatite host for rare ions luminescence and up-conversion processes. The post preparing annealing of nanarticles significantly enhanced the luminescence intensity. The Tm/Yb doped fluorapatite shows intense up-conversion luminescence in 790-800 nm spectral region and is potentially useful for biomedical applications.

Monitoring Delamination of Thermal Barrier Coatings by Near-Infrared and Upconversion Luminescence Imaging

NASA Technical Reports Server (NTRS)

Eldridge, J. I.; Martin, R. E.; Singh, Jogender; Wolfe, Doug E.

2008-01-01

Previous work has demonstrated that TBC delamination can be monitored by incorporating a thin luminescent sublayer that produces greatly increased luminescence intensity from delaminated regions of the TBC. Initial efforts utilized visible-wavelength luminescence from either europium or erbium doped sublayers. This approach exhibited good sensitivity to delamination of electron-beam physical-vapor-deposited (EB-PVD) TBCs, but limited sensitivity to delamination of the more highly scattering plasma-sprayed TBCs due to stronger optical scattering and to interference by luminescence from rare-earth impurities. These difficulties have now been overcome by new strategies employing near-infrared (NIR) and upconversion luminescence imaging. NIR luminescence at 1550 nm was produced in an erbium plus ytterbium co-doped yttria-stabilized zirconia (YSZ) luminescent sublayer using 980-nm excitation. Compared to visible-wavelength luminescence, these NIR emission and excitation wavelengths are much more weakly scattered by the TBC and therefore show much improved depth-probing capabilities. In addition, two-photon upconversion luminescence excitation at 980 nm wavelength produces luminescence emission at 562 nm with near-zero fluorescence background and exceptional contrast for delamination indication. The ability to detect TBC delamination produced by Rockwell indentation and by furnace cycling is demonstrated for both EB-PVD and plasma-sprayed TBCs. The relative strengths of the NIR and upconversion luminescence methods for monitoring TBC delamination are discussed.

Upconversion of Tm3+ ions in BaY2F8

NASA Astrophysics Data System (ADS)

Ruan, Yongfeng; Tsuboi, Taiju

1999-06-01

Up-conversion of red light with wavelength of 660 nm in Tm3+-doped BaY2F8 powder results in the two violet luminescence bands with peaks at 417 and 430 nm and two blue luminescence bands with peaks at 455 and 470 nm. The two violet bands are observed to be stronger than the blue bands. The blue luminescence is also observed by pumping with 993 nm light. The up-conversion is explained by a multiple excited state absorption process.

Multifunctional Optical Sensors for Nanomanometry and Nanothermometry: High-Pressure and High-Temperature Upconversion Luminescence of Lanthanide-Doped Phosphates-LaPO4/YPO4:Yb3+-Tm3.

PubMed

Runowski, Marcin; Shyichuk, Andrii; Tymiński, Artur; Grzyb, Tomasz; Lavín, Víctor; Lis, Stefan

2018-05-23

Upconversion luminescence of nano-sized Yb 3+ and Tm 3+ codoped rare earth phosphates, that is, LaPO 4 and YPO 4 , has been investigated under high-pressure (HP, up to ∼25 GPa) and high-temperature (293-773 K) conditions. The pressure-dependent luminescence properties of the nanocrystals, that is, energy red shift of the band centroids, changes of the band ratios, shortening of upconversion lifetimes, and so forth, make the studied nanomaterials suitable for optical pressure sensing in nanomanometry. Furthermore, thanks to the large energy difference (∼1800 cm -1 ), the thermalized states of Tm 3+ ions are spectrally well-separated, providing high-temperature resolution, required in optical nanothermometry. The temperature of the system containing such active nanomaterials can be determined on the basis of the thermally induced changes of the Tm 3+ band ratio ( 3 F 2,3 → 3 H 6 / 3 H 4 → 3 H 6 ), observed in the emission spectra. The advantage of such upconverting optical sensors is the use of near-infrared light, which is highly penetrable for many materials. The investigated nanomanometers/nanothermometers have been successfully applied, as a proof-of-concept of a novel bimodal optical gauge, for the determination of the temperature of the heated system (473 K), which was simultaneously compressed under HP (1.5 and 5 GPa).

Nd3+, Yb3+ and Ho3+ Codoped Oxyfluoride Glass Ceramics with High Efficient Green Upconversion Luminescence

NASA Astrophysics Data System (ADS)

Zhang, Jun-Jie; Kawamoto, Yoji; Dai, Shi-Xun; Zhang, Li-Yan; Hu, Li-Li

2004-06-01

New oxyfluoride glasses and glass ceramic codoped with Nd3+, Yb3+ and Ho3+ were prepared. The x-ray diffraction analysis revealed that the heat treatments of the oxyfluoride glasses could cause the precipitation of (Nd3+, Yb3+, Ho3+)-doped fluorite-type crystals. Very strong green up-conversion luminescence due to the Ho3+: (5F4, 5S2)rightarrow5I8 transition under 800-nm excitation was observed in these transparent glass ceramics. The intensity of the green up-conversion luminescence in a 1-mol% YbF3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho3+ up-conversion luminescence in the oxyfluoride glass ceramics is discussed.

Self-assembly of an upconverting nanocomplex and its application to turn-on detection of metalloproteinase-9 in living cells

NASA Astrophysics Data System (ADS)

Nguyen, Phuong-Diem; Thanh Cong, Vu; Baek, Changyoon; Min, Junhong

2016-10-01

Upcoversion nanoparticles are an emerging luminescent nanomaterial with excellent photophysical properties that have great benefits in biological sensing. In this study, a luminescent turn-on biosensor for cell-secreted protease activity assay is established based on resonance energy transfer in an upconversion nanoparticle-graphene oxide nano-assembly. The proposed biosensor consists of a blue-emitting upconversion nanoparticle covered with a quenching complex, comprising gelatin as the proteinase substrate and graphene oxide nanosheets as luminescence acceptors. After enzymatic digestion, the upconversion nanoparticles lose the gelatin cover due to the disassembly of the quenching complex, thus the upconverting luminescence in the blue region is restored (a turn-on response). The recovered upconverting luminescence is proportional to the protease concentration; the limit of detection was 12 ng ml-1. Finally, the upconversion-graphene oxide nanocomplex was successfully applied in the detection of cell-secreted protease-metalloproteinase in MCF-7 cancer cells with high sensitivity and specificity.

Tuning upconversion luminescence of LiYF4:Yb3+,Er3+/Tm3+/Ho3+ microcrystals synthesized through a molten salt process.

PubMed

Niu, Na; He, Fei; Wang, Liuzhen; Wang, Lin; Wang, Yan; Gai, Shili; Yang, Piaoping

2014-05-01

In this paper, well-defined tetragonal-phase LiYF4:Yb3+,Er3+/Tm3+/Ho3+ micro-crystals with octahedral morphology were successfully prepared through a surfactant-free molten salt process for the first time. By gradually increasing the LiF content in the NaNO3-KNO3 reaction medium, the crystal phase transforms from a mixture of YF3 and LiYF4 to pure tetragonal-phase LiYF4. The possible formation process for the phase and morphology evolution is also presented. Moreover, upon 980 nm laser diode (LD) excitation, the lanthanide ions (Yb3+, Er3+/Tm3+/Ho3+) doped LiYF4 crystals exhibit intense upconversion emission lights. By tuning the sensitizer concentrations of Yb3+ ions in LiYF4:Yb3+,Er3+, the relative intensities of green and red emissions can be precisely adjusted under single wavelength excitation. Consequently, multicolor upconversion emissions can be obtained. On the other hand, UC mechanisms were also given based on the emission spectra and the plot of luminescence intensity to pump power.

[Two-photon up-conversion fluorescence of a neodymium organic framework Nd(BTC)].

PubMed

Xu, Hui; Jin, Run-zhi; Wu, Chun-yang; Yang, Yu; Qian, Guo-dong

2008-08-01

In the present work, a neodymium organic framework Nd(BTC) was synthesized by the solvothermal reaction of Nd(NO3)3 x 5H2O and H3BTC (BTC = 1,3,5-benzenetricarboxylate) in mixed solvents of DMF, ethanol and water, and was identified by elemental analysis. This MOF complex was characterized using X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry (TGA-DSC) analysis, UV-visible absorption spectra and fluorescence spectra. This polycrystalline powder lost DMF and H2O when heated to 120 degrees C, then remained stable till the temperature reached 500 degrees C. Near infrared fluorescence at 1064 nm due to the 4 F3/2--> 4 I11/2 transition of Nd3+ ions was exhibited when excited by 808 nm laser beam. It was also been found that up-conversion fluorescence of Nd(BTC) peaked at about 450 nm due to 2 D5/2 -->4 I11/2 transition of Nd3+ ions can be observed under the excitation of a 580 nm laser line. The mechanism of the up-conversion fluorescence of Nd(BTC) at around 450 nm under the excitation of 580 nm laser can be ascribed to both excited-state absorption and energy transfer up-conversion. This result indicated that such MOF can be employed as an up-conversion luminescence material in many potential application areas such as bio-labeling and fluorescence image.

Structure and up-conversion luminescence in sol-gel derived Er 3+-Yb 3+ co-doped SiO 2:PbF 2 nano-glass-ceramics

NASA Astrophysics Data System (ADS)

del-Castillo, J.; Yanes, A. C.; Méndez-Ramos, J.; Tikhomirov, V. K.; Rodríguez, V. D.

2009-11-01

Transparent oxyfluoride nano-glass-ceramics 90(SiO 2)10(PbF 2) co-doped with 0.3 Yb 3+ and 0.1 Er 3+ (mol%) have been prepared by thermal treatment of precursor sol-gel glasses. X-ray diffraction and high resolution transmission electron microscopy analysis pointed out a precipitation of cubic β-PbF 2 nanocrystals of certain diameter in nano-glass-ceramics varying from 10 to 20 nm depending on heat treatment conditions. The incorporation of Yb 3+ and Er 3+ dopants in these nanocrystals has been confirmed by signatures of luminescence spectroscopy. Up-conversion luminescence pumped at 980 nm has been detected. Colour tuneability of up-conversion luminescence varying pump power has been analyzed in terms of standard chromaticity diagram. This tuneability opens applications for up-conversion phosphors and three-dimensional optical recording.

Crystal growth and upconversion luminescent properties of KLu2F7:Yb,Er nanocrystals

NASA Astrophysics Data System (ADS)

Xu, Dekang; Yao, Lu; Lin, Hao; Yang, Shenghong; Zhang, Yueli

2018-05-01

Crystal growth of KLu2F7 nanocrystals is investigated by dosage- and time-dependent analysis. XRD patterns reveal the phase transition along with the dosage of fluorine source and reaction times, where the cubic-phase KLu3F10 turns into orthorhombic KLu2F7. TEM images show that the dimensions of as-prepared samples are below a hundred nanometers, with different shapes from hexagonal plate to hexagonal rod. The upconversion properties of the as-prepared samples are investigated. It is found that the upconversion emission is lowered as the shape of the samples varies. Moreover, the orthorhombic KLu2F7:Yb,Er nanocrystals present more enormous upconversion luminescence than the cubic counterparts. In a word, the orthorhombic nanocrystals are found to be good candidate for upconversion luminescence and of great importance for potential applications in solar cells, multicolor display and bioimaging.

Laser-diode-excited blue upconversion in Tm3+/Yb3+ -codoped TeO2-Ga2O3-R2O (R=Li, Na, K) glasses.

PubMed

Zhao, Chun; Zhang, Qinyuan; Yang, Gangfeng; Jiang, Zhonghong

2008-01-01

This paper reports on intense blue upconversion in Tm(3+)/Yb(3+) codoped TeO(2)-Ga(2)O(3)-R(2)O(R=Li, Na, K) glasses upon excitation with commercial available laser diode (LD). Effects of alkali ions on the Raman spectra, thermal stability and spectroscopic properties of the tellurite-gallium glasses have also been investigated. Energy transfer and the involved upconversion mechanisms have been discussed. Intense blue upconversion emission centered at 476 nm along with a weak red emission at 650 nm has been observed upon excitation of 977 nm LD, assigned to the transitions of 1G4-->3H6, and 1G4-->3H4 and/or 3F(2,3)-->3H6 of Tm(3+), respectively. The blue upconversion intensity has a cubelike dependence on incident pump laser power, indicating a three-photon process. However, a quadratic dependence of the 476 nm upconversion intensity on the incident pump laser power has been observed when samples under excitation of 808 nm LD due to a two-photon absorption process. Enhanced upconversion luminescence have been observed with replacing K(+) for Na(+) and Li(+).

Lanthanide-Doped KLu2F7 Nanoparticles with High Upconversion Luminescence Performance: A Comparative Study by Judd-Ofelt Analysis and Energy Transfer Mechanistic Investigation

NASA Astrophysics Data System (ADS)

Xu, Dekang; Li, Anming; Yao, Lu; Lin, Hao; Yang, Shenghong; Zhang, Yueli

2017-02-01

The development, design and the performance evaluation of rare-earth doped host materials is important for further optical investigation and industrial applications. Herein, we successfully fabricate KLu2F7 upconversion nanoparticles (UCNPs) through hydrothermal synthesis by controlling the fluorine-to-lanthanide-ion molar ratio. The structural and morphological results show that the samples are orthorhombic-phase hexagonal-prisms UCNPs, with average side length of 80 nm and average thickness of 110 nm. The reaction time dependent crystal growth experiment suggests that the phase transformation is a thermo-dynamical process and the increasing F-/Ln3+ ratio favors the formation of the thermo-dynamical stable phase - orthorhombic KLu2F7 structure. The upconversion luminescence (UCL) spectra display that the orthorhombic KLu2F7:Yb/Er UCNPs present stronger UCL as much as 280-fold than their cubic counterparts. The UCNPS also display better UCL performance compared with the popular hexagonal-phase NaREF4 (RE = Y, Gd). Our mechanistic investigation, including Judd-Ofelt analysis and time decay behaviors, suggests that the lanthanide tetrad clusters structure at sublattice level accounts for the saturated luminescence and highly efficient UCL in KLu2F7:Yb/Er UCNPs. Our research demonstrates that the orthorhombic KLu2F7 is a promising host material for UCL and can find potential applications in lasing, photovoltaics and biolabeling techniques.

Enhanced electrical properties, color-tunable up-conversion luminescence, and temperature sensing behaviour in Er-doped Bi3Ti1.5W0.5O9 multifunctional ferroelectric ceramics

NASA Astrophysics Data System (ADS)

Zhang, Ying; Li, Jun; Chai, Xiaona; Wang, Xusheng; Li, Yongxiang; Yao, Xi

2017-03-01

Er-doped Bi3Ti1.5W0.5O9 (BTW-x) ferroelectric ceramics were prepared by a conventional solid-state reaction synthesis method, and their structure, electrical properties, up-conversion (UC) luminescence, and temperature sensing behaviour were investigated. A high piezoelectric coefficient d33 (9.6 pC/N), a large remnant polarization Pr (12.75 μC/cm2), a high Curie temperature Tc (730.2 °C), and the optimal luminescent intensity are obtained for the samples at x = 0.05. By changing the Er doped concentration, the BTW-x ceramics are capable of generating various UC spectra and the color could be tunable from green to yellow. According to the fluorescence intensity ratio of green emissions at 532.6 nm and 549.2 nm in the temperature range from 83 K to 423 K, optical temperature sensing properties are investigated and the maximum sensing sensitivity is found to be 0.00314 K-1 at 423 K. The results conclude that BTW-x would be a candidate in high temperature sensor, fluorescence thermometry, and opto-electronic integration applications.

Upconversion luminescence from Er-N codoped of ZnO nanowires prepared by ion implantation method

NASA Astrophysics Data System (ADS)

Zhong, Kun; Xu, Jie; Su, Jing; Chen, Yu lin

2011-02-01

Nitrogen and erbium co-doped of ZnO nanowires (NWs) are fabricated by ion implantation and subsequent annealing in air. The incorporation of Er3+ and N+ ions is verified by energy dispersive X-ray spectroscopy (EDS) and Raman spectra. The samples exhibit upconversion photoluminescence around ∼550 nm and ∼660 nm under an excitation at 980 nm. It is discovered that the N-doped can drastically increase the upconversion photoluminescence intensity by modifying the local structure around Er3+ in ZnO matrix. The enhancement of the PL intensity by the N-doped is caused by the formation of ErO6-xNx octahedron complexes. With the increase of the annealing temperature (Ta), the Er3+ ions diffuse towards the surface of the NWs, which benefits the red emission and evokes the variation of intensity ratio owing to the existence of some organic groups.

Simultaneous quasi-one-dimensional propagation and tuning of upconversion luminescence through waveguide effect

PubMed Central

Gao, Dangli; Tian, Dongping; Zhang, Xiangyu; Gao, Wei

2016-01-01

Luminescence-based waveguide is widely investigated as a promising alternative to conquer the difficulties of efficiently coupling light into a waveguide. But applications have been still limited due to employing blue or ultraviolet light as excitation source with the lower penetration depth leading to a weak guided light. Here, we show a quasi-one-dimensional propagation of luminescence and then resulting in a strong luminescence output from the top end of a single NaYF4:Yb3+/Er3+ microtube under near infrared light excitation. The mechanism of upconversion propagation, based on the optical waveguide effect accompanied with energy migration, is proposed. The efficiency of luminescence output is highly dependent on the concentration of dopant ions, excitation power, morphology, and crystallinity of tube as an indirect evidence of the existence of the optical actived waveguide effect. These findings provide the possibility for the construction of upconversion fiber laser. PMID:26926491

Enhanced Upconversion Luminescence in Yb3+/Tm3+-Codoped Fluoride Active Core/Active Shell/Inert Shell Nanoparticles through Directed Energy Migration.

PubMed

Qiu, Hailong; Yang, Chunhui; Shao, Wei; Damasco, Jossana; Wang, Xianliang; Ågren, Hans; Prasad, Paras N; Chen, Guanying

2014-01-03

The luminescence efficiency of lanthanide-doped upconversion nanoparticles is of particular importance for their embodiment in biophotonic and photonic applications. Here, we show that the upconversion luminescence of typically used NaYF₄:Yb 3+ 30%/Tm 3+ 0.5% nanoparticles can be enhanced by ~240 times through a hierarchical active core/active shell/inert shell (NaYF₄:Yb 3+ 30%/Tm 3+ 0.5%)/NaYbF₄/NaYF₄ design, which involves the use of directed energy migration in the second active shell layer. The resulting active core/active shell/inert shell nanoparticles are determined to be about 11 times brighter than that of well-investigated (NaYF₄:Yb 3+ 30%/Tm 3+ 0.5%)/NaYF₄ active core/inert shell nanoparticles when excited at ~980 nm. The strategy for enhanced upconversion in Yb 3+ /Tm 3+ -codoped NaYF₄ nanoparticles through directed energy migration might have implications for other types of lanthanide-doped upconversion nanoparticles.

Titanium mesh supported TiO2 nanowire arrays/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles novel composites for flexible dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Liu, Wenwu; Zhang, Huanyu; Wang, Hui-gang; Zhang, Mei; Guo, Min

2017-11-01

Ti-mesh supported TiO2 nanowire arrays (NWAs)/upconversion luminescence Er3+-Yb3+ codoped TiO2 nanoparticles (UC-EY-TiO2 NPs) composite structured photoanodes for fully flexible dye sensitized solar cells (DSSCs) were firstly constructed via a hydrothermal and spin coating process. UV-vis-NIR absorption spectra of the TiO2 NWAs/UC-EY-TiO2 NPs composites exhibited strong absorption around near infrared (NIR) 980 nm. The composites excited by 980 nm NIR laser could emit upconversion fluorescence at 489, 526, 549 and 658 nm, which expanded the spectral response range and sunlight capturing capability of formed flexible DSSCs. Moreover, the TiO2 NWAs/UC-EY-TiO2 NPs was coated with an Nb2O5 thin layer to further suppress electron recombination losses. The complete flexible DSSCs based on Nb2O5 coated TiO2 NWAs/2.0 mol% Er3+-1.0 mol% Yb3+ codoped TiO2 NPs photoanode and Pt/ITO-PEN counter electrode exhibited an enhanced photon to current conversion efficiency of 8.10%, a 68% improvement compared to TiO2 NWAs/undoped TiO2 NPs based DSSCs (4.82%).

Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

PubMed

Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

2016-04-01

For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display.

Luminescence upconversion under hydrostatic pressure in the 3d-metal systems Ti2+:NaCl and Ni2+:CsCdCl3

NASA Astrophysics Data System (ADS)

Wenger, Oliver S.; Salley, G. Mackay; Valiente, Rafael; Güdel, Hans U.

2002-06-01

We present a study of upconversion materials and processes under external hydrostatic pressure. The near-infrared to visible photon upconversion properties of Ti2+-doped NaCl and Ni2+-doped CsCdCl3 at 15 K are studied as a function of external hydrostatic pressure. It is found that in Ti2+:NaCl pressure can be used to switch on an efficient upconversion mechanism, which is inactive at ambient pressure, leading to an order-of-magnitude enhancement of the overall upconversion efficiency of this material. For Ni2+:CsCdCl3 it is demonstrated that upconversion luminescence excitation spectroscopy can be used to study the pressure dependence of excited state absorption transitions. The results demonstrate the ability to tune upconversion properties by altering the local crystal field of active ions, in addition to probing the pressure dependence of excited state absorption transitions via upconversion spectroscopy.

Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

PubMed

Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

2011-08-15

Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

Highly efficient upconversion luminescence in hexagonal NaYF4:Yb3+, Er3+ nanocrystals synthesized by a novel reverse microemulsion method

NASA Astrophysics Data System (ADS)

Gunaseelan, M.; Yamini, S.; Kumar, G. A.; Senthilselvan, J.

2018-01-01

A new reverse microemulsion system is proposed for the first time to synthesize NaYF4:Yb,Er nanocrystals, which demonstrated high upconversion emission in 550 and 662 nm at 980 nm diode laser excitation. The reverse microemulsion (μEs) system is comprised of CTAB and oleic acid as surfactant and 1-butanol co-surfactant and isooctane oil phase. The surfactant to water ratio is able to tune the microemulsion droplet size from 14 to 220 nm, which eventually controls the crystallinity and particulate morphology of NaYF4:Yb,Er. Also, the microemulsion precursor and calcination temperature plays certain role in transforming the cubic NaYF4:Yb,Er to highly luminescent hexagonal crystal structured upconversion material. Single phase hexagonal NaYF4:YbEr nanorod prepared by water-in-oil reverse microemulsion (μEs) gives intense red upconversion emission. Both nanosphere and nanorod shaped NaYF4:Yb,Er was obtained, but nanorod morphology resulted an enhanced upconversion luminescence. The structural, morphological, thermal and optical luminescence properties of the NaYF4:Yb,Er nanoparticles are discussed in detail by employing powder X-ray diffraction, dynamic light scattering, high resolution electron microscopy, TGA-DTA, UV-DRS, FTIR and photoluminescence spectroscopy. Intense upconversion emission achieved in the microemulsion synthesized NaYF4:Yb3+,Er3+ nanocrystal can make it as useful optical phosphor for solar cell applications.

Delivery and reveal of localization of upconversion luminescent microparticles and quantum dots in the skin in vivo by fractional laser microablation, multimodal imaging, and optical clearing

NASA Astrophysics Data System (ADS)

Volkova, Elena K.; Yanina, Irina Yu; Genina, Elina A.; Bashkatov, Alexey N.; Konyukhova, Julia G.; Popov, Alexey P.; Speranskaya, Elena S.; Bucharskaya, Alla B.; Navolokin, Nikita A.; Goryacheva, Irina Yu.; Kochubey, Vyacheslav I.; Sukhorukov, Gleb B.; Meglinski, Igor V.; Tuchin, Valery V.

2018-02-01

Delivery and spatial localization of upconversion luminescent microparticles [Y2O3:Yb, Er] (mean size ˜1.6 μm) and quantum dots (QDs) (CuInS2/ZnS nanoparticles coated with polyethylene glycol-based amphiphilic polymer, mean size ˜20 nm) inside rat skin was studied in vivo using a multimodal optical imaging approach. The particles were embedded into the skin dermis to the depth from 300 to 500 μm through microchannels performed by fractional laser microablation. Low-frequency ultrasound was applied to enhance penetration of the particles into the skin. Visualization of the particles was revealed using a combination of luminescent spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis. Optical clearing was used to enhance the image contrast of the luminescent signal from the particles. It was demonstrated that the penetration depth of particles depends on their size, resulting in a different detection time interval (days) of the luminescent signal from microparticles and QDs inside the rat skin in vivo. We show that luminescent signal from the upconversion microparticles and QDs was detected after the particle delivery into the rat skin in vivo during eighth and fourth days, respectively. We hypothesize that the upconversion microparticles have created a long-time depot localized in the laser-created channels, as the QDs spread over the surrounding tissues.

Enhanced Upconversion Luminescence in Yb3+/Tm3+-Codoped Fluoride Active Core/Active Shell/Inert Shell Nanoparticles through Directed Energy Migration

PubMed Central

Qiu, Hailong; Yang, Chunhui; Shao, Wei; Damasco, Jossana; Wang, Xianliang; Ågren, Hans; Prasad, Paras N.; Chen, Guanying

2014-01-01

The luminescence efficiency of lanthanide-doped upconversion nanoparticles is of particular importance for their embodiment in biophotonic and photonic applications. Here, we show that the upconversion luminescence of typically used NaYF4:Yb3+30%/Tm3+0.5% nanoparticles can be enhanced by ~240 times through a hierarchical active core/active shell/inert shell (NaYF4:Yb3+30%/Tm3+0.5%)/NaYbF4/NaYF4 design, which involves the use of directed energy migration in the second active shell layer. The resulting active core/active shell/inert shell nanoparticles are determined to be about 11 times brighter than that of well-investigated (NaYF4:Yb3+30%/Tm3+0.5%)/NaYF4 active core/inert shell nanoparticles when excited at ~980 nm. The strategy for enhanced upconversion in Yb3+/Tm3+-codoped NaYF4 nanoparticles through directed energy migration might have implications for other types of lanthanide-doped upconversion nanoparticles. PMID:28348285

Temperature dependence of luminescence behavior in Er3+-doped BaY2F8 single crystal

NASA Astrophysics Data System (ADS)

Wang, Shuai; Ruan, Yongfeng; Tsuboi, Taiju; Tong, Hongshuang; Wang, Youfa; Zhang, Shouchao

2013-12-01

BaY2F8 single crystals doped with Er3+ ions have been grown by the temperature gradient method. The absorption, excitation and emission spectra for Er3+-doped BaY2F8 crystals were measured at room temperature (297 K) and 12 K. The effect of temperature on the luminescence intensity and effective bandwidth was investigated in the range of 12-297 K. The temperature dependence of the fluorescence intensity ratio (FIR) for the 522 nm emission (2H11/2→4I15/2 transition) and the 552 nm emission (4S3/2→4I15/2 transition) was also studied in the range of 12-297 K. Based on the fitting FIR curve, the value of the constant term B (2.25) was obtained. The fitting FIR curve and FIR equation may have a potential application in the temperature measurement. In addition, the up-conversion spectrum at room temperature was recorded under excitation of 980 nm and the up-conversion mechanism was analyzed in detail.

Near-infrared-emitting colloidal Ag2S quantum dots exhibiting upconversion luminescence

NASA Astrophysics Data System (ADS)

Zhang, Yanyan; Jiang, Danyu; Yang, Wei; Wang, Dandan; Zheng, Huiping; Du, Yuansheng; Li, Xi; Li, Qiang

2017-02-01

Ag2S quantum dots (QDs) coated with thioglycolic acid (Ag2S QDs-TGA) have been synthesized in an organic solvent via a stepwise addition of reagents. When excited by a 980 nm laser, the near-infrared-emitting colloidal Ag2S QDs-TGA exhibit upconversion luminescence (UCL). The observed photoluminescence (PL) was attributed to the presence of ligand-modified Ag2S on the QD surfaces. Hence, upon dilution of the solution, the PL intensity initially increased before subsequently decreasing, accompanied by a blue shift in the PL spectra. The PL phenomena can be attributed to the increase in the amount of ligand-modified Ag2S on the QD surfaces upon dilution, which in turn affected the fluorescence resonance energy transfer (FRET) and re-emission of the surface energy level. The relations between the emission intensity of Ag2S QDs-TGA and the excitation power are investigated, and the results confirm that the UCL in Ag2S QDs-TGA can be ascribed to a two-photon-assisted absorption process via a real energy state.

Highly efficient green up-conversion luminescence of Nd3+-Yb3+-Ho3+ codoped fluorite-type nanocrystals in transparent glass ceramics

NASA Astrophysics Data System (ADS)

Qiu, Jianbei; Kawamoto, Yoji; Zhang, Junjie

2002-11-01

Oxyfluoride glasses were developed with composition 30SiO2[middle dot]15AlO1.5[middle dot]28PbF2[middle dot]22CdF2[middle dot](4.8-x)GdF3[middle dot]0.1NdF3[middle dot]0.1HoF3[middle dot]xYbF3 (x=0, 0.1, 0.2, 0.5, 1, 2, 3, 4, and 4.8) in mole percent. Powder x-ray diffraction analysis revealed that the heat treatments of the oxyfluoride glasses at 450 degC for 0.5 h cause the precipitation of Nd3+-Yb3+-Ho3+ codoped fluorite-type nanocrystals of about 16.3 nm in diameter in the glass matrix. These transparent glass ceramics exhibited very strong green up-conversion luminescence due to the Ho3+: (5F4, 5S2)[right arrow]5I8 transition under 800 nm excitation. The intensity of the green up-conversion luminescence in a 1 mol % YbF3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho3+ up-conversion luminescence in the oxyfluoride glass ceramics is discussed. An up-conversion mechanism is also proposed.

Up-conversion multiwave (White) luminescence in the visible spectral range under excitation by IR laser diodes in the active BaY2F8:Yb3+,Pr3+ medium

NASA Astrophysics Data System (ADS)

Pushkar', A. A.; Uvarova, T. V.; Kiiko, V. V.

2011-08-01

The possibilities of occupying high-lying 4 f states of Pr3+ ions in the active BaY2F8:Yb3+,Pr3+ medium according to the photon avalanche and step-by-step sensitization mechanisms are compared. It is shown that the photon avalanche is unlikely to occur in the BaY2F8:Yb3+,Pr3+ crystal. The multiband luminescence spectra in the visible spectral range (white emission) under single- and multiwave pumping of BaY2F8:Yb3+,Pr3+ crystal by IR laser diodes are reported.

Quantum Dots' Photo-luminescence Line Shape Modeling

NASA Astrophysics Data System (ADS)

Hua, Muchuan; Decca, Ricardo

Two usual phenomena observed in quantum dots (QDs) photo-luminescence (PL) spectra are line broadening and energy shift between absorption and emission peaks. They have been attributed to electron-phonon coupling and surface trapping during the PL process. Although many qualitative work describing these phenomena has been carried out, quantitative results are far less common. In this work, a semi-empirical model is introduced to simulate steady state QDs' PL processes at room temperature. It was assumed that the vast majority of radiative recombination happens from surface trapped states. Consequently, the PL line shape should be highly modulated by transition rates between states in the conduction band and between them and surface trapping states. CdSe/ZnS (core/shell) colloidal QD samples with different sizes were used to examine the model. The model was able to successfully reproduce the PL spectra of these samples even when the excitation happens within the emission spectra, giving raise to up-conversion events. This model might help understand and make more precise predictions of QDs' PL spectra and could also aid on the design of QDs' optical devices.

Up-Conversion Y2O3:Yb(3+),Er(3+) Hollow Spherical Drug Carrier with Improved Degradability for Cancer Treatment.

PubMed

Ge, Kun; Zhang, Cuimiao; Sun, Wentong; Liu, Huifang; Jin, Yi; Li, Zhenhua; Liang, Xing-Jie; Jia, Guang; Zhang, Jinchao

2016-09-28

The rare earth hollow spheres with up-conversion luminescence properties have shown potential applications in drug delivery and bioimaging fields. However, there have been few reports for the degradation properties of rare earth oxide drug carriers. Herein, uniform and well-dispersed Y2O3:Yb(3+),Er(3+) hollow spheres (YOHSs) have been fabricated by a general Pechini sol-gel process with melamine formaldehyde colloidal spheres as template. The novel YOHSs with up-conversion luminescence has good drug loading amount and drug-release efficiency; moreover, it exhibits pH-responsive release patterns. In particular, the YOHSs sample exhibits low cytotoxicity and excellent degradable properties in acid buffer. After the sample was loaded with anticancer drug doxorubicin (DOX), the antitumor result in vitro indicates that YOHS-DOX might be effective in cancer treatment. The animal imaging test also reveals that the YOHSs drug carrier can be used as an outstanding luminescent probe for bioimaging in vivo application prospects. The results suggest that the degradable drug carrier with up-conversion luminescence may enhance the delivery efficiency of drugs and improve the cancer therapy in clinical applications.

A highly sensitive biosensing platform based on upconversion nanoparticles and graphene quantum dots for the detection of Ag+

NASA Astrophysics Data System (ADS)

He, Lu; Yang, Lin; Zhu, Hao; Dong, Wenkui; Ding, Yujie; Zhu, Jun-Jie

2017-06-01

A novel luminescence ‘Turn-On’ nanoplatform for the sensitive sensing of Ag+ was fabricated based on luminescence resonance energy transfer technique between sodium citrate functionalized upconversion nanoparticles (Cit-UCNPs, energy donor) and graphene quantum dots (GQDs, energy acceptor). Amino-labeled single-stranded DNA (NH2-ssDNA) containing a number of cytosine (C) was conjugated on the surface of the Cit-UCNPs to capture Ag+ ions. Due to the π-π stacking interaction between NH2-ssDNA and GQDs, the upconversion luminescence can be quenched. However, upon the addition of Ag+, the π-π stacking interaction weakens due to the formation of the hairpin structure of C-Ag+-C on the UCNPs. As a result, GQDs will leave the surface of the UCNPs and the upconversion luminescence can be enhanced (Turn-On). Based on this fact, the sensor was developed for the detection of Ag+ with a linear concentration range from 2 × 10-4 to 1 μM and a detection limit as low as 60 pM. The assay method is fairly simple with high selectivity and sensitivity, which can be used for the determination of Ag+ in environmental water samples.

Delivery and reveal of localization of upconversion luminescent microparticles and quantum dots in the skin in vivo by fractional laser microablation, multimodal imaging, and optical clearing.

PubMed

Volkova, Elena K; Yanina, Irina Yu; Genina, Elina A; Bashkatov, Alexey N; Konyukhova, Julia G; Popov, Alexey P; Speranskaya, Elena S; Bucharskaya, Alla B; Navolokin, Nikita A; Goryacheva, Irina Yu; Kochubey, Vyacheslav I; Sukhorukov, Gleb B; Meglinski, Igor V; Tuchin, Valery V

2018-02-01

Delivery and spatial localization of upconversion luminescent microparticles [Y2O3:Yb, Er] (mean size ∼1.6  μm) and quantum dots (QDs) (CuInS2/ZnS nanoparticles coated with polyethylene glycol-based amphiphilic polymer, mean size ∼20  nm) inside rat skin was studied in vivo using a multimodal optical imaging approach. The particles were embedded into the skin dermis to the depth from 300 to 500  μm through microchannels performed by fractional laser microablation. Low-frequency ultrasound was applied to enhance penetration of the particles into the skin. Visualization of the particles was revealed using a combination of luminescent spectroscopy, optical coherence tomography, confocal microscopy, and histochemical analysis. Optical clearing was used to enhance the image contrast of the luminescent signal from the particles. It was demonstrated that the penetration depth of particles depends on their size, resulting in a different detection time interval (days) of the luminescent signal from microparticles and QDs inside the rat skin in vivo. We show that luminescent signal from the upconversion microparticles and QDs was detected after the particle delivery into the rat skin in vivo during eighth and fourth days, respectively. We hypothesize that the upconversion microparticles have created a long-time depot localized in the laser-created channels, as the QDs spread over the surrounding tissues. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

The upconversion luminescence and magnetism in Yb3+/Ho3+ co-doped LaF3 nanocrystals for potential bimodal imaging

NASA Astrophysics Data System (ADS)

Syamchand, Sasidharanpillai S.; George, Sony

2016-12-01

Biocompatible upconversion nanoparticles with multifunctional properties can serve as potential nanoprobes for multimodal imaging. Herein, we report an upconversion nanocrystal based on lanthanum fluoride which is developed to address the imaging modalities, upconversion luminescence imaging and magnetic resonance imaging (MRI). Lanthanide ions (Yb3+ and Ho3+) doped LaF3 nanocrystals (LaF3 Yb3+/Ho3+) are fabricated through a rapid microwave-assisted synthesis. The hexagonal phase LaF3 nanocrystals exhibit nearly spherical morphology with average diameter of 9.8 nm. The inductively coupled plasma mass spectrometry (ICP-MS) analysis estimated the doping concentration of Yb3+ and Ho3+ as 3.99 and 0.41%, respectively. The nanocrystals show upconversion luminescence when irradiated with near-infrared (NIR) photons of wavelength 980 nm. The emission spectrum consists of bands centred at 542, 645 and 658 nm. The stronger green emission at 542 nm and the weak red emissions at 645 and 658 nm are assigned to 5S2 → 5I8 and 5F5 → 5I8 transitions of Ho3+, respectively. The pump power dependence of luminescence intensity confirmed the two-photon upconversion process. The nanocrystals exhibit paramagnetism due to the presence of lanthanide ion dopant Ho3+ and the magnetization is 19.81 emu/g at room temperature. The nanocrystals exhibit a longitudinal relaxivity ( r 1) of 0.12 s-1 mM-1 and transverse relaxivity ( r 2) of 28.18 s-1 mM-1, which makes the system suitable for developing T2 MRI contrast agents based on holmium. The LaF3 Yb3+/Ho3+ nanocrystals are surface modified by PEGylation to improve biocompatibility and enhance further functionalisation. The PEGylated nanocrystals are found to be non-toxic up to 50 μg/mL for 48 h of incubation, which is confirmed by the MTT assay as well as morphological studies in HeLa cells. The upconversion luminescence and magnetism together with biocompatibility enables the adaptability of the present system as a nanoprobe for potential bimodal imaging.

Upconversion luminescence nanosensor for TNT selective and label-free quantification in the mixture of nitroaromatic explosives.

PubMed

Ma, Yingxin; Wang, Leyu

2014-03-01

This paper reports a rapid, sensitive, and selective nanosensor for the detection of 2,4,6-trinitrotoluene (TNT) in the mixture aqueous solution of nitroaromatics independent of immunoassay or molecularly imprinted technology and complicated instruments. Despite many strategies including immunoassay and molecularly imprinted technologies been successfully developed for the detection of TNT, it is not easy to differentiate TNT from 2,4,6-trinitrophenol (TNP) due to their very similar chemical structures and properties. In this work, the amine functionalized NaYF4:Yb(3+)/Er(3+) upconversion luminescence nanoparticles (UCNPs) whose excitation (980 nm) and emission (543 nm) wavelength were far from the absorbance bands of other usual interference nitroaromatics including 2,4-dinitrotoluene (DNT), nitrobenzene (NB), and especially TNP, were utilized as the luminescent nanosensors for TNT luminescence detection. To make these UCNPs highly water stable and render the charge transfer from UCNPs to TNT easier, amino groups were introduced onto the surface of the UCNPs by coating a polymer layer of ethylene glycol dimethacrylate (EGDMA) hybridized with 3-aminopropyltriethoxysilane (APTS). After binding with TNT through amino groups on the UCNPs, the naked eye visible green upconversion luminescence of the UCNPs was dramatically quenched and thus a sensitive UC luminescence nanosensor was developed for TNT detection. However, other nitroaromatics including TNP, DNT, and NB have no influence on the green UC luminescence and thus no influence on the TNT detection. The luminescence intensity is negatively proportional to the concentration of TNT in the range of 0.01-9.0 µg/mL with the 3σ limit of detection (LOD) of 9.7 ng/mL. The present studies provide a novel and facile strategy to fabricate the upconversion luminescence sensors with highly selective recognition ability in aqueous media and are desirable for label free analysis of TNT in mixed solution independent of immunoassay and molecularly imprinted technology and complicated instruments. © 2013 Published by Elsevier B.V.

Deep Photoacoustic/Luminescence/Magnetic Resonance Multimodal Imaging in Living Subjects Using High-Efficiency Upconversion Nanocomposites.

PubMed

Liu, Yu; Kang, Ning; Lv, Jing; Zhou, Zijian; Zhao, Qingliang; Ma, Lingceng; Chen, Zhong; Ren, Lei; Nie, Liming

2016-08-01

A gadolinium-doped multi-shell upconversion nanoparticle under 800 nm excitation is synthesized with a 10-fold fluorescence-intensity enhancement over that under 980 nm. The nanoformulations exhibit excellent photoacoustic/luminescence/magnetic resonance tri-modal imaging capabilities, enabling visualization of tumor morphology and microvessel distribution at a new imaging depth. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Intersection of CMOS Microsystems and Upconversion Nanoparticles for Luminescence Bioimaging and Bioassays

PubMed Central

Wei, Liping.; Doughan, Samer.; Han, Yi.; DaCosta, Matthew V.; Krull, Ulrich J.; Ho, Derek.

2014-01-01

Organic fluorophores and quantum dots are ubiquitous as contrast agents for bio-imaging and as labels in bioassays to enable the detection of biological targets and processes. Upconversion nanoparticles (UCNPs) offer a different set of opportunities as labels in bioassays and for bioimaging. UCNPs are excited at near-infrared (NIR) wavelengths where biological molecules are optically transparent, and their luminesce in the visible and ultraviolet (UV) wavelength range is suitable for detection using complementary metal-oxide-semiconductor (CMOS) technology. These nanoparticles provide multiple sharp emission bands, long lifetimes, tunable emission, high photostability, and low cytotoxicity, which render them particularly useful for bio-imaging applications and multiplexed bioassays. This paper surveys several key concepts surrounding upconversion nanoparticles and the systems that detect and process the corresponding luminescence signals. The principle of photon upconversion, tuning of emission wavelengths, UCNP bioassays, and UCNP time-resolved techniques are described. Electronic readout systems for signal detection and processing suitable for UCNP luminescence using CMOS technology are discussed. This includes recent progress in miniaturized detectors, integrated spectral sensing, and high-precision time-domain circuits. Emphasis is placed on the physical attributes of UCNPs that map strongly to the technical features that CMOS devices excel in delivering, exploring the interoperability between the two technologies. PMID:25211198

Perspectives and challenges of photon-upconversion nanoparticles - Part I: routes to brighter particles and quantitative spectroscopic studies.

PubMed

Resch-Genger, Ute; Gorris, Hans H

2017-10-01

Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the focus of many research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of these fascinating nanomaterials, a number of challenges have to be overcome, such as the low brightness, particularly of small UCNPs, and the reliable quantification of the excitation-power-density-dependent upconversion luminescence. In this series of critical reviews, recent developments in the design, synthesis, optical-spectroscopic characterization, and application of UCNPs are presented with special focus on bioanalysis and the life sciences. Here we guide the reader from the synthesis of UCNPs to different concepts to enhance their luminescence, including the required optical-spectroscopic assessment to quantify material performance; surface modification strategies and bioanalytical applications as well as selected examples of the use of UCNPs as reporters in different assay formats are addressed in part II. Future trends and challenges in the field of upconversion are discussed with special emphasis on UCNP synthesis and material characterization, particularly quantitative luminescence studies. Graphical Abstract Both synthesis and spectroscopy as well bioanalytical applications of UCNPs are driven and supported by COST Action CM1403 "The European Upconversion Network".

Enhancement of luminescence emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor by Li{sup +} co-doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavrilović, Tamara V.; Jovanović, Dragana J., E-mail: draganaj@vinca.rs; Lojpur, Vesna M.

2014-09-15

This paper demonstrates the effects of Li{sup +} co-doping on the structure, morphology, and luminescence properties of GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor prepared using a high-temperature solid-state chemistry method. The GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} powders synthesized with the Li{sup +} co-dopant (in concentrations of 0, 5, 10, and 15 mol%) are characterized by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectroscopy. Structural analysis showed that powders co-doped with Li{sup +} have larger crystallite sizes and slightly smaller crystal lattice parameters than powders prepared without Li{sup +} ions. Photoluminescence down-conversion (345-nm excitation) and up-conversion (980-nm excitation) spectra show characteristic Er{supmore » 3+} emissions, with the most intense bands peaking at 525 nm ({sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition) and 552 nm ({sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}). The intensity of up-conversion emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} is enhanced (by a factor of four) by co-doping with 5 mol% of Li{sup +} ions. The mechanisms responsible for this emission enhancement are discussed. - Graphical abstract: UC emission spectra for GdVO{sub 4}:1.5-mol% Er{sup 3+}/20-mol% Yb{sup 3+} powders co-doped with different concentrations of Li{sup +} ions, recorded under 980-nm excitation. - Highlights: • 5-mol% Li{sup +} co-doped powders have 400% enhanced up-conversion emission intensity. • 15-mol% Li{sup +} co-doping produces 40% higher emission in down-conversion. • Li{sup +} co-doped powders have larger crystallite size and smaller lattice parameters.« less

A near-infrared luminescent Mn2+-doped NaYF4:Yb,Tm/Fe3+ upconversion nanoparticles redox reaction system for the detection of GSH/Cys/AA.

PubMed

Zhang, Liping; Ling, Bo; Wang, Lun; Chen, Hongqi

2017-09-01

An upconversion luminescence method was developed for the determination of glutathione (GSH), L-cysteine (Cys) or L-ascorbic acid (AA) based on redox reaction. We synthesized poly(acrylic acid) (PAA)-modified Mn 2+ -doped NaYF 4 :Yb,Tm upconversion nanoparticles (UCNPs), and the luminescence of these UCNPs was effectively quenched due to their carboxyl groups coordinating with Fe 3+ to form a UCNPs/Fe 3+ system. GSH, Cys or AA reduced Fe 3+ to Fe 2+ , which induced the luminescence recovery of the UCNPs. Under the optimized conditions, wide linear concentration ranges from 0.25-300μM for GSH, 0.5-875μM for Cys and 0.5-350μM for AA were found, and the detection limits (3S/K) were 0.2μM, 0.5μM and 0.2μM, respectively. Thus, the UCNPs/Fe 3+ system was successfully applied for sensing GSH, Cys or AA. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation Mechanism, Structural, and Upconversion Properties of Alkaline Rare-Earth Fluoride Nanocrystals Doped With Yb3+/Er3+ Ions.

PubMed

Grzyb, Tomasz; Przybylska, Dominika

2018-06-04

Ultrasmall (9-30 nm) Yb 3+ /Er 3+ -doped, upconverting alkaline rare-earth fluorides that are promising for future applications were synthesized by the microwave-assisted hydrothermal method. The formation mechanism was proposed, indicating the influence of the stability of metal ions complexes with ethylenediaminetetraacetic acid on the composition of the product and tendency to form M 2 REF 7 (M 0.67 RE 0.33 F 2.33 ) cubic compounds in the M-RE-F systems. Their physicochemical properties (structure, morphology, and spectroscopic properties) are compared and discussed. The obtained nanoparticles exhibited emission of light in the visible spectra under excitation by 976 nm laser radiation. Excitation and emission spectra, luminescence decays, laser energy dependencies, and upconversion quantum yields were measured to determine the spectroscopic properties of prepared materials. The Yb 3+ /Er 3+ pair of ions used as dopants was responsible for an intense yellowish-green emission. The upconversion quantum yields determined for the first time for M 2 REF 7 -based materials were 0.0192 ± 0.001% and 0.0176 ± 0.001% for Sr 2 LuF 7 :Yb 3+ ,Er 3+ and Ba 2 LuF 7 :Yb 3+ ,Er 3+ respectively, the two best emitting samples. These results indicated the prepared materials are good and promising alternatives for the most studied NaYF 4 :Yb 3+ ,Er 3+ nanoparticles.

Multicolor tunability and upconversion enhancement of fluoride nanoparticles by oxygen dopant

NASA Astrophysics Data System (ADS)

Niu, Wenbin; Wu, Suli; Zhang, Shufen; Su, Liap Tat; Tok, Alfred Iing Yoong

2013-08-01

The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a strategy for simultaneously tuning color output and enhancing upconversion emission of Yb/Er doped fluoride UCNPs, based on adjusting the oxygen doping level. The synthesis of multicolored multifunctional NaGdF4:Yb,Er UCNPs was used as the model host system to demonstrate this protocol. Ammonium nitrate (NH4NO3) was used as the oxygen source and added into the reaction system at the beginning stage of nucleation and growth process of fluoride UCNPs, which facilitates the formation of enough oxygen atoms and the diffusion of these into the fluoride host matrix. The results revealed that multicolour output and upconversion enhancement mainly resulted from the variation of phonon energy and crystal field symmetry of the host lattice, respectively. This strategy can be further expanded to other fluoride host matrices. As an example of an application, multicolored UCNPs were used as a color converter in light emitting diodes, which can effectively convert near-infrared light into visible light. It is expected that these multicolored UCNPs will be promising for applications in multiplexing biodetection, bioimaging (optical and magnetic resonance imaging) and other optical technologies, and the present method for the control of O2- doping may also be used in other functional nanomaterials.The ability to manipulate the upconversion luminescence of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) is particularly important and highly desired due to their wide applications in color displays, multiplexing bioassays and multicolor imaging. Here, we developed a strategy for simultaneously tuning color output and enhancing upconversion emission of Yb/Er doped fluoride UCNPs, based on adjusting the oxygen doping level. The synthesis of multicolored multifunctional NaGdF4:Yb,Er UCNPs was used as the model host system to demonstrate this protocol. Ammonium nitrate (NH4NO3) was used as the oxygen source and added into the reaction system at the beginning stage of nucleation and growth process of fluoride UCNPs, which facilitates the formation of enough oxygen atoms and the diffusion of these into the fluoride host matrix. The results revealed that multicolour output and upconversion enhancement mainly resulted from the variation of phonon energy and crystal field symmetry of the host lattice, respectively. This strategy can be further expanded to other fluoride host matrices. As an example of an application, multicolored UCNPs were used as a color converter in light emitting diodes, which can effectively convert near-infrared light into visible light. It is expected that these multicolored UCNPs will be promising for applications in multiplexing biodetection, bioimaging (optical and magnetic resonance imaging) and other optical technologies, and the present method for the control of O2- doping may also be used in other functional nanomaterials. Electronic supplementary information (ESI) available: Upconversion spectra of NaYF4:Yb,Er UCNPs prepared with various oxygen sources (trimethylamine N-oxide and ammonium carbonate, Fig. S1) and different addition temperatures of NH4NO3 (Fig. S2), enlarged XRD patterns (Fig. S3), the intensity ratios of green to red emissions of NaGdF4:Yb,Er UCNPs prepared with various amounts of NH4NO3 (Fig. S4), power dependence of upconversion spectra of NaGdF4:Yb,Er UCNPs prepared at 300 °C for 1 h (Fig. S5), upconversion spectra of the product after further reaction between as-prepared NaYF4:Yb,Er and 50 mg of NH4NO3 at 300 °C for 1 h (Fig. S6), XRD patterns of NaYF4:Yb,Er and NaLuF4:Yb,Er UCNPs prepared with various amounts of NH4NO3 (Fig. S7 and S8), the corresponding magnetization curves of NaGdF4:Yb,Er UCNPs (Fig. S9). See DOI: 10.1039/c3nr01612a

Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Page, R.H.; Schaffers, K.I.; Waide, P.A.

We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beammore » profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.« less

Nanocrystals feel the heat

NASA Astrophysics Data System (ADS)

Liang, Liangliang; Liu, Xiaogang

2018-03-01

Phosphors often suffer luminescence quenching at elevated temperatures. Now, thermal quenching can be combated with surface phonon-assisted energy transfer, enabling the luminescence of ultrasmall upconversion nanophosphors to be dramatically enhanced.

Phytotoxicity, Translocation, and Biotransformation of NaYF₄ Upconversion Nanoparticles in a Soybean Plant.

PubMed

Yin, Wenyan; Zhou, Liangjun; Ma, Yuhui; Tian, Gan; Zhao, Jiating; Yan, Liang; Zheng, Xiaopeng; Zhang, Peng; Yu, Jie; Gu, Zhanjun; Zhao, Yuliang

2015-09-01

The increasing uses of rare-earth-doped upconversion nanoparticles (UCNPs) have obviously caused many concerns about their potential toxicology on live organisms. In addition, the UCNPs can be released into the environment, then transported into edible crop plants, and finally entered into food chain. Here, the soybean is chosen as a model plant to study the subchronic phytotoxicity, translocation, and biotransformation of NaYF4 UCNPs. The incubation with UCNPs at a relative low concentration of 10 μg mL(-1) leads to growth promotion for the roots and stems, while concentration exceeding 50 μg mL(-1) brings concentration-dependent inhibition. Upconversion luminescence imaging and scanning electron microscope characterization show that the UCNPs can be absorbed by roots and parts of the adsorbed UCNPs are then transported through vessels to stems and leaves. The near-edge X-ray absorption fine structure spectra reveal that the adsorbed NaYF4 nanoparticles are relatively stable during a 10 d incubation. Energy-dispersive X-ray spectrum further indicates that a small amount of NaYF4 is dissolved/digested and can transform into Y-phosphate clusters in roots. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly intensified upconversion luminescence of Ca(2+) -doped Yb/Er:NaGdF(4) nanocrystals prepared by a solvothermal route.

PubMed

Lei, Lei; Chen, Daqin; Xu, Ju; Zhang, Rui; Wang, Yuansheng

2014-03-01

Upon introducing Ca(2+) dopants into the grain lattices by substituting Gd(3+) ions, irregular Yb/Er:NaGdF4 nanocrystals prepared through a simple solvothermal route convert into highly uniform nanorods. Meanwhile, their upconversion luminescence intensifies by about 200 times, probably due to a modification of the crystal structure of NaGdF4 and an improvement in the crystallinity of the nanophase. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upconversion luminescence in Er3+ doped and Er3+/Yb3+ codoped zirconia and hafnia nanocrystals excited at 980 nm

NASA Astrophysics Data System (ADS)

Gómez, Luis A.; Menezes, Leonardo de S.; de Araújo, Cid B.; Gonçalves, Rogeria R.; Ribeiro, Sidney J. L.; Messaddeq, Younes

2010-06-01

Frequency upconversion (UC) luminescence in nanocrystalline zirconia (ZrO2) and hafnia (HfO2) doped with Er3+ and Yb3+ was studied under continuous-wave excitation at 980 nm. Samples of ZrO2:Er3+, ZrO2:Er3+/Yb3+, and HfO2:Er3+/Yb3+ were prepared by the sol-gel technique and characterized using x-ray diffraction and electron microscopy. A study of the infrared-to-green and infrared-to-red UC processes was performed including the analysis of the spectral and the temporal behavior. The mechanisms contributing to the UC luminescence were identified as excited state absorption and energy transfer among rare-earth ions.

Controlled synthesis and luminescence properties of β-NaGdF4: Yb3+, Er3+ upconversion nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Yueli; Yao, Lu; Xu, Dekang; Lin, Hao; Yang, Shenghong

2018-06-01

β-NaGdF4:Yb3+,Er3+ upconversion (UC) nanoparticles (UCNPs) were prepared by a facile hydrothermal process with the assistance of sodium ethylene diaminetetraacetate salt (EDTA-2Na). The morphologies of the β-NaGdF4 UCNPs were controlled by changing the doses of EDTA-2Na and NaOH in precursor. With increasing concentration of EDTA-2Na in precursor, the size of crystals decreased, resulting in the decreasing of luminescence intensity. With increasing concentration of NaOH in precursor, the morphology became more homogeneous. However, due to the reduction of grain size and crystal quality, the luminescence intensity decreased. Nevertheless, the above results demonstrated a simple route to fabricate homogeneous UCNPs.

Enhancing multiphoton upconversion through energy clustering at sublattice level

NASA Astrophysics Data System (ADS)

Wang, Juan; Deng, Renren; MacDonald, Mark A.; Chen, Bolei; Yuan, Jikang; Wang, Feng; Chi, Dongzhi; Andy Hor, Tzi Sum; Zhang, Peng; Liu, Guokui; Han, Yu; Liu, Xiaogang

2014-02-01

The applications of lanthanide-doped upconversionnanocrystals in biological imaging, photonics, photovoltaics and therapeutics have fuelled a growing demand for rational control over the emission profiles of the nanocrystals. A common strategy for tuning upconversion luminescence is to control the doping concentration of lanthanide ions. However, the phenomenon of concentration quenching of the excited state at high doping levels poses a significant constraint. Thus, the lanthanide ions have to be stringently kept at relatively low concentrations to minimize luminescence quenching. Here we describe a new class of upconversion nanocrystals adopting an orthorhombic crystallographic structure in which the lanthanide ions are distributed in arrays of tetrad clusters. Importantly, this unique arrangement enables the preservation of excitation energy within the sublattice domain and effectively minimizes the migration of excitation energy to defects, even in stoichiometric compounds with a high Yb3+ content (calculated as 98 mol%). This allows us to generate an unusual four-photon-promoted violet upconversion emission from Er3+ with an intensity that is more than eight times higher than previously reported. Our results highlight that the approach to enhancing upconversion through energy clustering at the sublattice level may provide new opportunities for light-triggered biological reactions and photodynamic therapy.

Photon up-conversion production in Tb{sup 3+}–Yb{sup 3+} co-doped CaF{sub 2} phosphors prepared by combustion synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br; Guimarães, Renato B.; Maciel, Glauco S., E-mail: glauco@if.uff.br

2016-02-15

Graphical abstract: Up-conversion luminescence from Tb{sup 3+} obtained by energy transfer from Yb{sup 3+} pairs in CaF{sub 2} powder prepared by combustion synthesis. - Highlights: • Calcium fluoride (CaF{sub 2}) powders were prepared by combustion synthesis. • Rare-earth ions doped in this material were found in interstitial sites. • Cooperative up-conversion was observed in Tb{sup 3+}:Yb{sup 3+}:CaF{sub 2} powder. • Energy transfer between Tb{sup 3+} and pairs of Yb{sup 3+} was analyzed using rate equations. - Abstract: Calcium fluoride (CaF{sub 2}) crystalline powders were successfully prepared by the combustion synthesis method. The powder material containing luminescent rare-earth ions, more specificallymore » terbium (Tb{sup 3+}) and ytterbium (Yb{sup 3+}), was studied by X-ray diffraction, scanning electronic microscopy and optical spectroscopy. These ions are allocated in charge compensated interstitial positions of tetragonal (C{sub 4v}) and trigonal (C{sub 3v}) symmetry sites of the cubic (O{sub h}) CaF{sub 2} lattice. Up-conversion (UC) luminescence in Tb{sup 3+} was achieved using a low power diode laser operating at 975 nm. Tb{sup 3+} is insensitive to near-infrared radiation but UC can be achieved via energy transfer from pairs of Yb{sup 3+} ions to Tb{sup 3+} ions. The UC luminescence dynamics of Tb{sup 3+} was used to study the energy transfer mechanism.« less

Surface modification of upconverting nanoparticles by layer-by-layer assembled polyelectrolytes and metal ions.

PubMed

Palo, Emilia; Salomäki, Mikko; Lastusaari, Mika

2017-12-15

Modificating and protecting the upconversion luminescence nanoparticles is important for their potential in various applications. In this work we demonstrate successful coating of the nanoparticles by a simple layer-by-layer method using negatively charged polyelectrolytes and neodymium ions. The layer fabrication conditions such as number of the bilayers, solution concentrations and selected polyelectrolytes were studied to find the most suitable conditions for the process. The bilayers were characterized and the presence of the desired components was studied and confirmed by various methods. In addition, the upconversion luminescence of the bilayered nanoparticles was studied to see the effect of the surface modification on the overall intensity. It was observed that with selected deposition concentrations the bilayer successfully shielded the particle resulting in stronger upconversion luminescence. The layer-by-layer method offers multiple possibilities to control the bilayer growth even further and thus gives promises that the use of upconverting nanoparticles in applications could become even easier with less modification steps in the future. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhanced performance of dye-sensitized solar cells based on TiO{sub 2} with NIR-absorption and visible upconversion luminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Li; Yulin, Yang, E-mail: ylyang@hit.edu.cn; Mi, Zhou

2013-02-15

TiO{sub 2} with NIR-absorption and visible upconversion luminescence (UC-TiO{sub 2}) is prepared by a sol-gel method and calcined at 700 Degree-Sign C for 6 h. The material broadens the response region of dye sensitized solar cells (DSSCs) from an ultraviolet-visible region to the whole region of the solar spectrum. It shifts NIR sunlight to visible light which matches the strong absorbing region of the dye (N719). DSSCs based on UC-TiO{sub 2} achieved higher conversion efficiency than that on raw TiO{sub 2}. UC-TiO{sub 2} was mixed with commercial raw TiO{sub 2} as additive, and the short-circuit current density, open-circuit voltage andmore » conversion efficiency of the DSSC reached to the optimum values 13.38 mA/cm{sup 2}, 0.78 V and 6.63% (AM1.5 global), comparing with the blank values: 7.99 mA/cm{sup 2}, 0.75 V and 4.07%, respectively. Also the mechanisms of upconversion by multiphoton absorption and energy transfer processes are interpreted in this paper. - Graphical abstract: By introducing TiO{sub 2} with NIR-absorption and visible up-conversion luminescence into DSSC, a signal reflection was explored from ultra-violet region to visible region, and to near-IR region. Highlights: Black-Right-Pointing-Pointer TiO{sub 2} with NIR-absorption and visible up-conversion luminescence (UC-TiO{sub 2}) was prepared by a sol-gel method. Black-Right-Pointing-Pointer A systematic characterization and analysis was carried out to discuss the mechanism. Black-Right-Pointing-Pointer A significantly enhanced performance of DSSC was explored by using UC-TiO{sub 2} as an additive.« less

[A study on the concentration quenching of Tm3+ upconversion luminescence].

PubMed

Chen, B; Wang, H; Huang, S

2001-06-01

In this work, we have a designation and preparation of MFT glasses for upconversion, the glasses consisted of TeO2 and fluoride: PbF2, AlF3, BaF2, NaF and the impurity Tm2O3. In this glass system the oxide improve forming ability, the fluorides improve the microscopic environment around RE ions in glasses. In this glass host the content of Tm2O3 achieves to 4% mol and crystallization no occurred. A detail study on the concentration quenching of upconversion luminescence for 1G4-->3H6 and 1D2-->3H4 transitions was completed. The experimental results directed that the quenching concentration was 0.6 mol.% and higher 3 times than in other glasses materials. The cross relaxation and mechanism of concentration quenching were discussed.

Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm(3+) and Yb(3+).

PubMed

Soares, M R N; Ferro, M; Costa, F M; Monteiro, T

2015-12-21

Lanthanide doped inorganic nanoparticles with upconversion luminescence are of utmost importance for biomedical applications, solid state lighting and photovoltaics. In this work we studied the downshifted luminescence, upconversion luminescence (UCL) and blackbody radiation of tetragonal yttrium stabilized zirconia co-doped with Tm(3+) and Yb(3+) single crystals and nanoparticles produced by laser floating zone and laser ablation in liquids, respectively. The photoluminescence (PL) and PL excitation (PLE) were investigated at room temperature (RT). PL spectra exhibit the characteristic lines in UV, blue/green, red and NIR regions of the Tm(3+) (4f(12)) under resonant excitation into the high energy (2S+1)LJ multiplets. Under NIR excitation (980 nm), the samples placed in air display an intense NIR at ∼800 nm due to the (1)G4→(3)H5/(3)H4→(3)H6 transitions. Additionally, red, blue/green and ultraviolet UCL is observed arising from higher excited (1)G4 and (1)D2 multiplets. The power excitation dependence of the UCL intensity indicated that 2-3 low energy absorbed photons are involved in the UCL for low power levels, while for high powers, the identified saturation is dependent on the material size with a enhanced effect on the NPs. The temperature dependence of the UCL was investigated for single crystals and targets used in the ablation. An overall increase of the integrated intensity was found to occur between 12 K and the RT. The thermally activated process is described by activation energies of 10 meV and 30 meV for single crystals and targets, respectively. For the NPs, the UCL was found to be strongly sensitive to pressure conditions. Under vacuum conditions, instead of the narrow lines of the Tm(3+), a wide blackbody radiation was detected, responsible for the change in the emission colour from blue to orange. This phenomenon is totally reversible when the NPs are placed at ambient pressure. The UCL/blackbody radiation in the nanosized material exhibits non-contact pressure colour-based sensor characteristics. Moreover, tuning the color of the blackbody radiation in the nanoparticles by harvesting the low energy photons into the visible spectral region was found to be possible by adjusting the excitation power, paving the way for further developments of these nanoparticles for lighting and photovoltaic applications.

Highly Efficient LiYF4:Yb(3+), Er(3+) Upconversion Single Crystal under Solar Cell Spectrum Excitation and Photovoltaic Application.

PubMed

Chen, Xu; Xu, Wen; Song, Hongwei; Chen, Cong; Xia, Haiping; Zhu, Yongsheng; Zhou, Donglei; Cui, Shaobo; Dai, Qilin; Zhang, Jiazhong

2016-04-13

Luminescent upconversion is a promising way to harvest near-infrared (NIR) sunlight and transforms it into visible light that can be directly absorbed by active materials of solar cells and improve their power conversion efficiency (PCE). However, it is still a great challenge to effectively improve the PCE of solar cells with the assistance of upconversion. In this work, we demonstrate the application of the transparent LiYF4:Yb(3+), Er(3+) single crystal as an independent luminescent upconverter to improve the PCE of perovskite solar cells. The LiYF4:Yb(3+), Er(3+) single crystal is prepared by an improved Bridgman method, and its internal quantum efficiency approached to 5.72% under 6.2 W cm(-2) 980 nm excitation. The power-dependent upconversion luminescence indicated that under the excitation of simulated sunlight the (4)F(9/2)-(4)I(15/2) red emission originally results from the cooperation of a 1540 nm photon and a 980 nm photon. Furthermore, when the single crystal is placed in front of the perovskite solar cells, the PCE is enhanced by 7.9% under the irradiation of simulated sunlight by 7-8 solar constants. This work implies the upconverter not only can serve as proof of principle for improving PCE of solar cells but also is helpful to practical application.

Photoluminescence of transparent glass-ceramics based on ZnO nanocrystals and co-doped with Eu3+, Yb3+ ions

NASA Astrophysics Data System (ADS)

Arzumanyan, Grigory M.; Kuznetsov, Evgeny A.; Zhilin, Aleksandr A.; Dymshits, Olga S.; Shemchuk, Daria V.; Alekseeva, Irina P.; Mudryi, Alexandr V.; Zhivulko, Vadim D.; Borodavchenko, Olga M.

2016-12-01

Glasses of the K2Osbnd ZnOsbnd Al2O3sbnd SiO2 system co-doped with Eu2O3 and Yb2O3 were prepared by the melt-quenching technique. Transparent zincite (ZnO) glass-ceramics were obtained by secondary heat-treatments at 680-860 °C. At 860 °C, traces of Eu oxyapatite appeared in addition to ZnO nanocrystals. The average crystal size obtained from the X-ray diffraction data was found to range between 14 and 35 nm. Absorption spectra of the initial glasses are composed of an absorption edge and absorption bands due to electronic transitions of Eu3+ ions. With heat-treatment, the absorption edge pronouncedly shifts to the visible spectral range. The luminescence properties of the glass and glass-ceramics were studied by measuring their excitation and emission spectra at 300, 78, and 4.2 K. Strong red emission of Eu3+ ions dominated by the 5D0-7F2 (612 nm) electric dipole transition was detected. Changes in the luminescence properties of the Eu3+-related excitation and emission bands were observed after heat-treatments at 680 °C and 860 °C. The ZnO nanocrystals showed both broad luminescence (400-850 nm) and free-exciton emission near 3.3 eV at room temperature. The upconversion luminescence spectrum of the initial glass was obtained under excitation of the 976 nm laser source.

Upconversion luminescence in BaMoO{sub 4}:Pr{sup 3+} phosphor for display devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soni, Abhishek Kumar; Rai, Vineet Kumar, E-mail: vineetkrrai@yahoo.co.in

2015-08-28

The frequency upconversion is an important nonlinear optical property by which near infrared light is converted into the visible light. The BaMoO{sub 4}:Pr{sup 3+} powder phosphor has been synthesized by solid state reaction method. The upconversion emission bands are recorded under the excitation of 808 nm diode laser. The phase formation of the prepared phosphor has been identified by powder X-ray diffraction (XRD) technique. The upconversion emission mechanism and colour coordinate have been explained by using energy level and CIE (International Commission on Illumination) chromaticity diagram study, respectively.

Multifunctional upconversion nanoparticles based on NaYGdF4 for laser induced heating, non-contact temperature sensing and controlled hyperthermia with use of pulsed periodic laser excitation

NASA Astrophysics Data System (ADS)

Pominova, Daria V.; Ryabova, Anastasia V.; Romanishkin, Igor D.; Grachev, Pavel V.; Burmistrov, Ivan A.; Kuznetsov, Sergei V.

2018-04-01

For clinical application in photothermal therapy the nanoparticles should be efficient light-to-heat converters and luminescent markers. In this work, we investigate upconversion nanoparticles with NaYxGd1-xF4 (x=0-1) host lattice as self-monitored thermo-agents for bioimaging and local laser hyperthermia with real-time temperature control. The ability of non-contact temperature sensing using NaYxGd1-xF4 on one hand and laser induced heating on the other hand was shown. It was found, that the heat conversion luminescence efficiency is strongly affected by the concentration ratio of Gd3+ to Y3+ ions in host lattice. The optimal composition among the studied is NaY0.4Gd0.4Yb0.17Er0.03 with luminescence efficiency of 3.5% under 1 W/cm2 pumping power. Higher Gd3+ concentrations lead to higher heating temperature, but also to the decrease of the luminescence intensity and the accuracy of the ratiometric temperature determination. It was also shown that the optimization of Yb3+ doping concentration is one of the possible ways for optimization of the conditions of laser induced photothermal effects. Experimental in vitro study of hyperthermia with use of upconversion nanoparticles on HeLa and C6 cell lines was performed. The investigated nanoparticles are capable of in vitro photothermal heating, luminescent localization and thermal sensing.

Synthesis of NaYF4:Yb/Er/Gd up-conversion luminescent nanoparticles and luminescence resonance energy transfer-based protein detection

PubMed Central

Zhang, Jingpu; Mi, Congcong; Wu, Hongyan; Huang, Huaiqing; Mao, Chuanbin; Xu, Shukun

2012-01-01

High-quality NaYF4:Yb/Er/Gd up-conversion nanoparticles (UCNPs) were first synthesized by a solvothermal method using rare earth stearate, sodium fluoride, ethanol, water, and oleic acid as precursors. Doped Gd3+ ions can promote the transition of NaYF4 from cubic to hexagonal phase, shorten the reaction time, and reduce the reaction temperature without reducing the luminescence intensity of NaYF4:Yb/Er UCNPs. X-ray diffraction, infrared spectroscopy, transmission electron microscopy, and luminescence spectroscopy were applied to characterize the UCNPs. The nanoparticles exhibited small size and excellent green up-conversion photoluminescence, making them suitable for biological applications. After the surfaces of NaYF4:Yb/Er/Gd UCNPs were modified with amino groups through the Stöber method, they could be brought close enough to the analytically important protein called R-phycoerythrin (R-PE) bearing multiple carboxyl groups so that energy transfer could occur. A luminescence resonance energy transfer (LRET) system was developed using NaYF4:Yb/Er/Gd UCNPs as an energy donor and R-PE as an energy acceptor. As a result, a detection limit of R-PE of 0.5 μg/ml was achieved by the LRET system with a relative standard deviation of 2.0%. Although this approach was first used successfully to detect R-PE, it can also be extended to the detection of other biological molecules. PMID:22155069

Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence† †Electronic supplementary information (ESI) available: General details, synthesis and spectroscopy data of new compounds. Experimental details on optical, chiroptical, electrochemical and on-surface measurements. Crystal data and structure refinement of compounds 1, and 6. Further details on theoretical calculations and Cartesian coordinates of computed structures. VT-H1NMR, 2D-NMR and HRMS spectra of 1. CCDC 1561552 and 1561553. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc00427g

PubMed Central

Cruz, Carlos M.; Márquez, Irene R.; Mariz, Inês F. A.; Blanco, Victor; Sánchez-Sánchez, Carlos; Sobrado, Jesús M.; Martín-Gago, José A.; Cuerva, Juan M.

2018-01-01

Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This system is shown to combine two-photon absorption and circularly polarized luminescence and a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity while the push–pull geometry and the extended network of sp2 carbons are factors favoring the nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results. PMID:29780523

Application of upconversion luminescent-magnetic microbeads with weak background noise and facile separation in ochratoxin A detection

NASA Astrophysics Data System (ADS)

Liao, Zhenyu; Zhang, Ying; Su, Lin; Chang, Jin; Wang, Hanjie

2017-02-01

Ochratoxin A (OTA), the most harmful and abundant ochratoxin, is chemically stable and commonly existed in foodstuffs. In this work, upconversion luminescent-magnetic microbeads (UCLMMs) -based cytometric bead array for OTA detection with a less reagent consumption and high sensitivity has been established and optimized. In UCLMMs, upconversion nanocrystals (UCNs) for optical code present a weak background noise and no spectral cross talk between the encoding signals and target labels under two excitation conditions to improve detection sensitivity. While the superparamagnetic Fe3O4 nanoparticles (Fe3O4 NPs) aim for rapid analysis. The results show that the developed method has a sensitivity of 9.553 ppt below HPLC with a 50-μL sample and can be completed in <2 h with good accuracy and high reproducibility. Therefore, different colors of UCLMMs will become a promising assay platform for multiple mycotoxins after further improvement.

Dye-Sensitized Core/Active Shell Upconversion Nanoparticles for Optogenetics and Bioimaging Applications

DOE PAGES

Wu, Xiang; Zhang, Yuanwei; Takle, Kendra; ...

2016-01-06

A near-infrared (NIR) dye-sensitized upconversion nanoparticles (UCNPs) can broaden the absorption range and boost upconversion efficiency of UCNPs. We achieved significantly enhanced upconversion luminescence in dye-sensitized core/active shell UCNPs via the doping of ytterbium ions (Yb 3+ ) in the UCNP shell, which bridged the energy transfer from the dye to the UCNP core. As a result, we synergized the two most practical upconversion booster effectors (dye-sensitizing and core/shell enhancement) to amplify upconversion efficiency. We also demonstrated two biomedical applications using these UCNPs. By using dye-sensitized core/active shell UCNP embedded poly(methyl methacrylate) polymer implantable systems, we successfully shifted the optogeneticmore » neuron excitation window to a biocompatible and deep tissue penetrable 800 nm wavelength. Furthermore, UCNPs were water-solubilized with Pluronic F127 with high upconversion efficiency and can be imaged in a mouse model.« less

Investigating the evolution of local structure around Er and Yb in ZnO:Er and ZnO:Er, Yb on annealing using X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Anjana, R.; Jayaraj, M. K.; Yadav, A. K.; Jha, S. N.; Bhattacharyya, D.

2018-04-01

The local structure around Er and Yb centre in ZnO favouring upconversion luminescence was studied using EXAFS (Extended X-ray absorption fine structure spectroscopy). Due to the ionic radii difference between Zn and Er, Yb ions, the dopants cannot replace Zn in the ZnO lattice properly. Er2O3 and Yb2O3 impurity phases are formed at the grain boundaries of ZnO. It is found that the local structure around the Er centre in ZnO is modified on annealing in air. The symmetry around both erbium and ytterbium reduces with increase in annealing temperature. Symmetry reduction will favour the intra-4f transition and the energy transitions causing upconversion luminescence. By fitting the EXAFS data with theoretically simulated data, it is found that the Er centre forms a local structure similar to C4ν symmetry which is a distorted octahedron. On annealing the sample to 1200 °C, all the erbium centres are transformed to C4ν symmetry causing enhanced upconversion emission. Yb centre has also been modified on annealing. The decrease in co-ordination number with annealing temperature will decrease the symmetry and increase the near infrared absorption cross section. The decrease in symmetry around both the erbium and ytterbium centre and formation of C4ν symmetry around Er centre is the reason behind the activation of upconversion luminescence with high temperature annealing in both Er doped and Er, Yb co-doped ZnO samples. The study will be useful for the synthesis of high efficiency upconversion materials.

The laser-diode-excited 5 d-4 f luminescence of Ce3+ and Pr3+ ions embedded into a BaR2F8 matrix

NASA Astrophysics Data System (ADS)

Pushkar', A. A.; Uvarova, T. V.; Kozlova, N. S.; Kuznetsov, S. Yu.; Uvarova, A. G.

2013-06-01

We show the possibility of obtaining UV luminescence from 5 d-4 f transitions of rare-earth ions in the BaY2F8: (Yb3+, Pr3+, Ce3+) crystal under upconversion excitation by standard laser diodes with lasing wavelengths of 960, 808, and 840 nm. Various upconversion mechanisms of pumping for populating the higher-lying energy levels of the active ions, as well as methods of adaptation of the active medium BaY2F8: (Yb3+, Pr3+, Ce3+) to these mechanisms, are considered.

Luminescence resonance energy transfer (LRET) aptasensor for ochratoxin A detection using upconversion nanoparticles

NASA Astrophysics Data System (ADS)

Jo, Eun-Jung; Byun, Ju-Young; Mun, Hyoyoung; Kim, Min-Gon

2017-07-01

We report an aptasensor for homogeneous ochratoxin A (OTA) detection based on luminescence resonance energy transfer (LRET). This system uses upconversion nanoparticles (UCNPs), such as NaYF4:Yb3+, Er 3+, as the donor. The aptamer includes the optimum-length linker (5-mer-length DNA) and OTA-specific aptamer sequences. Black hole quencher 1 (BHQ1), as the acceptor, was modified at the 3' end of the aptamer sequence. BHQ1 plays as a quencher in LRET aptasensor and shows absorption at 543 nm, which overlaps with well the emission of the UCNPs. When OTA is added, the BHQ1-labeled OTA aptamer was folded due to the formation of the G-quadruplex-OTA complex, which induced the BHQ1 close to the UCNPs. Consequently, resonance energy transfer between UCNPs (donor) and BHQ1 (acceptor) enables quenching of upconversion luminescence signals under laser irradiation of 980 nm. Our results showed that the LRET-based aptasensor allows specific OTA analysis with a limit of detection of 0.03 ng/mL. These results demonstrated that the OTA in diverse foods can be detected specifically and sensitively in a homogeneous manner.

Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence.

PubMed

Cruz, Carlos M; Márquez, Irene R; Mariz, Inês F A; Blanco, Victor; Sánchez-Sánchez, Carlos; Sobrado, Jesús M; Martín-Gago, José A; Cuerva, Juan M; Maçôas, Ermelinda; Campaña, Araceli G

2018-04-28

Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This system is shown to combine two-photon absorption and circularly polarized luminescence and a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity while the push-pull geometry and the extended network of sp 2 carbons are factors favoring the nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results.

Near-infrared-to-near-infrared down-shifting and upconversion luminescence of KY{sub 3}F{sub 10} with single dopant of Nd{sup 3+} ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Huihong; State Key Laboratory of Luminescence Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641; Yu, Ting

2016-01-25

We have studied the structural and near-infrared (NIR) luminescent properties of KY{sub 3}F{sub 10} phosphors, singly doped with Nd{sup 3+} serving as both sensitizer and activator. With a single laser diode at the wavelength of 808 nm as a pump source, simultaneous NIR-to-NIR upconversion (UC) and down-shifting (DS) emissions are effectively achieved, due to the specific energy levels of Nd{sup 3+} dopant and the low phonon energy of the host. The luminescence mechanism related to energy transfer is discussed. The luminescence can be modulated through controlling the population of Nd{sup 3+}:{sup 4}F{sub 3/2} state in our experiment. Interestingly, both UC andmore » DS emissions of the material fall within the dual biological window, suggesting that the prepared phosphors have potential applications in the bioimaging field.« less

Detection of early primary colorectal cancer with upconversion luminescent NP-based molecular probes

NASA Astrophysics Data System (ADS)

Liu, Chunyan; Qi, Yifei; Qiao, Ruirui; Hou, Yi; Chan, Kaying; Li, Ziqian; Huang, Jiayi; Jing, Lihong; Du, Jun; Gao, Mingyuan

2016-06-01

Early detection and diagnosis of cancers is extremely beneficial for improving the survival rate of cancer patients and molecular imaging techniques are believed to be relevant for offering clinical solutions. Towards early cancer detection, we developed a primary animal colorectal cancer model and constructed a tumor-specific imaging probe by using biocompatible NaGdF4:Yb,Er@NaGdF4 upconversion luminescent NPs for establishing a sensitive early tumor imaging method. The primary animal tumor model, which can better mimic the human colorectal cancer, was built upon continual administration of 1,2-dimethylhydrazine in Kunming mice and the tumor development was carefully monitored through histopathological and immunohistochemical analyses to reveal the pathophysiological processes and molecular features of the cancer microenvironment. The upconversion imaging probe was constructed through covalent coupling of PEGylated core-shell NPs with folic acid whose receptor is highly expressed in the primary tumors. Upon 980 nm laser excitation, the primary colorectal tumors in the complex abdominal environment were sensitively imaged owing to the ultralow background of the upconversion luminescence and the high tumor-targeting specificity of the nanoprobe. We believe that the current studies provide a highly effective and potential approach for early colorectal cancer diagnosis and tumor surgical navigation.Early detection and diagnosis of cancers is extremely beneficial for improving the survival rate of cancer patients and molecular imaging techniques are believed to be relevant for offering clinical solutions. Towards early cancer detection, we developed a primary animal colorectal cancer model and constructed a tumor-specific imaging probe by using biocompatible NaGdF4:Yb,Er@NaGdF4 upconversion luminescent NPs for establishing a sensitive early tumor imaging method. The primary animal tumor model, which can better mimic the human colorectal cancer, was built upon continual administration of 1,2-dimethylhydrazine in Kunming mice and the tumor development was carefully monitored through histopathological and immunohistochemical analyses to reveal the pathophysiological processes and molecular features of the cancer microenvironment. The upconversion imaging probe was constructed through covalent coupling of PEGylated core-shell NPs with folic acid whose receptor is highly expressed in the primary tumors. Upon 980 nm laser excitation, the primary colorectal tumors in the complex abdominal environment were sensitively imaged owing to the ultralow background of the upconversion luminescence and the high tumor-targeting specificity of the nanoprobe. We believe that the current studies provide a highly effective and potential approach for early colorectal cancer diagnosis and tumor surgical navigation. Electronic supplementary information (ESI) available: (1) Molecular structure of Jeffamine-modified FA; (2) immunohistochemical analysis of FR expression in the colorectal tissue derived from mice treated with NaCl at different weeks; (3) biodistributions of probes of NP-FA and NP-IgG in the main organs of mice. See DOI: 10.1039/c5nr07858j

Near-infrared photocatalysts of BiVO4/CaF2:Er3+, Tm3+, Yb3+ with enhanced upconversion properties

NASA Astrophysics Data System (ADS)

Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Gu, Lin; Miao, Chen; Yuan, Haiping; Shan, Aidang

2014-01-01

Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO).Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO). Electronic supplementary information (ESI) available: Additional tables and figures. See DOI: 10.1039/c3nr05266d

High efficiency upconversion nanophosphors for high-contrast bioimaging

NASA Astrophysics Data System (ADS)

Alkahtani, Masfer H.; Alghannam, Fahad S.; Sanchez, Carlos; Gomes, Carmen L.; Liang, Hong; Hemmer, Philip R.

2016-12-01

Upconversion nanoparticles (UCNPs) are of interest because they allow suppression of tissue autofluorescence and are therefore visible deep inside biological tissue. Compared to upconversion dyes, UCNPs have a lower pump intensity threshold, better photostability, and less toxicity. Recently, YVO4: Er+3, Yb+3 nanoparticles were shown to exhibit strong up-conversion luminescence with a relatively low 10 kW cm-2 excitation intensity even in water, which makes them excellent bio-imaging candidates. Herein, we investigate their use as internal probes in insects by injecting YVO4 : Er+3, Yb+3 nanoparticles into fire ants as a biological model, and obtain 2D optical images with 980 nm illumination. High-contrast images with high signal-to-noise ratio are observed by detecting the up-conversion fluorescence as the excitation laser is scanned.

Upconversion excitations in Pr3+-doped BaY2F8 crystal

NASA Astrophysics Data System (ADS)

Piramidowicz, R.; Mahiou, R.; Boutinaud, P.; Malinowski, M.

2011-09-01

We report the orange-to-blue and infrared-(IR)-to-blue wavelengths upconversion luminescence in Pr3+:BaY2F8 crystals. Mechanism of the orange light upconversion into blue 3P0 state emission was confirmed to be energy transfer between two Pr3+ ions in the 1D2 state. IR-to-blue upconversion has only been observed under two different color IR pumping. The first resonant step was the 3H4→1G4 ground state absorption transition, and the second resonant transition was the excited state absorption from the 1G4 to 1I6 and 3PJ levels. A comparison of the efficiency of the IR-to-blue upconversion in several praseodymium activated host is presented and discussed. A model of the IR pumped upconversion praseodymium blue laser is presented and the population inversion conditions are calculated.

Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics tuneable up-conversion phosphor

NASA Astrophysics Data System (ADS)

Méndez-Ramos, J.; Rodriguez, V. D.; Tikhomirov, V. K.; Del-Castillo, J.; Yanes, A. C.

2008-08-01

Transparent Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics have been prepared, 32(SiO{2}) 9(AlO{1.5}) 31.5(CdF{2}) 18.5(PbF{2}) 5.5(ZnF{2}): 3.5(Yb-Er-TmF{3}) mol%, where the co-dopants partition mostly to the fluoride PbF{2}-based nano-crystals. A comparative study of the up-conversion luminescence in nano-glass-ceramics and its precursor glass indicates that these materials can be used as blue/green/red tuneable up-conversion phosphor, in particular for white light generation. A ratio between blue, green and red emission bands of the Tm3+ and Er3+ can be widely varied with nano-ceramming of the precursor glass and with changing a pump power of luminescence. The change in the ratio between the blue, green and red emission bands is explained to be due to substantial lowering phonon energy and shortening of inter-dopant distances with nano-ceramming of the precursor glass and due to change in the ratio of 2- and 3-photon up-conversion processes with pump power.

Structural morphology, upconversion luminescence and optical thermometric sensing behavior of Y2O3:Er(3+)/Yb(3+) nano-crystalline phosphor.

PubMed

Joshi, C; Dwivedi, A; Rai, S B

2014-08-14

Infrared-to-visible upconverting rare earths Er(3+)/Yb(3+) co-doped Y2O3 nano-crystalline phosphor samples have been prepared by solution combustion method followed by post-heat treatment at higher temperatures. A slight increase in average crystallite size has been found on calcinations verified by X-ray analysis. Transmission electron microscopy (TEM) confirms the nano-crystalline nature of the as-prepared and calcinated samples. Fourier transform infrared (FTIR) analysis shows the structural changes in as-prepared and calcinated samples. Upconversion and downconversion emission recorded using 976 and 532 nm laser sources clearly demonstrates a better luminescence properties in the calcinated samples as compared to as-prepared sample. Upconversion emission has been quantified in terms of standard chromaticity diagram (CIE) showing a shift in overall upconversion emission of as-prepared and calcinated samples. Temperature sensing behaviour of this material has also been investigated by measurement of fluorescence intensity ratio (FIR) of various signals in green emission in the temperature range of 315 to 555 K under 976 nm laser excitation. Copyright © 2014 Elsevier B.V. All rights reserved.

Excitonic luminescence upconversion in a two-dimensional semiconductor

DOE PAGES

Jones, Aaron M.; Yu, Hongyi; Schaibley, John R.; ...

2015-12-21

Photon upconversion is an elementary light-matter interaction process in which an absorbed photon is re-emitted at higher frequency after extracting energy from the medium. Furthermore, this phenomenon lies at the heart of optical refrigeration in solids(1), where upconversion relies on anti-Stokes processes enabled either by rare-earth impurities(2) or exciton-phonon coupling(3). We demonstrate a luminescence upconversion process from a negatively charged exciton to a neutral exciton resonance in monolayer WSe2, producing spontaneous anti-Stokes emission with an energy gain of 30 meV. Polarization-resolved measurements find this process to be valley selective, unique to monolayer semiconductors(4). Since the charged exciton binding energy(5) closelymore » matches the 31 meV A(1)' optical phonon(6-9), we ascribe the spontaneous excitonic anti-Stokes to doubly resonant Raman scattering, where the incident and outgoing photons are in resonance with the charged and neutral excitons, respectively. Additionally, we resolve a charged exciton doublet with a 7 meV splitting, probably induced by exchange interactions, and show that anti-Stokes scattering is efficient only when exciting the doublet peak resonant with the phonon, further confirming the excitonic doubly resonant picture.« less

Synthesis and application of nanohybrids based on upconverting nanoparticles and polymers.

PubMed

Cheng, Ziyong; Lin, Jun

2015-05-01

Lanthanide-doped upconversion nanoparticles (UCNPs) have been an emerging and exciting research field in recent years due to their unique luminescent properties of converting near-infrared light to shorter wavelength radiation. UCNPs offer excellent prospects in luminescent labeling, displays, bioimaging, bioassays, drug delivery, sensors, and anticounterfeiting applications. Along with the abundant studies and rapid progress in this area, UCNPs are promising to be a new class of luminescent probe owing to their special advantages over the conventional organic dyes and quantum dots. Among them, polymers play an important role to improve properties or endow new function of UCNPs such as for matrix materials, water solubility, linking active targeting molecules, biocompatibility, and stimuli-responsive behavior. This article briefly reviews the compositions, optical mechanisms, architectures of upconversion nanocrystals and highlights the works on various functional UCNPs/polymer nanohybrids as well as many new interesting fruits in applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upconversion in solar cells

PubMed Central

2013-01-01

The possibility to tune chemical and physical properties in nanosized materials has a strong impact on a variety of technologies, including photovoltaics. One of the prominent research areas of nanomaterials for photovoltaics involves spectral conversion. Modification of the spectrum requires down- and/or upconversion or downshifting of the spectrum, meaning that the energy of photons is modified to either lower (down) or higher (up) energy. Nanostructures such as quantum dots, luminescent dye molecules, and lanthanide-doped glasses are capable of absorbing photons at a certain wavelength and emitting photons at a different (shorter or longer) wavelength. We will discuss upconversion by lanthanide compounds in various host materials and will further demonstrate upconversion to work for thin-film silicon solar cells. PMID:23413889

Photoluminescence upconversion at GaAs /InGa P2 interfaces driven by a sequential two-photon absorption mechanism

NASA Astrophysics Data System (ADS)

Hylton, N. P.; Hinrichsen, T. F.; Vaquero-Stainer, A. R.; Yoshida, M.; Pusch, A.; Hopkinson, M.; Hess, O.; Phillips, C. C.; Ekins-Daukes, N. J.

2016-06-01

This paper reports on the results of an investigation into the nature of photoluminescence upconversion at GaAs /InGa P2 interfaces. Using a dual-beam excitation experiment, we demonstrate that the upconversion in our sample proceeds via a sequential two-photon optical absorption mechanism. Measurements of photoluminescence and upconversion photoluminescence revealed evidence of the spatial localization of carriers in the InGa P2 material, arising from partial ordering of the InGa P2 . We also observed the excitation of a two-dimensional electron gas at the GaAs /InGa P2 heterojunction that manifests as a high-energy shoulder in the GaAs photoluminescence spectrum. Furthermore, the results of upconversion photoluminescence excitation spectroscopy demonstrate that the photon energy onset of upconversion luminescence coincides with the energy of the two-dimensional electron gas at the GaAs /InGa P2 interface, suggesting that charge accumulation at the interface can play a crucial role in the upconversion process.

Controllable red, green, blue (RGB) and bright white upconversion luminescence of Lu2O3:Yb3+/Er3+/Tm3+ nanocrystals through single laser excitation at 980 nm.

PubMed

Yang, Jun; Zhang, Cuimiao; Peng, Chong; Li, Chunxia; Wang, Lili; Chai, Ruitao; Lin, Jun

2009-01-01

Light fantastic! Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals with controllable red, green, blue (RGB) and bright white upconversion luminescence by a single laser excitation of 980 nm have been successfully synthesized (see picture). Due to abundant UC PL colors, it can potentially be used as fluorophores in the field of color displays, back light, UC lasers, photonics, and biomedicine.Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals have been successfully synthesized by a solvothermal process followed by a subsequent heat treatment at 800 degrees C. Powder X-ray diffraction, transmission electron microscopy, upconversion photoluminescence spectra, and kinetic decay were used to characterize the samples. Under single-wavelength diode laser excitation of 980 nm, the bright blue emissions of Lu(2)O(3):Yb(3+), Tm(3+) nanocrystals near 477 and 490 nm were observed due to the (1)G(4)-->(3)H(6) transition of Tm(3+). The bright green UC emissions of Lu(2)O(3):Er(3+) nanocrystals appeared near 540 and 565 nm were observed and assigned to the (2)H(11/2)-->(4)I(15/2) and (4)S(3/2)-->(4)I(15/2) transitions, respectively, of Er(3+). The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of concentration of Yb(3+) in Lu(2)O(3):Er(3+) nanocrystals. In sufficient quantities of Yb(3+) with resprct to Er(3+), the bright red UC emission of Lu(2)O(3):Yb(3+)/Er(3+) centered at 662 nm was predominant, due to the (4)F(9/2)-->(4)I(15/2) transition of Er(3+). Based on the generation of red, green, and blue emissions in the different doped Lu(2)O(3):RE(3+) nanocrystals, it is possible to produce the luminescence with a wide spectrum of colors, including white, by the appropriate doping of Yb(3+), Tm(3+), and Er(3+) in the present Lu(2)O(3) nanocrystals. Namely, Lu(2)O(3):3 %Yb(3+)/0.2 %Tm(3+)/0.4 %Er(3+) nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light with CIE-x=0.3456 and CIE-y=0.3179, which is very close to the standard equal energy white light illuminate (x=0.33, y=0.33). Because of abundant luminescent colors from RGB to white in Lu(2)O(3):Yb(3+)/Er(3+)/Tm(3+) nanocrystals under 980 nm laser diode (LD) excitation, they can potentially be used as fluorophores in the field of color displays, back light, UC lasers, photonics, and biomedicine.

Er-doped lead borate glasses and transparent glass ceramics for near-infrared luminescence and up-conversion applications.

PubMed

Pisarski, Wojciech A; Goryczka, Tomasz; Pisarska, Joanna; Ryba-Romanowski, Witold

2007-03-15

Lead borate based glasses have been analyzed using Raman and infrared spectroscopy. The formation of different borate groups and the direction of BO3 <--> BO4 conversion strongly depends on the PbO- and/or PbF2-to-B2O3 ratio in chemical composition. PbF2-PbO-B2O3 based glasses containing Er3+ ions have been studied after annealing. The orthorhombic PbF2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence at 1530 nm and green up-conversion at 545 nm have been registered for samples before and after annealing. The luminescence bands correspond to 4I13/2-4I15/2 and 4S3/2-4I15/2 transitions of Er3+ ions, respectively. In comparison to the precursor glasses, the luminescence intensities are higher in the studied transparent oxyfluoride glass ceramics. Simultaneously, the half-width of the luminescence lines slightly decreases. It can be the evidence that a small amount of the Er3+ ions is incorporated into the orthorhombic PbF2 phase.

Clean synthesis of YOF:Er3+, Yb3+ upconversion colloidal nanoparticles in water through liquid phase pulsed laser ablation for imaging applications

NASA Astrophysics Data System (ADS)

Anjana, R.; Kurias, K. M.; Jayaraj, M. K.

2017-10-01

Upconversion luminescent nanomaterials have great outlook towards imaging applications. These materials have high chemical and thermal stability, low auto fluorescence, high photo stability and IR excitation does not cause photo damage to living cells and penetrate deeply into tissue. Most of the reported nanoparticles are synthesized through chemical methods in which surface modification is needed for dispersing nanoparticles in water. In this paper we report clean and simple synthesis of upconversion luminescent yttrium oxyfluoride (YOF) nanoparticles through laser ablation in deionized water. YOF:Er3+, Yb3+ pellets were used for ablation. Er3+ is the emission centre Yb3+ is the sensitizer. Obtained colloidal solution is transparent to day light and showing red emission on exciting with 980 nm IR laser. By controlling ablation parameters particles of size less than 10 nm dispersed uniformly in water can be obtained through this surfactant free method. The synthesized nanoparticles can be used for cell imaging.

Oligonucleotide Sensor Based on Selective Capture of Upconversion Nanoparticles Triggered by Target-Induced DNA Interstrand Ligand Reaction

PubMed Central

2017-01-01

We present a sensor that exploits the phenomenon of upconversion luminescence to detect the presence of specific sequences of small oligonucleotides such as miRNAs among others. The sensor is based on NaYF4:Yb,Er@SiO2 nanoparticles functionalized with ssDNA that contain azide groups on the 3′ ends. In the presence of a target sequence, interstrand ligation is possible via the click-reaction between one azide of the upconversion probe and a DBCO-ssDNA-biotin probe present in the solution. As a result of this specific and selective process, biotin is covalently attached to the surface of the upconversion nanoparticles. The presence of biotin on the surface of the nanoparticles allows their selective capture on a streptavidin-coated support, giving a luminescent signal proportional to the amount of target strands present in the test samples. With the aim of studying the analytical properties of the sensor, total RNA samples were extracted from healthy mosquitoes and were spiked-in with a specific target sequence at different concentrations. The result of these experiments revealed that the sensor was able to detect 10–17 moles per well (100 fM) of the target sequence in mixtures containing 100 ng of total RNA per well. A similar limit of detection was found for spiked human serum samples, demonstrating the suitability of the sensor for detecting specific sequences of small oligonucleotides under real conditions. In contrast, in the presence of noncomplementary sequences or sequences having mismatches, the luminescent signal was negligible or conspicuously reduced. PMID:28332400

Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core-shell nanoparticles for biomedical imaging

NASA Astrophysics Data System (ADS)

Kamińska, Izabela; Elbaum, Danek; Sikora, Bożena; Kowalik, Przemysław; Mikulski, Jakub; Felcyn, Zofia; Samol, Piotr; Wojciechowski, Tomasz; Minikayev, Roman; Paszkowicz, Wojciech; Zaleszczyk, Wojciech; Szewczyk, Maciej; Konopka, Anna; Gruzeł, Grzegorz; Pawlyta, Mirosława; Donten, Mikołaj; Ciszak, Kamil; Zajdel, Karolina; Frontczak-Baniewicz, Małgorzata; Stępień, Piotr; Łapiński, Mariusz; Wilczyński, Grzegorz; Fronc, Krzysztof

2018-01-01

Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core-shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core-shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+-{{{{MoO}}}4}2- (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core-shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.

Two-photon absorption and upconversion luminescence of colloidal CsPbX3 quantum dots

NASA Astrophysics Data System (ADS)

Han, Qiuju; Wu, Wenzhi; Liu, Weilong; Yang, Qingxin; Yang, Yanqiang

2018-01-01

The nonlinear optical and the upconversion luminescence (UCL) properties of CsPbX3 (X = Br or its binary mixtures with Cl, I) quantum dots (QDs) are investigated by femtosecond open-aperture (OA) Z-scan and time-resolved luminescence techniques in nonresonant spectral region. The OA Z-scan results show that CsPbX3 QDs have strong reverse saturable absorption (RSA), which is ascribed to two-photon absorption. Partially changing halide composition from Cl to Br, to I, two-photon absorption cross sections become larger at the same laser excitation intensity. The composition-tunable nonlinear absorption should be attributed to the gradual decrease of the lowest direct band gaps with the halide substitute. Moreover, the strong UCL can be observed under near infrared femtosecond laser excitation. Halide composition-tunable UCL dynamics of CsPbX3 QDs is analyzed by use of two-exponential fitting with deconvolution. When CsPbX3 QDs have similar sizes (10-13 nm), with partially changing halide composition from Cl to Br, to I, the average UCL lifetime becomes longer due to the variation of Kane energy. Our findings suggest all-inorganic perovskite QDs can be used as excellent gain medium for high-performance frequency-upconversion lasers and provide reference to engineer such QDs toward practical optoelectronic applications.

PEGylated NaLuF4: Yb/Er upconversion nanophosphors for in vivo synergistic fluorescence/X-ray bioimaging and long-lasting, real-time tracking.

PubMed

Yi, Zhigao; Lu, Wei; Xu, Yaru; Yang, Jing; Deng, Li; Qian, Chao; Zeng, Tianmei; Wang, Haibo; Rao, Ling; Liu, Hongrong; Zeng, Songjun

2014-12-01

Simultaneous in vivo luminescence and X-ray bioimaging in a tissue or animal integrates the advantages of each single-modal imaging technology, and will find widespread application in biological and clinical fields. However, synergistic dual-modal bioimaging that utilizes a new generation of upconversion nanoprobes is still limited. In addition, investigations concentrated on in vivo biodistribution of these nanoprobes may contribute to diagnosis and treatment, but long-term in vivo tracking based on these nanoprobes is rarely reported. In this work, water-soluble NaLuF4: Yb/Er nanophosphors were prepared through modified one-pot simultaneous synthesis and surface modification method. Owing to the outstanding upconverting emissions and large X-ray absorption coefficient/K-edge value of Lu and doped Yb ions, the obtained nanoprobes were successfully used as luminescent nanoprobes and X-ray contrast agents for in vivo synergistic upconversion luminescence and X-ray bioimaging. The in vivo biodistribution of these nanoprobes were observed, and the results based on long-term tracking reveal that the as-prepared nanoprobes first aggregated in the lung of the mouse, transferred to the liver, and finally moved to the spleen. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recent Advances of Rare-Earth Ion Doped Luminescent Nanomaterials in Perovskite Solar Cells.

PubMed

Qiao, Yu; Li, Shuhan; Liu, Wenhui; Ran, Meiqing; Lu, Haifei; Yang, Yingping

2018-01-15

Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand the range of absorption spectra and improve the stability due to its upconversion and downconversion effect. This article reviews recent progress in using RE-ion-doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cells. Finally, we discuss the challenges facing the effective use of RE-ion-doped nanomaterials in perovskite solar cells and present some prospects for future research.

Up-conversion luminescence properties and energy transfer of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Jing; Mei, Lefu, E-mail: mlf@cugb.edu.cn; Deng, Junru

2015-11-15

Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} up-conversion (UC) phosphors were successfully synthesized by high temperature solid-state reaction method. The X-ray diffraction (XRD) results show that synthesized phosphor co-doped with 0.75% Tm/10% Yb has the optimum pure phase of BaLa{sub 2}ZnO{sub 5} among different co-doping concentrations. The structure of BaLa{sub 2}ZnO{sub 5}:0.75% Tm/10% Yb phosphor was refined by the Rietveld method and results show the decreased unit cell parameters and cell volume after doping Tm{sup 3+}/Yb{sup 3+}, indicating that Tm{sup 3+}/Yb{sup 3+} have successfully replaced La{sup 3+}. Under excitation at 980 nm, Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} phosphorsmore » present bright blue emission near 478 nm generated by the {sup 1}G{sub 4}→{sup 3}H{sub 6} transition and weak red emissions around 653 nm and 692 nm generated by the {sup 1}G{sub 4}→{sup 3}F{sub 4} and {sup 3}F{sub 3}→{sup 3}H{sub 6} transitions of Tm{sup 3+}, respectively. The UC luminescence properties of BaLa{sub 2}ZnO{sub 5} phosphors co-doped with different Tm{sup 3+}/Yb{sup 3+} concentrations were investigated, and the related UC mechanisms of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} depending on pump power were studied in detail. - Graphical abstract: Up-conversion luminescence of BaLa{sub 2}ZnO{sub 5}:Tm{sup 3+}/Yb{sup 3+} and its crystal structure and up-conversion mechanisms. - Highlights: • Up-conversion phosphors BaLa{sub 2}ZnO{sub 5} co-doped with Tm{sup 3+}/Yb{sup 3+} were synthesized by high temperature solid-state reaction method. • The crystal structure of BaLa{sub 2}ZnO{sub 5} and the changes of cell parameters and volume of BaLa{sub 2}ZnO{sub 5} after doping Tm{sup 3+} and Yb{sup 3+} have been discussed. • Up-conversion luminescence properties and energy transfer between Tm{sup 3+} and Yb{sup 3+} in BaLa{sub 2}ZnO{sub 5} have been discussed in detail.« less

Synthesis and up-conversion luminescence of Er{sup 3+} and Y b{sup 3+} codoped nanocrystalline tetra- (KLaP{sub 4}O{sub 12}) and pentaphosphates (LaP{sub 5}O{sub 14})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marciniak, L., E-mail: l.marciniak@int.pan.wroc.pl; Stefanski, M.; Tomala, R.

2015-09-07

The up-converting nanocrystals of KLa{sub 0.95}Er{sub 0.05}Y b{sub x}P{sub 4}O{sub 12} and La{sub 0.95−x}Er{sub 0.05}Y b{sub x}P{sub 5}O{sub 14} were prepared using co-precipitation method. The spectroscopic properties of these materials were investigated in a function of Y b{sup 3+} concentration. The up-conversion emission, power dependence of emission intensities, and the luminescence decay times were investigated. It was found that the green to red and {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2} to {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} emission intensity ratio were strongly affected by the Y b{sup 3+} concentration. Moreover, the order of up-conversion emission and threshold powermore » rises up with Y b{sup 3+} concentration for {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transition. The luminescence decay time of the {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} emission increases with Y b{sup 3+} concentration while the {sup 4}F{sub 9/2} → {sup 4}I{sub 15/2} emission is independent of dopant concentration. The influence of the Y b{sup 3+} concentration on the up-conversion emission intensities was discussed in terms of concentration dependent hetero looped photon avalanche process. A comparison of the up-conversion properties of KLa{sub 0.95}Er{sub 0.05}Y b{sub x}P{sub 4}O{sub 12} and La{sub 0.95−x}Er{sub 0.05}Y b{sub x}P{sub 5}O{sub 14} nanocrystals was presented.« less

Strong upconversion from Er3Al5O12 ceramic powders prepared by low temperature direct combustion synthesis

NASA Astrophysics Data System (ADS)

Maciel, Glauco S.; Rakov, Nikifor; Fokine, Michael; Carvalho, Isabel C. S.; Pinheiro, Carlos B.

2006-08-01

Crystalline ceramic powders of Er3Al5O12 were obtained by low temperature direct combustion synthesis. Irradiating the sample with a low-power continuous-wave infrared (1.48μm) diode laser led to ultraviolet, violet, blue, green, and red (380, 410, 456, 495, 525, 550, and 660nm) emissions. The strong upconversion luminescence appeared to the eyes as an intense green color. The presence of efficient four- and three-photon frequency upconversion processes makes this material an excellent candidate for use in photonic devices based on upconverter phosphors.

Advances in highly doped upconversion nanoparticles.

PubMed

Wen, Shihui; Zhou, Jiajia; Zheng, Kezhi; Bednarkiewicz, Artur; Liu, Xiaogang; Jin, Dayong

2018-06-20

Lanthanide-doped upconversion nanoparticles (UCNPs) are capable of converting near-infra-red excitation into visible and ultraviolet emission. Their unique optical properties have advanced a broad range of applications, such as fluorescent microscopy, deep-tissue bioimaging, nanomedicine, optogenetics, security labelling and volumetric display. However, the constraint of concentration quenching on upconversion luminescence has hampered the nanoscience community to develop bright UCNPs with a large number of dopants. This review surveys recent advances in developing highly doped UCNPs, highlights the strategies that bypass the concentration quenching effect, and discusses new optical properties as well as emerging applications enabled by these nanoparticles.

[Multiply upconversion emission in oxyfluoride ceramics].

PubMed

Xiao, Si-guo; Yang, Xiao-liang; Liu, Zhen-wei

2003-02-01

Oxyfluoride ceramics with the host composition of SiO2 and PbF2 have been prepared. X-ray diffraction analysis of the ceramics revealed that fluoride type beta-PbF2 solid solution regions are precipitated in the glass matrix. Rare earth ions in the beta-PbF2 solid solution show highly efficient upconversion performance due to the very small multi-phonon relaxation rates. Eight upconversion emission bands whose central wavelength are 846, 803, 665, 549, 523, 487, 456 and 411 nm have been observed when the sample was excited with 930 nm diode light. Four possible energy transfer processes between Er3+ and Yb3+ cause the electronic population of high energy level of Er3+ and realize the abound upconversion luminescence bands.

One-step nucleotide-programmed growth of porous upconversion nanoparticles: application to cell labeling and drug delivery

NASA Astrophysics Data System (ADS)

Zhou, Li; Li, Zhenhua; Liu, Zhen; Yin, Meili; Ren, Jinsong; Qu, Xiaogang

2014-01-01

A simple and ``green'' strategy has been reported for the first time to fabricate upconversion nanoparticles (UCNPs) by utilizing nucleotides as bio-templates. The influence of the functionalities present on the nucleotide on the production of nanoparticles was investigated in detail. Through the effects of nucleotides, the obtained nanoparticles possessed a porous structure. The use of the as-prepared UCNPs for cell imaging, drug delivery and versatile therapy applications were demonstrated. In view of the bright up-conversion luminescence as well as the excellent biocompatibility, and the good colloidal stability of the as-prepared UCNPs, we envision that our synthesis protocol might advance both the fields of UCNPs and biomolecule-based nanotechnology for future studies.A simple and ``green'' strategy has been reported for the first time to fabricate upconversion nanoparticles (UCNPs) by utilizing nucleotides as bio-templates. The influence of the functionalities present on the nucleotide on the production of nanoparticles was investigated in detail. Through the effects of nucleotides, the obtained nanoparticles possessed a porous structure. The use of the as-prepared UCNPs for cell imaging, drug delivery and versatile therapy applications were demonstrated. In view of the bright up-conversion luminescence as well as the excellent biocompatibility, and the good colloidal stability of the as-prepared UCNPs, we envision that our synthesis protocol might advance both the fields of UCNPs and biomolecule-based nanotechnology for future studies. Electronic supplementary information (ESI) available: Supporting figures. See DOI: 10.1039/c3nr04255c

Singlet oxygen generation of photosensitizers effectively activated by Nd3+-doped upconversion nanoparticles of luminescence intensity enhancing with shell thickness decreasing

NASA Astrophysics Data System (ADS)

Zou, Haixia; Jin, Fengmin; Song, Xiaoyan; Xing, Jinfeng

2017-04-01

The introduction of a thick shell structure has been widely used to enhance the emission intensity of upconversion nanoparticles (UCNPs). However, a thick shell could increase the distance between UCNPs and photosensitizers, which is not favourable to the generation of singlet oxygen (1O2) in photodynamic therapy (PDT) due to the low fluorescence resonance energy transfer (FRET) efficiency. In this study, we used a facile method to prepare UCNPs that the emission intensity could increase with the shell thickness decreasing, which facilitated the efficient FRET between UCNPs and photosensitizers. In detail, the Nd3+-doped UCNPs with different dopant concentration of Yb3+ were prepared and characterized firstly. The Ir/g (intensity of red luminescence to green luminescence) was tuned to increase largely by precisely controlling Yb3+ concentration in core-shell, which could make UCNPs effectively activate methylene blue (MB). Then, a unique procedure was used to prepare NaYF4:Yb/Er/Nd@NaYF4:Nd (Yb3+:30%) core-shell nanoparticles with different shell thickness by tuning the amount of the core. The upconversion luminescence (UCL) intensity of those UCNPs enhanced dramatically with the shell thickness decreasing. Furthermore, UCNPs and MB were encapsulated into SiO2 nanoparticles. FRET efficiency between UCNPs and MB largely increased with the shell thickness of UCNPs decreasing. Correspondingly, the efficiency of 1O2 generation obviously increased. We provided a new method to optimize the UCL intensity and FRET efficiency at the same time to produce 1O2 efficiently.

Upconversion luminescence of CsScF4 crystals doped with erbium and ytterbium

NASA Astrophysics Data System (ADS)

Ikonnikov, D. A.; Voronov, V. N.; Molokeev, M. S.; Aleksandrovsky, A. S.

2016-10-01

Tetragonal CsScF4 crystals doped with (5 at.%) Er and Er/Yb (0.5 at.%/5 at.%) are grown and their crystal structure is determined to belong to Pmmn space group. Er and Yb ions are shown to occupy distorted octahedral Sc sites with the center of inversion. Bright visible upconversion luminescence was observed under 970-980 nm pumping with red (4F9/2), yellow (4S3/2) and green (2H11/2) bands of comparable intensity. UCL tuning curves maximize at 972 nm (CSF:Er) and at 969.7 nm (CSF:Er,Yb) pumping wavelengths. Different ratios between yellow-green and red luminescence intensities in CSF:Er and CSF:Er, Yb are explained by contribution of cross-relaxation in CSF:Er UCL. UC in CSF:Er is a three stage process while UC in CSF:Er, Yb is a two stage process. The peculiarities of power dependences are explained by the power-dependent repopulation between starting levels of UC.

Upconversion luminescence resonance energy transfer-based aptasensor for the sensitive detection of oxytetracycline.

PubMed

Zhang, Hui; Fang, Congcong; Wu, Shijia; Duan, Nuo; Wang, Zhouping

2015-11-15

In this work, a biosensor based on luminescence resonance energy transfer (LRET) from NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) to SYBR Green I has been developed. The aptamers are covalently linked to UCNPs and hybridized with their complementary strands. The subsequent addition of SYBR Green allows SYBR Green I to insert into the formed double-stranded DNA (dsDNA) duplex and brings the energy donor and acceptor into close proximity, leading to the fluorescence of UCNPs transferred to SYBR Green I. When excited at 980 nm, the UCNPs emit luminescence at 477 nm, and this energy is transferred to SYBR Green I, which emits luminescence at 530 nm. In the presence of oxytetracycline (OTC), the aptamers prefer to bind to its corresponding analyte and dehybridize with the complementary DNA. This dehybridization leads to the liberation of SYBR Green I, which distances SYBR Green I from the UCNPs and recovers the UCNPs' luminescence. Under optimal conditions, a linear calibration is obtained between the ratio of I530 to I477 nm (I530/I477) and the OTC concentration, which ranges from 0.1 to 10 ng/ml with a limit of detection (LOD) of 0.054 ng/ml. Copyright © 2015 Elsevier Inc. All rights reserved.

Ultrasensitive Detection of Ebola Virus Oligonucleotide Based on Upconversion Nanoprobe/Nanoporous Membrane System.

PubMed

Tsang, Ming-Kiu; Ye, WeiWei; Wang, Guojing; Li, Jingming; Yang, Mo; Hao, Jianhua

2016-01-26

Ebola outbreaks are currently of great concern, and therefore, development of effective diagnosis methods is urgently needed. The key for lethal virus detection is high sensitivity, since early-stage detection of virus may increase the probability of survival. Here, we propose a luminescence scheme of assay consisting of BaGdF5:Yb/Er upconversion nanoparticles (UCNPs) conjugated with oligonucleotide probe and gold nanoparticles (AuNPs) linked with target Ebola virus oligonucleotide. As a proof of concept, a homogeneous assay was fabricated and tested, yielding a detection limit at picomolar level. The luminescence resonance energy transfer is ascribed to the spectral overlapping of upconversion luminescence and the absorption characteristics of AuNPs. Moreover, we anchored the UCNPs and AuNPs on a nanoporous alumina (NAAO) membrane to form a heterogeneous assay. Importantly, the detection limit was greatly improved, exhibiting a remarkable value at the femtomolar level. The enhancement is attributed to the increased light-matter interaction throughout the nanopore walls of the NAAO membrane. The specificity test suggested that the nanoprobes were specific to Ebola virus oligonucleotides. The strategy combining UCNPs, AuNPs, and NAAO membrane provides new insight into low-cost, rapid, and ultrasensitive detection of different diseases. Furthermore, we explored the feasibility of clinical application by using inactivated Ebola virus samples. The detection results showed great potential of our heterogeneous design for practical application.

Experimental demonstration of plasmon enhanced energy transfer rate in NaYF4:Yb3+,Er3+ upconversion nanoparticles

PubMed Central

Lu, Dawei; Mao, Chenchen; Cho, Suehyun K.; Ahn, Sungmo; Park, Wounjhang

2016-01-01

Energy transfer upconversion (ETU) is known to be the most efficient frequency upconversion mechanism. Surface plasmon can further enhance the upconversion process, opening doors to many applications. However, ETU is a complex process involving competing transitions between multiple energy levels and it has been difficult to precisely determine the enhancement mechanisms. In this paper, we report a systematic study on the dynamics of the ETU process in NaYF4:Yb3+,Er3+ nanoparticles deposited on plasmonic nanograting structure. From the transient near-infrared photoluminescence under various excitation power densities, we observed faster energy transfer rates under stronger excitation conditions until it reached saturation where the highest internal upconversion efficiency was achieved. The experimental data were analyzed using the complete set of rate equations. The internal upconversion efficiency was found to be 56% and 36%, respectively, with and without the plasmonic nanograting. We also analyzed the transient green emission and found that it is determined by the infrared transition rate. To our knowledge, this is the first report of experimentally measured internal upconversion efficiency in plasmon enhanced upconversion material. Our work decouples the internal upconversion efficiency from the overall upconverted luminescence efficiency, allowing more targeted engineering for efficiency improvement. PMID:26739230

Multicolor Upconversion Nanoprobes Based on a Dual Luminescence Resonance Energy Transfer Assay for Simultaneous Detection and Bioimaging of [Ca2+ ]i and pHi in Living Cells.

PubMed

Song, Xinyue; Yue, Zihong; Zhang, Jiayu; Jiang, Yanxialei; Wang, Zonghua; Zhang, Shusheng

2018-04-25

Intracellular [Ca 2+ ] i and pH i have a close relationship, and their abnormal levels can result in cell dysfunction and accompanying diseases. Thus, simultaneous determination of [Ca 2+ ] i and pH i can more accurately investigate complex biological processes in an integrated platform. Herein, multicolor upconversion nanoparticles (UCNPs) were prepared with the advantages of no spectral overlapping, single NIR excitation wavelengths, and greater tissue penetration depth. The upconversion nanoprobes were easily prepared by the attachment of two fluorescent dyes, Fluo-4 and SNARF-4F. Based on the dual luminescence resonance energy transfer (LRET) process, the blue and green fluorescence of the UCNPs were specially quenched and selectively recovered after the detachment and/or absorbance change of the attached fluorescent dyes, enabling dual detection. Importantly, the developed nanoprobe could successfully be applied for the detection of [Ca 2+ ] i and pH i change in adenosine triphosphate (ATP) and ethylene glycol tetraacetic acid (EGTA) stimulation in living cells. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) with remarkably enhanced upconversion luminescence.

PubMed

Su, Yue; Liu, Xiuling; Lei, Pengpeng; Xu, Xia; Dong, Lile; Guo, Xianmin; Yan, Xingxu; Wang, Peng; Song, Shuyan; Feng, Jing; Zhang, Hongjie

2016-07-05

Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) have been successfully fabricated via the thermal decomposition method. Upconversion nanoparticles (UCNPs) were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectroscopy, etc. Under 980 nm excitation, the emission intensities of the UCNPs are remarkably enhanced after coating the MF2 (M = Ca, Sr, and Ba) shell. Among these samples, CaF2 coated UCNPs show the strongest overall emission, while BaF2 coated UCNPs exhibit the longest lifetime. These results demonstrate that alkaline earth metal fluorides are ideal materials to improve the UCL properties. Meanwhile, although the lattice mismatch between the ternary NaREF4 core and the binary MF2 (M = Sr and Ba) shell is relatively large, the successfully synthesized NaLuF4:Yb/Er@NaLuF4:Yb@MF2 indicates a new outlook on the fabrication of heterostructural core-shell UCNPs.

Biocompatible Er, Yb co-doped fluoroapatite upconversion nanoparticles for imaging applications

NASA Astrophysics Data System (ADS)

Anjana, R.; K. M., Kurias; M. K., Jayaraj

2017-08-01

Upconversion luminescence, visible emission on infra red (IR) excitation was achieved in a biocompatible material, fluoroapatite. Fluoroapatite crystals are well known biomaterials, which is a component of tooth enamel. Also it can be considered as an excellent host material for lanthanide doping since the ionic radii of lanthanide is similar to that of calcium ion(Ca2+) hence successful incorporation of dopants within the lattice is possible. Erbium (Er), Ytterbium (Yb) co-doped fluorapatite (FAp) nanoparticles were prepared by precipitation method. The particles show intense visible emission when excited with 980 nm laser. Since upconversion luminescence is a multiphoton process the excitation power dependence on emission will give number of photons involved in the emission of single photon. Excitation power dependence studies show that two photons are involved in the emission of single photons. The value of slope was different for different emission peak because of the difference in intermediate energy level involved. The crystal structure and morphology of the particle were determined using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). These particles with surface functionalisation can be used for live cell imaging.

Recent Advances of Rare-Earth Ion Doped Luminescent Nanomaterials in Perovskite Solar Cells

PubMed Central

Qiao, Yu; Li, Shuhan; Liu, Wenhui; Ran, Meiqing; Lu, Haifei

2018-01-01

Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand the range of absorption spectra and improve the stability due to its upconversion and downconversion effect. This article reviews recent progress in using RE-ion-doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cells. Finally, we discuss the challenges facing the effective use of RE-ion-doped nanomaterials in perovskite solar cells and present some prospects for future research. PMID:29342950

Effect of Gallium and Indium Co-Substituting on Upconversion Properties of Er/Yb:Yttrium Aluminum Garnet Powders Prepared by the Co-Precipitation Method.

PubMed

Zhang, Wei; Liang, Yun-Ling; Hu, Zheng-Fa; Feng, Zu-Yong; Lun, Ma; Zhang, Xiu-ping; Sheng, Xia; Liu, Qian; Luo, Jie

2016-04-01

Gallium and Indium co-substituted Yb, Er:YAG was fabricated through the chemical co-precipitation method. The formation process and structure of the Ga3+ and In3+ substituted phosphor powders were characterized by the X-ray diffraction, thermo-gravimetry analyzer, infrared spectra, and X-ray photoelectron spectroscopy, and the effects of Ga3+ and In3+ concentration on the luminescence properties were investigated by spectrum. The results showed that the blue shift occurred after the substitution of Ga3+ and In3+ for Al3+ in matrix, and the intensity of emission spectrum was affected by the concentration of Ga3+ and In3+.

Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

PubMed

Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

2014-01-01

Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of an optically-based tension-indicating implanted orthopedic screw with a luminescent spectral ruler

NASA Astrophysics Data System (ADS)

Ravikumar, Nakul; Rogalski, Melissa M.; Benza, Donny; Lake, Joshua; Urban, Matthew; Pelham, Hunter; Anker, Jeffrey N.; DesJardins, John D.

2017-03-01

An orthopaedic screw was designed with an optical tension-indicator to non-invasively quantify screw tension and monitor the load sharing between the bone and the implant. The screw both applies load to the bone, and measures this load by reporting the strain on the screw. The screw contains a colorimetric optical encoder that converts axial strain into colorimetric changes visible through the head of the screw, or luminescent spectral changes that are detected through tissue. Screws were tested under cyclic mechanical loading to mimic in-vivo conditions to verify the sensitivity, repeatability, and reproducibility of the sensor. In the absence to tissue, color was measured using a digital camera as a function of axial load on a stainless steel cannulated (hollow) orthopedic screw, modified by adding a passive colorimetric strain gauge through the central hole. The sensor was able to quantify clinically-relevant bone healing strains. The sensor exhibited good repeatability and reproducibility but also displayed hysteresis due to the internal mechanics of the screw. The strain indicator was also modified for measurement through tissue by replacing the reflective colorimetric sensor with a low-background X-ray excited optical luminescence signal. Luminescent spectra were acquired through 6 mm of chicken breast tissue. Overall, this research shows feasibility for a unique device which quantifies the strain on an orthopedic screw. Future research will involve reducing hysteresis by changing the mechanism of strain transduction in the screw, miniaturizing the luminescent strain gauge, monitoring bending as well as tension, using alternative luminescent spectral rulers based upon near infrared fluorescence or upconversion luminescence, and application to monitoring changes in pretension and load sharing during bone healing.

Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release

PubMed Central

Büldt, Laura A.

2017-01-01

Some complexes of Cr(iii) and Cr(0) have long been known to exhibit interesting photophysical and photochemical properties, but in the past few years important conceptual progress was made. This Perspective focuses on the recent developments of Cr(iii) complexes as luminophores and dyes for solar cells, their application in photoredox catalysis, their use as sensitizers in upconversion processes, and their performance as photochemical nitric oxide sources. The example of a luminescent Cr(0) isocyanide complex illustrates the possibility of obtaining photoactive analogues of d6 metal complexes that are commonly made from precious metals such as Ru(ii) or Ir(iii). The studies highlighted herein illustrate the favorable excited-state properties of robust first-row transition metal complexes with broad application potential. PMID:29163886

Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release.

PubMed

Büldt, Laura A; Wenger, Oliver S

2017-11-01

Some complexes of Cr(iii) and Cr(0) have long been known to exhibit interesting photophysical and photochemical properties, but in the past few years important conceptual progress was made. This Perspective focuses on the recent developments of Cr(iii) complexes as luminophores and dyes for solar cells, their application in photoredox catalysis, their use as sensitizers in upconversion processes, and their performance as photochemical nitric oxide sources. The example of a luminescent Cr(0) isocyanide complex illustrates the possibility of obtaining photoactive analogues of d 6 metal complexes that are commonly made from precious metals such as Ru(ii) or Ir(iii). The studies highlighted herein illustrate the favorable excited-state properties of robust first-row transition metal complexes with broad application potential.

Energy conversion of X-ray, ultraviolet and infrared radiation in Gd2O3 crystals doped with Er3+ ions

NASA Astrophysics Data System (ADS)

Trofimova, E. S.; Pustovarov, V. A.; Kuznetsova, Yu. A.; Zatsepin, A. F.

2017-09-01

Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.0 eV, PL excitation spectra (2.8-5.8 eV), PL decay kinetics were measured in Gd2O3 crystals doped both with Er3+ and Zn2+ ions. Synchrotron radiation (VEPP-3 storage ring, Novosibirsk, Russia) were used for XRL measurements. PL spectra were studied at room temperature and T= 88 K under excitation with energy Eexc: a) in fundamental absorption region (Eexc≥Eg); b) in intracenter excitation region (Eexc

Triple-functional core-shell structured upconversion luminescent nanoparticles covalently grafted with photosensitizer for luminescent, magnetic resonance imaging and photodynamic therapy in vitro

NASA Astrophysics Data System (ADS)

Qiao, Xiao-Fei; Zhou, Jia-Cai; Xiao, Jia-Wen; Wang, Ye-Fu; Sun, Ling-Dong; Yan, Chun-Hua

2012-07-01

Upconversion luminescent nanoparticles (UCNPs) have been widely used in many biochemical fields, due to their characteristic large anti-Stokes shifts, narrow emission bands, deep tissue penetration and minimal background interference. UCNPs-derived multifunctional materials that integrate the merits of UCNPs and other functional entities have also attracted extensive attention. Here in this paper we present a core-shell structured nanomaterial, namely, NaGdF4:Yb,Er@CaF2@SiO2-PS, which is multifunctional in the fields of photodynamic therapy (PDT), magnetic resonance imaging (MRI) and fluorescence/luminescence imaging. The NaGdF4:Yb,Er@CaF2 nanophosphors (10 nm in diameter) were prepared via sequential thermolysis, and mesoporous silica was coated as shell layer, in which photosensitizer (PS, hematoporphyrin and silicon phthalocyanine dihydroxide) was covalently grafted. The silica shell improved the dispersibility of hydrophobic PS molecules in aqueous environments, and the covalent linkage stably anchored the PS molecules in the silica shell. Under excitation at 980 nm, the as-fabricated nanomaterial gave luminescence bands at 550 nm and 660 nm. One luminescent peak could be used for fluorescence imaging and the other was suitable for the absorption of PS to generate singlet oxygen for killing cancer cells. The PDT performance was investigated using a singlet oxygen indicator, and was investigated in vitro in HeLa cells using a fluorescent probe. Meanwhile, the nanomaterial displayed low dark cytotoxicity and near-infrared (NIR) image in HeLa cells. Further, benefiting from the paramagnetic Gd3+ ions in the core, the nanomaterial could be used as a contrast agent for magnetic resonance imaging (MRI). Compared with the clinical commercial contrast agent Gd-DTPA, the as-fabricated nanomaterial showed a comparable longitudinal relaxivities value (r1) and similar imaging effect.Upconversion luminescent nanoparticles (UCNPs) have been widely used in many biochemical fields, due to their characteristic large anti-Stokes shifts, narrow emission bands, deep tissue penetration and minimal background interference. UCNPs-derived multifunctional materials that integrate the merits of UCNPs and other functional entities have also attracted extensive attention. Here in this paper we present a core-shell structured nanomaterial, namely, NaGdF4:Yb,Er@CaF2@SiO2-PS, which is multifunctional in the fields of photodynamic therapy (PDT), magnetic resonance imaging (MRI) and fluorescence/luminescence imaging. The NaGdF4:Yb,Er@CaF2 nanophosphors (10 nm in diameter) were prepared via sequential thermolysis, and mesoporous silica was coated as shell layer, in which photosensitizer (PS, hematoporphyrin and silicon phthalocyanine dihydroxide) was covalently grafted. The silica shell improved the dispersibility of hydrophobic PS molecules in aqueous environments, and the covalent linkage stably anchored the PS molecules in the silica shell. Under excitation at 980 nm, the as-fabricated nanomaterial gave luminescence bands at 550 nm and 660 nm. One luminescent peak could be used for fluorescence imaging and the other was suitable for the absorption of PS to generate singlet oxygen for killing cancer cells. The PDT performance was investigated using a singlet oxygen indicator, and was investigated in vitro in HeLa cells using a fluorescent probe. Meanwhile, the nanomaterial displayed low dark cytotoxicity and near-infrared (NIR) image in HeLa cells. Further, benefiting from the paramagnetic Gd3+ ions in the core, the nanomaterial could be used as a contrast agent for magnetic resonance imaging (MRI). Compared with the clinical commercial contrast agent Gd-DTPA, the as-fabricated nanomaterial showed a comparable longitudinal relaxivities value (r1) and similar imaging effect. Electronic supplementary information (ESI) available: More TEM, emission spectra, longitudinal and transverse relaxation times, t2-weighted MR images of the as-prepared nanomaterial, and confocal fluorescent images of HeLa cells. See DOI: 10.1039/c2nr30938f

Dye-Sensitized Core/Active Shell Upconversion Nanoparticles for Optogenetics and Bioimaging Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xiang; Zhang, Yuanwei; Takle, Kendra

2016-01-26

Near Infrared (NIR) dye-sensitized upconversion nanoparticles (UCNPs) have recently been proposed in order to broaden the absorption range and to boost upconversion efficiency. However, implementing this strategy has been limited only to bare core UCNP structures that are faintly luminescent. Herein, we report on an approach to achieve significantly enhanced upconversion luminescence in dye-sensitized core-active shell UCNPs with a broadened absorption range via the doping of ytterbium ions in the UCNP shell in order to bridge the energy transfer from the dye to the UCNP core. As a result, we have been able to synergize the two most practical upconversionmore » booster effectors (dye-sensitizing and core/shell enhancement). The absolute quantum yield of our dye-sensitized core/active shell UCNPs at 800 nm was determined to be ~6% at 2 W/cm2, about 33 times larger than the highest value reported to date for existing 800 nm excitable UCNPs. Moreover, for the first time, by using dye-sensitized core/active shell UCNP embedded poly(methyl methacrylate) polymer implantable systems, we successfully shifted the optogenetic neuron excitation window to a wavelength that is compatible with deep tissue penetrable near the infrared wavelength at 800 nm. Finally, amphiphilic triblock copolymer, Pluronic F127 coatings permit the transfer of hydrophobic UCNPs into water, resulting in water-soluble nanoparticles with well-preserved optical property in aqueous solution. We believe that this research offers a new solution to enhance upconversion efficiency for photonic and biophotonic purposes and opens up new opportunities to use UCNPs as a NIR relay for optogenetic applications.« less

Enhancement of luminescence properties in Er3+ doped TeO2-Na2O-PbX (X=O and F) ternary glasses.

PubMed

Kumar, Kaushal; Rai, S B; Rai, D K

2007-04-01

An enhancement of luminescence properties in Er3+ doped ternary glasses is observed on the addition of PbO/PbF2. The infrared to visible upconversion emission bands are observed at 410, 525, 550 and 658 nm, due to the 2H9/2-->4I15/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 transitions respectively, on excitation with 797 nm laser line. A detailed study reveals that the 2H9/2-->4I15/2 transition arises due to three step upconversion process while other transitions arise due to two step absorption. On excitation with 532 nm radiation, ultraviolet and violet upconversion bands centered at 380, 404, 410 and 475 nm wavelengths are observed along with one photon luminescence bands at 525, 550, 658 and 843 nm wavelengths. These bands are found due to the 4G11/2-->4I15/2, 2P3/2-->4I13/2, 2H9/2-->4I15/2, 2P3/2-->4I11/2, 2H11/2-->4I15/2, 4S3/2-->4I15/2, 4F9/2-->4I15/2 and 4S3/2-->4I13/2 transitions, respectively. Though incorporation of PbO and PbF2 both enhances fluorescence intensities however, PbF2 content has an important influence on upconversion luminescence emission. The incorporation of PbF2 enhances the red emission (658 nm) intensity by 1.5 times and the violet emission (410 nm) intensity by 2.0 times. A concentration dependence study of fluorescence reveals the rapid increase in the red (4F9/2-->4I15/2) emission intensity relative to the green (4S3/2-->4I15/2) emission with increase in the Er3+ ion concentration. This behaviour has been explained in terms of an energy transfer by relaxation between excited ions.

Spatial height directed microfluidic synthesis of transparent inorganic upconversion nano film

NASA Astrophysics Data System (ADS)

Liu, Xiaoxia; Zhu, Cheng; Liao, Wei; Jin, Junyang; Ni, Yaru; Lu, Chunhua; Xu, Zhongzi

2017-11-01

A microfluidic-based synthesis of an inorganic upconversion nano film has been developed with a large area of dense-distributed NaYF4 crystal grains in a silica glass micro-reactor and the film exhibits high transparence, strong upconversion luminescence and robust adhesion with the substrate. The spatial heights of micro-reactors are tuned between 31 and 227 mm, which can regulate flow regimes. The synergistic effect of spatial height and fluid regime is put forward, which influences diffusion paths and assembly ways of different precursor molecules and consequently directs final distributions and morphologies of crystal grains, as well as optical properties due to diversity of surface and thickness of films. The spatial height of 110 mm is advantageous for high transmittance of upconversion film due to the flat surface and appropriate film thickness of 67 nm. The height of 150 mm is in favor of uniform distribution of upconversion fluorescence and achieving the strongest fluorescence due to minimized optical loss. Such a transparent upconversion film with a large area of uniform distribution is promising to promote the application of upconversion materials and spatial height directed microfluidic regime have a certain significance on many microfluidic synthesis.

Enhanced upconversion emission in colloidal (NaYF4:Er(3+))/NaYF4 core/shell nanoparticles excited at 1523 nm.

PubMed

Shao, Wei; Chen, Guanying; Damasco, Jossana; Wang, Xianliang; Kachynski, Aliaksandr; Ohulchanskyy, Tymish Y; Yang, Chunhui; Ågren, Hans; Prasad, Paras N

2014-03-15

In this work, we report on efficient visible and near-IR upconversion emissions in colloidal hexagonal-phase core/shell NaYF4:Er(3+)/NaYF4 nanoparticles (∼38  nm) under IR laser excitation at 1523 nm. Varying amounts of Er(3+) dopants were introduced into the core NaYF4:Er(3+) nanoparticles, revealing an optimized Er(3+) concentration of 10% for the highest luminescent efficiency. An inert epitaxial shell layer of NaYF4 grown onto the core of the NaYF4:Er(3+) 10% nanoparticle increased its upconversion emission intensity fivefold due to suppression of surface-related quenching mechanisms, yielding the absolute upconversion efficiency to be as high as ∼3.9±0.3% under an excitation density of 18  W/cm(2). The dependence of the intensity of upconversion emission peaks on laser excitation density in the core/shell nanoparticle displayed "saturation effects" at low excitation density in the range of 1.5-18  W/cm(2), which again demonstrates high upconversion efficiency.

Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal.

PubMed

Chen, Guanying; Damasco, Jossana; Qiu, Hailong; Shao, Wei; Ohulchanskyy, Tymish Y; Valiev, Rashid R; Wu, Xiang; Han, Gang; Wang, Yan; Yang, Chunhui; Ågren, Hans; Prasad, Paras N

2015-11-11

Lanthanide-doped upconversion nanoparticles hold promises for bioimaging, solar cells, and volumetric displays. However, their emission brightness and excitation wavelength range are limited by the weak and narrowband absorption of lanthanide ions. Here, we introduce a concept of multistep cascade energy transfer, from broadly infrared-harvesting organic dyes to sensitizer ions in the shell of an epitaxially designed core/shell inorganic nanostructure, with a sequential nonradiative energy transfer to upconverting ion pairs in the core. We show that this concept, when implemented in a core-shell architecture with suppressed surface-related luminescence quenching, yields multiphoton (three-, four-, and five-photon) upconversion quantum efficiency as high as 19% (upconversion energy conversion efficiency of 9.3%, upconversion quantum yield of 4.8%), which is about ~100 times higher than typically reported efficiency of upconversion at 800 nm in lanthanide-based nanostructures, along with a broad spectral range (over 150 nm) of infrared excitation and a large absorption cross-section of 1.47 × 10(-14) cm(2) per single nanoparticle. These features enable unprecedented three-photon upconversion (visible by naked eye as blue light) of an incoherent infrared light excitation with a power density comparable to that of solar irradiation at the Earth surface, having implications for broad applications of these organic-inorganic core/shell nanostructures with energy-cascaded upconversion.

Efficient upconversion emission in Ho3+/Nd3+ co-doped oxyfluorosilicate glasses

NASA Astrophysics Data System (ADS)

Devarajulu, G.; Raju, B. Deva Prasad

2018-04-01

We report on an efficient Ho3+ and Ho3+/Nd3+ co-doped oxyfluorosilicate glasses upon excitation with an 808 nm laser diode. The detailed fluorescence have been studied under this excitation source and energy transfer mechanisms in Ho3+/Nd3+ co-doped oxyfluorosilicate glasses. The upconversion peaks at 486, 547 and 596 nm were observed in Nd3+/Ho3+ co-doped sample. The intensity of upconversion emission transitions in Ho3+ depends on the neodymium codopent concentration. These results indicate that Nd3+ ions can be potentially used as sensitizer for Ho3+ ions to stimulate the intense upconversion emission. The energy transfer mechanism between Nd3+ and Ho3+ was analyzed pursuant to the absorption spectra, upconversion spectra and the energy level structures of Nd3+ and Ho3+ ions have been briefly discussed.

Luminescent and transparent nanopaper based on rare-earth up-converting nanoparticle grafted nanofibrillated cellulose derived from garlic skin.

PubMed

Zhao, Jingpeng; Wei, Zuwu; Feng, Xin; Miao, Miao; Sun, Lining; Cao, Shaomei; Shi, Liyi; Fang, Jianhui

2014-09-10

Highly flexible, transparent, and luminescent nanofibrillated cellulose (NFC) nanopaper with heterogeneous network, functionalized by rare-earth up-converting luminescent nanoparticles (UCNPs), was rapidly synthesized by using a moderate pressure extrusion paper-making process. NFC was successfully prepared from garlic skin using an efficient extraction approach combined with high frequency ultrasonication and high pressure homogenization after removing the noncellulosic components. An efficient epoxidation treatment was carried out to enhance the activity of the UCNPs (NaYF4:Yb,Er) with oleic acid ligand capped on the surface. The UCNPs after epoxidation then reacted with NFC in aqueous medium to form UCNP-grafted NFC nanocomposite (NFC-UCNP) suspensions at ambient temperature. Through the paper-making process, the assembled fluorescent NFC-UCNP hybrid nanopaper exhibits excellent properties, including high transparency, strong up-conversion luminescence, and good flexibility. The obtained hybrid nanopaper was characterized by transmission electron microscopy (TEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), field emission-scanning electron microscope (FE-SEM), up-conversion luminescence (UCL) spectrum, and ultraviolet and visible (UV-vis) spectrophotometer. The experimental results demonstrate that the UCNPs have been successfully grafted to the NFC matrix with heterogeneous network. And the superiorly optical transparent and luminescent properties of the nanopaper mainly depend on the ratio of UCNPs to NFC. Of importance here is that, NFC and UCNPs afford the nanopaper a prospective candidate for multimodal anti-counterfeiting, sensors, and ion probes applications.

Color-coded multilayer photopatterned microstructures using lanthanide (III) ion co-doped NaYF4 nanoparticles with upconversion luminescence for possible applications in security.

PubMed

Kim, Won Jin; Nyk, Marcin; Prasad, Paras N

2009-05-06

We report a method for fabricating predefined photopatterns of upconversion nanophosphors using a chemical amplification reaction for direct writing of films with multilayer color-coded patterning for security applications. To photopattern the nanocrystal film we have synthesized rare-earth ion (Er(3+)/Yb(3+) or Tm(3+)/Yb(3+)) co-doped sodium yttrium fluoride (alpha-NaYF(4)) nanophosphors and functionalized the nanocrystal surfaces by incorporation of a photopatternable ligand such as t-butoxycarbonyl (t-BOC). The surface modification allows photopatterning of the nanophosphor solid state film. Furthermore, upconversion nanophosphors show a nearly quadratic dependence of the upconversion photoluminescence (PL) intensity on the excitation light power, and tailoring of the PL wavelength is possible by changing the lanthanide ions. We have demonstrated the capability of anchoring nanophosphors at desirable locations by a photolithography technique. The photopatterned films exhibit fixed nanophosphor structures clearly identifiable by strong upconversion photoluminescence under IR illumination which is useful for a number of applications in security.

Activation of the surface dark-layer to enhance upconversion in a thermal field

NASA Astrophysics Data System (ADS)

Zhou, Jiajia; Wen, Shihui; Liao, Jiayan; Clarke, Christian; Tawfik, Sherif Abdulkader; Ren, Wei; Mi, Chao; Wang, Fan; Jin, Dayong

2018-03-01

Thermal quenching, in which light emission experiences a loss with increasing temperature, broadly limits luminescent efficiency at higher temperature in optical materials, such as lighting phosphors1-3 and fluorescent probes4-6. Thermal quenching is commonly caused by the increased activity of phonons that leverages the non-radiative relaxation pathways. Here, we report a kind of heat-favourable phonons existing at the surface of lanthanide-doped upconversion nanomaterials to combat thermal quenching. It favours energy transfer from sensitizers to activators to pump up the intermediate excited-state upconversion process. We identify that the oxygen moiety chelating Yb3+ ions, [Yb...O], is the key underpinning this enhancement. We demonstrate an approximately 2,000-fold enhancement in blue emission for 9.7 nm Yb3+-Tm3+ co-doped nanoparticles at 453 K. This strategy not only provides a powerful solution to illuminate the dark layer of ultra-small upconversion nanoparticles, but also suggests a new pathway to build high-efficiency upconversion systems.

Optical transitions of Ho(3+) in oxyfluoride glasses and upconversion luminescence of Ho(3+)/Yb(3+)-codoped oxyfluoride glasses.

PubMed

Feng, Li; Wu, Yinsu

2015-05-05

Optical properties of Ho(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Ho(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980nm excitation. The effects of composition, concentration of the doping ions, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2015 Elsevier B.V. All rights reserved.

Optical transitions of Tm3+ in oxyfluoride glasses and compositional and thermal effect on upconversion luminescence of Tm3+/Yb3+-codoped oxyfluoride glasses.

PubMed

Feng, Li; Wu, Yinsu; Liu, Zhuo; Guo, Tao

2014-01-24

Optical properties of Tm(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Tm(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980 nm excitation. The effects of composition, concentration of the doping ions, temperature, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, Structural Characterization and Up-Conversion Luminescence Properties of NaYF4:Er3+,Yb3+@MOFs Nanocomposites

NASA Astrophysics Data System (ADS)

Giang, Lam Thi Kieu; Marciniak, Lukasz; Huy, Tran Quang; Vu, Nguyen; Le, Ngo Thi Hong; Binh, Nguyen Thanh; Lam, Tran Dai; Minh, Le Quoc

2017-10-01

This paper describes a facile synthesis of NaYF4:Er3+,Yb3+ nanoparticles embraced in metal-organic frameworks (MOFs), known as NaYF4:Er3+, Yb3+@MOFs core/shell nanostructures, by using iron(III) carboxylate (MIL-100) and zeolitic imidazolate frameworks (ZIF-8). Morphological, structural and optical characterization of these nanostructures were investigated by field emission-scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, and up-conversion luminescence measurements. Results showed that spherical-shaped NaYF4:Er3+,Yb3+@MIL-100 nanocomposites with diameters of 150-250 nm, and rod-shaped NaYF4:Er3+,Yb3+@ZIF-8 nanocomposites with lengths of 300-550 nm, were successfully synthesized. Under a 980-nm laser excitation at room temperature, the NaYF4:Er3+,Yb3+@MOFs nanocomposites exhibited strong up-conversion luminescence with two emission bands in the green part of spectrum at 520 nm and 540 nm corresponding to the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+ ions, respectively, and a red emission band at 655 nm corresponding to the 4F9/2 → 4I15/2 transition of Er3+ ions. The above properties of NaYF4:Er3+,Yb3+@MOFs make them promising candidates for applications in biotechnology.

Microwave sol–gel synthesis and upconversion photoluminescence properties of CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with incommensurately modulated structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Chang Sung; Aleksandrovsky, Aleksandr; Department of Photonics and Laser Technologies, Siberian Federal University, Krasnoyarsk 660079

2015-08-15

CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method. The crystal structure of CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} particles exhibited a strong 525-nm and a weak 550-nm emission bandsmore » in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd{sub 2}(WO{sub 4}){sub 4} revealed about 12 narrow lines. The strongest band observed at 903 cm{sup −1} was assigned to the ν{sub 1} symmetric stretching vibration of WO{sub 4} tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er{sup 3+} luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition is weak in the range of erbium doping level x{sub Er}=0.05–0.2, while, for transition {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}, the signs of concentration quenching become pronounced at x{sub Er}=0.2. - Graphical abstract: CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method and the crystal structure refinement, and upconversion photoluminescence properties have been investigated. - Highlights: • CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors have been synthesized by the microwave sol–gel method. • The crystal structure of CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} tungstates have been refined. • The upconversion photoluminescence properties have been investigated.« less

Structural and luminescent properties of a NaYF4-aerogel composite

NASA Astrophysics Data System (ADS)

Alattar, Ashraf M.; Drexler, Matthew; Twej, Wesam A. A.; Alamgir, Faisal M.

2018-07-01

Upconversion materials, capable of energy-shifting light, have direct application in devices where the tunability of the optical spectrum can result in higher performance. Due to the low transparency of upconversion nanomaterials, it is beneficial to disperse them in a medium with a low optical attenuation coefficient in order to allow light to reach and increase the contributions from each individual particle. Silica aerogels, with their high transparency and open porosity, are ideal media for the dispersion of the nanomaterials throughout a volume. NaYF4-based nanocrystals with differing dopants were incorporated into silica xerogels and aerogels to observe the effect of the composites on the properties of each. It was observed that, while the average surface area of the aerogel decreased in the composite, the shape and phase of the nanocrystals were preserved during xerogel processing. The luminescence of the nanoparticles increased upon incorporation into the xerogel composites. By accounting for effects emerging from collection geometry and the composite morphology, it is argued that the increase in the composite luminescent intensity is due to the nanoparticles being shielded from quenching effects by the silica matrix.

Study of visible luminescence spectra from Nd3+ doped TPO glass upon 808 nm excitation

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar

2018-05-01

The Nd3+ doped TPO glasses have been prepared by melting and quenching method using the high temperature electric furnace. The upconversion (UC) spectra of Nd3+ doped TPO glasses at different concentration of rare ions have been recorded in the 400-700 nm wavelength range upon 808 nm laser excitation source. In the UC emission process, there are four bands centered at ˜495 nm, 546 nm, 602 nm and 653 nm respectively in the visible range were observed. But the green and red bands centered at˜546 nm and ˜653 nm corresponding to the 4G7/2 → 4I9/2 and 4G7/2 → 4I13/2 transitions respectively have been observed as the strong bands. The UC emission mechanism was observed as two photon process. The material can be used as a good NIR to visible upconverter and non-colour tunable display.

Rare Earth Ion-Doped Upconversion Nanocrystals: Synthesis and Surface Modification

PubMed Central

Chang, Hongjin; Xie, Juan; Zhao, Baozhou; Liu, Botong; Xu, Shuilin; Ren, Na; Xie, Xiaoji; Huang, Ling; Huang, Wei

2014-01-01

The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation information technology, optical communication, bioimaging, and therapy. However, the inherent upconversion luminescent properties of UCNPs are influenced by various parameters, including the size, shape, crystal structure, and chemical composition of the UCNPs, and even the chosen synthesis process and the surfactant molecules used. This review will provide a complete summary on the synthesis methods and the surface modification strategies of UCNPs reported so far. Firstly, we summarize the synthesis methodologies developed in the past decades, such as thermal decomposition, thermal coprecipitation, hydro/solvothermal, sol-gel, combustion, and microwave synthesis. In the second part, five main streams of surface modification strategies for converting hydrophobic UCNPs into hydrophilic ones are elaborated. Finally, we consider the likely directions of the future development and challenges of the synthesis and surface modification, such as the large-scale production and actual applications, stability, and so on, of the UCNPs. PMID:28346995

White up-conversion emission in Ho3+/Tm3+/Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals

NASA Astrophysics Data System (ADS)

Li, Chenxia; Xu, Shiqing; Ye, Rengguang; Deng, Degang; Hua, Youjie; Zhao, Shilong; Zhuang, Songlin

2011-04-01

Ho3+/Tm3+/Yb3+ tri-doped glass ceramics with white light emitting have been developed and demonstrated. Pumped by 980 nm laser diode (LD), intensive red, green and blue up-conversions (UC) were obtained. The green emission is assigned to Ho3+ ion and the blue emission is assigned to Tm3+ ion, whereas the red emission is the combination contribution of the Ho3+ and Tm3+ ions. The RGB intensities could be adjusted by tuning the rare-earth ion concentration and pump power intensity. Thus, multicolor of the luminescence, including perfect white light with CIE-X=0.329 and CIE-Y=0.342 in the 1931 CIE chromaticity diagram can be obtained in 0.15 Ho3+/0.2Tm3+/3Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals pumped by a single infrared laser diode source of 980 nm at 500 mW. The up-conversion luminescence mechanism of Yb3+ sensitize Ho3+ and Tm3+ ions and the energy transfer from Ho3+ to Tm3+ in oxy-fluoride silicate glass ceramics were analyzed.

Design, Synthesis, and Structure-Property Relationships of Er3+-Doped TiO2 Luminescent Particles Synthesized by Sol-Gel

PubMed Central

Lopez-Iscoa, Pablo; Baldi, Giovanni

2018-01-01

Titania particles doped with various concentrations of Erbium were synthesized by the sol-gel method followed by different heat treatments. The shape and the grain growth of the particles were noticeably affected by the concentration of Erbium and the heat treatment conditions. An infrared emission at 1530 nm, as well as green and red up-conversion emissions at 550 and 670 nm, were observed under excitation at 976 nm from all of the synthesized particles. The emission spectra and lifetime values appeared to be strongly influenced by the presence of the different crystalline phases. This work presents important guidelines for the synthesis of functional Er3+-doped titania particles with controlled and tailored spectroscopic properties for photonic applications. PMID:29301282

Achieving high-efficiency emission depletion nanoscopy by employing cross relaxation in upconversion nanoparticles.

PubMed

Zhan, Qiuqiang; Liu, Haichun; Wang, Baoju; Wu, Qiusheng; Pu, Rui; Zhou, Chao; Huang, Bingru; Peng, Xingyun; Ågren, Hans; He, Sailing

2017-10-20

Stimulated emission depletion microscopy provides a powerful sub-diffraction imaging modality for life science studies. Conventionally, stimulated emission depletion requires a relatively high light intensity to obtain an adequate depletion efficiency through only light-matter interaction. Here we show efficient emission depletion for a class of lanthanide-doped upconversion nanoparticles with the assistance of interionic cross relaxation, which significantly lowers the laser intensity requirements of optical depletion. We demonstrate two-color super-resolution imaging using upconversion nanoparticles (resolution ~ 66 nm) with a single pair of excitation/depletion beams. In addition, we show super-resolution imaging of immunostained cytoskeleton structures of fixed cells (resolution ~ 82 nm) using upconversion nanoparticles. These achievements provide a new perspective for the development of photoswitchable luminescent probes and will broaden the applications of lanthanide-doped nanoparticles for sub-diffraction microscopic imaging.

Realizing up-conversion fluorescence tuning in lanthanide-doped nanocrystals by femtosecond pulse shaping method

PubMed Central

Zhang, Shian; Yao, Yunhua; Shuwu, Xu; Liu, Pei; Ding, Jingxin; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong

2015-01-01

The ability to tune color output of nanomaterials is very important for their applications in laser, optoelectronic device, color display and multiplexed biolabeling. Here we first propose a femtosecond pulse shaping technique to realize the up-conversion fluorescence tuning in lanthanide-doped nanocrystals dispersed in the glass. The multiple subpulse formation by a square phase modulation can create different excitation pathways for various up-conversion fluorescence generations. By properly controlling these excitation pathways, the multicolor up-conversion fluorescence can be finely tuned. This color tuning by the femtosecond pulse shaping technique is realized in single material by single-color laser field, which is highly desirable for further applications of the lanthanide-doped nanocrystals. This femtosecond pulse shaping technique opens an opportunity to tune the color output in the lanthanide-doped nanocrystals, which may bring a new revolution in the control of luminescence properties of nanomaterials. PMID:26290391

Smartphone based visual and quantitative assays on upconversional paper sensor.

PubMed

Mei, Qingsong; Jing, Huarong; Li, You; Yisibashaer, Wuerzha; Chen, Jian; Nan Li, Bing; Zhang, Yong

2016-01-15

The integration of smartphone with paper sensors recently has been gain increasing attentions because of the achievement of quantitative and rapid analysis. However, smartphone based upconversional paper sensors have been restricted by the lack of effective methods to acquire luminescence signals on test paper. Herein, by the virtue of 3D printing technology, we exploited an auxiliary reusable device, which orderly assembled a 980nm mini-laser, optical filter and mini-cavity together, for digitally imaging the luminescence variations on test paper and quantitative analyzing pesticide thiram by smartphone. In detail, copper ions decorated NaYF4:Yb/Tm upconversion nanoparticles were fixed onto filter paper to form test paper, and the blue luminescence on it would be quenched after additions of thiram through luminescence resonance energy transfer mechanism. These variations could be monitored by the smartphone camera, and then the blue channel intensities of obtained colored images were calculated to quantify amounts of thiram through a self-written Android program installed on the smartphone, offering a reliable and accurate detection limit of 0.1μM for the system. This work provides an initial demonstration of integrating upconversion nanosensors with smartphone digital imaging for point-of-care analysis on a paper-based platform. Copyright © 2015 Elsevier B.V. All rights reserved.

Structural and light up-conversion luminescence properties of Er3+-Yb3+-W6+ substituted Bi4Ti3O12

NASA Astrophysics Data System (ADS)

Bokolia, Renuka; Rai, Vineet K.; Chauhan, Lalita; Sreenivas, K.

2016-05-01

The structural and light up-conversion (UC) luminescence properties of W6+ substituted Bi3.79Er0.03Yb0.18Ti3-xWxO12 (0 ≤ x ≤ 0.10) ceramics prepared by solid state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of single phase material with orthorhombic structure. A decrease in the lattice parameters and unit cell volume is observed with increasing W content. Strong UC luminescence at 527, 548 and 662 nm is seen under an excitation of 980 nm for an optimum W content (x = 0.06) and is attributed to the transitions 2H11/2 →4I15/2, 4S3/2 →4I15/2 and 4F9/2 →4I15/2 respectively. The improved UC luminescence is ascribed to the reduced defects such as oxygen vacancies and change in the crystal field around Er3+ ions due to B-site (Ti4+) substitution with W6+ ions. Enhanced UC emission is observed for an optimum content of w6+ in the prepared composition Bi3.79Er0.03Yb0.18Ti3-xWxO12 for x = 0.06.

Fabrication of a LRET-based upconverting hybrid nanocomposite for turn-on sensing of H2O2 and glucose

NASA Astrophysics Data System (ADS)

Wu, Shuang; Kong, Xiang-Juan; Cen, Yao; Yuan, Jing; Yu, Ru-Qin; Chu, Xia

2016-04-01

Blood glucose detecting has aroused considerable attention because diabetes mellitus has become a worldwide publish health problem. Herein, we construct an exceptionally simple upconverting hybrid nanocomposite, composed of DNA-templated Ag nanoparticles (DNA-AgNPs) and NaYF4:Yb/Tm@NaYF4 core-shell upconversion nanoparticles (UCNPs), for the sensing of H2O2 and glucose. In this design, UCNPs with bared surface act as the donor, and DNA-AgNPs serve as efficient quenchers. DNA-AgNPs can be directly assembled on the bared surface of UCNPs, which further decreases the distance of donor-to-acceptor. The formation of DNA-AgNPs/UCNP nanocomposite results in luminescence quenching of UCNP by DNA-AgNPs through luminescence resonance energy transfer (LRET). Upon H2O2 addition, AgNPs can be etched and transformed into Ag+, leading to inhibition of the LRET process and causing the recovery of upconversion luminescence. Based on the conversion of glucose into H2O2 by glucose oxidase, the DNA-AgNPs/UCNP nanocomposite can also be exploited for glucose sensing. Moreover, due to the non-autofluorescence offered by UCNPs, the approach developed can be applied to monitor glucose levels in human serum samples with satisfactory results.Blood glucose detecting has aroused considerable attention because diabetes mellitus has become a worldwide publish health problem. Herein, we construct an exceptionally simple upconverting hybrid nanocomposite, composed of DNA-templated Ag nanoparticles (DNA-AgNPs) and NaYF4:Yb/Tm@NaYF4 core-shell upconversion nanoparticles (UCNPs), for the sensing of H2O2 and glucose. In this design, UCNPs with bared surface act as the donor, and DNA-AgNPs serve as efficient quenchers. DNA-AgNPs can be directly assembled on the bared surface of UCNPs, which further decreases the distance of donor-to-acceptor. The formation of DNA-AgNPs/UCNP nanocomposite results in luminescence quenching of UCNP by DNA-AgNPs through luminescence resonance energy transfer (LRET). Upon H2O2 addition, AgNPs can be etched and transformed into Ag+, leading to inhibition of the LRET process and causing the recovery of upconversion luminescence. Based on the conversion of glucose into H2O2 by glucose oxidase, the DNA-AgNPs/UCNP nanocomposite can also be exploited for glucose sensing. Moreover, due to the non-autofluorescence offered by UCNPs, the approach developed can be applied to monitor glucose levels in human serum samples with satisfactory results. Electronic supplementary information (ESI) available: Experimental details and supplementary figures. See DOI: 10.1039/c6nr00470a

Amplified stimulated emission in upconversion nanoparticles for super-resolution nanoscopy

NASA Astrophysics Data System (ADS)

Liu, Yujia; Lu, Yiqing; Yang, Xusan; Zheng, Xianlin; Wen, Shihui; Wang, Fan; Vidal, Xavier; Zhao, Jiangbo; Liu, Deming; Zhou, Zhiguang; Ma, Chenshuo; Zhou, Jiajia; Piper, James A.; Xi, Peng; Jin, Dayong

2017-02-01

Lanthanide-doped glasses and crystals are attractive for laser applications because the metastable energy levels of the trivalent lanthanide ions facilitate the establishment of population inversion and amplified stimulated emission at relatively low pump power. At the nanometre scale, lanthanide-doped upconversion nanoparticles (UCNPs) can now be made with precisely controlled phase, dimension and doping level. When excited in the near-infrared, these UCNPs emit stable, bright visible luminescence at a variety of selectable wavelengths, with single-nanoparticle sensitivity, which makes them suitable for advanced luminescence microscopy applications. Here we show that UCNPs doped with high concentrations of thulium ions (Tm3+), excited at a wavelength of 980 nanometres, can readily establish a population inversion on their intermediate metastable 3H4 level: the reduced inter-emitter distance at high Tm3+ doping concentration leads to intense cross-relaxation, inducing a photon-avalanche-like effect that rapidly populates the metastable 3H4 level, resulting in population inversion relative to the 3H6 ground level within a single nanoparticle. As a result, illumination by a laser at 808 nanometres, matching the upconversion band of the 3H4 → 3H6 transition, can trigger amplified stimulated emission to discharge the 3H4 intermediate level, so that the upconversion pathway to generate blue luminescence can be optically inhibited. We harness these properties to realize low-power super-resolution stimulated emission depletion (STED) microscopy and achieve nanometre-scale optical resolution (nanoscopy), imaging single UCNPs; the resolution is 28 nanometres, that is, 1/36th of the wavelength. These engineered nanocrystals offer saturation intensity two orders of magnitude lower than those of fluorescent probes currently employed in stimulated emission depletion microscopy, suggesting a new way of alleviating the square-root law that typically limits the resolution that can be practically achieved by such techniques.

Thermal, optical and vibrational studies of tyrosine doped LaF3:Ce nanoparticles for bioimaging and biotagging

NASA Astrophysics Data System (ADS)

Singh, Amit T.

2018-05-01

Upconversion quantum dots of tyrosine doped LaF3:Ce nanoparticles have been synthesized by wet chemical route. The thermal studies (TGA/DTA) confirm the crystallinity and stability of different phases of synthesized nanoparticles. The UV-Visible spectra show multiple absorption edges at 215.60 nm and 243.10 nm indicating quantum dot nature of the synthesized nanoparticles. The PL spectra showed upconversion with sharp emission peak at 615 nm (red colour). The FT-RAMAN spectra of the synthesized nanoparticles show the modification of the surface of the nanoparticles in the form of functional groups and skeletal groups. Upconversion nature of the synthesized nanoparticles indicates their potential application in bioimaging and biotagging.

Er{sup 3+}/Yb{sup 3+}co-doped bismuth molybdate nanosheets upconversion photocatalyst with enhanced photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, Rajesh; Gyawali, Gobinda; Cho, Sung Hun

2014-01-15

In this paper, we report the microwave hydrothermal synthesis of Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst. Crystal structure, morphology, elemental composition, optical properties and BET surface area were analyzed in detail. Infrared to visible upconversion luminescence at 532 nm and 546 nm of the co-doped samples was investigated under excitation at 980 nm. The results revealed that the co-doping of Er{sup 3+}/Yb{sup 3+} into Bi{sub 2}MoO{sub 6} exhibited enhanced photocatalytic activity for the decomposition of rhodamine B under simulated solar light irradiation. Enhanced photocatalytic activity can be attributed to the energy transfer between Er{sup 3+}/Yb{sup 3+} andmore » Bi{sub 2}MoO{sub 6} via infrared to visible upconversion from Er{sup 3+}/Yb{sup 3+} ion and higher surface area of the Bi{sub 2}MoO{sub 6} nanosheets. Therefore, this synthetic approach may exhibit a better alternative to fabricate upconversion photocatalyst for integral solar light absorption. - Graphical abstract: Schematic illustration of the upconversion photocatalysis. Display Omitted - Highlights: • Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst is successfully synthesized. • We obtained the nanosheets having high surface area. • Upconversion of IR to visible light was confirmed. • Upconversion phenomena can be utilized for effective photocatalysis.« less

Luminescence properties of Tm3+ ions single-doped YF3 materials in an unconventional excitation region.

PubMed

Chen, Yuan; Liu, Qing; Lin, Han; Yan, Xiaohong

2018-05-01

According to the spectral distribution of solar radiation at the earth's surface, under the excitation region of 1150 to 1350 nm, the up-conversion luminescence of Tm 3+ ions was investigated. The emission bands were matched well with the spectral response region of silicon solar cells, achieved by Tm 3+ ions single-doped yttrium fluoride (YF 3 ) phosphor, which was different from the conventional Tm 3+ /Yb 3+ ion couple co-doped materials. Additionally, the similar emission bands of Tm 3+ ions were achieved under excitation in the ultraviolet region. It is expected that via up-conversion and down-conversion routes, Tm 3+ -sensitized materials could convert photons to the desired wavelengths in order to reduce the energy loss of silicon solar cells, thereby enhancing the photovoltaic efficiency. Copyright © 2018 John Wiley & Sons, Ltd.

Optical thermometry using fluorescence intensities multi-ratios in NaGdTiO4:Yb3+/Tm3+ phosphors

NASA Astrophysics Data System (ADS)

Zhou, Aihua; Song, Feng; Song, Feifei; Feng, Ming; Adnan, Khan; Ju, Dandan; Wang, Xueqing

2018-04-01

The NaGdTiO4:Yb3+/Tm3+ phosphor has been effectively synthesized by the traditional solid-state reaction method and its down-conversion and up-conversion luminescence properties were systematically studied. The results indicate that the electric dipole-dipole interaction is the main mechanism for the luminescence quenching. The fact that the ratios of the up-conversion intensities, i.e., I795nm/I798nm, I807nm/I798nm, and I812nm/I798nm, increase linearly with temperature (100 K-300 K) provides us a simple and accurate temperature measurement method. Multi-ratios can be more accurate than using only one ratio, allowing for self-referenced temperature determination. It's promising for NaGdTiO4: Yb3+/Tm3+ to be used for optical temperature sensors.

Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

NASA Technical Reports Server (NTRS)

Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

2011-01-01

This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and surface & interface temperatures), the TBC was more tolerant of damage. The main conclusions were that high heat flux conditions can not only accelerate TBC debond progression but can also grossly alter the pathway of delamination.

Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides.

PubMed

Lee, Sung-Min; Dhar, Purnim; Chen, Huandong; Montenegro, Angelo; Liaw, Lauren; Kang, Dongseok; Gai, Boju; Benderskii, Alexander V; Yoon, Jongseung

2017-04-25

Ultrathin silicon solar cells fabricated by anisotropic wet chemical etching of single-crystalline wafer materials represent an attractive materials platform that could provide many advantages for realizing high-performance, low-cost photovoltaics. However, their intrinsically limited photovoltaic performance arising from insufficient absorption of low-energy photons demands careful design of light management to maximize the efficiency and preserve the cost-effectiveness of solar cells. Herein we present an integrated flexible solar module of ultrathin, nanostructured silicon solar cells capable of simultaneously exploiting spectral upconversion and downshifting in conjunction with multispectral luminescent waveguides and a nanostructured plasmonic reflector to compensate for their weak optical absorption and enhance their performance. The 8 μm-thick silicon solar cells incorporating a hexagonally periodic nanostructured surface relief are surface-embedded in layered multispectral luminescent media containing organic dyes and NaYF 4 :Yb 3+ ,Er 3+ nanocrystals as downshifting and upconverting luminophores, respectively, via printing-enabled deterministic materials assembly. The ultrathin nanostructured silicon microcells in the composite luminescent waveguide exhibit strongly augmented photocurrent (∼40.1 mA/cm 2 ) and energy conversion efficiency (∼12.8%) than devices with only a single type of luminescent species, owing to the synergistic contributions from optical downshifting, plasmonically enhanced upconversion, and waveguided photon flux for optical concentration, where the short-circuit current density increased by ∼13.6 mA/cm 2 compared with microcells in a nonluminescent medium on a plain silver reflector under a confined illumination.

High-Precision Pinpointing of Luminescent Targets in Encoder-Assisted Scanning Microscopy Allowing High-Speed Quantitative Analysis.

PubMed

Zheng, Xianlin; Lu, Yiqing; Zhao, Jiangbo; Zhang, Yuhai; Ren, Wei; Liu, Deming; Lu, Jie; Piper, James A; Leif, Robert C; Liu, Xiaogang; Jin, Dayong

2016-01-19

Compared with routine microscopy imaging of a few analytes at a time, rapid scanning through the whole sample area of a microscope slide to locate every single target object offers many advantages in terms of simplicity, speed, throughput, and potential for robust quantitative analysis. Existing techniques that accommodate solid-phase samples incorporating individual micrometer-sized targets generally rely on digital microscopy and image analysis, with intrinsically low throughput and reliability. Here, we report an advanced on-the-fly stage scanning method to achieve high-precision target location across the whole slide. By integrating X- and Y-axis linear encoders to a motorized stage as the virtual "grids" that provide real-time positional references, we demonstrate an orthogonal scanning automated microscopy (OSAM) technique which can search a coverslip area of 50 × 24 mm(2) in just 5.3 min and locate individual 15 μm lanthanide luminescent microspheres with standard deviations of 1.38 and 1.75 μm in X and Y directions. Alongside implementation of an autofocus unit that compensates the tilt of a slide in the Z-axis in real time, we increase the luminescence detection efficiency by 35% with an improved coefficient of variation. We demonstrate the capability of advanced OSAM for robust quantification of luminescence intensities and lifetimes for a variety of micrometer-scale luminescent targets, specifically single down-shifting and upconversion microspheres, crystalline microplates, and color-barcoded microrods, as well as quantitative suspension array assays of biotinylated-DNA functionalized upconversion nanoparticles.

Synergistically Enhanced Performance of Ultrathin Nanostructured Silicon Solar Cells Embedded in Plasmonically Assisted, Multispectral Luminescent Waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sung-Min; Dhar, Purnim; Chen, Huandong

Ultrathin silicon solar cells fabricated by anisotropic wet chemical etching of single-crystalline wafer materials represent an attractive materials platform that could provide many advantages for realizing high-performance, low-cost photovoltaics. However, their intrinsically limited photovoltaic performance arising from insufficient absorption of low-energy photons demands careful design of light management to maximize the efficiency and preserve the cost-effectiveness of solar cells. Herein we present an integrated flexible solar module of ultrathin, nanostructured silicon solar cells capable of simultaneously exploiting spectral upconversion and downshifting in conjunction with multispectral luminescent waveguides and a nanostructured plasmonic reflector to compensate for their weak optical absorption andmore » enhance their performance. The 8 μm-thick silicon solar cells incorporating a hexagonally periodic nanostructured surface relief are surface-embedded in layered multispectral luminescent media containing organic dyes and NaYF4:Yb3+,Er3+ nanocrystals as downshifting and upconverting luminophores, respectively, via printing-enabled deterministic materials assembly. The ultrathin nanostructured silicon microcells in the composite luminescent waveguide exhibit strongly augmented photocurrent (~40.1 mA/cm2) and energy conversion efficiency (~12.8%) than devices with only a single type of luminescent species, owing to the synergistic contributions from optical downshifting, plasmonically enhanced upconversion, and waveguided photon flux for optical concentration, where the short-circuit current density increased by ~13.6 mA/cm2 compared with microcells in a nonluminescent medium on a plain silver reflector under a confined illumination.« less

Spiny Nanorod and Upconversion Nanoparticle Satellite Assemblies for Ultrasensitive Detection of Messenger RNA in Living Cells.

PubMed

Gao, Rui; Hao, Changlong; Xu, Liguang; Xu, Chuanlai; Kuang, Hua

2018-04-17

Quantitation and in situ monitoring of target mRNA (mRNA) in living cells remains a significant challenge for the chemical and biomedical communities. To quantitatively detect mRNA expression levels in living cells, we have developed DNA-driven gold nanorod coated platinum-upconversion nanoparticle satellite assemblies (termed Au NR@Pt-UCNP satellites) for intracellular thymidine kinase 1 (TK1) mRNA analysis. The nanostructures were capable of recognizing target mRNA in a sequence-specific manner as luminescence of UCNPs was effectively quenched by Au NR@Pt within the assemblies. Following recognition, UCNPs detached from Au NR@Pt, resulting in luminescence restoration to achieve effective in situ imaging and quantifiable detection of target mRNA. The upconversional luminescence intensity of confocal images showed a good linear relationship with intracellular TK1 mRNA ranging from 1.17 to 65.21 fmol/10 μg RNA and a limit of detection (LOD) of 0.67 fmol/10 μg RNA. We believe that our present assay can be broadly applied for detection of endogenous biomolecules at the cellular and tissue levels and restoration of tissue homeostasis in vivo.

Magnetic nanosensor particles in luminescence upconversion capability.

PubMed

Wilhelm, Stefan; Hirsch, Thomas; Scheucher, Elisabeth; Mayr, Torsten; Wolfbeis, Otto S

2011-09-05

Nanoparticles (NPs) exhibit interesting size-dependent electrical, optical, magnetic, and chemical properties that cannot be observed in their bulk counterparts. The synthesis of NPs (i.e., crystalline particles ranging in size from 1 to 100 nm) has been intensely studied in the past decades. Magnetic nanoparticles (MNPs) form a particularly attractive class of NPs and have found numerous applications such as in magnetic resonance imaging to visualize cancer, cardiovascular, neurological and other diseases. Other uses include drug targeting, tissue imaging, magnetic immobilization, hyperthermia, and magnetic resonance imaging. MNPs, due to their magnetic properties, can be easily separated from (often complex) matrices and manipulated by applying external magnetic field. Near-infrared to visible upconversion luminescent nanoparticles (UCLNPs) form another type of unusual nanoparticles. They are capable of emitting visible light upon NIR light excitation. Lanthanide-doped (Yb, Er) hexagonal NaYF₄ UCLNPs are the most efficient upconversion phosphors known up to now. The use of UCLNPs for in vitro imaging of cancer cells and in vivo imaging in tissues has been demonstrated. UCLNPs show great potential as a new class of luminophores for biological, biomedical, and sensor applications. We are reporting here on our first results on the combination of MNP and UCLNP technology within an ongoing project supported by the DFG and the FWF (Austria).

The influence of Ag content and annealing time on structural and optical properties of SGS antimony-germanate glass doped with Er3+ ions

NASA Astrophysics Data System (ADS)

Zmojda, J.; Kochanowicz, M.; Miluski, P.; Baranowska, A.; Basa, A.; Jadach, R.; Sitarz, M.; Dorosz, D.

2018-05-01

A series of erbium doped SGS antimony-germanate glass embedding silver (Ag0) nanoparticles have been synthesized by a one-step melt-quench thermochemical reduction technique. The effect of NPs concentration and annealing time on the structural and photoluminescent (PL) properties were investigated. The Raman spectra as a function of temperature measured in-situ allow to determine the structural changes in vicinity of Ag+ ions and confirmed thermochemical reduction of Ag+ ions by Sb3+ ions. The surface plasmon resonance absorption band was evidenced near 450 nm. The impact of local field effect generated by Ag0 nanoparticles (NPs) and energy transfer from surface of silver NPs to trivalent erbium ions on near-infrared and up-conversion luminescence was described in terms of enhancement and quench phenomena.

NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Er{sup 3+}/Yb{sup 3+}) microspheres: the synthesis and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Zhiyi; Wang, Zhiying; Fu, Linlin

The strong green upconversion (UC) emission were observed in various Er{sup 3+}, Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples synthesized via a hydrothermal route. The UC intensity depends on the dopant concentration, and the optimal UC emission was obtained in NaLa(MoO{sub 4}){sub 2}: 0.02Er{sup 3+}/0.10 Yb{sup 3+}. - Highlights: • The NaLa(MoO{sub 4}){sub 2} microspheres doped with Eu{sup 3+}, Sm{sup 3+} and Er{sup 3+}/Yb{sup 3+} were synthesized by a hydrothermal method. • The effects of the EDTA in the initial solution crystal phase and morphology were studied. • The down-conversion luminescence properties of NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+}more » = Eu{sup 3+}, Sm{sup 3+}) were investigated. • The UC luminescence properties and mechanism of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} was discussed. - Abstract: NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}) microspheres have been synthesized at 180 °C via a facile EDTA-mediated hydrothermal route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the samples. It was found that the amount of EDTA in the initial solution was responsible for crystal phase and shape determination. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity was also investigated in details. Furthermore, the up-conversion (UC) emissions have been observed in a series of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples. Concentration dependent studies revealed that the optimal composition was realized for a 2% Er{sup 3+} and 10% Yb{sup 3+}-doping concentration.« less

Chemical sensing and imaging based on photon upconverting nano- and microcrystals: a review

NASA Astrophysics Data System (ADS)

Christ, Simon; Schäferling, Michael

2015-09-01

The demand for photostable luminescent reporters that absorb and emit light in the red to near-infrared (NIR) spectral region continues in biomedical research and bioanalysis. In recent years, classical organic fluorophores have increasingly been displaced by luminescent nanoparticles. These consist of either polymer or silica based beads that are loaded with luminescent dyes, conjugated polymers, or inorganic nanomaterials such as semiconductor nanocrystals (quantum dots), colloidal clusters of silver and gold, or carbon dots. Among the inorganic materials, photon upconversion nanocrystals exhibit a high potential for application to bioimaging or biomolecular assays. They offer an exceptionally high photostability, can be excited in the NIR, and their anti-Stokes emission enables luminescence detection free of background and perturbing scatter effects even in complex biological samples. These lanthanide doped inorganic crystals have multiple emission lines that can be tuned by the selection of the dopants. This review article is focused on the applications of functionalized photon upconversion nanoparticles (UCNPs) to chemical sensing. This is a comparatively new field of research activity and mainly directed at the sensing and imaging of ubiquitous chemical analytes in biological samples, particularly in living cells. For this purpose, the particles have to be functionalized with suitable indicator dyes or recognition elements, as they do not show an intrinsic or specific luminescence response to most of these analytes (e.g. pH, oxygen, metal ions). We describe the strategies for the design of such responsive nanocomposites utilizing either luminescence resonance energy transfer or emission-reabsorption (inner filter effect) mechanisms and also highlight examples for their use either immobilized in sensor layers or directly as nanoprobes for intracellular sensing and imaging.

Infrared-to-visible conversion luminescence of Er 3+ ions in lead borate transparent glass-ceramics

NASA Astrophysics Data System (ADS)

Pisarski, Wojciech A.; Pisarska, Joanna; Lisiecki, Radosław; Grobelny, Łukasz; Dominiak-Dzik, Grażyna; Ryba-Romanowski, Witold

2009-10-01

Transparent glass-ceramics were successfully prepared during controlled heat treatment of lead borate glasses. The PbF 2 particles were dispersed into a borate glass matrix which was evidenced by X-ray diffraction analysis. The phase identification revealed that crystalline peaks can be related to the orthorhombic PbF 2 phase. Green up-conversion luminescence due to the 4S 3/2- 4I 15/2 transition of Er 3+ ions was registered. In comparison to the precursor glass the luminescence intensity was considerably higher, whereas the luminescence linewidth slightly decreased in the studied oxyfluoride transparent glass-ceramics. It indicated that a part of the trivalent erbium was incorporated into the PbF 2 crystalline phase.

NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties.

PubMed

Li, Anming; Xu, Dekang; Lin, Hao; Yang, Shenghong; Shao, Yuanzhi; Zhang, Yueli

2016-08-10

Pure tetragonal phase, uniform and well-crystallized sodium gadolinium molybdate (NaGd(MoO4)2) nanocrystals with diverse morphologies, e.g. nanocylinders, nanocubes and square nanoplates have been selectively synthesized via oleic acid-mediated hydrothermal method. The phase, structure, morphology and composition of the as-synthesized products are studied. Contents of both sodium molybdate and oleic acid of the precursor solutions are found to affect the morphologies of the products significantly, and oleic acid plays a key role in the morphology-controlled synthesis of NaGd(MoO4)2 nanocrystals with diverse morphologies. Growth mechanism of NaGd(MoO4)2 nanocrystals is proposed based on time-dependent morphology evolution and X-ray diffraction analysis. Morphology-dependent down-shifting photoluminescence properties of NaGd(MoO4)2: Eu(3+) nanocrystals, and upconversion photoluminescence properties of NaGd(MoO4)2: Yb(3+)/Er(3+) and Yb(3+)/Tm(3+) nanoplates are investigated in detail. Charge transfer band in the down-shifting excitation spectra shows a slight blue-shift, and the luminescence intensities and lifetimes of Eu(3+) are decreased gradually with the morphology of the nanocrystals varying from nanocubes to thin square nanoplates. Upconversion energy transfer mechanisms of NaGd(MoO4)2: Yb(3+)/Er(3+), Yb(3+)/Tm(3+) nanoplates are proposed based on the energy level scheme and power dependence of upconversion emissions. Thermometric properties of NaGd(MoO4)2: Yb(3+)/Er(3+) nanoplates are investigated, and the maximum sensitivity is determined to be 0.01333 K(-1) at 285 K.

NaGd(MoO4)2 nanocrystals with diverse morphologies: controlled synthesis, growth mechanism, photoluminescence and thermometric properties

PubMed Central

Li, Anming; Xu, Dekang; Lin, Hao; Yang, Shenghong; Shao, Yuanzhi; Zhang, Yueli

2016-01-01

Pure tetragonal phase, uniform and well-crystallized sodium gadolinium molybdate (NaGd(MoO4)2) nanocrystals with diverse morphologies, e.g. nanocylinders, nanocubes and square nanoplates have been selectively synthesized via oleic acid-mediated hydrothermal method. The phase, structure, morphology and composition of the as-synthesized products are studied. Contents of both sodium molybdate and oleic acid of the precursor solutions are found to affect the morphologies of the products significantly, and oleic acid plays a key role in the morphology-controlled synthesis of NaGd(MoO4)2 nanocrystals with diverse morphologies. Growth mechanism of NaGd(MoO4)2 nanocrystals is proposed based on time-dependent morphology evolution and X-ray diffraction analysis. Morphology-dependent down-shifting photoluminescence properties of NaGd(MoO4)2: Eu3+ nanocrystals, and upconversion photoluminescence properties of NaGd(MoO4)2: Yb3+/Er3+ and Yb3+/Tm3+ nanoplates are investigated in detail. Charge transfer band in the down-shifting excitation spectra shows a slight blue-shift, and the luminescence intensities and lifetimes of Eu3+ are decreased gradually with the morphology of the nanocrystals varying from nanocubes to thin square nanoplates. Upconversion energy transfer mechanisms of NaGd(MoO4)2: Yb3+/Er3+, Yb3+/Tm3+ nanoplates are proposed based on the energy level scheme and power dependence of upconversion emissions. Thermometric properties of NaGd(MoO4)2: Yb3+/Er3+ nanoplates are investigated, and the maximum sensitivity is determined to be 0.01333 K−1 at 285 K. PMID:27506629

Facile EG/ionic liquid interfacial synthesis of uniform RE(3+) doped NaYF(4) nanocubes.

PubMed

Zhang, Chao; Chen, Ji

2010-01-28

Uniform multicolor upconversion luminescent RE(3+) doped NaYF(4) nanocubes are fabricated through a facile ethylene glycol (EG)/ionic liquid interfacial synthesis route at 80 degrees C, with the ionic liquids acting as both reagents and templates.

Synthesis of novel branched β-NaLuF4: Yb/Er upconversion luminescence material and investigation of its optical properties

NASA Astrophysics Data System (ADS)

Ding, Yanli; Yang, Tonghui; Yin, Naiqiang; Shu, Fangjie; Zhao, Ying; Zhang, Xiaodan

2018-05-01

Branched β-NaLuF4: Yb/Er was synthesized using a simple hydrothermal method by controlling the NaF/Ln molar ratio. In contrast to the β-NaYF4: Yb/Er hexagonal disks, the branched β-NaLuF4: Yb/Er has stronger emission intensity. The integrated intensities of green and red emission bands were as 6.2 and 3.3 times as that of NaYF4, respectively. The branched β-NaLuF4: Yb/Er has the smaller unit cell volume, the higher absorption intensity around 980 nm and the lower crystal field symmetry than NaYF4, which made a significant contribution to the stronger upconversion (UC) fluorescence emissions. The results indicate that the branched β-NaLuF4: Yb/Er is an excellent UC luminescence material. The current research has a great potential in improving near-infrared conversion efficiency of solar cells.

M2+ Doping Induced Simultaneous Phase/Size Control and Remarkable Enhanced Upconversion Luminescence of NaLnF4 Probes for Optical-Guided Tiny Tumor Diagnosis.

PubMed

Li, Youbin; Li, Xiaolong; Xue, Zhenluan; Jiang, Mingyang; Zeng, Songjun; Hao, Jianhua

2017-05-01

Doping has played a vital role in constructing desirable hybrid materials with tunable functions and properties via incorporating atoms into host matrix. Herein, a simple strategy for simultaneously modifying the phase, size, and upconversion luminescence (UCL) properties of the NaLnF 4 (Ln = Y, Yb) nanocrystals by high-temperature coprecipitation through nonequivalent M 2+ doping (M = Mg 2+ , Co 2+ ) has been demonstrated. The phase transformation from cubic to hexagonal is readily achieved by doping M 2+ . Compared with Mg-free sample, a remarkable enhancement of overall UCL (≈27.5 times) is obtained by doping Mg 2+ . Interestingly, owing to the efficient UCL, red UCL-guided tiny tumor (down to 3 mm) diagnosis is demonstrated for the first time. The results open up a new way of designing high efficient UCL probe with combination of hexagonal phase and small size for tiny tumor detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multifunctional nanoparticles for upconversion luminescence/MR multimodal imaging and magnetically targeted photothermal therapy.

PubMed

Cheng, Liang; Yang, Kai; Li, Yonggang; Zeng, Xiao; Shao, Mingwang; Lee, Shuit-Tong; Liu, Zhuang

2012-03-01

Theranostics, the combination of diagnostics and therapies, has become a new concept in the battles with various major diseases such as cancer. Herein, we develop multifunctional nanoparticles (MFNPs) with highly integrated functionalities including upconversion luminescence, superparamagnetism, and strong optical absorption in the near-infrared (NIR) region with high photostability. In vivo dual modal optical/magnetic resonance imaging of mice uncovers that by placing a magnet nearby the tumor, MFNPs tend to migrate toward the tumor after intravenous injection and show high tumor accumulation, which is ~8 folds higher than that without magnetic targeting. NIR laser irradiation is then applied to the tumors grown on MFNP-injected mice under magnetic tumor-targeting, obtaining an outstanding photothermal therapeutic efficacy with 100% of tumor elimination in a murine breast cancer model. We present here a strategy for multimodal imaging-guided, magnetically targeted physical cancer therapy and highlight the promise of using multifunctional nanostructures for cancer theranostics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Quadratic general rotary unitized design for doping concentrations and up-conversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jiashi, E-mail: sunjs@dlmu.edu.cn; Shi, Linlin; Li, Shuwei

Highlights: • NaLa(MoO4)2: Er3+/Yb3+ phosphor is synthesized by solid state method. • QGRUD is first applied to the codoping concentration option. • Optimized phosphor presents more stable UC emissions than the commercial phosphor. - Abstract: It is still a great challenge that designing proper codoping concentrations of rare earth ions for achieving intensest expected emission from the studied phosphor. In this work, the quadratic general rotary unitized design (QGRUD) was introduced into the codoping concentration option of NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor for upconversion (UC) applications, and the optimum doping concentrations of Er{sup 3+} and Yb{sup 3+} formore » achieving maximum UC luminescence intensity, which is close to commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor, were obtained. The two-photon process was assigned to the green UC emissions in the optimized NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor. It was also demonstrated that the optimized phosphor presented more stable upconversion emissions than the commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor.« less

In vitro cell imaging using multifunctional small sized KGdF4:Yb3+,Er3+ upconverting nanoparticles synthesized by a one-pot solvothermal process

NASA Astrophysics Data System (ADS)

Wong, Hon-Tung; Tsang, Ming-Kiu; Chan, Chi-Fai; Wong, Ka-Leung; Fei, Bin; Hao, Jianhua

2013-03-01

Multifunctional KGdF4:18%Yb3+,2%Er3+ nanoparticles with upconversion fluorescence and paramagnetism are synthesized. The average sizes of the nanoparticles capped with branched polyethyleneimine (PEI) and 6-aminocaproic acid (6AA) are ~14 and ~13 nm, respectively. Our KGdF4 host does not exhibit any phase change with the decrease of particle size, which can prevent the detrimental significant decrease in upconversion luminescence caused by this effect observed in the well-known NaYF4 host. The branched PEI and 6AA capping ligands endow our nanoparticles with water-dispersibility and biocompatibility, which can favor internalization of our nanoparticles into the cytoplasm of HeLa cells and relatively high cell viability. The strong upconversion luminescence detected at the cytoplasm of HeLa cells incubated with the branched PEI-capped nanoparticles is probably attributed to the reported high efficiency of cellular uptake. The magnetic mass susceptibility of our nanoparticle is 8.62 × 10-5 emu g-1 Oe-1. This is the highest value ever reported in trivalent rare-earth ion-doped KGdF4 nanoparticles of small size (<=14 nm), and is very close to that of nanoparticles used as T1 contrast agents in magnetic resonance imaging. These suggest the potential of our KGdF4:Yb3+,Er3+ nanoparticles as small-sized multifunctional bioprobes.

Multiple Temperature-Sensing Behavior of Green and Red Upconversion Emissions from Stark Sublevels of Er³⁺.

PubMed

Cao, Baosheng; Wu, Jinlei; Wang, Xuehan; He, Yangyang; Feng, Zhiqing; Dong, Bin

2015-12-10

Upconversion luminescence properties from the emissions of Stark sublevels of Er(3+) were investigated in Er(3+)-Yb(3+)-Mo(6+)-codoped TiO₂ phosphors in this study. According to the energy levels split from Er(3+), green and red emissions from the transitions of four coupled energy levels, ²H11/2(I)/²H11/2(II), ⁴S3/2(I)/⁴S3/2(II), ⁴F9/2(I)/⁴F9/2(II), and ²H11/2(I) + ²H11/2(II)/⁴S3/2(I) + ⁴S3/2(II), were observed under 976 nm laser diode excitation. By utilizing the fluorescence intensity ratio (FIR) technique, temperature-dependent upconversion emissions from these four coupled energy levels were analyzed at length. The optical temperature-sensing behaviors of sensing sensitivity, measurement error, and operating temperature for the four coupled energy levels are discussed, all of which are closely related to the energy gap of the coupled energy levels, FIR value, and luminescence intensity. Experimental results suggest that Er(3+)-Yb(3+)-Mo(6+)-codoped TiO₂ phosphor with four pairs of energy levels coupled by Stark sublevels provides a new and effective route to realize multiple optical temperature-sensing through a wide range of temperatures in an independent system.

Current advances in lanthanide ion (Ln(3+))-based upconversion nanomaterials for drug delivery.

PubMed

Yang, Dongmei; Ma, Ping'an; Hou, Zhiyou; Cheng, Ziyong; Li, Chunxia; Lin, Jun

2015-03-21

Lanthanide ion (Ln(3+))-based upconversion nano/micromaterials that emit higher-energy visible light when excited by low-energy NIR light have aroused considerable attention in the forefront of materials science and biomedical fields, which stems from their unique optical and chemical properties including minimum photodamage to living organisms, low autofluorescence, high signal-to-noise ratio and detection sensitivity, and high penetration depth in biological or environmental samples. Thus, Ln(3+)-based upconversion materials are rising new stars and are quickly emerging as potential candidates to revolutionize novel biomedical applications. In this review article, we mainly focus on the recent progress in various chemical syntheses of Ln(3+)-based upconversion nanomaterials, with special emphasis on their application in stimuli-response controlled drug release and subsequent therapy. Functional groups that are introduced into the stimuli-responsive system can respond to external triggers, such as pH, temperature, light, and even magnetic fields, which can regulate the movement of the pharmaceutical cargo and release the drug at a desired time and in a desired area. This is crucial to boost drug efficacy in cancer treatment while minimizing the side effects of cytotoxic drugs. Many multifunctional (magnetic/upconversion luminescence and porous) composite materials based on Ln(3+) have been designed for controlled drug delivery and multimodal bioimaging. Finally, the challenges and future opportunities for Ln(3+)-based upconversion materials are discussed.

Lanthanide-doped NaScF4 nanoprobes: crystal structure, optical spectroscopy and biodetection

NASA Astrophysics Data System (ADS)

Ai, Yu; Tu, Datao; Zheng, Wei; Liu, Yongsheng; Kong, Jintao; Hu, Ping; Chen, Zhuo; Huang, Mingdong; Chen, Xueyuan

2013-06-01

Trivalent lanthanide ions (Ln3+)-doped inorganic nanoparticles (NPs) as potential luminescent bioprobes have been attracting tremendous interest because of their unique upconversion (UC) and downconversion (DC) luminescence properties. NaScF4, as an important host material, has been rarely reported and its crystal structure remains unclear. Herein, based on the single crystal X-ray diffraction, the space group of NaScF4 crystals was determined to be P31 containing multiple sites of Sc3+ with crystallographic site symmetry of C1, which was verified by high-resolution photoluminescence spectroscopy of Eu3+ at low temperature (10 K). Furthermore, monodisperse and size-controllable NaScF4:Ln3+ NPs were synthesized via a facile thermal decomposition method. The biotinylated NaScF4:Er3+/Yb3+ NPs were demonstrated for their applications as a heterogeneous UC luminescence bioprobe to detect avidin with a detection limit of 180 pM. After bioconjugation with amino-terminal fragment (ATF) of urokinase plasminogen activator (uPA), NaScF4:Ln3+ NPs also exhibited specific recognition of cancer cells overexpressed with uPA receptor (uPAR, an important marker of tumor biology and metastasis), showing great potentials in tumor-targeted bioimaging.Trivalent lanthanide ions (Ln3+)-doped inorganic nanoparticles (NPs) as potential luminescent bioprobes have been attracting tremendous interest because of their unique upconversion (UC) and downconversion (DC) luminescence properties. NaScF4, as an important host material, has been rarely reported and its crystal structure remains unclear. Herein, based on the single crystal X-ray diffraction, the space group of NaScF4 crystals was determined to be P31 containing multiple sites of Sc3+ with crystallographic site symmetry of C1, which was verified by high-resolution photoluminescence spectroscopy of Eu3+ at low temperature (10 K). Furthermore, monodisperse and size-controllable NaScF4:Ln3+ NPs were synthesized via a facile thermal decomposition method. The biotinylated NaScF4:Er3+/Yb3+ NPs were demonstrated for their applications as a heterogeneous UC luminescence bioprobe to detect avidin with a detection limit of 180 pM. After bioconjugation with amino-terminal fragment (ATF) of urokinase plasminogen activator (uPA), NaScF4:Ln3+ NPs also exhibited specific recognition of cancer cells overexpressed with uPA receptor (uPAR, an important marker of tumor biology and metastasis), showing great potentials in tumor-targeted bioimaging. Electronic supplementary information (ESI) available: Crystallographic data (CCDC 931481) in CIF format. EDX analysis of NaScF4:Er3+/Yb3+ NPs. 10 K PL excitation spectra of NaScF4:Eu3+ microcrystals. Selected bond lengths and angles for NaScF4 crystals. Atomic coordinates and equivalent isotropic displacement parameters for NaScF4 crystals. UC quantum yield data of NaScF4:Er3+/Yb3+ NPs. See DOI: 10.1039/c3nr01529g

Tunable green/red luminescence by infrared upconversion in biocompatible forsterite nanoparticles with high erbium doping uptake

NASA Astrophysics Data System (ADS)

Zampiva, Rúbia Young Sun; Acauan, Luiz Henrique; Venturini, Janio; Garcia, Jose Augusto Martins; da Silva, Diego Silverio; Han, Zhaohong; Kassab, Luciana Reyes Pires; Wetter, Niklaus Ursus; Agarwal, Anuradha; Alves, Annelise Kopp; Bergmann, Carlos Pérez

2018-02-01

Nanoparticles represent a promising platform for diagnostics and therapy of human diseases. For biomedical applications, these nanoparticles are usually coated with photosensitizers regularly activated in a spectral window of 530-700 nm. The emissions at 530 nm (green) and 660 nm (red) are of particular interest for imaging and photodynamic therapy, respectively. This work presents the Mg2SiO4:Er3+ system, produced by reverse strike co-precipitation, with up to 10% dopant and no secondary phase formation. These nanoparticles when excited at 985 nm show upconversion emission with peaks around 530 and 660 nm, although excitation at 808 nm leads to only a single emission peak at around 530 nm. The direct upconversion of this biomaterial without a co-dopant, and its tunability by the excitation source, renders Mg2SiO4:Er3+ nanoparticles a promising system for biomedical applications.

Tuning sputtered gold thickness to enhance absorption and emission in core-shell type erbium doped upconversion nanoparticles

NASA Astrophysics Data System (ADS)

Manurung, R. V.; Wu, C. T.; Chattopadhyay, S.

2018-03-01

Upconversion nanoparticles (UCNPs) converts near-infrared excitation to visible emission with advantages e.g. photostable, non-blinking, and background-free probes for bioimaging and biosensor. However, low quantum yield and low efficiency (∼1%) as drawback need to be enhanced. A plasmonic gold nano-structured surface was designed and fabricated to couple with the 980 nm radiation and produce plasmonic enhancement of the upconversion luminescence. The synthesis of the UCNPs was done by thermal decomposition and SiO2 coating prepared by the reverse microemulsion process. Here, we report a novel tunable plasmon-enhanced fluorescence by modulating the thickness and surface roughness of gold island film on Si. The localized surface plasmon resonance (LSPR) at 980 nm was obtained, matched with the native excitation of UCNPs resulting in maximum enhancement of 10-fold of green emission band at 540 nm for the Er-doped UCNPs.

Frequency upconversion in Er3+ doped tungsten tellurite glass containing Ag nanoparticles

NASA Astrophysics Data System (ADS)

Mahajan, S. K.; Parashar, J.

2018-05-01

The frequency upconversion emission in Er3+ doped TeO2-WO3-Li2O containing Ag nanoparticle (TWLEOAG) glasses at 980nm excitation is reported. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around 525nm and 650 nm. The spherical AgNPs with average size ˜38 nm in the glassy matrix is evidenced from the TEM measurement. Under 980nm laser excitation upconversion emission spectra show two major emission at 550nm and 638nm originating from 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively was observed. Upconversion emission enhancement factor 7 fold has been measured for sample heat treated during 40h. However for 18h heat treated TWLEOAG sample under 980 nm flash lamp excitation produced Intense green compare to red emission. Since the 980nm frequency is far from the AgNPs surface plasmon resonance frequency, visible emission ehancement is attributed to local field increase in proximity of the Ag NPs and not energy tranfer from NPs to emitters. Possible energy transfer upconversion mechanism has been also discussed.

Simultaneous realization of Hg2+ sensing, magnetic resonance imaging and upconversion luminescence in vitro and in vivo bioimaging based on hollow mesoporous silica coated UCNPs and ruthenium complex

NASA Astrophysics Data System (ADS)

Ge, Xiaoqian; Sun, Lining; Ma, Binbin; Jin, Di; Dong, Liang; Shi, Liyi; Li, Nan; Chen, Haige; Huang, Wei

2015-08-01

We have constructed a multifunctional nanoprobe with sensing and imaging properties by using hollow mesoporous silica coated upconversion nanoparticles (UCNPs) and Hg2+ responsive ruthenium (Ru) complex. The Ru complex was loaded into the hollow mesoporous silica and the UCNPs acted as an energy donor, transferring luminescence energy to the Ru complex. Furthermore, polyethylenimine (PEI) was assembled on the surface of mesoporous silica to achieve better hydrophilic and bio-compatibility. Upon addition of Hg2+, a blue shift of the absorption peak of the Ru complex is observed and the energy transfer process between the UCNPs and the Ru complex was blocked, resulting in an increase of the green emission intensity of the UCNPs. The un-changed 801 nm emission of the nanoprobe was used as an internal standard reference and the detection limit of Hg2+ was determined to be 0.16 μM for this nanoprobe in aqueous solution. In addition, based on the low cytotoxicity as studied by CCK-8 assay, the nanoprobe was successfully applied for cell imaging and small animal imaging. Furthermore, when doped with Gd3+ ions, the nanoprobe was successfully applied to in vivo magnetic resonance imaging (MRI) of Kunming mice, which demonstrates its potential as a MRI positive-contrast agent. Therefore, the method and results may provide more exciting opportunities to afford nanoprobes with multimodal bioimaging and multifunctional applications.We have constructed a multifunctional nanoprobe with sensing and imaging properties by using hollow mesoporous silica coated upconversion nanoparticles (UCNPs) and Hg2+ responsive ruthenium (Ru) complex. The Ru complex was loaded into the hollow mesoporous silica and the UCNPs acted as an energy donor, transferring luminescence energy to the Ru complex. Furthermore, polyethylenimine (PEI) was assembled on the surface of mesoporous silica to achieve better hydrophilic and bio-compatibility. Upon addition of Hg2+, a blue shift of the absorption peak of the Ru complex is observed and the energy transfer process between the UCNPs and the Ru complex was blocked, resulting in an increase of the green emission intensity of the UCNPs. The un-changed 801 nm emission of the nanoprobe was used as an internal standard reference and the detection limit of Hg2+ was determined to be 0.16 μM for this nanoprobe in aqueous solution. In addition, based on the low cytotoxicity as studied by CCK-8 assay, the nanoprobe was successfully applied for cell imaging and small animal imaging. Furthermore, when doped with Gd3+ ions, the nanoprobe was successfully applied to in vivo magnetic resonance imaging (MRI) of Kunming mice, which demonstrates its potential as a MRI positive-contrast agent. Therefore, the method and results may provide more exciting opportunities to afford nanoprobes with multimodal bioimaging and multifunctional applications. Electronic supplementary information (ESI) available: DLS of Ru-UCNPs@HmSiO2-PEI in water. The zeta potential. The XRD patterns. EDX spectrum of Ru-UCNPs@HmSiO2-PEI. FT-IR spectra. N2 adsorption-desorption isotherm and pore size distribution. The investigation of the stability of Ru-UCNPs@HmSiO2-PEI. TG curves. UV/Vis absorption spectra of Ru complex at different concentrations. The sensitivity test of Ru-UCNPs@HmSiO2-PEI towards Hg2+. Cell viabilities of HeLa cells incubated with Ru-UCNPs@HmSiO2-PEI. See DOI: 10.1039/c5nr04006j

3D assembly of upconverting NaYF4 nanocrystals by AFM nanoxerography: creation of anti-counterfeiting microtags

NASA Astrophysics Data System (ADS)

Sangeetha, Neralagatta M.; Moutet, Pierre; Lagarde, Delphine; Sallen, Gregory; Urbaszek, Bernhard; Marie, Xavier; Viau, Guillaume; Ressier, Laurence

2013-09-01

Formation of 3D close-packed assemblies of upconverting NaYF4 colloidal nanocrystals (NCs) on surfaces, by Atomic Force Microscopy (AFM) nanoxerography is presented. The surface potential of the charge patterns, the NC concentration, the polarizability of the NCs and the polarity of the dispersing solvent are identified as the key parameters controlling the assembly of NaYF4 NCs into micropatterns of the desired 3D architecture. This insight allowed us to fabricate micrometer sized Quick Response (QR) codes encoded in terms of upconversion luminescence intensity or color. Topographically hidden messages could also be readily incorporated within these microtags. This work demonstrates that AFM nanoxerography has enormous potential for generating high-security anti-counterfeiting microtags.Formation of 3D close-packed assemblies of upconverting NaYF4 colloidal nanocrystals (NCs) on surfaces, by Atomic Force Microscopy (AFM) nanoxerography is presented. The surface potential of the charge patterns, the NC concentration, the polarizability of the NCs and the polarity of the dispersing solvent are identified as the key parameters controlling the assembly of NaYF4 NCs into micropatterns of the desired 3D architecture. This insight allowed us to fabricate micrometer sized Quick Response (QR) codes encoded in terms of upconversion luminescence intensity or color. Topographically hidden messages could also be readily incorporated within these microtags. This work demonstrates that AFM nanoxerography has enormous potential for generating high-security anti-counterfeiting microtags. Electronic supplementary information (ESI) available: Detailed experimental procedures for the synthesis of upconverting NaYF4 nanocrystals and their transmission electron microscopy images. KFM and AFM images corresponding to the assembly of positively charged β-NaYF4:Er3+,Yb3+ nanocrystals from water suspensions by AFM nanoxerography. Photoluminescence spectra of β-NaYF4:Er3+,Yb3+ nanocrystals in a hexane suspension and assembled on charge patterns. See DOI: 10.1039/c3nr02734a

Ultrafast fluorescence spectroscopy via upconversion applications to biophysics.

PubMed

Xu, Jianhua; Knutson, Jay R

2008-01-01

This chapter reviews basic concepts of nonlinear fluorescence upconversion, a technique whose temporal resolution is essentially limited only by the pulse width of the ultrafast laser. Design aspects for upconversion spectrophotofluorometers are discussed, and a recently developed system is described. We discuss applications in biophysics, particularly the measurement of time-resolved fluorescence spectra of proteins (with subpicosecond time resolution). Application of this technique to biophysical problems such as dynamics of tryptophan, peptides, proteins, and nucleic acids is reviewed.

Enhancement of red upconversion emission of cubic phase NaLuF{sub 4}: Yb{sup 3+}/Ho{sup 3+}/Ce{sup 3+} nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Wei, E-mail: gaowei@xupt.edu.com; Dong, Jun, E-mail: dongjun@xupt.edu.cn; Liu, Jihong

Highlights: • The upconversion emission of Ho{sup 3+} ions was tuned from green to red. • The upconversion mechanism of Ho{sup 3+} ions was discussed based on emission spectrum. • The conversion efficiency between Ho{sup 3+} and Ce{sup 3+} were studied and calculated. - Abstract: The red upconversion emission of lanthanide-doped fluoride nanocrystals have great potential applications in color display and anticounterfeiting applications, especially for biological imaging and biomedical. In this work, a significant enhancement of red upconversion emission of Ho{sup 3+} ions was successfully obtained in the cubic phase NaLuF{sub 4} nanocrystals through codoping Ce{sup 3+} ions under NIRmore » 980 nm excitation. The ratio of red-to-green emission of Ho{sup 3+} ions was enhanced about 10-fold, which is due to two efficient cross relaxation processes derived from Ho{sup 3+} and Ce{sup 3+} ions promoted the red emission and quenched the green emission. The upconversion emission and luminescent colors of NaLuF{sub 4}: Yb{sup 3+}/Ho{sup 3+} nanocrystals were carefully investigated by a confocal microscopy setup. The possible upconversion emission mechanism and conversion efficiency of cross relaxation between Ho{sup 3+} and Ce{sup 3+} ions were discussed in detail. The current study suggests that strong red emission of NaLuF{sub 4}: Yb{sup 3+}/Ho{sup 3+}/Ce{sup 3+} nanomaterials can be used for color display and anticounterfeiting techniques.« less

A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

NASA Astrophysics Data System (ADS)

Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

2016-02-01

The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale. Electronic supplementary information (ESI) available: Characterization, structural and morphological characterization of nanocrystals, the measurement setup. See DOI: 10.1039/c5nr08223d

Multicolour synthesis in lanthanide-doped nanocrystals through cation exchange in water

NASA Astrophysics Data System (ADS)

Han, Sanyang; Qin, Xian; An, Zhongfu; Zhu, Yihan; Liang, Liangliang; Han, Yu; Huang, Wei; Liu, Xiaogang

2016-10-01

Meeting the high demand for lanthanide-doped luminescent nanocrystals across a broad range of fields hinges upon the development of a robust synthetic protocol that provides rapid, just-in-time nanocrystal preparation. However, to date, almost all lanthanide-doped luminescent nanomaterials have relied on direct synthesis requiring stringent controls over crystal nucleation and growth at elevated temperatures. Here we demonstrate the use of a cation exchange strategy for expeditiously accessing large classes of such nanocrystals. By combining the process of cation exchange with energy migration, the luminescence properties of the nanocrystals can be easily tuned while preserving the size, morphology and crystal phase of the initial nanocrystal template. This post-synthesis strategy enables us to achieve upconversion luminescence in Ce3+ and Mn2+-activated hexagonal-phased nanocrystals, opening a gateway towards applications ranging from chemical sensing to anti-counterfeiting.

Infrared upconversion for astronomical applications. [laser applications to astronomical spectroscopy of infrared spectra

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Kostiuk, T.; Ogilvie, K. W.

1975-01-01

The performance of an upconversion system is examined for observation of astronomical sources in the low to middle infrared spectral range. Theoretical values for the performance parameters of an upconversion system for astronomical observations are evaluated in view of the conversion efficiencies, spectral resolution, field of view, minimum detectable source brightness and source flux. Experimental results of blackbody measurements and molecular absorption spectrum measurements using a lithium niobate upconverter with an argon-ion laser as the pump are presented. Estimates of the expected optimum sensitivity of an upconversion device which may be built with the presently available components are given.

Ultrafast Fluorescence Spectroscopy via Upconversion: Applications to Biophysics

PubMed Central

Xu, Jianhua; Knutson, Jay R.

2012-01-01

This chapter reviews basic concepts of nonlinear fluorescence upconversion, a technique whose temporal resolution is essentially limited only by the pulse width of the ultrafast laser. Design aspects for upconversion spectrophotofluorometers are discussed, and a recently developed system is described. We discuss applications in biophysics, particularly the measurement of time-resolved fluorescence spectra of proteins (with subpicosecond time resolution). Application of this technique to biophysical problems such as dynamics of tryptophan, peptides, proteins, and nucleic acids is reviewed. PMID:19152860

Cubic sub-20 nm NaLuF(4)-based upconversion nanophosphors for high-contrast bioimaging in different animal species.

PubMed

Yang, Tianshe; Sun, Yun; Liu, Qian; Feng, Wei; Yang, Pengyuan; Li, Fuyou

2012-05-01

A new upconversion luminescence (UCL) nanophosphors based on host matrix of cubic NaLuF(4) with bright luminescence have been synthesized by a solvothermal method, facilitate the nanocrystals potential candidates for imaging in vivo, especially large-animals. The sub-20 nm NaLuF(4) co-doped Yb(3+) and Er(3+) (Tm(3+)) showed about 10-fold stronger UCL emission than that of corresponding hexagonal NaYF(4)-based nanocrystals with a 20 nm diameter. Near-infrared to near-infrared (NIR-to-NIR) UCL emission of PAA-coated NaLuF(4):20%Yb,1%Tm (PAA-Lu(Tm)) can penetrate >1.5 cm tissue of pork with high contrast. Based on super-strong UCL emission and deep penetration, PAA-Lu(Tm) as optical bioprobe has been demonstrated by in vivo UCL imaging of a normal black mouse, even rabbit with excellent signal-to-noise ratio. Furthermore, such cubic NaLuF(4)-based nanophosphor was applied in lymph node imaging of live Kunming mouse with rich white fur. Copyright © 2012 Elsevier Ltd. All rights reserved.

Paradigms and challenges for bioapplication of rare earth upconversion luminescent nanoparticles: small size and tunable emission/excitation spectra.

PubMed

Sun, Ling-Dong; Wang, Ye-Fu; Yan, Chun-Hua

2014-04-15

Rare earth (RE) materials, which are excited in the ultraviolet and emit in the visible light spectrum, are widely used as phosphors for lamps and displays. In the 1960's, researchers reported an abnormal emission phenomenon where photons emitted from a RE element carried more energy than those absorbed, owing to the sequential energy transfer between two RE ions--Yb(3+)-sensitized Er(3+) or Tm(3+)--in the solid state. After further study, researchers named this abnormal emission phenomenon upconversion (UC) emission. More recent approaches take advantage of solution-based synthesis, which allows creation of homogenous RE nanoparticles (NPs) with controlled size and structure that are capable of UC emission. Such nanoparticles are useful for many applications, especially in biology. For these applications, researchers seek small NPs with high upconversion emission intensity. These UCNPs have the potential to have multicolor and tunable emissions via various activators. A vast potential for future development remains by developing molecular antennas and energy transfer within RE ions. We expect UCNPs with optimized spectra behavior to meet the increasing demand of potential applications in bioimaging, biological detection, and light conversion. This Account focuses on efforts to control the size and modulate the spectra of UCNPs. We first review efforts in size control. One method is careful control of the synthesis conditions to manipulate particle nucleation and growth, but more recently researchers have learned that the doping conditions can affect the size of UCNPs. In addition, constructing homogeneous core/shell structures can control nanoparticle size by adjusting the shell thickness. After reviewing size control, we consider how diverse applications impose different requirements on excitation and/or emission photons and review recent developments on tuning of UC spectral profiles, especially the extension of excitation/emission wavelengths and the adjustment and purification of emission colors. We describe strategies that employ various dopants and others that build rationally designed nanostructures and nanocomposites to meet these goals. As the understanding of the energy transfer in the UC process has improved, core/shell structures have been proved useful for simultaneous tuning of excitation and emission wavelengths. Finally, we present a number of typical examples to highlight the upconverted emission in various applications, including imaging, detection, and sensing. We believe that with deeper understanding of emission phenomena and the ability to tune spectral profiles, UCNPs could play an important role in light conversion studies and applications.

Synthesis and Characterization of Monodisperse Core-shell Lanthanide Upconversion Nanoparticles NaYF4: Yb,Tm/SiO2

NASA Astrophysics Data System (ADS)

Manurung, R. V.; Wiranto, G.; Hermida, I. D. P.

2018-05-01

Lanthanide up-converting luminescent nanoparticles (UCNPs) are exciting and promising materials for optical bioimaging, biosensor and theranostic due to their unique and advantageous optical and chemical properties. The UCNPs absorb low energy near-infrared (NIR) light and emit high-energy shorter wavelength photons (visible light). Their unique features allow them to overcome various problems associated with conventional imaging probes such as photostability, lack of toxicity, and to provide versatility for creating nanoplatforms with both imaging and therapeutic modalities. This paper reports synthesis and characterization of core-shell structured of NaYF4:Yb,Tm/SiO2 microspheres. The synthesis of lanthanide upconversion nanoparticles NaYF4:Yb,Tm was prepared by thermal decomposition process which involves dissolving organic precursors in high-boiling-point solvents oleic acid (OA) and octadecene (ODE). After that, the NaYF4:Yb,Tm phosphors was coated by silica via reverse microemulsion process to obtain core-shell structured NaYF4:Yb,Tm/SiO2. Scanning electron microscopy, transmission electron microscopy, specific area electron diffraction, and photoluminescence were applied to characterize these samples. The obtained core-shell structured NaYF4:Yb,Tm/SiO2 phosphors exhibit a perfect cubic morphology with narrow size distribution and smooth surface. Upon IR excitation at 980 nm, the NaYF4:Yb,Tm/SiO2 samples exhibit whitish blue upconversion (UC) luminescence, respectively. These phosphors show potential applications in the displaying on biological fields and biosensing.

Flexible transparent displays based on core/shell upconversion nanophosphor-incorporated polymer waveguides

PubMed Central

Park, Bong Je; Hong, A-Ra; Park, Suntak; Kyung, Ki-Uk; Lee, Kwangyeol; Seong Jang, Ho

2017-01-01

Core/shell (C/S)-structured upconversion nanophosphor (UCNP)-incorporated polymer waveguide-based flexible transparent displays are demonstrated. Bright green- and blue-emitting Li(Gd,Y)F4:Yb,Er and Li(Gd,Y)F4:Yb,Tm UCNPs are synthesized via solution chemical route. Their upconversion luminescence (UCL) intensities are enhanced by the formation of C/S structure with LiYF4 shell. The Li(Gd,Y)F4:Yb,Er/LiYF4 and Li(Gd,Y)F4:Yb,Tm/LiYF4 C/S UCNPs exhibit 3.3 and 2.0 times higher UCL intensities than core counterparts, respectively. In addition, NaGdF4:Yb,Tm/NaGdF4:Eu C/S UCNPs are synthesized and they show red emission via energy transfer and migration of Yb3+ → Tm3+ → Gd3+ → Eu3+. The C/S UCNPs are incorporated into bisphenol A ethoxylate diacrylate which is used as a core material of polymer waveguides. The fabricated stripe-type polymer waveguides are highly flexible and transparent (transmittance > 90% in spectral range of 443–900 nm). The polymer waveguides exhibit bright blue, green, and red luminescence, depending on the incorporated UCNPs into the polymer core, under coupling with a near infrared (NIR) laser. Moreover, patterned polymer waveguide-based display devices are fabricated by reactive ion etching process and they realize bright blue-, green-, and red-colored characters under coupling with an NIR laser. PMID:28368021

Accurate Quantitative Sensing of Intracellular pH based on Self-ratiometric Upconversion Luminescent Nanoprobe.

PubMed

Li, Cuixia; Zuo, Jing; Zhang, Li; Chang, Yulei; Zhang, Youlin; Tu, Langping; Liu, Xiaomin; Xue, Bin; Li, Qiqing; Zhao, Huiying; Zhang, Hong; Kong, Xianggui

2016-12-09

Accurate quantitation of intracellular pH (pH i ) is of great importance in revealing the cellular activities and early warning of diseases. A series of fluorescence-based nano-bioprobes composed of different nanoparticles or/and dye pairs have already been developed for pH i sensing. Till now, biological auto-fluorescence background upon UV-Vis excitation and severe photo-bleaching of dyes are the two main factors impeding the accurate quantitative detection of pH i . Herein, we have developed a self-ratiometric luminescence nanoprobe based on förster resonant energy transfer (FRET) for probing pH i , in which pH-sensitive fluorescein isothiocyanate (FITC) and upconversion nanoparticles (UCNPs) were served as energy acceptor and donor, respectively. Under 980 nm excitation, upconversion emission bands at 475 nm and 645 nm of NaYF 4 :Yb 3+ , Tm 3+ UCNPs were used as pH i response and self-ratiometric reference signal, respectively. This direct quantitative sensing approach has circumvented the traditional software-based subsequent processing of images which may lead to relatively large uncertainty of the results. Due to efficient FRET and fluorescence background free, a highly-sensitive and accurate sensing has been achieved, featured by 3.56 per unit change in pH i value 3.0-7.0 with deviation less than 0.43. This approach shall facilitate the researches in pH i related areas and development of the intracellular drug delivery systems.

Accurate Quantitative Sensing of Intracellular pH based on Self-ratiometric Upconversion Luminescent Nanoprobe

NASA Astrophysics Data System (ADS)

Li, Cuixia; Zuo, Jing; Zhang, Li; Chang, Yulei; Zhang, Youlin; Tu, Langping; Liu, Xiaomin; Xue, Bin; Li, Qiqing; Zhao, Huiying; Zhang, Hong; Kong, Xianggui

2016-12-01

Accurate quantitation of intracellular pH (pHi) is of great importance in revealing the cellular activities and early warning of diseases. A series of fluorescence-based nano-bioprobes composed of different nanoparticles or/and dye pairs have already been developed for pHi sensing. Till now, biological auto-fluorescence background upon UV-Vis excitation and severe photo-bleaching of dyes are the two main factors impeding the accurate quantitative detection of pHi. Herein, we have developed a self-ratiometric luminescence nanoprobe based on förster resonant energy transfer (FRET) for probing pHi, in which pH-sensitive fluorescein isothiocyanate (FITC) and upconversion nanoparticles (UCNPs) were served as energy acceptor and donor, respectively. Under 980 nm excitation, upconversion emission bands at 475 nm and 645 nm of NaYF4:Yb3+, Tm3+ UCNPs were used as pHi response and self-ratiometric reference signal, respectively. This direct quantitative sensing approach has circumvented the traditional software-based subsequent processing of images which may lead to relatively large uncertainty of the results. Due to efficient FRET and fluorescence background free, a highly-sensitive and accurate sensing has been achieved, featured by 3.56 per unit change in pHi value 3.0-7.0 with deviation less than 0.43. This approach shall facilitate the researches in pHi related areas and development of the intracellular drug delivery systems.

Flexible transparent displays based on core/shell upconversion nanophosphor-incorporated polymer waveguides

NASA Astrophysics Data System (ADS)

Park, Bong Je; Hong, A.-Ra; Park, Suntak; Kyung, Ki-Uk; Lee, Kwangyeol; Seong Jang, Ho

2017-04-01

Core/shell (C/S)-structured upconversion nanophosphor (UCNP)-incorporated polymer waveguide-based flexible transparent displays are demonstrated. Bright green- and blue-emitting Li(Gd,Y)F4:Yb,Er and Li(Gd,Y)F4:Yb,Tm UCNPs are synthesized via solution chemical route. Their upconversion luminescence (UCL) intensities are enhanced by the formation of C/S structure with LiYF4 shell. The Li(Gd,Y)F4:Yb,Er/LiYF4 and Li(Gd,Y)F4:Yb,Tm/LiYF4 C/S UCNPs exhibit 3.3 and 2.0 times higher UCL intensities than core counterparts, respectively. In addition, NaGdF4:Yb,Tm/NaGdF4:Eu C/S UCNPs are synthesized and they show red emission via energy transfer and migration of Yb3+ → Tm3+ → Gd3+ → Eu3+. The C/S UCNPs are incorporated into bisphenol A ethoxylate diacrylate which is used as a core material of polymer waveguides. The fabricated stripe-type polymer waveguides are highly flexible and transparent (transmittance > 90% in spectral range of 443-900 nm). The polymer waveguides exhibit bright blue, green, and red luminescence, depending on the incorporated UCNPs into the polymer core, under coupling with a near infrared (NIR) laser. Moreover, patterned polymer waveguide-based display devices are fabricated by reactive ion etching process and they realize bright blue-, green-, and red-colored characters under coupling with an NIR laser.

Recent advances in enhanced luminescence upconversion of lanthanide-doped NaYF4 phosphors

NASA Astrophysics Data System (ADS)

Kumar, Deepak; Verma, Kartikey; Verma, Shefali; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

2018-04-01

NaYF4 is regarded as the best upconversion (UC) matrix owing to its low phonon energy, more chemical stability, and a superior refractive index. This review reports on the various synthesis techniques of lanthanide-doped NaYF4 phosphors for UC application. The UC intensity depends on different properties of the matrix and those are discussed in detail. Plasmon-enhanced luminescence UC of the lanthanide-doped NaYF4 core-shells structure is discussed based on a literature survey. The present review provides the information about how the UC intensity can be enhanced. The idea about the UC is then deliberately used for versatile applications such as luminescent materials, display devices, biomedical imaging and different security appliances. In addition, the present review demonstrates the recent trends of NaYF4 UC materials in solar cell devices. The role of NaYF4 phosphor to eradicate the spectral variance among the incident solar spectrum, semiconductor as well as the sub-band gap nature of the semiconductor materials is also discussed in detail. Considering the fact that the research status on NaYF4 phosphor for photovoltaic application is now growing, the present review is therefore very important to the researchers. More importantly, this may promote more interesting research platforms to investigate the realistic use of UC nanophosphors as spectral converters for solar cells.

Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting in Tb and Yb co-doped glass containing Ag nanoparticles

NASA Astrophysics Data System (ADS)

Pan, Z.; Sekar, G.; Akrobetu, R.; Mu, R.; Morgan, S. H.

2011-10-01

Tb, Yb, and Ag co-doped glass nano-composites were synthesized in a lithium-lanthanum-aluminosilicate glass matrix (LLAS) by a melt-quench technique. Ag nanoparticles (NPs) were formed in the glass matrix and confirmed by optical absorption and transmission electron microscopy (TEM). Plasmon enhanced luminescence was observed. Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting were studied for samples with different thermal annealing times. Because the Yb3+ emission at 940 - 1020 nm is matched well with the band gap of crystalline Si, the quantum cutting effect may have its potential application in silicon-based solar cells.

Fabrication and evaluation of chitosan/NaYF4:Yb3+/Tm3+ upconversion nanoparticles composite beads based on the gelling of Pickering emulsion droplets.

PubMed

Yan, Huiqiong; Chen, Xiuqiong; Shi, Jia; Shi, Zaifeng; Sun, Wei; Lin, Qiang; Wang, Xianghui; Dai, Zihao

2017-02-01

The rare earth ion doped upconversion nanoparticles (UCNPs) synthesized by hydrophobic organic ligands possess poor solubility and low fluorescence quantum yield in aqueous media. To conquer this issue, NaYF 4 :Yb 3+ /Tm 3+ UCNPs, synthesized by a hydrothermal method, were coated with F127 and then assembled with chitosan to fabricate the chitosan/NaYF 4 :Yb 3+ /Tm 3+ composite beads (CS/NaYF 4 :Yb 3+ /Tm 3+ CBs) by Pickering emulsion system. The characterization results revealed that the as-synthesized NaYF 4 :Yb 3+ /Tm 3+ UCNPs with an average size of 20nm exhibited spherical morphology, high crystallinity and characteristic emission upconversion fluorescence with an overall blue color output. The NaYF 4 :Yb 3+ /Tm 3+ UCNPs were successfully conjugated on the surface of chitosan beads by the gelling of emulsion droplets. The resultant CS/NaYF 4 :Yb 3+ /Tm 3+ CBs showed good upconversion luminescent property, drug-loading capacity, release performance and excellent biocompatibility, exhibiting great potentials in targeted drug delivery and tissue engineering with potential tracking capability and lasting release performance. Copyright © 2016 Elsevier B.V. All rights reserved.

DNA-assisted upconversion nanoplatform for imaging-guided synergistic therapy and laser-switchable drug detoxification.

PubMed

Li, Luoyuan; Hao, Panlong; Wei, Peng; Fu, Limin; Ai, Xicheng; Zhang, Jianping; Zhou, Jing

2017-08-01

The side effects of chemotherapy bring significant physical and psychological suffering to patients. To solve this urgent medical problem, Yb 3+ and Er 3+ co-doped NaLuF 4 upconversion nanoparticles (UCNPs) were constructed for upconversion luminescence (UCL)-labeled diagnosis under 980 nm laser irradiation. The UCNPs were then modified layer by layer with polypyrrole and a special programming DNA segment as photothermal conversion agents and controllable drug carriers, respectively. The nanoplatform was successfully used for imaging-guided synergistic therapy (photothermal therapy and chemotherapy) at a safe power density (300 mW cm -2 ), and DNA-assisted detoxification at lower temperature in cancer cells when the laser off. The synergistic therapy of the nanoplatform achieved a higher therapeutic index (∼85%) than chemotherapy only (∼44%) and photothermal therapy only (∼25%) in vitro. In vivo experiments also suggested that the nanoplatform had a higher therapeutic effect and lower side effects. The toxicity study was also evaluated, indicating the nanoplatform is low toxic to living system. This multifunctional upconversion nanoplatform provided an innovative method for imaging-guided photothermal-chemotherapy and laser-switchable drug detoxification. Copyright © 2017 Elsevier Ltd. All rights reserved.

Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices.

PubMed

McKenna, Barry; Evans, Rachel C

2017-07-01

Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e.g., c-Si, GaAs) and emerging (perovskite, organic, dye-sensitized) cell types. Current challenges and emerging research directions, which need to be addressed for the development of next-generation luminescent solar devices, are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Advances in Inorganic Nanoparticle-Based NIR Luminescence Imaging: Semiconductor Nanoparticles and Lanthanide Nanoparticles.

PubMed

Kim, Dokyoon; Lee, Nohyun; Park, Yong Il; Hyeon, Taeghwan

2017-01-18

Several types of nanoparticle-based imaging probes have been developed to replace conventional luminescent probes. For luminescence imaging, near-infrared (NIR) probes are useful in that they allow deep tissue penetration and high spatial resolution as a result of reduced light absorption/scattering and negligible autofluorescence in biological media. They rely on either an anti-Stokes or a Stokes shift process to generate luminescence. For example, transition metal-doped semiconductor nanoparticles and lanthanide-doped inorganic nanoparticles have been demonstrated as anti-Stokes shift-based agents that absorb NIR light through two- or three-photon absorption process and upconversion process, respectively. On the other hand, quantum dots (QDs) and lanthanide-doped nanoparticles that emit in NIR-II range (∼1000 to ∼1350 nm) were suggested as promising Stokes shift-based imaging agents. In this topical review, we summarize and discuss the recent progress in the development of inorganic nanoparticle-based luminescence imaging probes working in NIR range.

Up-conversion green emission of Yb3+/Er3+ ions doped YVO4 nanocrystals obtained via modified Pechini's method

NASA Astrophysics Data System (ADS)

Szczeszak, Agata; Runowski, Marcin; Wiglusz, Rafal J.; Grzyb, Tomasz; Lis, Stefan

2017-12-01

A series of lanthanide doped yttrium vanadates were prepared by Pechini's method (sol-gel process). The as-prepared precursors, in the presence of citric acid, were calcined in the temperature range of 600-900 °C. The obtained products were composed of small nanoparticles, in the size range of 20-50 nm, depending on the annealing temperature, exhibiting a bright green up-conversion emission, under NIR laser irradiation, and emission lifetimes in the range of 4.7-18.3 μs. Their structural, morphological and spectroscopic properties were investigated in detail by XRD, HR-TEM including FFT analysis, EDX and spectroscopic techniques (emission, power dependence and emission kinetics). The luminescence quenching phenomenon, manifested in a decrease of up-conversion intensity and shortening of emission lifetime, was observed with increasing of the Yb3+ ion concentration and decreasing the particle size. The optimal concentration of the Yb3+ ions was found to be 15 mol% (YVO4: Yb3+ 15 mol%, Er3+ 2 mol%).

Upconversion luminescence, intensity saturation effect, and thermal effect in Gd{sub 2}O{sub 3}:Er{sup 3},Yb{sup 3+} nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei Yanqiang; Song Hongwei; Yang Linmei

2005-11-01

In this paper, the upconversion luminescent properties of Gd{sub 2}O{sub 3}:Er{sup 3+},Yb{sup 3+} nanowires as a function of Yb concentration and excitation power were studied under 978-nm excitation. The results indicated that the relative intensity of the red emission ({sup 4}F{sub 9/2}-{sup 4}I{sub 15/2}) increased with increasing the Yb{sup 3+} concentration, while that of the green emission ({sup 4}S{sub 3/2}/{sup 2}H{sub 11/2}-{sup 4}I{sub 15/2}) decreased. As a function of excitation power in ln-ln plot, the green emission of {sup 4}S{sub 3/2}-{sup 4}I{sub 15/2} yielded a slope of {approx}2, while the red emission of {sup 4}F{sub 9/2}-{sup 4}I{sub 15/2} yielded amore » slope of {approx}1. Moreover, the slope decreased with increasing the Yb{sup 3+} concentration. This was well explained by the expanded theory of competition between linear decay and upconversion processes for the depletion of the intermediate excited states. As the excitation power density was high enough, the emission intensity of upconversion decreased due to thermal quenching. The thermal effect caused by the exposure of the 978-nm laser was studied according to the intensity ratio of {sup 2}H{sub 11/2}-{sup 4}I{sub 15/2} to {sup 4}S{sub 3/2}-{sup 4}I{sub 15/2}. The practical sample temperature at the exposed spot as a function of excitation power and Yb{sup 3+} concentration was deduced. The result indicated that at the irradiated spot (0.5x0.5 mm{sup 2}) the practical temperature considerably increased.« less

Upconverting core-shell nanocrystals with high quantum yield under low irradiance: On the role of isotropic and thick shells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, Stefan; Goldschmidt, Jan Christoph; Johnson, Noah J. J.

2015-11-21

Colloidal upconverter nanocrystals (UCNCs) that convert near-infrared photons to higher energies are promising for applications ranging from life sciences to solar energy harvesting. However, practical applications of UCNCs are hindered by their low upconversion quantum yield (UCQY) and the high irradiances necessary to produce relevant upconversion luminescence. Achieving high UCQY under practically relevant irradiance remains a major challenge. The UCQY is severely limited due to non-radiative surface quenching processes. We present a rate equation model for migration of the excitation energy to show that surface quenching does not only affect the lanthanide ions directly at the surface but also manymore » other lanthanide ions quite far away from the surface. The average migration path length is on the order of several nanometers and depends on the doping as well as the irradiance of the excitation. Using Er{sup 3+}-doped β-NaYF{sub 4} UCNCs, we show that very isotropic and thick (∼10 nm) β-NaLuF{sub 4} inert shells dramatically reduce the surface-related quenching processes, resulting in much brighter upconversion luminescence at simultaneously considerably lower irradiances. For these UCNCs embedded in poly(methyl methacrylate), we determined an internal UCQY of 2.0% ± 0.2% using an irradiance of only 0.43 ± 0.03 W/cm{sup 2} at 1523 nm. Normalized to the irradiance, this UCQY is 120× higher than the highest values of comparable nanomaterials in the literature. Our findings demonstrate the important role of isotropic and thick shells in achieving high UCQY at low irradiances from UCNCs. Additionally, we measured the additional short-circuit current due to upconversion in silicon solar cell devices as a proof of concept and to support our findings determined using optical measurements.« less

Size-tunable and monodisperse Tm³⁺/Gd³⁺-doped hexagonal NaYbF₄ nanoparticles with engineered efficient near infrared-to-near infrared upconversion for in vivo imaging.

PubMed

Damasco, Jossana A; Chen, Guanying; Shao, Wei; Ågren, Hans; Huang, Haoyuan; Song, Wentao; Lovell, Jonathan F; Prasad, Paras N

2014-08-27

Hexagonal NaYbF4:Tm(3+) upconversion nanoparticles hold promise for use in high contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and in vivo bioimaging. However, significant hurdles remain in their preparation and control of their morphology and size, as well as in enhancement of their upconversion efficiency. Here, we describe a systematic approach to produce highly controlled hexagonal NaYbF4:Tm(3+) nanoparticles with superior upconversion. We found that doping appropriate concentrations of trivalent gadolinium (Gd(3+)) can convert NaYbF4:Tm(3+) 0.5% nanoparticles with cubic phase and irregular shape into highly monodisperse NaYbF4:Tm(3+) 0.5% nanoplates or nanospheres in a pure hexagonal-phase and of tunable size. The intensity and the lifetime of the upconverted NIR luminescence at 800 nm exhibit a direct dependence on the size distribution of the resulting nanoparticles, being ascribed to the varied surface-to-volume ratios determined by the different nanoparticle size. Epitaxial growth of a thin NaYF4 shell layer of ∼2 nm on the ∼22 nm core of hexagonal NaYbF4:Gd(3+) 30%/Tm(3+) 0.5% nanoparticles resulted in a dramatic 350 fold NIR upconversion efficiency enhancement, because of effective suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered saline.

Size-Tunable and Monodisperse Tm3+/Gd3+-Doped Hexagonal NaYbF4 Nanoparticles with Engineered Efficient Near Infrared-to-Near Infrared Upconversion for In Vivo Imaging

PubMed Central

2015-01-01

Hexagonal NaYbF4:Tm3+ upconversion nanoparticles hold promise for use in high contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and in vivo bioimaging. However, significant hurdles remain in their preparation and control of their morphology and size, as well as in enhancement of their upconversion efficiency. Here, we describe a systematic approach to produce highly controlled hexagonal NaYbF4:Tm3+ nanoparticles with superior upconversion. We found that doping appropriate concentrations of trivalent gadolinium (Gd3+) can convert NaYbF4:Tm3+ 0.5% nanoparticles with cubic phase and irregular shape into highly monodisperse NaYbF4:Tm3+ 0.5% nanoplates or nanospheres in a pure hexagonal-phase and of tunable size. The intensity and the lifetime of the upconverted NIR luminescence at 800 nm exhibit a direct dependence on the size distribution of the resulting nanoparticles, being ascribed to the varied surface-to-volume ratios determined by the different nanoparticle size. Epitaxial growth of a thin NaYF4 shell layer of ∼2 nm on the ∼22 nm core of hexagonal NaYbF4:Gd3+ 30%/Tm3+ 0.5% nanoparticles resulted in a dramatic 350 fold NIR upconversion efficiency enhancement, because of effective suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered saline. PMID:25027118

Direct observation of the core/double-shell architecture of intense dual-mode luminescent tetragonal bipyramidal nanophosphors

NASA Astrophysics Data System (ADS)

Kim, Su Yeon; Jeong, Jong Seok; Mkhoyan, K. Andre; Jang, Ho Seong

2016-05-01

Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce3+ to Tb3+ under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm-2 and 73.0 +/- 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered.Highly efficient downconversion (DC) green-emitting LiYF4:Ce,Tb nanophosphors have been synthesized for bright dual-mode upconversion (UC) and DC green-emitting core/double-shell (C/D-S) nanophosphors--Li(Gd,Y)F4:Yb(18%),Er(2%)/LiYF4:Ce(15%),Tb(15%)/LiYF4--and the C/D-S structure has been proved by extensive scanning transmission electron microscopy (STEM) analysis. Colloidal LiYF4:Ce,Tb nanophosphors with a tetragonal bipyramidal shape are synthesized for the first time and they show intense DC green light via energy transfer from Ce3+ to Tb3+ under illumination with ultraviolet (UV) light. The LiYF4:Ce,Tb nanophosphors show 65 times higher photoluminescence intensity than LiYF4:Tb nanophosphors under illumination with UV light and the LiYF4:Ce,Tb is adapted into a luminescent shell of the tetragonal bipyramidal C/D-S nanophosphors. The formation of the DC shell on the core significantly enhances UC luminescence from the UC core under irradiation of near infrared light and concurrently generates DC luminescence from the core/shell nanophosphors under UV light. Coating with an inert inorganic shell further enhances the UC-DC dual-mode luminescence by suppressing the surface quenching effect. The C/D-S nanophosphors show 3.8% UC quantum efficiency (QE) at 239 W cm-2 and 73.0 +/- 0.1% DC QE. The designed C/D-S architecture in tetragonal bipyramidal nanophosphors is rigorously verified by an energy dispersive X-ray spectroscopy (EDX) analysis, with the assistance of line profile simulation, using an aberration-corrected scanning transmission electron microscope equipped with a high-efficiency EDX. The feasibility of these C/D-S nanophosphors for transparent display devices is also considered. Electronic supplementary information (ESI) available: XRD patterns, PL and PLE spectra, SEM and HR-TEM images, PL decay times, photographs showing the transparent nanophosphor solutions and their dual-mode luminescence, and additional EDX data. See DOI: 10.1039/c5nr05722a

Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals.

PubMed

Lin, Hao; Xu, Dekang; Li, Anming; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

2016-06-16

A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb(3+), Tm(3+), Er(3+) and Li(+) doped β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+). Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb(3+)/Tm(3+)/Er(3+) doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm(3+):(3)F4 → (3)H6 to Er(3+):(4)I11/2 → (4)F9/2 and the cross-relaxation (CR) effect [Er(3+):(4)S3/2 + (4)I15/2 → (4)I9/2 + (4)I13/2] rather than the long-accepted mechanism [CR process among Er(3+):(4)F7/2 + (4)I11/2 → (4)F9/2 + (4)F9/2]. In addition, compared to the Li(+)-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb(3+), 1% Tm(3+), 20% Er(3+) with 15 mol% Li(+) doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies.

Morphology evolution and pure red upconversion mechanism of β-NaLuF4 crystals

PubMed Central

Lin, Hao; Xu, Dekang; Li, Anming; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

2016-01-01

A series of β-NaLuF4 crystals were synthesized via a hydrothermal method. Hexagonal phase microdisks, microprisms, and microtubes were achieved by simply changing the amount of citric acid in the initial reaction solution. Pure red upconversion (UC) luminescence can be observed in β-NaLuF4:Yb3+, Tm3+, Er3+ and Li+ doped β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+. Based on the rate equations, we report the theoretical model about the pure red UC mechanism in Yb3+/Tm3+/Er3+ doped system. It is proposed that the pure red UC luminescence is mainly ascribed to the energy transfer UC from Tm3+:3F4 → 3H6 to Er3+:4I11/2 → 4F9/2 and the cross-relaxation (CR) effect [Er3+:4S3/2 + 4I15/2 → 4I9/2 + 4I13/2] rather than the long-accepted mechanism [CR process among Er3+:4F7/2 + 4I11/2 → 4F9/2 + 4F9/2]. In addition, compared to the Li+-free counterpart, the pure red UC luminescence in β-NaLuF4:20% Yb3+, 1% Tm3+, 20% Er3+ with 15 mol% Li+ doping is enhanced by 13.7 times. This study provides a general and effective approach to obtain intense pure red UC luminescence, which can be applied to other synthetic strategies. PMID:27306720

A temperature sensor based on the enhanced upconversion luminescence of Li+ doped NaLuF4:Yb3+,Tm3+/Er3+ nano/microcrystals.

PubMed

Qiang, Qinping; Du, Shanshan; Ma, Xinlong; Chen, Wenbo; Zhang, Gangyi; Wang, Yuhua

2018-05-09

In this paper, fluorescent and optical temperature sensing bi-functional Li+-doping NaLuF4:Ln (Ln = Yb3+, Tm3+/Er3+) nanocrystals were synthesized via a simple hydrothermal method using oleic acid as a capping ligand. The crystal phase, size, upconversion (UC) properties, and optical temperature sensing characteristics of the crystals can be easily modified by Li+ doping. The results reveal that additional Li+ can promote the transformation from the hexagonal phase to the cubic phase and reduce the size of the nanocrystals. In addition, NaLuF4:Ln (Ln = Yb3+, Tm3+, Li+) nanocrystals present efficient near infrared (NIR) emission, which is beneficial for in vivo biomedical applications due to the increased penetration depth and low radiation damage of NIR light in bio-tissues. More importantly, under 980 nm excitation, the temperature dependent UCL from the 2H11/2 and 4S3/2 levels of Er3+ ions in NaLuF4:Yb3+,Er3+,Li+ microcrystals was investigated systematically. The fluorescence intensity ratios (FIR) of the pairs of thermally coupled levels were studied as a function of temperature in the range of 298-523 K. The maximum sensor sensitivities were found to be about 0.0039 K-1 (523 K) by exploiting the UC emissions from the 2H11/2 and 4S3/2 levels. This suggests that the Li+-doped upconversion luminescence (UCL) materials are promising prototypes for application as multi-mode probes for use in bio-separation and optical thermometers.

Highly efficient up-conversion and bright white light in RE co-doped KYF4 nanocrystals in sol-gel silica matrix

NASA Astrophysics Data System (ADS)

Méndez-Ramos, J.; Yanes, A. C.; Santana-Alonso, A.; del-Castillo, J.

2013-01-01

Transparent nano-glass-ceramics comprising Yb3+, Er3+ and Tm3+ co-doped KYF4 nanocrystals have been developed from sol-gel method. A structural analysis by means of X-ray diffraction confirmed the precipitation of cubic KYF4 nanocrystals into a silica matrix. Visible luminescence has been analyzed as function of treatment temperature of precursor sol-gel glasses. Highly efficient up-conversion emissions have been obtained under 980 nm excitation and studied by varying the doping level, processing temperature and pump power. Color tuneability has been quantified in terms of CIE diagram and in particular, a white-balanced overall emission has been achieved for a certain doping level and thermal treatment.

Efficient near-infrared up-conversion photoluminescence in carbon nanotubes

PubMed Central

Akizuki, Naoto; Aota, Shun; Mouri, Shinichiro; Matsuda, Kazunari; Miyauchi, Yuhei

2015-01-01

Photoluminescence phenomena normally obey Stokes' law of luminescence according to which the emitted photon energy is typically lower than its excitation counterparts. Here we show that carbon nanotubes break this rule under one-photon excitation conditions. We found that the carbon nanotubes exhibit efficient near-infrared photoluminescence upon photoexcitation even at an energy lying >100–200 meV below that of the emission at room temperature. This apparently anomalous phenomenon is attributed to efficient one-phonon-assisted up-conversion processes resulting from unique excited-state dynamics emerging in an individual carbon nanotube with accidentally or intentionally embedded localized states. These findings may open new doors for energy harvesting, optoelectronics and deep-tissue photoluminescence imaging in the near-infrared optical range. PMID:26568250

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Li-Ping; Zhang, Qiang; State Key Laboratory of Pollution Control and Resource Reuse

Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H{sub 2}O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF{sub 5} (RE = Ce, Pr,more » Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba{sub 2}REF{sub 7} (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd{sup 3+}, Eu{sup 3+}, Tb{sup 3+}) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba{sub 2}LaF{sub 7}:Yb, Tm(Er), Ba{sub 2}REF{sub 7}:Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed.« less

Alleviating Luminescence Concentration Quenching in Upconversion Nanoparticles through Organic Dye Sensitization.

PubMed

Wei, Wei; Chen, Guanying; Baev, Alexander; He, Guang S; Shao, Wei; Damasco, Jossana; Prasad, Paras N

2016-11-23

The phenomenon of luminescence concentration quenching exists widely in lanthanide-based luminescent materials, setting a limit on the content of lanthanide emitter that can be used to hold the brightness. Here, we introduce a concept involving energy harvesting by a strong absorber and subsequent energy transfer to a lanthanide that largely alleviates concentration quenching. We apply this concept to Nd 3+ emitters, and we show both experimentally and theoretically that the optimal doping concentration of Nd 3+ in colloidal NaYF 4 :Nd upconverting nanoparticles is increased from 2 to 20 mol% when an energy harvestor organic dye (indocyanine green, ICG) is anchored onto the nanoparticle surface, resulting in ∼10 times upconversion brightness. Theoretical analysis indicated that a combination of efficient photon harvesting due to the large absorption cross section of ICG (∼30 000 times higher than that of Nd 3+ ), non-radiative energy transfer (efficiency ∼57%) from ICG to the surface bound Nd 3+ ions, and energy migration among the Nd 3+ ions was able to activate Nd 3+ ions inside the nanoparticle at a rate comparable with that of the pronounced short-range quenching interaction at elevated Nd 3+ concentrations. This resulted in the optimal concentration increase to produce significantly enhanced brightness. Theoretical modeling shows a good agreement with the experimental observation. This strategy can be utilized for a wide range of other lanthanide-doped nanomaterials being utilized for bioimaging and solar cell applications.

Fabrication and Luminescence Characterization of a Silica Nanomatrix Embedded with NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Thangaraju, Dheivasigamani; Santhana, Vedi; Matsuda, Satoshi; Hayakawa, Yasuhiro

2018-05-01

Hexagonal NaYF4:Yb:Er:Tm@NaGdF4 core-shell nanocrystals were synthesized using a seed mediated hot injection method, and monodispersed Fe3O4 (4 nm) nanoparticles were prepared from iron(II) actylacetonate by a precursor thermal decomposition method. Structural and morphology verified NaYF4:Yb:Er:Tm@NaGdF4 and Fe3O4 nanoparticles were utilized for the preparation of NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4@SiO2 nanocomposite using a micro-emulsion method. Existence of Fe3O4 in NaYF4:Yb:Er:Tm@NaGdF4 in SiO2 nano-spheres were confirmed with transmission electron microscopy. Luminescence measurement revealed that NaYF4:Yb:Er:Tm@NaGdF4 exhibited strong emissions at green and red regions, in addition to a weak blue emission also observed under 980 nm excitation. Up-conversion emission of the nanoparticle-embedded silica nanocomposite showed that the up-conversion emission was not affected by Fe3O4 nanoparticles.

Yb3+ sensitized Tm3+ upconversion in tellurite lead oxide glass.

PubMed

Mohanty, Deepak Kumar; Rai, Vineet Kumar; Dwivedi, Y

2012-04-01

Triply ionized thulium/thulium--ytterbium doped/codoped TeO2-Pb3O4 (TPO) glasses have been fabricated by classical quenching method. The upconversion emission spectra in the Tm3+/Tm3+-Yb3+ doped/codoped glasses upon excitation with a diode laser lasing at ∼980 nm has been studied. Effect of the addition of the Yb3+ on the upconversion emission intensity in the visible and near infrared regions of the Tm3+ doped in TPO glass has been studied and the processes involved explored. Copyright © 2011 Elsevier B.V. All rights reserved.

808 nm-excited upconversion nanoprobes with low heating effect for targeted magnetic resonance imaging and high-efficacy photodynamic therapy in HER2-overexpressed breast cancer.

PubMed

Zeng, Leyong; Pan, Yuanwei; Zou, Ruifen; Zhang, Jinchao; Tian, Ying; Teng, Zhaogang; Wang, Shouju; Ren, Wenzhi; Xiao, Xueshan; Zhang, Jichao; Zhang, Lili; Li, Aiguo; Lu, Guangming; Wu, Aiguo

2016-10-01

To avoid the overheating effect of excitation light and improve the efficacy of photodynamic therapy (PDT) of upconversion nanoplatform, a novel nanoprobe based on 808 nm-excited upconversion nanocomposites (T-UCNPs@Ce6@mSiO2) with low heating effect and deep penetration has been successfully constructed for targeted upconversion luminescence, magnetic resonance imaging (MRI) and high-efficacy PDT in HER2-overexpressed breast cancer. In this nanocomposite, photosensitizers (Ce6) were covalently conjugated inside of mesoporous silica to enhance the PDT efficacy by shortening the distance of fluorescence resonance energy transfer and to decrease the cytotoxicity by preventing the undesired leakage of Ce6. Compared with UCNPs@mSiO2@Ce6, UCNPs@Ce6@mSiO2 greatly promoted the singlet oxygen generation and amplified the PDT efficacy under the excitation of 808 nm laser. Importantly, the designed nanoprobe can greatly improve the uptake of HER2-positive cells and tumors by modifying the site-specific peptide, and the in vivo experiments showed excellent MRI and PDT via intravenous injection by modeling MDA-MB-435 tumor-bearing nude mice. Our strategy may provide an effective solution for overcoming the heating effect and improving the PDT efficacy of upconversion nanoprobes, and has potential application in visualized theranostics of HER2-overexpressed breast cancer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improvement Photocatalytic Activity of P25 by Modification with a Rare Earth-Free Upconversion Nanocrystal.

PubMed

Yin, Dongguang; Liu, Yumin; Zhao, Feifei; Zhang, Xinyu; Zhang, Tingting; Wu, Chenglong; Chang, Na; Chen, Zhiwen

2018-05-01

It has been reported that coupling TiO2 with rare earth upconversion nanocrystals (UCNCs) is an efficient strategy to significantly improve photocatalytic activity of TiO2. However, the rare earth materials are scarcity and cost, and the synthesis process of UCNCs using the rare earth materials is complicated. In the present study, we have designed a new approach using a rare earth-free upconversion nanocrystal (REF-UCNCs) as upconversion luminescent material to replace the rare earth UCNCs. A novel nanocomposite photocatalyst of REF-UCNCs@P25: Mo/GN was developed for the first time. Based on the designed structure, the REF-UCNCs, Mo-doping, and GN (graphene) have a synergistic effect that can improve catalytic activity of P25 significantly. The results of photocatalytic experiments using RhB as a model pollutant under simulated solar light irradiation show that the photocatalytic efficiency of the as-prepared catalyst is 3-folds higher than that of benchmark substance P25. This work provides a new strategy for efficiently improving catalytic activity of semiconductor photocatalysts by coupling with REF-UCNCs. This approach is facile and low-cost which can be widely applied for modification of semiconductor photocatalysts and facilitates their applications in environmental protection issues using solar light.

Yb3+/Ho3+ Co-Doped Apatite Upconversion Nanoparticles to Distinguish Implanted Material from Bone Tissue.

PubMed

Li, Xiyu; Chen, Haifeng

2016-10-07

The exploration of bone reconstruction with time requires the combination of a biological method and a chemical technique. Lanthanide Yb 3+ and Ho 3+ co-doped fluorapatite (FA:Yb 3+ /Ho 3+ ) and hydroxyapatite (HA:Yb 3+ /Ho 3+ ) particles with varying dopant concentrations were prepared by hydrothermal synthesis and thermal activation. Controllable green and red upconversion emissions were generated under 980 nm near-infrared excitation; the FA:Yb 3+ /Ho 3+ particles resulted in superior green luminescence, while HA:Yb 3+ /Ho 3+ dominated in red emission. The difference in the green and red emission behavior was dependent on the lattice structure and composition. Two possible lattice models were proposed for Yb 3+ /Ho 3+ co-doped HA and FA along the hydroxyl channel and fluorine channel of the apatite crystal structure. We first reported the use of the upconversion apatite particles to clearly distinguish implanted material from bone tissue on stained histological sections of harvested in vivo samples. The superposition of the tissue image and material image is a creative method to show the material-tissue distribution and interrelation. The upconversion apatite particles and image superposition method provide a novel strategy for long-term discriminable fluorescence tracking of implanted material or scaffold during bone regeneration.

NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} core/shell nanocomposite: A highly efficient visible-light-driven photocatalyst utilizing upconversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yuanyuan; Wang, Wenzhong, E-mail: wzwang@mail.sic.ac.cn; Sun, Songmei

2014-04-01

Highlights: • Design and synthesis of NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} based on upconversion. • NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} nanocomposite was prepared for the first time. • Core–shell structure benefits the properties. • Upconversion contributed to the enhanced photocatalytic activity. • Helps to understand the functionality of new type photocatalysts. - Abstract: NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} core/shell nanocomposite was designed and prepared for the first time based on upconversion. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectra (DRS). The results revealed that the as-synthesizedmore » NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} consisted of spheres with a core diameter of about 26 nm and a shell diameter of around 6 nm. The core was upconversion illuminant NaYF{sub 4}:Er,Yb and the shell was Bi{sub 2}MoO{sub 6} around the core, which was confirmed by EDS. The NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} exhibited higher photocatalytic activity for the photodecomposition of Rhodamine B (RhB) under the irradiation of Xe lamp and green light emitting diode (g-LED). The mechanism of the high photocatalytic activity was discussed by photoluminescence spectra (PL), which is mainly attributed to upconversion of NaYF{sub 4}:Er,Yb in the NaYF{sub 4}:Er,Yb/Bi{sub 2}MoO{sub 6} nanocomposite and the core–shell structure.« less

Down- and up-conversion luminescent carbon dot fluid: inkjet printing and gel glass fabrication

NASA Astrophysics Data System (ADS)

Wang, Fu; Xie, Zheng; Zhang, Bing; Liu, Yun; Yang, Wendong; Liu, Chun-Yan

2014-03-01

Room temperature liquid-like nanoparticles have emerged as an exciting new research and development area, because their properties could be tailored over a broad range by manipulating geometric and chemical characteristics of the inorganic core and organic canopy. However, related applications are rarely reported due to the multi-step synthesis process and potential toxicity of cadmium based nanomaterials. In this study, we prepared inexpensive and eco-friendly carbon dot fluid by the direct thermal decomposition method. The carbon dot fluid can be excited from UV to near infrared light, and can be prepared as highly concentrated luminescent ink or incorporated into sol-gel derived organically modified silicate glass, suggesting that it has great application potential in the field of printable electronics, solid state lighting and so on.Room temperature liquid-like nanoparticles have emerged as an exciting new research and development area, because their properties could be tailored over a broad range by manipulating geometric and chemical characteristics of the inorganic core and organic canopy. However, related applications are rarely reported due to the multi-step synthesis process and potential toxicity of cadmium based nanomaterials. In this study, we prepared inexpensive and eco-friendly carbon dot fluid by the direct thermal decomposition method. The carbon dot fluid can be excited from UV to near infrared light, and can be prepared as highly concentrated luminescent ink or incorporated into sol-gel derived organically modified silicate glass, suggesting that it has great application potential in the field of printable electronics, solid state lighting and so on. Electronic supplementary information (ESI) available: Details of FTIR, XRD and DLS of CDF, optical properties of CDF, TEM images of other obtained products, luminescent spectra of CDF at different temperatures, and the optical photographs of CDF inks and silica glasses with different concentrations under normal, UV and 800 nm light. See DOI: 10.1039/c3nr05869g

Comparative analysis of luminescent properties of germanate glass and double-clad optical fibers co-doped with Yb3+/Ho3+ ions

NASA Astrophysics Data System (ADS)

Pietrzycki, Marcin; Kochanowicz, Marcin; Romańczuk, Patryk; Żmojda, Jacek; Miluski, Piotr; Ragiń, Tomasz; Jeleń, Piotr; Sitarz, Maciej; Dorosz, Dominik

2016-09-01

The 2 μm and visible emission of low phonon (805 cm-1) germanate glasses and double - clad optical fiber co-doped with 0.7Yb2O3/(0.07-0.7)Ho2O3 ions have been investigated. Luminescence at 2 μm corresponding to Ho3+: 5I7 → 5I8 as well as upconversion luminescence in the visible spectral range corresponding to the Ho3+: 5S2(5F4)→5I8 (545 nm), and Ho3+: 5F5→5I8 (655 nm) transition, respectively were obtained. The optimization of the acceptor content and donor-acceptor ratio were conducted with the purpose of maximizing the luminescence intensity. The highest luminescence intensity in both spectral range was obtained in glass co-doped with 0.7Yb2O3/0.15 Ho2O3. Despite relatively small effective absorption coefficient of the optical fiber comparative analysis of luminescent properties of fabricated glasses (further core) and double - clad optical fiber showed significant contribution of reabsorption process of emitted ASE signal.

Synthesis of Gd2O3:Ho3+/Yb3+ upconversion nanoparticles for latent fingermark detection on difficult surfaces

NASA Astrophysics Data System (ADS)

Kumar, A.; Tiwari, S. P.; Singh, A. K.; Kumar, K.

2016-07-01

Infrared to visible upconversion fluorescent nanoparticles of Gd2O3 codoped with Ho3+/Yb3+ ions are synthesized via thermal decomposition process. The X-ray diffraction analysis of as-synthesized nanoparticles and annealed sample at 1000 °C has shown body-centered cubic phase of Gd2O3. The synthesized phosphor has shown intense green emission upon 980-nm excitation. High-contrast latent fingermarks on some difficult semi-porous and non-porous surfaces under 980-nm diode laser excitation were developed through powder dusting and colloidal solution spraying techniques and the results are compared with the commercial green luminescent fingermark powder. The latent fingermarks were developed on transparent (biological glass slides), single-color (aluminum foil) and multicolor (plywood, plastic bottle and book cover page) background surfaces. The present study depicts that the upconversion-based latent fingermarks detection using Gd2O3:Ho3+/Yb3+ phosphor material is suitable over the other conventional powders and has potential for practical applications in forensic science.

Strategies for the design of bright upconversion nanoparticles for bioanalytical applications

NASA Astrophysics Data System (ADS)

Wiesholler, Lisa M.; Hirsch, Thomas

2018-06-01

In recent years upconversion nanoparticles (UCNPs) received great attention because of their outstanding optical properties. Especially in bioanalytical applications this class of materials can overcome limitations of common probes like high background fluorescence or blinking. Nevertheless, the requirements for UCNPs to be applicable in biological samples, e.g. small size, water-dispersibility, excitation at low power density are in contradiction with the demand of high brightness. Therefore, a lot of attention is payed to the enhancement of the upconversion luminescence. This review discuss the recent trends and strategies to boost the brightness of UCNPs, classified in three main directions: a) improving the efficiency of energy absorption by the sensitizer via coupling to plasmonic or photonic structures or via attachment of ligands for light harvesting; b) minimizing non-radiative deactivation by variations in the architecture of UCNPs; and c) changing the excitation wavelength to get bright particles at low excitation power density for applications in aqueous systems. These strategies are critically reviewed including current limitations as well as future perspectives for the design of efficient UCNPs especially for sensing application in biological samples or cells.

Differentiation of black writing ink on paper using luminescence lifetime by time-resolved luminescence spectroscopy.

PubMed

Suzuki, Mototsugu; Akiba, Norimitsu; Kurosawa, Kenji; Akao, Yoshinori; Higashikawa, Yoshiyasu

2017-10-01

The time-resolved luminescence spectra and the lifetimes of eighteen black writing inks were measured to differentiate pen ink on altered documents. The spectra and lifetimes depended on the samples. About half of the samples only exhibited short-lived luminescence components on the nanosecond time scale. On the other hand, the other samples exhibited short- and long-lived components on the microsecond time scale. The samples could be classified into fifteen groups based on the luminescence spectra and dynamics. Therefore, luminescence lifetime can be used for the differentiation of writing inks, and luminescence lifetime imaging can be applied for the examination of altered documents. Copyright © 2017 Elsevier B.V. All rights reserved.

Multicolor upconversion emission from Tm3++Ho3++Yb3+ codoped tellurite glass on NIR excitations

NASA Astrophysics Data System (ADS)

Giri, N. K.; Rai, D. K.; Rai, S. B.

2008-06-01

Multicolor emission has been produced using 798 nm and 980 nm laser excitation in a Tm3++Ho3++Yb3+ codoped tellurite based glass. This glass generates simultaneously red, green and blue (RGB) emission on 798 nm excitation. Multicolor emission thus obtained was tuned to white luminescence by adjusting the Ho3+ ion concentration. There is a close match between the calculated color coordinate for the white luminescence obtained here and the point of equal energy which represents white in the 1931 CIE chromaticity diagram. The 980 nm excitation of the same sample on the other hand gives intense green and red emission and the glass appears greenish.

Luminescence spectra of a cholesteric photonic crystal

NASA Astrophysics Data System (ADS)

Dolganov, P. V.

2017-05-01

The transmission and luminescence spectra of a cholesteric photonic crystal doped with an organic dye are measured. The density of photon states is calculated using the material parameters obtained from the comparison of the experimental and theoretical spectra. The shape of the luminescence spectra is modified with respect to the density of photon states owing to the difference in the structure of the normal modes of the photonic crystal near the short-wavelength and long-wavelength edges of the photonic quasi-band gap upon the "pushing" of the photon states from the gap and to the nonvanishing orientation ordering of the luminescent molecules. The luminescence spectrum calculated taking into account the chiral structure of the photonic crystal agrees with the experimental spectrum.

All-inorganic colloidal upconversion quantum dots (Conference Presentation)

NASA Astrophysics Data System (ADS)

Oron, Dan; Teitelboim, Ayelet

2017-02-01

Upconversion (UC) is a nonlinear process in which two, or more, long wavelength photons are converted to a shorter wavelength photon. This process is based on sequential absorption of two or more photons, involving metastable, long lived intermediate energy states, thus is not restricted to ultrashort pulsed excitation. Hence, requirements for UC processes are long lived excited states, a ladder like arrangement of energy levels and a mechanism inhibiting cooling of the hot charge carrier. UC holds great promise for bioimaging, enabling to perform multiphoton imaging in scattering specimen at very low powers. Rare-earth-doped nanocrystals, the most commonly used ones for UC, typically require a minimal particle diameter of several tens of nanometers and have a limited action spectrum. Here, we present a novel luminescence upconversion nano-system based on colloidal semiconductor double quantum dots, consisting of a NIR-absorbing component and a visible emitting component separated by a tunneling barrier in a spherical onion-like geometry. These dual near-infrared and visible core/shell/shell PbSe/CdSe/CdS nanocrystals are shown to efficiently upconvert a broad range of NIR wavelengths up to 1.2 microns to visible emission at room temperature, covering a spectral range where there are practically no alternative upconversion systems. The particle diameter is less than ten nanometers, and the synthesis enables versatility and tunability of both the visible emission color and the NIR absorption edge. The physical mechanism for upconversion in this type of structures, as well as potential advances and extensions on this system will be discussed.

Decorating fiber nanotip with single perovskite quantum dot and other luminescent nanocrystals synthesized in oil-phase

NASA Astrophysics Data System (ADS)

Qian, Yu; Xing, Xing; Xu, Ya; Lu, Zhenda; Zhang, Weihua

2017-11-01

We report a simple yet robust method for fabricating single perovskite quantum dot (QD) decorated fiber nanotips. In this method, a single QD is directly picked up and subsequently glued on the apex of a specially fabricated cantilever fiber tip with a high success rate (approx. 70%) without using expensive close-loop feedback systems. Thanks to the flexibility and robustness of the fiber tips, no damage of the tips was observed in the process. Moreover, nanocrystal (NC) dispersing technique was developed to avoid undesired aggregations of QDs, and it guarantees that only one QD is glued each time. Finally, we demonstrate that this technique can also be applied to other oil-phase synthesized NCs, including CdSe QDs and upconversion luminescent NCs. It leads to many important applications on probing the local environment using high performance luminescent nanoprobes.

Up-conversion luminescence coupled to plasmonic gold nanorods for light harvesting and hydrogen production.

PubMed

AlGhamdi, H; Katsiev, K; Wahab, A K; Llorca, J; Idriss, H

2017-12-05

The conversion of infrared light to visible-light which allows a larger fraction of sun-light to be used is needed to improve light-harvesting. In this work a tri-functional material composed of an up-converter (NaYF 4 -Yb-Tm), plasmonic gold nanorods and CdS was made photocatalytically active using 980 nm wavelength light for the reduction of H + to H 2 .

A Paper-Based Sandwich Format Hybridization Assay for Unlabeled Nucleic Acid Detection Using Upconversion Nanoparticles as Energy Donors in Luminescence Resonance Energy Transfer.

PubMed

Zhou, Feng; Noor, M Omair; Krull, Ulrich J

2015-09-24

Bioassays based on cellulose paper substrates are gaining increasing popularity for the development of field portable and low-cost diagnostic applications. Herein, we report a paper-based nucleic acid hybridization assay using immobilized upconversion nanoparticles (UCNPs) as donors in luminescence resonance energy transfer (LRET). UCNPs with intense green emission served as donors with Cy3 dye as the acceptor. The avidin functionalized UCNPs were immobilized on cellulose paper and subsequently bioconjugated to biotinylated oligonucleotide probes. Introduction of unlabeled oligonucleotide targets resulted in a formation of probe-target duplexes. A subsequent hybridization of Cy3 labeled reporter with the remaining single stranded portion of target brought the Cy3 dye in close proximity to the UCNPs to trigger a LRET-sensitized emission from the acceptor dye. The hybridization assays provided a limit of detection (LOD) of 146.0 fmol and exhibited selectivity for one base pair mismatch discrimination. The assay was functional even in undiluted serum samples. This work embodies important progress in developing DNA hybridization assays on paper. Detection of unlabeled targets is achieved using UCNPs as LRET donors, with minimization of background signal from paper substrates owing to the implementation of low energy near-infrared (NIR) excitation.

Local symmetric distortion boosted photon up-conversion and thermometric sensitivity in lanthanum oxide nanospheres.

PubMed

Suo, Hao; Zhao, Xiaoqi; Zhang, Zhiyu; Shi, Rui; Wu, Yanfang; Xiang, Jinmeng; Guo, Chongfeng

2018-05-17

It is essential to simultaneously boost the luminescence intensity and thermometric sensitivity of up-converted optical thermometers towards potential biomedical sensing applications. Herein, the effects of local site symmetry on the up-conversion (UC) emission and thermal sensing ability in trigonal-phased La2O3:Er3+/Yb3+ nanospheres were qualitatively explored using cubic-phased Lu2O3 and Y2O3 with a similar shape and phonon energy as contrasts. Under 980 nm light excitation, much stronger UC emissions were detected in La2O3 samples than that in cubic Lu2O3 and Y2O3 samples, and the possible mechanisms were elaborately proposed using Eu3+ as a luminescent probe. Thermo-responsive emission intensity from 2H11/2/4S3/2 levels was monitored to evaluate the absolute sensitivity of three samples, which strongly depends on the dopant-induced local site symmetric distortions according to the Judd-Ofelt theory. The potentiality of La2O3:Er3+/Yb3+ for sub-tissue thermometry was also validated by ex vivo experiments. Results open a promising avenue for realizing highly sensitive thermometry with a large signal-to-noise ratio in sub-tissues via finely tailoring the local site symmetry.

White light upconversion emissions in Er3+/Tm3+/Yb3+ tridoped oxyfluoride glass

NASA Astrophysics Data System (ADS)

Guan, Xiaoping; Xu, Wei; Zhu, Shuang; Song, Qiutong; Wu, Xijun; Liu, Hailong

2015-10-01

Rare earth ions doped glasses producing visible upconversion emissions are of great interest due to their potential applications in the photonics filed. In fact, practical application of upconversion emissions has been used to obtain color image displays and white light sources. However, there are few reports on the thermal effect on tuning the emission color of the RE doped materials. In this work, the Er3+/Tm3+/Yb3+ tridoped oxyfluoride glasses were prepared through high temperature solid-state method. Under a 980 nm diode laser excitation, the upconversion emissions from the samples were studied. At room-temperature, bright white luminescence, whose CIE chromaticity coordinate was about (0.28, 0.31), can be obtained when the excitation power was 120 mW. The emission color was changed by varying the intensity ratios between RGB bands, which are strongly dependent on the rare earth ions concentration. The temperature dependent color emissions were also investigated. As temperature increased, the intensities for the emission bands presented different decay rates, finally resulting in the changing of the CIE coordinate. When the temperature was 573 K, white light with color coordinate of (0.31, 0.33) was achieved, which matches well with the white reference (0.33, 0.33). The color tunability, high quality of white light and intense emission intensity make the transparent oxyfluoride glasses excellent candidates for applications in solid-state lighting.

Smart Self-Assembled Nanosystem Based on Water-Soluble Pillararene and Rare-Earth-Doped Upconversion Nanoparticles for pH-Responsive Drug Delivery.

PubMed

Li, Haihong; Wei, Ruoyan; Yan, Gui-Hua; Sun, Ji; Li, Chunju; Wang, Haifang; Shi, Liyi; Capobianco, John A; Sun, Lining

2018-02-07

Exploring novel drug delivery systems with good stability and new structure to integrate pillararene and upconversion nanoparticles (UCNPs) into one system continues to be an important challenge. Herein, we report a novel preparation of a supramolecular upconversion nanosystem via the host-guest complexation based on carboxylate-based pillar[5]arene (WP5) and 15-carboxy-N,N,N-trialkylpentadecan-1-ammonium bromide (1)-functionalized UCNPs to produce WP5⊃1-UCNPs that can be loaded with the chemotherapeutic drug doxorubicin (DOX). Importantly, the WP5 on the surface of the drug-loaded nanosystem can be efficiently protonated under acidic conditions, resulting in the collapse of the nanosystem and drug release. Moreover, cellular uptake confirms that the nanosystem can enter human cervical cancer (HeLa) cells, resulting in drug accumulation in the cells. More importantly, cytotoxicity experiments demonstrated the excellent biocompatibility of WP5⊃1-UCNPs without loading DOX and that the nanosystem DOX-WP5⊃1-UCNPs exhibited an ability of killing HeLa cells effectively. We also investigated magnetic resonance imaging and upconversion luminescence imaging, which may be employed as visual imaging agents in cancer diagnosis and treatment. Thus, in the present work, we show a simple yet powerful strategy to combine UCNPs and pillar[5]arene to produce a unified nanosystem for dual-mode bioimaging-guided therapeutic applications.

Developing core-shell upconversion nanoparticles for optical encoding

NASA Astrophysics Data System (ADS)

Huang, Kai

Lanthanide-doped upconversion nanoparticles (UCNPs) are an emerging class of luminescent materials that emit UV or visible light under near infra-red (NIR) excitations, thereby possessing a large anti-Stokes shift property. Also considering their sharp emission bands, excellent photo- and chemical stability, and almost zero auto-fluorescence of their NIR excitation, UCNPs are advantageous for optical encoding. Fabricating core-shell structured UCNPs provides a promising strategy to tune and enhance their upconverting luminescence. However, the energy transfer between core and shell had been rarely studied. Moreover, this strategy had been limited by the difficulty of coating thick shells onto the large cores of UCNPs. To overcome these constraints, the overall aim of this project is to study the inter-layers energy transfer in core-shell UCNPs and to develop an approach for coating thicker shell onto the core UCNPs, in order to fabricate UCNPs with enhanced and tunable luminescence for optical encoding. The strategy for encapsulating UCNPs into hydrogel droplet to fabricate multi-color bead barcodes has also been developed. Firstly, to study the inter-layers energy transfer between the core and shell of coreshell UCNPs, the activator and sensitizer ions were separately doped in the core or shell by fabricating NaYF4:Er NaYF4:Yb and NaYF4:Yb NaYF4:Er UCNPs. This eliminated the intra-layer energy transfer, resulting in a luminescence that is solely based on the energy transfer between layers, which facilitated the study of inter-layers energy transfer. The results demonstrated that the NaYF4:Yb NaYF4:Er structure, with sensitizer ions doped in the core, was preferable because of the strong luminescence, through minimizing the cross relaxations between Er3+ and Yb3+ and the surface quenching. Based on these information, a strategy of enhancing and tuning upconversion luminescence of core-shell UCNPs by accumulating sensitizer in the core has been developed. Next, a strategy of coating a thick shell by lutetium doping has been developed. With a smaller ion radius compared to Y3+, when Lu3+ partially replace Y3+ in the NaYF4 UCNPs during nanoparticle synthesis, nucleation process is suppressed and the growth process is promoted, which are favorable for increasing the nanoparticle size and coating a thicker shell onto the core UCNPs. Through the rational doping of Lu3+, core UCNPs with bigger sizes and enhanced luminescence were produced. Using NaLuF4 as the shell material, shells with tremendous thickness were coated onto core UCNPs, with the shell/core ratio of up to 10:1. This led to the fabrication of multi-color UCNPs with well-designed core-shell structures with multiple layers and controllable thicknesses. Finally, a strategy of encapsulating these UCNPs to produce optically encoded micro-beads through high-throughput microfluidics has been developed. The hydrophobic UCNPs were first modified with Pluronic F127 to render them hydrophilic and uniformly distributed in the poly (ethylene glycol) diacrylate (PEGDA) hydrogel precursor. Droplets of the hydrogel precursor were formed in a microfluidic device and cross-linked into micro-beads under UV irradiation. Through encapsulation of multi-color UCNPs and by controlling their ratio, optically encoded multi-color micro-beads have been easily fabricated. These multi-color UCNPs and micro-bead barcodes have great potential for use in multiplexed bioimaging and detection.

Luminescence of Er 3+-doped nanostructured SiO 2-LaF 3 glass-ceramics prepared by the sol-gel method

NASA Astrophysics Data System (ADS)

Rodríguez, V. D.; Del Castillo, J.; Yanes, A. C.; Méndez-Ramos, J.; Torres, M.; Peraza, J.

2007-07-01

Transparent glass ceramics with composition of 95SiO2-5LaF3 doped with 0.1 mol% of Er3+ were synthesized by thermal treatment of precursor sol-gel glasses. Segregated LaF3 nanocrystals in the glass were confirmed from a structural analysis performed by X-ray diffraction. Blue, green and red efficient up-conversion emissions were observed under 980 nm excitation at room temperature. Under this excitation near infrared down-conversion at 1.55 μm is also observed. These results could be attributed to the precipitation of LaF3 nanocrystals and the incorporation of most Er3+ ions in these nanocrystals. The mechanisms involved in the up-conversion emissions could be ascribed to two and three photon processes.

Bright Photon Upconversion on Composite Organic Lanthanide Molecules through Localized Thermal Radiation.

PubMed

Ye, Huanqing; Bogdanov, Viktor; Liu, Sheng; Vajandar, Saumitra; Osipowicz, Thomas; Hernández, Ignacio; Xiong, Qihua

2017-12-07

Converting low-energy photons via thermal radiation can be a potential approach for utilizing infrared (IR) photons to improve photovoltaic efficiency. Lanthanide-containing materials have achieved great progress in IR-to-visible photon upconversion (UC). Herein, we first report bright photon, tunable wavelength UC through localized thermal radiation at the molecular scale with low excitation power density (<10 W/cm 2 ) realized on lanthanide complexes of perfluorinated organic ligands. This is enabled by engineering the pathways of nonradiative de-excitation and energy transfer in a composite of ytterbium and terbium perfluoroimidodiphosphinates. The IR-excited thermal UC and wavelength control is realized through the terbium activators sensitized by the ytterbium sensitizers having high luminescence efficiency. The metallic molecular composite thus can be a potential energy material in the use of the IR solar spectrum for thermal photovoltaic applications.

Electro-holographic display using a ZBLAN glass as the image space.

PubMed

Son, Jung-Young; Lee, Hyoung; Byeon, Jina; Zhao, Jiangbo; Ebendorff-Heidepriem, Heike

2017-04-01

An Er³⁺-doped ZBLAN glass is used to display a 360° viewable reconstructed image from a hologram on a DMD. The reconstructed image, when the hologram is illuminated by a 852 nm wavelength laser beam, is situated at the inside of the glass, and then a 1530 nm wavelength laser beam is crossed through the image to light it with an upconversion green light, which is viewable at all surrounding directions. This enables us to eliminate the limitation of the viewing zone angle imposed by the finite size of pixels in electro-holographic displays based on digital display chips/panels. The amount of the green light is much higher than that known previously. This is partly caused by the upconversion luminescence induced by 852 and 1530 nm laser beams.

Aptamer-Mediated Up-conversion Core/MOF Shell Nanocomposites for Targeted Drug Delivery and Cell Imaging

PubMed Central

Deng, Kerong; Hou, Zhiyao; Li, Xuejiao; Li, Chunxia; Zhang, Yuanxin; Deng, Xiaoran; Cheng, Ziyong; Lin, Jun

2015-01-01

Multifunctional nanocarriers for targeted bioimaging and drug delivery have attracted much attention in early diagnosis and therapy of cancer. In this work, we develop a novel aptamer-guided nanocarrier based on the mesoporous metal-organic framework (MOF) shell and up-conversion luminescent NaYF4:Yb3+/Er3+ nanoparticles (UCNPs) core for the first time to achieve these goals. These UCNPs, chosen as optical labels in biological assays and medical imaging, could emit strong green emission under 980 nm laser. The MOF structure based on iron (III) carboxylate materials [MIL-100 (Fe)] possesses high porosity and non-toxicity, which is of great value as nanocarriers for drug storage/delivery. As a unique nanoplatform, the hybrid inorganic-organic drug delivery vehicles show great promising for simultaneous targeted labeling and therapy of cancer cells. PMID:25597762

Fabrication and characterization of biological tissue phantoms with embedded nanoparticles

NASA Astrophysics Data System (ADS)

Skaptsov, A. A.; Ustalkov, S. O.; Mohammed, A. H. M.; Savenko, O. A.; Novikova, A. S.; Kozlova, E. A.; Kochubey, V. I.

2017-11-01

Phantoms are imitations of biological tissue, which are used for modelling of the light propagation in biological tissues. Carrying out any biophysical experiments requires an indispensable constancy of the initial experiment conditions. The use of solid undegradable phantoms is the basis to obtain reliable reproducible experimental results. The fabrication of biological tissues phantoms containing high absorbance or fluorescence nanoparticles and corresponding to specific mechanical, optical properties is an actual task. This work describes development, fabrication and characterization of such solid tissue phantoms with embedded CdSe/ZnS quantum dots, gold and upconversion nanoparticles. Luminescence of samples with CdSe/ZnS quantum dots and upconversion nanoparticles were recorded. A sample of gold nanorods was analyzed using thermal gravimetric analysis. It can be concluded that the samples are well suited for experiments on laser thermolysis.

FLUORESCENCE CHARACTERIZATION OF IHSS HUMIC SUBSTANCES: TOTAL LUMINESCENCE SPECTRA WITH ABSORBANCE CORRECTION. (R822251)

EPA Science Inventory

Total luminescence spectroscopy was applied to the fluorescence characterization of humic substances obtained from the International Humic Substances Society (IHSS). Results show that total luminescence spectra, represented as excitation-emission matrices (EEMs), may be used to d...

2D IR Spectroscopy using Four-Wave Mixing, Pulse Shaping, and IR Upconversion: A Quantitative Comparison

PubMed Central

Rock, William; Li, Yun-Liang; Pagano, Philip; Cheatum, Christopher M.

2013-01-01

Recent technological advances have led to major changes in the apparatuses used to collect 2D IR spectra. Pulse shaping offers several advantages including rapid data collection, inherent phase stability, and phase cycling capabilities. Visible array detection via upconversion allows the use of visible detectors that are cheaper, faster, more sensitive, and less noisy than IR detectors. However, despite these advantages, many researchers are reluctant to implement these technologies. Here we present a quantitative study of the S/N of 2D IR spectra collected with a traditional four-wave mixing (FWM) apparatus, with a pulse shaping apparatus, and with visible detection via upconversion to address the question of whether or not weak chromophores at low concentrations are still accessible with such an apparatus. We find that the enhanced averaging capability of the pulse shaping apparatus enables the detection of small signals that would be challenging to measure even with the traditional FWM apparatus, and we demonstrate this ability on a sample of cyanylated dihydrofolate reductase (DHFR). PMID:23687988

The Quality of In Vivo Upconversion Fluorescence Signals Inside Different Anatomic Structures.

PubMed

Wang, Lijiang; Draz, Mohamed Shehata; Wang, Wei; Liao, Guodong; Xu, Yuhong

2015-02-01

Fluorescence imaging is a broadly interesting and rapidly growing strategy for non-invasive clinical applications. However, because of interference from light scattering, absorbance, and tissue autofluorescence, the images can exhibit low sensitivity and poor quality. Upconversion fluorescence imaging, which is based on the use of near-infrared (NIR) light for excitation, has recently been introduced as an improved approach to minimize the effects of light scattering and tissue autofluorescence. This strategy is promising for ultrasensitive and deep tissue imaging applications. However, the emitted upconversion fluorescence signals are primarily in the visible range and are likely to be absorbed and scattered by tissues. Therefore, different anatomic structures could impose various effects on the quality of the images. In this study, we used upconversion-core/silica-shell nanoprobes to evaluate the quality of upconversion fluorescence at different anatomic locations in athymic nude mice. The nanoprobe contained an upconversion core, which was green (β-NaYF4:Yb3+/Ho3+) or red (β-NaYF4:Yb3+/Er3+), and a nonporous silica shell to allow for multicolor imaging. High-quality upconversion fluorescence signals were detected with signal-to-noise ratios of up to 170 at tissue depths of up to - 1.0 cm when a 980 nm laser excitation source and a bandpass emission filter were used. The presence of dense tissue structures along the imaging path reduced the signal intensity and imaging quality, and nanoprobes with longer-wavelength emission spectra were therefore preferable. This study offers a detailed analysis of the quality of upconversion signals in vivo inside different anatomic structures. Such information could be essential for the analysis of upconversion fluorescence images in any in vivo biodiagnostic and microbial tracking applications.

Thermometry properties of Er, Yb-Gd2O2S microparticles: dependence on the excitation mode (cw versus pulsed excitation) and excitation wavelength (980 nm versus 1500 nm)

NASA Astrophysics Data System (ADS)

Avram, Daniel; Tiseanu, Carmen

2018-04-01

Herein, we present a first report on the luminescence thermometry properties of Er, Yb doped Gd2O2S microparticles under near infrared up-conversion excitation at 980 and 1500 nm measured in the 280-800 K interval. The thermometry properties are assessed using both cw and ns pulsed excitation as well as tuning the excitation wavelength across Yb and Er absorption profiles. For low cw (300 mW cm-1) and pulsed ns (400 ÷ 550 mW cm-1) excitation modes, no thermal load is observed. At room-temperature (280 K), the maximum relative sensitivity values are comparable under pulsed excitation at 980 and 1500 nm, around ˜0.01 and ˜0.008% K-1, respectively. In addition, a relative intense up-conversion emission at 980 nm under excitation at 1500 nm is measured. Our findings evidence attractive up-conversion and thermometry properties Er, Yb doped Gd2O2S under near-infrared excitation and highlight the need to explore further these properties in the nanoparticulate regime.

Upconversion improvement in KLaF4:Yb3+/Er3+ nanoparticles by doping Al3+ ions

NASA Astrophysics Data System (ADS)

Zhou, Haifang; Wang, Xiechun; Lai, Yunfeng; Cheng, Shuying; Zheng, Qiao; Yu, Jinlin

2017-10-01

Rare-earth ion-doped upconversion (UC) materials show great potential applications in optical and optoelectronic devices due to their novel optical properties. In this work, hexagonal KLaF4:Yb3+/Er3+ nanoparticles (NPs) were successfully synthesized by a hydrothermal method, and remarkably enhanced upconversion luminescence in green and red emission bands in KLaF4:Yb3+/Er3+ NPs has been achieved by doping Al3+ ions under 980 nm excitation. Compared to the aluminum-free KLaF4:Yb3+/Er3+ NPs sample, the UC fluorescence intensities of the green and red emissions of NPs doped with 10 at.% Al3+ ions were significantly enhanced by 5.9 and 7.3 times, respectively. Longer lifetimes of the doped samples were observed for the 4S3/2 state and 4F9/2 state. The underlying reason for the UC enhancement by doping Al3+ ions was mainly ascribed to distortion of the local symmetry around Er3+ ions and adsorption reduction of organic ligands on the surface of NPs. In addition, the influence of doping Al3+ ions on the structure and morphology of the NPs samples was also discussed.

Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

NASA Astrophysics Data System (ADS)

Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

2018-04-01

Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

In vivo multimodality imaging and cancer therapy by near-infrared light-triggered trans-platinum pro-drug-conjugated upconverison nanoparticles.

PubMed

Dai, Yunlu; Xiao, Haihua; Liu, Jianhua; Yuan, Qinghai; Ma, Ping'an; Yang, Dongmei; Li, Chunxia; Cheng, Ziyong; Hou, Zhiyao; Yang, Piaoping; Lin, Jun

2013-12-18

Controlling anticancer drug activity and release on demand is very significant in cancer therapy. The photoactivated platinum(IV) pro-drug is stable in the dark and can be activated by UV light. In this study, we develop a multifunctional drug delivery system combining upconversion luminescence/magnetic resonance/computer tomography trimodality imaging and NIR-activated platinum pro-drug delivery. We use the core-shell structured upconversion nanoparticles to convert the absorbed NIR light into UV to activate the trans-platinum(IV) pro-drug, trans,trans,trans-[Pt(N3)2(NH3)(py)(O2CCH2CH2COOH)2]. Compared with using the UV directly, the NIR has a higher tissue penetration depth and is less harmful to health. Meanwhile, the upconversion nanoparticles can effectively deliver the platinum(IV) pro-drugs into the cells by endocytosis. The mice treated with pro-drug-conjugated nanoparticles under near-infrared (NIR) irradiation demonstrated better inhibition of tumor growth than that under direct UV irradiation. This multifunctional nanocomposite could be used as multimodality bioimaging contrast agents and transducers by converting NIR light into UV for control of drug activity in practical cancer therapy.

Phosphorus and Cu2+ removal by periphytic biofilm stimulated by upconversion phosphors doped with Pr3+-Li.

PubMed

Zhu, Yan; Zhang, Jianhong; Zhu, Ningyuan; Tang, Jun; Liu, Junzhuo; Sun, Pengfei; Wu, Yonghong; Wong, Po Keung

2018-01-01

Upconversion phosphors (UCPs) can convert visible light into luminescence, such as UV, which can regulate the growth of microbes. Based on these fundamentals, the community composition of periphytic biofilms stimulated by UCPs doped with Pr 3+ -Li + was proposed to augment the removal of phosphorus (P) and copper (Cu). Results showed that the biofilms with community composition optimized by UCPs doped with Pr 3+ -Li + had high P and Cu 2+ removal rates. This was partly due to overall bacterial and algal abundance and biomass increases. The synergistic actions of algal, bacterial biomass and carbon metabolic capacity in the Pr-Li stimulated biofilms facilitated the removal of P and Cu 2+ . The results show that the stimulation of periphytic biofilms by lanthanide-doped UCPs is a promising approach for augmenting P and Cu 2+ removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

X-ray Radiation-Controlled NO-Release for On-Demand Depth-Independent Hypoxic Radiosensitization.

PubMed

Fan, Wenpei; Bu, Wenbo; Zhang, Zhen; Shen, Bo; Zhang, Hui; He, Qianjun; Ni, Dalong; Cui, Zhaowen; Zhao, Kuaile; Bu, Jiwen; Du, Jiulin; Liu, Jianan; Shi, Jianlin

2015-11-16

Multifunctional stimuli-responsive nanotheranostic systems are highly desirable for realizing simultaneous biomedical imaging and on-demand therapy with minimized adverse effects. Herein, we present the construction of an intelligent X-ray-controlled NO-releasing upconversion nanotheranostic system (termed as PEG-USMSs-SNO) by engineering UCNPs with S-nitrosothiol (R-SNO)-grafted mesoporous silica. The PEG-USMSs-SNO is designed to respond sensitively to X-ray radiation for breaking down the S-N bond of SNO to release NO, which leads to X-ray dose-controlled NO release for on-demand hypoxic radiosensitization besides upconversion luminescent imaging through UCNPs in vitro and in vivo. Thanks to the high live-body permeability of X-ray, our developed PEG-USMSs-SNO may provide a new technique for achieving depth-independent controlled NO release and positioned radiotherapy enhancement against deep-seated solid tumors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical transitions of Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 glass.

PubMed

Shen, Xiang; Nie, Qiuhua; Xu, Tiefeng; Gao, Yuan

2005-10-01

Optical absorption and emission properties of the Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 (TWB) glass has been investigated. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd-Ofelt theory. The broad 1.5 microm fluorescence was observed under 970 nm excitation, and its full width at half maximum (FWHM) is 77 nm. The emission cross-section is calculated using the McCumber theory, and the peak emission cross-section is 1.03 x 10(-21) cm2 at 1.531 microm. This value is much larger than those of the silicate and phosphate glasses. Efficient green and weak red upconversion luminescence from Er3+ centers in the glass sample was observed at room temperature, and the upconversion excitation processes have been analyzed.

Magnetic Field Effects on Triplet-Triplet Annihilation in Solutions: Modulation of Visible/NIR Luminescence.

PubMed

Mani, Tomoyasu; Vinogradov, Sergei A

2013-08-06

Photon upconversion based on sensitized triplet-triplet annihilation (TTA) presents interest for such areas as photovoltaics and imaging. Usually energy upconversion is observed as p -type delayed fluorescence from molecules whose triplet states are populated via energy transfer from a suitable triplet donor, followed by TTA. Magnetic field effects (MFE) on delayed fluorescence in molecular crystals are well known; however, there exist only a few examples of MFE on TTA in solutions, and all of them are limited to UV-emitting materials. Here we present MFE on TTA-mediated visible and near infrared (NIR) emission, sensitized by far-red absorbing metalloporphyrins in solutions at room temperature. In addition to visible delayed fluorescence from annihilator, we also observed NIR emission from the sensitizer, occurring as a result of triplet-triplet energy transfer back from annihilator, termed "delayed phosphorescence". This emission also exhibits MFE, but opposite in sign to the annihilator fluorescence.

Hydrothermal synthesis infrared to visible upconversion luminescence of SrMoO4: Er3+/Yb3+ phosphor

NASA Astrophysics Data System (ADS)

Sinha, Shriya; Kumar, Kaushal

2018-04-01

The upconversion emission properties in Er3+/Yb3+ doped SrMoO4 phosphor synthesized via hydrothermal method is investigated upon 980 nm laser light excitation. The crystal structure and morphology of the synthesized phosphor are characterized by X-ray diffraction and field emission scanning electron microscopy. The X-ray diffraction pattern suggests that SrMoO4 phosphor has tetragonal phase structure. The phosphor emits strong green (525 and 552 nm) and red (665 nm) UC emissions along with weak blue (410 and 488 nm) and near infrared (798 nm) emission bands. The color emitted from the phosphor is shifted from yellow to green region with increasing the power density from 15 to 65 W/cm2. The result indicates that the present material is suitable for making infrared to visible up-converts and display devices.

Neuroendocrine Tumor-Targeted Upconversion Nanoparticle-Based Micelles for Simultaneous NIR-Controlled Combination Chemotherapy and Photodynamic Therapy, and Fluorescence Imaging.

PubMed

Chen, Guojun; Jaskula-Sztul, Renata; Esquibel, Corinne R; Lou, Irene; Zheng, Qifeng; Dammalapati, Ajitha; Harrison, April; Eliceiri, Kevin W; Tang, Weiping; Chen, Herbert; Gong, Shaoqin

2017-02-23

Although neuroendocrine tumors (NETs) are slow growing, they are frequently metastatic at the time of discovery and no longer amenable to curative surgery, emphasizing the need for the development of other treatments. In this study, multifunctional upconversion nanoparticle (UCNP)-based theranostic micelles are developed for NET-targeted and near-infrared (NIR)-controlled combination chemotherapy and photodynamic therapy (PDT), and bioimaging. The theranostic micelle is formed by individual UCNP functionalized with light-sensitive amphiphilic block copolymers poly(4,5-dimethoxy-2-nitrobenzyl methacrylate)-polyethylene glycol (PNBMA-PEG) and Rose Bengal (RB) photosensitizers. A hydrophobic anticancer drug, AB3, is loaded into the micelles. The NIR-activated UCNPs emit multiple luminescence bands, including UV, 540 nm, and 650 nm. The UV peaks overlap with the absorption peak of photocleavable hydrophobic PNBMA segments, triggering a rapid drug release due to the NIR-induced hydrophobic-to-hydrophilic transition of the micelle core and thus enabling NIR-controlled chemotherapy. RB molecules are activated via luminescence resonance energy transfer to generate 1 O 2 for NIR-induced PDT. Meanwhile, the 650 nm emission allows for efficient fluorescence imaging. KE108, a true pansomatostatin nonapeptide, as an NET-targeting ligand, drastically increases the tumoral uptake of the micelles. Intravenously injected AB3-loaded UCNP-based micelles conjugated with RB and KE108-enabling NET-targeted combination chemotherapy and PDT-induce the best antitumor efficacy.

Down- and up-conversion luminescent carbon dot fluid: inkjet printing and gel glass fabrication.

PubMed

Wang, Fu; Xie, Zheng; Zhang, Bing; Liu, Yun; Yang, Wendong; Liu, Chun-yan

2014-04-07

Room temperature liquid-like nanoparticles have emerged as an exciting new research and development area, because their properties could be tailored over a broad range by manipulating geometric and chemical characteristics of the inorganic core and organic canopy. However, related applications are rarely reported due to the multi-step synthesis process and potential toxicity of cadmium based nanomaterials. In this study, we prepared inexpensive and eco-friendly carbon dot fluid by the direct thermal decomposition method. The carbon dot fluid can be excited from UV to near infrared light, and can be prepared as highly concentrated luminescent ink or incorporated into sol-gel derived organically modified silicate glass, suggesting that it has great application potential in the field of printable electronics, solid state lighting and so on.

Spectral properties and anti-Stokes luminescence of TeO2-BaF2:Ho3+, Ho3+/Yb3+ ceramics and glass excited by 1.9-μm radiation of a Tm:LiYF4 laser

NASA Astrophysics Data System (ADS)

Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Perunin, I. Yu.; Krasheninnikova, O. V.; Grishin, I. A.

2017-07-01

We demonstrate the up-conversion of Tm:LiYF4 infrared (IR) laser radiation with 1908-nm wavelength into visible light with a spectral maximum at 650 nm by ceramics with a composition of (100 - x)TeO2- xBaF2 - 1 wt % HoF3- yYbF3, where x = 20, 30, or 40 mol % and y = 0 or 0.5 wt %. The samples of 60TeO2-40BaF2 - 1 wt % HoF3 - 0.5 wt % YbF3 exhibited anti-Stokes luminescence at a threshold radiation power density of 1.0-1.5 W cm-2.

A new near infrared photosensitizing nanoplatform containing blue-emitting up-conversion nanoparticles and hypocrellin A for photodynamic therapy of cancer cells

NASA Astrophysics Data System (ADS)

Jin, Shan; Zhou, Liangjun; Gu, Zhanjun; Tian, Gan; Yan, Liang; Ren, Wenlu; Yin, Wenyan; Liu, Xiaodong; Zhang, Xiao; Hu, Zhongbo; Zhao, Yuliang

2013-11-01

The utilization of up-conversion nanoparticles (UCNPs) for photodynamic therapy (PDT) has gained significant interest due to their unique ability to convert near infrared light to UV/visible light. Previous work mainly focused on the fabrication of green and red emitting UCNPs to load photosensitizers (PSs) for PDT. In this work, we firstly developed a new multifunctional nanoplatform combining blue-emitting UCNPs with blue-light excited PS (hypocrellin A, HA) as a NIR photosensitizing nanoplatform for PDT of cancer cells. Tween 20 coated NaYbF4:Tm, Gd@NaGdF4 UCNPs (Tween 20-UCNPs) with strong blue up-conversion luminescence and good water dispersibility were prepared for use as PS carriers. The blue emission band matched well with the efficient absorption band of HA, thereby facilitating the resonance energy transfer from UCNPs to HA and then activating HA to produce singlet oxygen (1O2). The in vitro study showed that these Tween 20-UCNPs@HA complexes could efficiently produce 1O2 to kill cancer cells under 980 nm NIR excitation. Moreover, these Gd3+ and Yb3+ containing nanoparticles also exhibited positive contrast effects in both T1 weighted magnetic resonance imaging (MRI) and computed tomography (CT) imaging, making them become a multifunctional platform for simultaneous PDT and bio-imaging.The utilization of up-conversion nanoparticles (UCNPs) for photodynamic therapy (PDT) has gained significant interest due to their unique ability to convert near infrared light to UV/visible light. Previous work mainly focused on the fabrication of green and red emitting UCNPs to load photosensitizers (PSs) for PDT. In this work, we firstly developed a new multifunctional nanoplatform combining blue-emitting UCNPs with blue-light excited PS (hypocrellin A, HA) as a NIR photosensitizing nanoplatform for PDT of cancer cells. Tween 20 coated NaYbF4:Tm, Gd@NaGdF4 UCNPs (Tween 20-UCNPs) with strong blue up-conversion luminescence and good water dispersibility were prepared for use as PS carriers. The blue emission band matched well with the efficient absorption band of HA, thereby facilitating the resonance energy transfer from UCNPs to HA and then activating HA to produce singlet oxygen (1O2). The in vitro study showed that these Tween 20-UCNPs@HA complexes could efficiently produce 1O2 to kill cancer cells under 980 nm NIR excitation. Moreover, these Gd3+ and Yb3+ containing nanoparticles also exhibited positive contrast effects in both T1 weighted magnetic resonance imaging (MRI) and computed tomography (CT) imaging, making them become a multifunctional platform for simultaneous PDT and bio-imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03515h

High quality polyacrylic acid modified multifunction luminescent nanorods for tri-modality bioimaging, in vivo long-lasting tracking and biodistribution

NASA Astrophysics Data System (ADS)

Yi, Zhigao; Lu, Wei; Liu, Hongrong; Zeng, Songjun

2014-12-01

Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging reveals that PAA-UCNRs can act as contrast agents for improved detection of the liver and spleen. In addition, a significant signal enhancement in the liver is observed in in vivo MRI, indicating that PAA-UCNRs are ideal T1-weighted MRI agents. More importantly, in vivo long-term tracking based on these PAA-UCNRs in the live mice and the corresponding ex vivo bioimaging of isolated organs also verify the translocation of PAA-UCNRs from the liver to the spleen, and the observed intense UC signals from the feces reveal the biliary excretion mechanism of these UCNRs. These findings contribute to understanding of the translocation and potential route for excretion of PAA-UCNRs, which can provide an important guide for the diagnosis and detection of diseases based on these UCNRs.Polyacrylic acid (PAA) modified NaYF4:Gd/Yb/Er upconversion nanorods (denoted as PAA-UCNRs) are demonstrated for tri-modal upconversion (UC) optical, computed X-ray tomography (CT), and magnetic resonance imaging (MRI). The hydrophilic PAA-UCNRs were obtained from hydrophobic oleic acid (OA) capped UCNRs (denoted as OA-UCNRs) using a ligand exchange method. The as-prepared UCNRs with a hexagonal phase structure present high monodispersity. These PAA-UCNRs are successfully used as ideal probes for in vivo UC luminescence bioimaging and synergistic X-ray and UC bioimaging. Moreover, X-ray CT imaging reveals that PAA-UCNRs can act as contrast agents for improved detection of the liver and spleen. In addition, a significant signal enhancement in the liver is observed in in vivo MRI, indicating that PAA-UCNRs are ideal T1-weighted MRI agents. More importantly, in vivo long-term tracking based on these PAA-UCNRs in the live mice and the corresponding ex vivo bioimaging of isolated organs also verify the translocation of PAA-UCNRs from the liver to the spleen, and the observed intense UC signals from the feces reveal the biliary excretion mechanism of these UCNRs. These findings contribute to understanding of the translocation and potential route for excretion of PAA-UCNRs, which can provide an important guide for the diagnosis and detection of diseases based on these UCNRs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05161k

The Effect of Inorganic Nanoparticles on the Luminescence Properties of the 5CB Liquid Crystal

NASA Astrophysics Data System (ADS)

Bezrodna, T. V.; Klishevich, G. V.; Curmei, N. D.; Melnyk, V. I.; Nesprava, V. V.

2017-09-01

The luminescence spectral characteristics of nanocomposites based on the 5CB liquid crystal with dispersions of inorganic particles of carbon nanotubes (CNTs), the mineral montmorillonite (MMT), and nanotubes of titanium dioxide TiO2 (TNT) were investigated in the temperature range of 4.3-300 K. The IR absorption spectra of the composites at room temperature in the region of 390-4000 cm-1 were studied. The dependence of the luminescent properties of the composites on the physical properties and parameters of the nanoparticles was studied. It was established that the longwave shift of the luminescence spectra of the composites in relation to the spectra of the pure liquid crystal is related to the specific surface area of the nanoparticles. The longwave shifts of the spectra at room and low temperatures are analyzed.

Synthesis of upconversion nanoparticles conjugated with graphene oxide quantum dots and their use against cancer cell imaging and photodynamic therapy.

PubMed

Choi, Seung Yoo; Baek, Seung Hoon; Chang, Sung-Jin; Song, Yohan; Rafique, Rafia; Lee, Kang Taek; Park, Tae Jung

2017-07-15

Multifunctional nanocomposite has a huge potential for cell imaging, drug delivery, and improving therapeutic effect with less side effects. To date, diverse approaches have been demonstrated to endow a single nanostructure with multifunctionality. Herein, we report the synthesis and application of core-shell nanoparticles composed with upconversion nanoparticle (UCNP) as a core and a graphene oxide quantum dot (GOQD) as a shell. The UCNP was prepared and applied for imaging-guided analyses of upconversion luminescence. GOQD was prepared and employed as promising drug delivery vehicles to improve anti-tumor therapy effect in this study. Unique properties of UCNPs and GOQDs were incorporated into a single nanostructure to provide desirable functions for cell imaging and drug delivery. In addition, hypocrellin A (HA) was loaded on GOQDs for photo-dynamic therapy (PDT). HA, a commonly used chemotherapy drug and a photo-sensitizer, was conjugated with GOQD by π-π interaction and loaded on PEGylated UCNP without complicated synthetic process, which can break structure of HA. Applying these core-shell nanoparticles to MTT assay, we demonstrated that the UCNPs with GOQD shell loaded with HA could be excellent candidates as multifunctional agents for cell imaging, drug delivery and cell therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Localized surface plasmons modulated nonlinear optical processes in metal film-coupled and upconversion nanocrystals-coated nanoparticles (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lei, Dangyuan

2016-09-01

In the first part of this talk, I will show our experimental investigation on the linear and nonlinear optical properties of metal film-coupled nanosphere monomers and dimers both with nanometric gaps. We have developed a new methodology - polarization resolved spectral decomposition and color decoding to "visualizing" unambiguously the spectral and radiation properties of the complex plasmonic gap modes in these hybrid nanostructures. Single-particle spectroscopic measurements indicate that these hybrid nanostructures can simultaneously enhance several nonlinear optical processes, such as second harmonic generation, two-photon absorption induced luminescence, and hyper-Raman scattering. In the second part, I will show how the polarization state of the emissions from sub-10 nm upconversion nanocrystals (UCNCs) can be modulated when they form a hybrid complex with a gold nanorod (GNR). Our single-particle scattering experiments expose how an interplay between excitation polarization and GNR orientation gives rise to an extraordinary polarized nature of the upconversion emissions from an individual hybrid nanostructure. We support our results by numerical simulations and, using Förster resonance energy transfer theory, we uncover how an overlap between the UCNC emission and GNR extinction bands as well as the mutual orientation between emission and plasmonic dipoles jointly determine the polarization state of the UC emissions.

Water-stable NaLuF4-based upconversion nanophosphors with long-term validity for multimodal lymphatic imaging.

PubMed

Zhou, Jing; Zhu, Xingjun; Chen, Min; Sun, Yun; Li, Fuyou

2012-09-01

Multimodal imaging is rapidly becoming an important tool for biomedical applications because it can compensate for the deficiencies of individual imaging modalities. Herein, multifunctional NaLuF(4)-based upconversion nanoparticles (Lu-UCNPs) were synthesized though a facile one-step microemulsion method under ambient condition. The doping of lanthanide ions (Gd(3+), Yb(3+) and Er(3+)/Tm(3+)) endows the Lu-UCNPs with high T(1)-enhancement, bright upconversion luminescence (UCL) emissions, and excellent X-ray absorption coefficient. Moreover, the as-prepared Lu-UCNPs are stable in water for more than six months, due to the protection of sodium glutamate and diethylene triamine pentacetate acid (DTPA) coordinating ligands on the surface. Lu-UCNPs have been successfully applied to the trimodal CT/MR/UCL lymphatic imaging on the modal of small animals. It is worth noting that Lu-UCNPs could be used for imaging even after preserving for over six months. In vitro transmission electron microscope (TEM), methyl thiazolyl tetrazolium (MTT) assay and histological analysis demonstrated that Lu-UCNPs exhibited low toxicity on living systems. Therefore, Lu-UCNPs could be multimodal agents for CT/MR/UCL imaging, and the concept can be served as a platform technology for the next-generation of probes for multimodal imaging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Lanthanide-doped upconversion nanocrystals: Synthesis and optical properties study

NASA Astrophysics Data System (ADS)

Sun, Qiang

Upconversion phosphor materials have attracted considerable attention in recent years for their potential applications in a wide range of fields, including three-dimensional displays technologies, bio-imaging and photovoltaics. This dissertation aims to develop novel lanthanide-doped upconversion luminescent nanomaterials by using wet chemistry methods. Considerable efforts have been devoted to manipulating the optical properties of the synthesized lanthanide-doped nanoparticles under excitation of different wavelengths, for example, 808, 980 and 1532 nm. In the first research work, a novel core-shell-shell design has been developed for finely tuning of energy migration upconversion of activators without long-lived mediated states, such as Eu3+ and Tb3+ upon excitation at 808 nm by using Nd3+ as sensitizer. Exquisite control the composition of each layer gives rise to maximized upconversion emissions of the activators. For example, with the use of core layer for energy harvesting (NaGdF4:Yb/Nd, active core), the optimal doping concentrations of Eu3+ and Tb3+ is fixed to 15 and 15 mol%, respectively. In contrast, active shell can also provide access to strong upconversion of Eu3+ and Tb3+ by doping Nd (40 mol%) into the outmost layer. Note that the effect of active shell is much stronger than active core in generating upconversion emissions of Eu3+ and Tb3+. Next, upconversion emission tuning of Er/Tm/Yb-doped NaYF4 upconversion nanoparticles has been conducted under excitation at 1532 nm. The output color of the nanoparticles is tunable by changing the doping levels of the lanthanides. With the use of core-shell design, the optical properties of the doped nanoparticles can be further optimized, for example, strongest upconversion emission was observed for NaYF4:Er(10 mol%) NaYF4:Er(0.5 mol%) with a relative emission of green-to-red of 1.2. This work provides a new dimension to control the color output of upconversion nanoparticles. It should be noted that the emission profiles of upconversion nanoparticles will be further enriched by using a combination of different excitation wavelengths. Finally, the orthorhombic-phase K2YF5 nanobelts doped with upconverting lanthanide ions (Er3+ and Tm3+) were synthesized by using a coprecipitation method. The growth kinetics of the nanobelts can be regulated by either control of the volume ratio of oleic acid in the synthetic system or period of reaction time. It was found that desirable lanthanide-doped K2YF5 nanobelts were yielded through the use of long time high-temperature annealing treatment (270 °C, 6 h) in the presence of low content of oleic acid. The assynthesized lanthanide-doped K2YF5 nanobelts show intense upconversion emissions upon excitation at 980 nm. For example, bright yellow emission was observed from K2YF5:Yb/Er(18/2 mol%), resulting from weak optical transitions of 2H11/2 → 4I15/2 (520 nm) and 4S3/2 → 4I15/2 (540 nm) and a dominant transition of 4F9/2 → 4I15/2 (centered at 650 nm) of the doped Er3+. In the case of K2YF5:Yb/Tm(30/0.5 mol%) nanobelts, three main emission bands centered at 479 (blue), 650 (red) and 800 nm (NIR) corresponding to 1D2 → 3H6, 1D2 → 3H4, and 3H4 ¨ 3H6 transition of Tm3+ were observed.

Red-light-controllable liquid-crystal soft actuators via low-power excited upconversion based on triplet-triplet annihilation.

PubMed

Jiang, Zhen; Xu, Ming; Li, Fuyou; Yu, Yanlei

2013-11-06

A red-light-controllable soft actuator has been achieved, driven by low-power excited triplet-triplet annihilation-based upconversion luminescence (TTA-UCL). First, a red-to-blue TTA-based upconversion system with a high absolute quantum yield of 9.3 ± 0.5% was prepared by utilizing platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP) as the sensitizer and 9,10-bis(diphenylphosphoryl)anthracene (BDPPA) as the annihilator. In order to be employed as a highly effective phototrigger of photodeformable cross-linked liquid-crystal polymers (CLCPs), the PtTPBP&BDPPA system was incorporated into a rubbery polyurethane film and then assembled with an azotolane-containing CLCP film. The generating assembly film bent toward the light source when irradiated with a 635 nm laser at low power density of 200 mW cm(-2) because the TTA-UCL was effectively utilized by the azotolane moieties in the CLCP film, inducing their trans-cis photoisomerization and an alignment change of the mesogens via an emission-reabsorption process. It is the first example of a soft actuator in which the TTA-UCL is trapped and utilized to create photomechanical effect. Such advantages of using this novel red-light-controllable soft actuator in potential biological applications have also been demonstrated as negligible thermal effect and its excellent penetration ability into tissues. This work not only provides a novel photomanipulated soft actuation material system based on the TTA-UCL technology but also introduces a new technological application of the TTA-based upconversion system in photonic devices.

Observation of Quartz Cathode-Luminescence in a Low Pressure Plasma Discharge

NASA Technical Reports Server (NTRS)

Foster, John E.

2004-01-01

Intense, steady-state cathode-luminescence has been observed from exposure of quartz powder to a low pressure rf-excited argon plasma discharge. The emission spectra (400 to 850 nm) associated with the powder luminescence were documented as a function of bias voltage using a spectrometer. The emission was broad-band, essentially washing out the line spectra features of the argon plasma discharge.

A luminescence-optical spectroscopy study of Rb2KTiOF5 single crystals

NASA Astrophysics Data System (ADS)

Pustovarov, V. A.; Ogorodnikov, I. N.; Kozlov, A. V.; Isaenko, L. I.

2018-06-01

Large single crystals of Rb2KTiOF5 (RKTF), grown by slow solidification method, were studied (7-400 K) for various types of optical and radiation effects. The optical absorption spectra, the parameters of the Urbach rule at 293 K (σ = 0.24 and EU = 105 meV), the low-temperature reflection spectra (T = 7 K, E = 3.7-22 eV) were determined. The luminescence spectra (1.2-6.2 eV) and luminescence decay kinetics are studied upon excitation by a nanosecond electron beam (PCL), ultraviolet and vacuum ultraviolet light (PL), or X-rays radiation (XRL). PL excitation spectra under selective photoexcitation by synchrotron radiation (E = 3.7-22 eV, T = 7 K), temperature dependences of the intensity of steady-state XRL in different emission bands, as well as thermoluminescence (7-400 K) are studied. In the visible spectral region, we detected three luminescence bands that were attributed to radiative annihilation of intrinsic excitons (2.25 eV), recombination-type luminescence (2.1 eV) and luminescence of higher TiOF5 complexes (1.9 eV). The exponential component with lifetime of about 19 μs was revealed in the PCL decay kinetics at 2.25 eV. The low-energy onset of the intrinsic host absorption Ec = 3.55 eV was determined on the basis of the experimental data obtained. Spectra of optical constants were calculated by the Kramers-Krönig method, the energy of the onset of the interband transitions Eg = 4.2 eV was determined, and the main peaks of the optical spectra were identified.

Total luminescence contour spectra of six topped crude oils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chisholm, B.R.; Eldering, H.G.; Giering, L.P.

1976-11-01

The results of a preliminary study of six topped crude oils by total luminescence are presented. Included are six contour spectra, six principal excitation/emission spectra, an interpretation of the contours by comparison with other data, a discussion of the method and recommendations for further related studies. These data are used in oil spill identification.

Simultaneous aptasensor for multiplex pathogenic bacteria detection based on multicolor upconversion nanoparticles labels.

PubMed

Wu, Shijia; Duan, Nuo; Shi, Zhao; Fang, Congcong; Wang, Zhouping

2014-03-18

A highly sensitive and specific multiplex method for the simultaneous detection of three pathogenic bacteria was fabricated using multicolor upconversion nanoparticles (UCNPs) as luminescence labels coupled with aptamers as the molecular recognition elements. Multicolor UCNPs were synthesized via doping with various rare-earth ions to obtain well-separated emission peaks. The aptamer sequences were selected using the systematic evolution of ligands by exponential enrichment (SELEX) strategy for Staphylococcus aureus, Vibrio parahemolyticus, and Salmonella typhimurium. When applied in this method, aptamers can be used for the specific recognition of the bacteria from complex mixtures, including those found in real food matrixes. Aptamers and multicolor UCNPs were employed to selectively capture and simultaneously quantify the three target bacteria on the basis of the independent peaks. Under optimal conditions, the correlation between the concentration of three bacteria and the luminescence signal was found to be linear from 50-10(6) cfu mL(-1). Improved by the magnetic separation and concentration effect of Fe3O4 magnetic nanoparticles, the limits of detection of the developed method were found to be 25, 10, and 15 cfu mL(-1) for S. aureus, V. parahemolyticus, and S. typhimurium, respectively. The capability of the bioassay in real food samples was also investigated, and the results were consistent with experimental results obtained from plate-counting methods. This proposed method for the detection of various pathogenic bacteria based on multicolor UCNPs has great potential in the application of food safety and multiplex nanosensors.

Neuroendocrine Tumor-Targeted Upconversion Nanoparticle-Based Micelles for Simultaneous NIR-Controlled Combination Chemotherapy and Photodynamic Therapy, and Fluorescence Imaging

PubMed Central

Chen, Guojun; Jaskula-Sztul, Renata; Esquibel, Corinne R.; Lou, Irene; Zheng, Qifeng; Dammalapati, Ajitha; Harrison, April; Eliceiri, Kevin W.; Tang, Weiping

2017-01-01

Although neuroendocrine tumors (NETs) are slow growing, they are frequently metastatic at the time of discovery and no longer amenable to curative surgery, emphasizing the need for the development of other treatments. In this study, multifunctional upconversion nanoparticle (UCNP)-based theranostic micelles are developed for NET-targeted and near-infrared (NIR)-controlled combination chemotherapy and photodynamic therapy (PDT), and bioimaging. The theranostic micelle is formed by individual UCNP functionalized with light-sensitive amphiphilic block copolymers poly(4,5-dimethoxy-2-nitrobenzyl methacrylate)-polyethylene glycol (PNBMA-PEG) and Rose Bengal (RB) photosensitizers. A hydrophobic anticancer drug, AB3, is loaded into the micelles. The NIR-activated UCNPs emit multiple luminescence bands, including UV, 540 nm, and 650 nm. The UV peaks overlap with the absorption peak of photocleavable hydrophobic PNBMA segments, triggering a rapid drug release due to the NIR-induced hydrophobic-to-hydrophilic transition of the micelle core and thus enabling NIR-controlled chemotherapy. RB molecules are activated via luminescence resonance energy transfer to generate 1O2 for NIR-induced PDT. Meanwhile, the 650 nm emission allows for efficient fluorescence imaging. KE108, a true pansomatostatin nonapeptide, as an NET-targeting ligand, drastically increases the tumoral uptake of the micelles. Intravenously injected AB3-loaded UCNP-based micelles conjugated with RB and KE108—enabling NET-targeted combination chemotherapy and PDT—induce the best antitumor efficacy. PMID:28989337

Bioimaging and toxicity assessments of near-infrared upconversion luminescent NaYF4:Yb,Tm nanocrystals.

PubMed

Zhou, Jia-Cai; Yang, Zheng-Lin; Dong, Wei; Tang, Ruo-Jin; Sun, Ling-Dong; Yan, Chun-Hua

2011-12-01

In vitro or in vivo bioimaging utilizing the upconversion (UC) luminescence of rare earth fluoride nanocrystals (NCs) has attracted much attention, especially for Yb(3+)/Tm(3+) doped NCs with a near-infrared (NIR) UC emission at 800 nm. Herein, water-soluble NaYF(4):Yb,Tm NCs with strong NIR UC emission were synthesized with a solvothermal method. In vitro and in vivo bioimaging and toxicity assessments were carried out with HeLa cell and Caenorhabditis elegans (C. elegans) cases, respectively. NaYF(4):Yb,Tm NCs afforded an efficient NIR image of the HeLa cells with an incubation concentration of 10 μg mL(-1), and CCK-8 assay revealed a low cytotoxicity. Fed with Escherichia coli (E. coli) and NCs together, the C. elegans showed a NIR image in the gut from the pharynx to the anus. Further, these NCs could be excreted out when those worms were then fed with only E. coli. Toxicity studies were further addressed with protein expression, life span, egg production, egg viability, and growth rate of the worms in comparison with those of the intact ones. The feeding of rare earth fluoride NCs with a dose of 100 μg does not arise obvious toxicity effect from the growth to procreation. The in vitro and in vivo studies confirm that NaYF(4):Yb,Tm NCs could be served as an excellent NIR emission bioprobe with low toxicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Tuning the morphology, luminescence and magnetic properties of hexagonal-phase NaGdF4: Yb, Er nanocrystals via altering the addition sequence of the precursors

NASA Astrophysics Data System (ADS)

Zhao, Shuwen; Xia, Donglin; Zhao, Ruimin; Zhu, Hao; Zhu, Yiru; Xiong, Yuda; Wang, Youfa

2017-01-01

Hexagonal-phase NaGdF4: Yb, Er upconversion nanocrystals (UCNCs) with tunable morphology and properties were successfully prepared via a thermal decomposition method. The influences of the adding sequence of the precursors on the morphology, chemical composition, luminescence and magnetic properties were investigated by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), upconversion (UC) spectroscopy, and a vibrating sample magnetometer (VSM). It was found that the resulting nanocrystals, with different sizes ranging from 24 to 224 nm, are in the shape of spheres, hexagonal plates and flakes; moreover, the composition percentage of Yb3+-Er3+ and Gd3+ ions was found to vary in a regular pattern with the adding sequence. Furthermore, the intensity ratios of emission colors (f g/r, f g/p), and the magnetic mass susceptibility of hexagonal-phase NaGdF4: Yb, Er nanocrystals change along with the composition of the nanocrystals. A positive correlation between the susceptibility and f g/r of NaGdF4: Yb, Er was proposed. The decomposition processes of the precursors were investigated by a thermogravimetric (TG) analyzer. The result indicated that the decomposition of the resolved lanthanide trifluoroacetate is greatly different from lanthanide trifluoroacetate powder. It is of tremendous help to recognize the decomposition process of the precursors and to understand the related reaction mechanism.

Room temperature synthesis of β-NaGdF 4 : RE 3+ (RE= Eu, Er) nanocrystallites and their luminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tessitore, Gabriella; Mudring, Anja-Verena; Kr?mer, Karl W.

In this study, a room temperature synthesis was developed for phase pure β-NaGdF 4 nanocrystallites as well as 5, 10, and 20% Eu 3+ or 5% Er 3+ doped material. Rare earth acetates and NaCl react in a 1:2 M ratio with a variable excess of NH 4F in ethylene glycol within 24 hours. Since the thermodynamic stability of the hexagonal phase decreases along the lanthanide series, a larger excess of NH 4F was required for the synthesis of luminescent samples doped with the smaller Er 3+ ions than for Eu 3+ doped or pure β-NaGdF 4. The materials weremore » characterized by powder X-ray diffraction, electron microscopy, and luminescence spectroscopy. The Eu 3+-doped samples show 5D 0→ 7F J and 5D 1→ 7F J luminescence after Eu 3+ excitation at 394 nm or Gd 3+ excitation at 273 nm and 308 nm. The ratio of 5D 1 vs. 5D 0 luminescence is influenced by the excitation wavelength and the Eu 3+ concentration. Lastly, the Er 3+-doped samples show green and red upconversion luminescence, respectively, from the 2H 11/2+ 4S 3/2→ 4I 15/2 and 4F 9/2→ 4I 15/2 transitions after 970 nm excitation.« less

Room temperature synthesis of β-NaGdF 4 : RE 3+ (RE= Eu, Er) nanocrystallites and their luminescence

DOE PAGES

Tessitore, Gabriella; Mudring, Anja-Verena; Kr?mer, Karl W.

2017-09-01

In this study, a room temperature synthesis was developed for phase pure β-NaGdF 4 nanocrystallites as well as 5, 10, and 20% Eu 3+ or 5% Er 3+ doped material. Rare earth acetates and NaCl react in a 1:2 M ratio with a variable excess of NH 4F in ethylene glycol within 24 hours. Since the thermodynamic stability of the hexagonal phase decreases along the lanthanide series, a larger excess of NH 4F was required for the synthesis of luminescent samples doped with the smaller Er 3+ ions than for Eu 3+ doped or pure β-NaGdF 4. The materials weremore » characterized by powder X-ray diffraction, electron microscopy, and luminescence spectroscopy. The Eu 3+-doped samples show 5D 0→ 7F J and 5D 1→ 7F J luminescence after Eu 3+ excitation at 394 nm or Gd 3+ excitation at 273 nm and 308 nm. The ratio of 5D 1 vs. 5D 0 luminescence is influenced by the excitation wavelength and the Eu 3+ concentration. Lastly, the Er 3+-doped samples show green and red upconversion luminescence, respectively, from the 2H 11/2+ 4S 3/2→ 4I 15/2 and 4F 9/2→ 4I 15/2 transitions after 970 nm excitation.« less

A Novel Approach to Synthesise a Dual-Mode Luminescent Composite Pigment for Uncloneable High-Security Codes to Combat Counterfeiting.

PubMed

Kanika; Kumar, Pawan; Singh, Satbir; Gupta, Bipin Kumar

2017-12-01

A strategy is demonstrated to protect valuable items, such as currency, pharmaceuticals, important documents, etc. against counterfeiting, by marking them with luminescent security codes. These luminescent security codes were printed by employing luminescent ink formulated from a cost effective dual-mode luminescent composite pigment of Gd 1.7 Yb 0.2 Er 0.1 O 3 and Zn 0.98 Mn 0.02 S phosphors using commercially available PVC Gold medium. In the composite, Gd 1.7 Yb 0.2 Er 0.1 O 3 and Zn 0.98 Mn 0.02 S account for upconversion and downconversion processes, respectively. The synthesis procedure of the composite involves the admixing of Gd 1.7 Yb 0.2 Er 0.1 O 3 nanorods and Zn 0.98 Mn 0.02 S phosphor, synthesised by hydrothermal and facile solid-state reaction methods, respectively. The structural, morphological, microstructural, and photoluminescent features of Gd 1.7 Yb 0.2 Er 0.1 O 3 nanorods, Zn 0.98 Mn 0.02 S phosphor and composite were characterised by using XRD, SEM, TEM, and photoluminescence (PL) techniques, respectively. The distribution of PL intensity of the printed pattern was examined by using confocal PL mapping microscopy. The obtained results reveal that security codes printed using ink formulated from this bi-luminescent composite pigment provide dual-stage security against counterfeiting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

GeS2–In2S3–CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence

PubMed Central

Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

2016-01-01

Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm3+, Er3+, and Dy3+) doped 65GeS2–25In2S3–10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm3+, Er3+, and Dy3+ ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions. PMID:27869231

An Anion-Induced Hydrothermal Oriented-Explosive Strategy for the Synthesis of Porous Upconversion Nanocrystals

PubMed Central

Qiu, Peiyu; Sun, Rongjin; Gao, Guo; Zhang, Chunlei; Chen, Bin; Yan, Naishun; Yin, Ting; Liu, Yanlei; Zhang, Jingjing; Yang, Yao; Cui, Daxiang

2015-01-01

Rare-earth (RE)-doped upconversion nanocrystals (UCNCs) are deemed as the promising candidates of luminescent nanoprobe for biological imaging and labeling. A number of methods have been used for the fabrication of UCNCs, but their assembly into porous architectures with desired size, shape and crystallographic phase remains a long-term challenging task. Here we report a facile, anion-induced hydrothermal oriented-explosive method to simultaneously control size, shape and phase of porous UCNCs. Our results confirmed the anion-induced hydrothermal oriented-explosion porous structure, size and phase transition for the cubic/hexagonal phase of NaLuF4 and NaGdF4 nanocrystals with various sizes and shapes. This general method is very important not only for successfully preparing lanthanide doped porous UCNCs, but also for clarifying the formation process of porous UCNCs in the hydrothermal system. The synthesized UCNCs were used for in vitro and in vivo CT imaging, and could be acted as the potential CT contrast agents. PMID:25767613

Design of an intelligent sub-50 nm nuclear-targeting nanotheranostic system for imaging guided intranuclear radiosensitization.

PubMed

Fan, Wenpei; Shen, Bo; Bu, Wenbo; Zheng, Xiangpeng; He, Qianjun; Cui, Zhaowen; Zhao, Kuaile; Zhang, Shengjian; Shi, Jianlin

2015-03-01

Clinically applied chemotherapy and radiotherapy is sometimes not effective due to the limited dose acting on DNA chains resident in the nuclei of cancerous cells. Herein, we develop a new theranostic technique of "intranuclear radiosensitization" aimed at directly damaging the DNA within the nucleus by a remarkable synergetic chemo-/radiotherapeutic effect based on intranuclear chemodrug-sensitized radiation enhancement. To achieve this goal, a sub-50 nm nuclear-targeting rattle-structured upconversion core/mesoporous silica nanotheranostic system was firstly constructed to directly transport the radiosensitizing drug Mitomycin C (MMC) into the nucleus for substantially enhanced synergetic chemo-/radiotherapy and simultaneous magnetic/upconversion luminescent (MR/UCL) bimodal imaging, which can lead to efficient cancer treatment as well as multi-drug resistance circumvention in vitro and in vivo . We hope the technique of intranuclear radiosensitization along with the design of nuclear-targeting nanotheranostics will contribute greatly to the development of cancer theranostics as well as to the improvement of the overall therapeutic effectiveness.

A core/satellite multifunctional nanotheranostic for in vivo imaging and tumor eradication by radiation/photothermal synergistic therapy.

PubMed

Xiao, Qingfeng; Zheng, Xiangpeng; Bu, Wenbo; Ge, Weiqiang; Zhang, Shengjian; Chen, Feng; Xing, Huaiyong; Ren, Qingguo; Fan, Wenpei; Zhao, Kuaile; Hua, Yanqing; Shi, Jianlin

2013-09-04

To integrate photothermal ablation (PTA) with radiotherapy (RT) for improved cancer therapy, we constructed a novel multifunctional core/satellite nanotheranostic (CSNT) by decorating ultrasmall CuS nanoparticles onto the surface of a silica-coated rare earth upconversion nanoparticle. These CSNTs could not only convert near-infrared light into heat for effective thermal ablation but also induce a highly localized radiation dose boost to trigger substantially enhanced radiation damage both in vitro and in vivo. With the synergistic interaction between PTA and the enhanced RT, the tumor could be eradicated without visible recurrence in 120 days. Notably, hematological analysis and histological examination unambiguously revealed their negligible toxicity to the mice within a month. Moreover, the novel CSNTs facilitate excellent upconversion luminescence/magnetic resonance/computer tomography trimodal imagings. This multifunctional nanocomposite is believed to be capable of playing a vital role in future oncotherapy by the synergistic effects between enhanced RT and PTA under the potential trimodal imaging guidance.

Clear-cut observation of clearance of sustainable upconverting nanoparticles from lymphatic system of small living mice

NASA Astrophysics Data System (ADS)

Park, Hye Sun; Nam, Sang Hwan; Kim, Jongwoo; Shin, Hyung Seon; Suh, Yung Doug; Hong, Kwan Soo

2016-06-01

The significance of lymphatic system has gathered great attention for immunotechnology related to cancer metastasis and immunotherapy. To develop innovative immunodiagnostics and immunotherapy in in vivo environments, it is very important to understand excretion pathways and clearance of injected cargoes. Herein, we employed Tm3+-doped upconverting nanoparticles (UCNPs) with versatile advantages suitable for long-term non-invasive in vivo optical imaging and tracking. Transport and retention of the UCNPs in the lymphatic system were evaluated with high-quality NIR-to-NIR upconversion luminescence (UCL) imaging. We obtained their kinetic luminescence profiles for the injection site and sentinel lymph node (SLN) and observed luminescence signals for one month; we also examined UCL images in SLN tissues, organs, and faeces at each time point. We speculate that the injected UCNPs in a footpad of a small mouse are transported rapidly from the lymphatic system to the blood system and then eventually result in an efficient excretion by the hepatobiliary route. These results will support development of novel techniques for SLN biopsy as well as immunotechnology.

Femtosecond excitation tuning and site energy memory of population transfer in poly(p-phenylenevinylene): Gated luminescence experiments and simulation

NASA Astrophysics Data System (ADS)

Sperling, J.; Milota, F.; Tortschanoff, A.; Warmuth, Ch.; Mollay, B.; Bässler, H.; Kauffmann, H. F.

2002-12-01

We present a comprehensive experimental and computational study on fs-relaxational dynamics of optical excitations in the conjugated polymer poly(p-phenylenevinylene) (PPV) under selective excitation tuning conditions into the long-wavelength, low-vibrational S1ν=0-density-of-states (DOS). The dependence of single-wavelength luminescence kinetics and time-windowed spectral transients on distinct, initial excitation boundaries at 1.4 K and at room temperature was measured applying the luminescence up-conversion technique. The typical energy-dispersive intra-DOS energy transfer was simulated by a combination of static Monte Carlo method with a dynamical algorithm for solving the energy-space transport Master-Equation in population-space. For various, selective excitations that give rise to specific S1-population distributions in distinct spatial and energetic subspaces inside the DOS, simulations confirm the experimental results and show that the subsequent, energy-dissipative, multilevel relaxation is hierarchically constrained, and reveals a pronounced site-energy memory effect with a migration-threshold, characteristic of the (dressed) excitation dynamics in the disordered PPV many-body system.

Upconversion fluorescence tyrosine doped LaF3:Dy quantum dots useful in biolabeling and biotagging

NASA Astrophysics Data System (ADS)

Singh, Amit T.; Khandpekar, M. M.

2018-04-01

Water soluble hexahedral colloidal quantum dots (QDOTs) of Tyrosine doped LaF3:Dy have been synthesized by wet chemical route. The nanoparticles have been irradiated by microwave during synthesis for drying and also to reduce agglomeration. The coating of the LaF3:Dy nanoparticles by the amino acid tyrosine results in colloidal quantum dots. XRD studies indicates hexagonal lattice and confirms JCPDS data. The average particle size obtained by XRD and SEM are 22.89nm and 25.5nm respectively. The average sizes of nanorods obtained from TEM are 55 nm. The presence of elements has been verified with EDAX and ICP-AES technique. The SAED pattern of the samples shows sharp concentric rings indicating the crystalline nature of the synthesized nanoparticles. The FTIR spectra have been used to study the surface modification of the nanoparticles. The optical studies have been done using UV-visible and PL spectra. The PL spectra showed upconversion nature of the synthesized nanoparticles with sharp emission at 618 nm. The nanoparticles synthesized have potential application as biomaterials in bio imaging and biotagging.

A cobalt oxyhydroxide-modified upconversion nanosystem for sensitive fluorescence sensing of ascorbic acid in human plasma

NASA Astrophysics Data System (ADS)

Cen, Yao; Tang, Jun; Kong, Xiang-Juan; Wu, Shuang; Yuan, Jing; Yu, Ru-Qin; Chu, Xia

2015-08-01

Ascorbic acid (AA), a potent antioxidant readily scavenging reactive species, is a crucial micronutrient involved in many biochemical processes. Here, we have developed a cobalt oxyhydroxide (CoOOH)-modified upconversion nanosystem for fluorescence sensing of AA activity in human plasma. The nanosystem consists of upconversion nanoparticles (UCNPs) NaYF4:30% Yb,0.5% Tm@NaYF4, which serve as energy donors, and CoOOH nanoflakes formed on the surface of UCNPs, which act as efficient energy acceptors. The fluorescence resonance energy transfer (FRET) process from the UCNPs to the absorbance of the CoOOH nanoflakes occurs in the nanosystem. The AA-mediated specific redox reaction reduces CoOOH into Co2+, leading to the inhibition of FRET, and resulting in the recovery of upconversion emission spectra. On the basis of these features, the nanosystem can be used for sensing AA activity with sensitivity and selectivity. Moreover, due to the minimizing background interference provided by UCNPs, the nanosystem has been applied to monitoring AA levels in human plasma sample with satisfactory results. The proposed approach may potentially provide an analytical platform for research and clinical diagnosis of AA related diseases.Ascorbic acid (AA), a potent antioxidant readily scavenging reactive species, is a crucial micronutrient involved in many biochemical processes. Here, we have developed a cobalt oxyhydroxide (CoOOH)-modified upconversion nanosystem for fluorescence sensing of AA activity in human plasma. The nanosystem consists of upconversion nanoparticles (UCNPs) NaYF4:30% Yb,0.5% Tm@NaYF4, which serve as energy donors, and CoOOH nanoflakes formed on the surface of UCNPs, which act as efficient energy acceptors. The fluorescence resonance energy transfer (FRET) process from the UCNPs to the absorbance of the CoOOH nanoflakes occurs in the nanosystem. The AA-mediated specific redox reaction reduces CoOOH into Co2+, leading to the inhibition of FRET, and resulting in the recovery of upconversion emission spectra. On the basis of these features, the nanosystem can be used for sensing AA activity with sensitivity and selectivity. Moreover, due to the minimizing background interference provided by UCNPs, the nanosystem has been applied to monitoring AA levels in human plasma sample with satisfactory results. The proposed approach may potentially provide an analytical platform for research and clinical diagnosis of AA related diseases. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03588k

Spectral management and morphology evolution of β-NaGdF4:Yb3+,Er3+ by tuning the concentration of citric acid

NASA Astrophysics Data System (ADS)

Yao, Lu; Xu, Dekang; Lin, Hao; Yang, Shenghong; Zhang, Yueli

2018-05-01

β-NaGdF4:Yb3+,Er3+ upconversion (UC) particles were prepared by a facile hydrothermal process with assistance of citric acid (CA). The morphologies of β-NaGdF4 UC particles were controlled by changing the doses of CA in precursor. With an increase CA concentration in precursor, increase sizes of crystals were observed, resulting in the increasing of luminescence intensity. The energy transfer ET mechanism was analyzed in detail.

Seeing the invisible plasma with transient phonons in cuprous oxide

DOE PAGES

Frazer, Laszlo; Schaller, Richard D.; Chang, Kelvin B.; ...

2016-12-12

Here, the emission of phonons from electron–hole plasma is the primary limit on the efficiency of photovoltaic devices operating above the bandgap. In cuprous oxide (Cu 2O) there is no luminescence from electron–hole plasma. Therefore, we searched for optical phonons emitted by energetic charge carriers using phonon-to-exciton upconversion transitions. We found 14 meV phonons with a lifetime of 0.916 ± 0.008 ps and 79 meV phonons that are longer lived and overrepresented. It is surprising that the higher energy phonon has a longer lifetime.

[Phosphorescent effect of Ir (ppy)3 on the luminescent characteristic of Rubrene].

PubMed

Xu, Hong-Hua; Xu, Zheng; Zhang, Fu-Jun; Zhao, Su-Ling; Yuan, Guang-Cai; Chen, Yue-Ning

2008-07-01

Many organic matters including heavy metal ions can validly utilize the singlet and triplet for luminescence owiog to the spin-orbit coupling. As a result, the internal quantum efficiency can easily achieve a value higher than traditional organic light emitting diodes in theory. There is a strong luminescence of PVK in PVK : PBD : Rubrene system. PL spectra excited by 345 nm of PVK : PBD : Rubrene thin film has a 410 nm PVK luminescent peak and a 560 nm Rubrene peak. EL still has a PVK luminescent peak, which should be kept from happening. Excitons can not adequately transferred from the matrix solution to Rubrene. The doping with Ir(ppy)3 improves the PVK : PBD : Rubrene system performance. PL spectra excited by 345 nm of PVK : PBD : Ir(ppy)3 : Rubrene with low concentration of Rubrene has a 510 nm Ir(ppy)3 peak and a new 548 nm one. However, the Ir(ppy)3 peak is smaller and the Rubrene one is bigger in EL spectra. Notably a strong and single luminescence of Rubrene is obtained in EL and PL spectra excited by 345 nm of PVK : PBD : Ir(ppy)3 : Rubrene with high concentration of Rubrene. Meanwhile, the Ir(ppy)3 luminescent peak disappears. The mechanism originates from the phosphorescent effect of Ir (ppy)3. The singlet excitons can basically be transferred from PVK : PBD or Ir(ppy)3 to Rubrene. But most excitons from Ir (ppy)3 can directly tunnel to the fluorescent material and come into being singlet states that can return to ground states and cause luminescence. Rubrene can accept proportional excitons with low concentration. While the concentration of Rubrene is higher, excitons can be entirely accepted by Rubrene. The effect also restricts the luminescent intensity of Ir(ppy)3 and boosts up that of Rubrene. Furthermore, the energy transfer in PVK : PBD : Ir(ppy)3 : Rubrene system is primary the Forester energy transfer. Excitation spectra of Rubrene and emission spectra of Ir(ppy)3 have a large overlap revealing that there is a strong energy transfer and further confirmed the phosphorescent effect of Ir(ppy)3. The doping system with phosphorescence material and small molecules can enhance the brightness and internal quantum efficiency.

Simultaneous isolation and detection of circulating tumor cells with a microfluidic silicon-nanowire-array integrated with magnetic upconversion nanoprobes.

PubMed

Wang, Chao; Ye, Min; Cheng, Liang; Li, Rui; Zhu, Wenwen; Shi, Zhen; Fan, Chunhai; He, Jinkang; Liu, Jian; Liu, Zhuang

2015-06-01

The development of sensitive and convenient methods for detection, enrichment, and analysis of circulating tumor cells (CTCs), which serve as an importance diagnostic indicator for metastatic progression of cancer, has received tremendous attention in recent years. In this work, a new approach characteristic of simultaneous CTC capture and detection is developed by integrating a microfluidic silicon nanowire (SiNW) array with multifunctional magnetic upconversion nanoparticles (MUNPs). The MUNPs were conjugated with anti-EpCAM antibody, thus capable to specifically recognize tumor cells in the blood samples and pull them down under an external magnetic field. The capture efficiency of CTCs was further improved by the integration with a microfluidic SiNW array. Due to the autofluorescence free nature in upconversion luminescence (UCL) imaging, our approach allows for highly sensitive detection of small numbers of tumor cells, which afterward could be collected for further analysis and re-culturing. We have further demonstrated that this approach can be applied to detect CTCs in clinical blood samples from lung cancer patients, and obtained consistent results by analyzing the UCL signals and the clinical outcomes of lung cancer metastasis. Therefore our approach represents a promising platform in CTC capture and detection with potential clinical utilization in cancer diagnosis and prognosis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multifunctional NaYF4:Yb, Er@mSiO2@Fe3O4-PEG nanoparticles for UCL/MR bioimaging and magnetically targeted drug delivery.

PubMed

Liu, Bei; Li, Chunxia; Ma, Ping'an; Chen, Yinyin; Zhang, Yuanxin; Hou, Zhiyao; Huang, Shanshan; Lin, Jun

2015-02-07

A low toxic multifunctional nanoplatform, integrating both mutimodal diagnosis methods and antitumor therapy, is highly desirable to assure its antitumor efficiency. In this work, we show a convenient and adjustable synthesis of multifunctional nanoparticles NaYF4:Yb, Er@mSiO2@Fe3O4-PEG (MFNPs) based on different sizes of up-conversion nanoparticles (UCNPs). With strong up-conversion fluorescence offered by UCNPs, superparamagnetism properties attributed to Fe3O4 nanoparticles and porous structure coming from the mesoporous SiO2 shell, the as-obtained MFNPs can be utilized not only as a contrast agent for dual modal up-conversion luminescence (UCL)/magnetic resonance (MR) bio-imaging, but can also achieve an effective magnetically targeted antitumor chemotherapy both in vitro and in vivo. Furthermore, the UCL intensity of UCNPs and the magnetic properties of Fe3O4 in the MFNPs were carefully balanced. Silica coating and further PEG modifying can improve the hydrophilicity and biocompatibility of the as-synthesized MFNPs, which was confirmed by the in vitro/in vivo biocompatibility and in vivo long-time bio-distributions tests. Those results revealed that the UCNPs based magnetically targeted drug carrier system we synthesized has great promise in the future for multimodal bio-imaging and targeted cancer therapy.

Surface modified α-glycine - EuF3: Gd nanoparticles for upconversion luminescence

NASA Astrophysics Data System (ADS)

Mahajan, Manoj P.; Khandpekar, M. M.

2018-04-01

Gadolinium doped EuF3 nanoparticles have been synthesized in the presence of α-glycine via chloride route with subsequent microwave drying. The XRD profile shows hexagonal phase structure with lattice parameters a = b = 6.920 A° and c = 7.085 A° (JCPDS No. 32-0373) with Debye-Scherer particle size of 51 nm. The SEM shows chipped morphology and TEM images exhibit shallow toroid like hexagonal - rounded nanostructures (30 - 50 nm) and their subsequent spontaneous transformation in to hyperboloid shaped nanostructures (200 - 600 nm) possibly with extension of the reaction time. SAED pattern confirms crystalline nature of nanoparticles and the planes are in agreement with XRD Peaks. Comparative FTTR and Raman spectrum shows presence of various functional groups confirming the capping of the glycine on EuF3:Gd core. A TGA/DTA spectrum shows decomposition in two stages. The photoluminescence spectrum shows up conversion luminescence at wavelength 653 nm (red).

Red, green, and blue luminescence by carbon dots: full-color emission tuning and multicolor cellular imaging.

PubMed

Jiang, Kai; Sun, Shan; Zhang, Ling; Lu, Yue; Wu, Aiguo; Cai, Congzhong; Lin, Hengwei

2015-04-27

A facile approach for preparation of photoluminescent (PL) carbon dots (CDs) is reported. The three resulting CDs emit bright and stable red, green and blue (RGB) colors of luminescence, under a single ultraviolet-light excitation. Alterations of PL emission of these CDs are tentatively proposed to result from the difference in their particle size and nitrogen content. Interestingly, up-conversion (UC)PL of these CDs is also observed. Moreover, flexible full-color emissive PVA films can be achieved through mixing two or three CDs in the appropriate ratios. These CDs also show low cytotoxicity and excellent cellular imaging capability. The facile preparation and unique optical features make these CDs potentially useful in numerous applications such as light-emitting diodes, full-color displays, and multiplexed (UC)PL bioimaging. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

YAG:Er3+, CaF2:Er3+, and Er2O3 Emission Spectra Under Laser and Laser Thermal Excitation

NASA Astrophysics Data System (ADS)

Marchenko, V. M.

2018-05-01

Experimental luminescence and selective-emission (SE) spectra of YAG:Er3+ (10 at.%) and CaF2:Er3+ (1 at.%) single crystals and Er2O3 polycrystal under laser and laser thermal excitation of the Er3+-ion multiplets are compared. Luminescence spectra under resonant excitation are determined by multiplet population relaxation with the corresponding radiative and nonradiative probabilities. The form of the SE spectra is determined by the thermal population of the multiplets and the probabilities of only radiative transitions. The SE band at 800 nm (4I9/2 → 4I15/2) is an indicator of high-temperature thermal emission of Er3+ ions. The absence of this band in luminescence spectra is explained by the short lifetime of the τ(4I9/2) level of 53 ns at T = 300 K.

Development of zirconia based phosphors for application in lighting and as luminescent bioprobes =

NASA Astrophysics Data System (ADS)

Soares, Maria Rosa Nunes

The strong progress evidenced in photonic and optoelectronic areas, accompanied by an exponential development in the nanoscience and nanotechnology, gave rise to an increasing demand for efficient luminescent materials with more and more exigent characteristics. In this field, wide band gap hosts doped with lanthanide ions represent a class of luminescent materials with a strong technological importance. Within wide band gap material, zirconia owns a combination of physical and chemical properties that potentiate it as an excellent host for the aforementioned ions, envisaging its use in different areas, including in lighting and optical sensors applications, such as pressure sensors and biosensors. Following the demand for outstanding luminescent materials, there is also a request for fast, economic and an easy scale-up process for their production. Regarding these demands, laser floating zone, solution combustion synthesis and pulsed laser ablation in liquid techniques are explored in this thesis for the production of single crystals, nanopowders and nanoparticles of lanthanides doped zirconia based hosts. Simultaneously, a detailed study of the morphological, structural and optical properties of the produced materials is made. The luminescent characteristics of zirconia and yttria stabilized zirconia (YSZ) doped with different lanthanide ions (Ce3+ (4f1), Pr3+ (4f2), Sm3+ (4f5), Eu3+ (4f6), Tb3+ (4f8), Dy3+ (4f9), Er3+ (4f11), Tm3+ (4f12), Yb3+ (4f13)) and co-doped with Er3+,Yb3+ and Tm3+,Yb3+ are analysed. Besides the Stokes luminescence, the anti- Stokes emission upon infrared excitation (upconversion and black body radiation) is also analysed and discussed. The comparison of the luminescence characteristics in materials with different dimensions allowed to analyse the effect of size in the luminescent properties of the dopant lanthanide ions. The potentialities of application of the produced luminescent materials in solid state light, biosensors and pressure sensors are explored taking into account their studied characteristics.

Spectroscopy and enhanced frequency upconversion in Nd3+-Yb3+ codoped TPO glasses: energy transfer and NIR to visible upconverter.

PubMed

Azam, Mohd; Rai, Vineet Kumar; Mohanty, Deepak Kumar

2017-09-22

TeO 2 -Pb 3 O 4 (TPO) glasses codoped with Nd 3+ and Yb 3+ ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ∼3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd 3+ doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd 3+ ions. The radiative transition probability for the 4 G 7/2  →  4 I 9/2 transition (∼1926 Hz) is found to be maximum compared to other 4 G 5/2  →  4 I 9/2 (∼1622 Hz) and 4 F 5/2  →  4 I 9/2 (∼865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb 3+ ions in the Nd 3+ doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ∼17, ∼12 and ∼42 times as compared to that of the Nd 3+ singly doped glass. The quantum efficiency for the 4 G 7/2 level is found to be ∼32%. The nephelauxetic ratio, bonding parameter and covalency of Nd 3+ ions have been found positive which represents the covalent bonding between Nd 3+ ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Spectroscopy and enhanced frequency upconversion in Nd3+-Yb3+ codoped TPO glasses: energy transfer and NIR to visible upconverter

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar; Mohanty, Deepak Kumar

2017-09-01

TeO2-Pb3O4 (TPO) glasses codoped with Nd3+ and Yb3+ ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ˜3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd3+ doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd3+ ions. The radiative transition probability for the 4G7/2 → 4I9/2 transition (˜1926 Hz) is found to be maximum compared to other 4G5/2 → 4I9/2 (˜1622 Hz) and 4F5/2 → 4I9/2 (˜865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb3+ ions in the Nd3+ doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ˜17, ˜12 and ˜42 times as compared to that of the Nd3+ singly doped glass. The quantum efficiency for the 4G7/2 level is found to be ˜32%. The nephelauxetic ratio, bonding parameter and covalency of Nd3+ ions have been found positive which represents the covalent bonding between Nd3+ ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Fluorine-18-labeled Gd3+/Yb3+/Er3+ co-doped NaYF4 nanophosphors for multimodality PET/MR/UCL imaging.

PubMed

Zhou, Jing; Yu, Mengxiao; Sun, Yun; Zhang, Xianzhong; Zhu, Xingjun; Wu, Zhanhong; Wu, Dongmei; Li, Fuyou

2011-02-01

Molecular imaging modalities provide a wealth of information that is highly complementary and rarely redundant. To combine the advantages of molecular imaging techniques, (18)F-labeled Gd(3+)/Yb(3+)/Er(3+) co-doped NaYF(4) nanophosphors (NPs) simultaneously possessing with radioactivity, magnetic, and upconversion luminescent properties have been fabricated for multimodality positron emission tomography (PET), magnetic resonance imaging (MRI), and laser scanning upconversion luminescence (UCL) imaging. Hydrophilic citrate-capped NaY(0.2)Gd(0.6)Yb(0.18)Er(0.02)F(4) nanophosphors (cit-NPs) were obtained from hydrophobic oleic acid (OA)-coated nanoparticles (OA-NPs) through a process of ligand exchange of OA with citrate, and were found to be monodisperse with an average size of 22 × 19 nm. The obtained hexagonal cit-NPs show intense UCL emission in the visible region and paramagnetic longitudinal relaxivity (r(1) = 0.405 s(-1)·(mM)(-1)). Through a facile inorganic reaction based on the strong binding between Y(3+) and F(-), (18)F-labeled NPs have been fabricated in high yield. The use of cit-NPs as a multimodal probe has been further explored for T(1)-weighted MR and PET imaging in vivo and UCL imaging of living cells and tissue slides. The results indicate that (18)F-labeled NaY(0.2)Gd(0.6)Yb(0.18)Er(0.02) is a potential candidate as a multimodal nanoprobe for ultra-sensitive molecular imaging from the cellular scale to whole-body evaluation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Giant enhancement of upconversion in ultra-small Er³⁺/Yb³⁺:NaYF₄ nanoparticles via laser annealing.

PubMed

Bednarkiewicz, A; Wawrzynczyk, D; Gagor, A; Kepinski, L; Kurnatowska, M; Krajczyk, L; Nyk, M; Samoc, M; Strek, W

2012-04-13

Most of the synthesis routes of lanthanide-doped phosphors involve thermal processing which results in nanocrystallite growth, stabilization of the crystal structure and augmentation of luminescence intensity. It is of great interest to be able to transform the sample in a spatially localized manner, which may lead to many applications like 2D and 3D data storage, anti-counterfeiting protection, novel design bio-sensors and, potentially, to fabrication of metamaterials, 3D photonic crystals or plasmonic devices. Here we demonstrate irreversible spatially confined infrared-laser-induced annealing (LIA) achieved in a thin layer of dried colloidal solution of ultra-small ∼8 nm NaYF₄ nanocrystals (NCs) co-doped with 2% Er³⁺ and 20% Yb³⁺ ions under a localized tightly focused beam from a continuous wave 976 nm medium power laser diode excitation. The LIA results from self-heating due to non-radiative relaxation accompanying the NIR laser energy upconversion in lanthanide ions. We notice that localized LIA appears at optical power densities as low as 15.5 kW cm⁻² (∼354 ± 29 mW) threshold in spots of 54 ± 3 µm diameter obtained with a 10 × microscope objective. In the course of detailed studies, a complete recrystallization to different phases and giant 2-3 order enhancement in luminescence yield is found. Our results are highly encouraging and let us conclude that the upconverting ultra-small lanthanide-doped nanophosphors are particularly promising for direct laser writing applications.

Giant enhancement of upconversion in ultra-small Er3+/Yb3+:NaYF4 nanoparticles via laser annealing

NASA Astrophysics Data System (ADS)

Bednarkiewicz, A.; Wawrzynczyk, D.; Gagor, A.; Kepinski, L.; Kurnatowska, M.; Krajczyk, L.; Nyk, M.; Samoc, M.; Strek, W.

2012-04-01

Most of the synthesis routes of lanthanide-doped phosphors involve thermal processing which results in nanocrystallite growth, stabilization of the crystal structure and augmentation of luminescence intensity. It is of great interest to be able to transform the sample in a spatially localized manner, which may lead to many applications like 2D and 3D data storage, anti-counterfeiting protection, novel design bio-sensors and, potentially, to fabrication of metamaterials, 3D photonic crystals or plasmonic devices. Here we demonstrate irreversible spatially confined infrared-laser-induced annealing (LIA) achieved in a thin layer of dried colloidal solution of ultra-small ˜8 nm NaYF4 nanocrystals (NCs) co-doped with 2% Er3+ and 20% Yb3+ ions under a localized tightly focused beam from a continuous wave 976 nm medium power laser diode excitation. The LIA results from self-heating due to non-radiative relaxation accompanying the NIR laser energy upconversion in lanthanide ions. We notice that localized LIA appears at optical power densities as low as 15.5 kW cm-2 (˜354 ± 29 mW) threshold in spots of 54 ± 3 µm diameter obtained with a 10 × microscope objective. In the course of detailed studies, a complete recrystallization to different phases and giant 2-3 order enhancement in luminescence yield is found. Our results are highly encouraging and let us conclude that the upconverting ultra-small lanthanide-doped nanophosphors are particularly promising for direct laser writing applications.

Luminescence concentration quenching and site-occupancy of Eu2+ ions in Na2Ca2Si3O9 phosphors derived from 45S5 glass-ceramics

NASA Astrophysics Data System (ADS)

Zhu, Yangguang; Tong, Chao; Xu, Chuanyan; Li, Yadong; Seo, Hyo Jin

2016-04-01

The phosphors of Na2Ca2-2xEu2xSi3O9 (x = 0, 0.03, 0.05, 0.07, 0.09) were first synthesized by sol-gel method. The crystal phase formations of the phosphors were detected by X-ray powder diffraction (XRD) measurements and the structure refinement. The photoluminescence spectra, the concentration quenching, the luminescence decay curves and the luminescence color chromaticity were measured, respectively. The excitation spectra indicate that the phosphors can be effectively excited by near UV-LED chips. Two kinds of Eu2+ sites centered at 545 nm and 505 nm were discussed by analyzing the spectra, concentration-dependent luminescence intensity and lifetimes. This is a potential tool for monitoring the bioactivity of 45S5 glass-ceramics in situ.

[Preparation and photoluminescence study of Er3+ : Y2O3 transparent ceramics].

PubMed

Luo, Jun-ming; Li, Yong-xiu; Deng, Li-ping

2008-10-01

Y2O3 acted as the matrix material, which was doped with different concentrations of Er3+, Er3+ : Y2O3 nanocrystalline powder was prepared by co-precipitation method, and Er3+ : Y2O3 transparent ceramics was fabricated by vacuum sintering at 1700 degrees C, 1 x 10(-3) Pa for 8 h. By using the X-ray diffraction (D/MAX-RB), transmission electron microscopy(Philips EM420), automatic logging spectrophotometer(DMR-22), fluorescence analyzer (F-4500) and 980 nm diode laser, the structural, morphological and luminescence properties of the sample were investigated. The results show that Er3+ dissolved completely in the Y2O3 cubic phase, the precursor was amorphous, weak diffraction peaks appeared after calcination at 400 degrees C, and if calcined at 700 degrees C, the precursor turned to pure cubic phase. With increasing the calcining temperature, the diffraction peaks became sharp quickly, and when the calcining temperature reached 1100 degrees C, the diffraction peaks became very sharp, indicating that the grains were very large. The particles of Er+ : Y2O3 is homogeneous and nearly spherical, the average diameter of the particles is in the range of 40-60 nm after being calcined at 1000 degrees C for 2 h. The relative density of Er3+ : Y2O3 transparent ceramics is 99.8%, the transmittance of the Er2+ : Y2O3 transparent ceramics is markedly lower than the single crystal at the short wavelength, but the transmittance is improved noticeably with increasing the wavelength, and the transmittance exceeds 60% at the wavelength of 1200 nm. Excited under the 980 nm diode laser, there are two main up-conversion emission bands, green emission centers at 562 nm and red emission centers at 660 nm, which correspond to (4)S(3/2) / (2)H(11/2) - (4)I(15/2) and (4)F(9/2) - (4)I(15/2) radiative transitions respectively. By changing the doping concentrations of Er3+, the color of up-conversion luminescence can be tuned from green to red gradually. The luminescence intensity is not reinforce with the increase in the concentration, so the doping concentration of Er3+ should not exceed 2%. If the doping concentration of Er3+ exceeds the range, the concentration has very small effect on the improvement of luminescence intensity.

Portable device for the detection of nitro-explosives based on optical properties of sensor's material

NASA Astrophysics Data System (ADS)

Baranova, A. A.; Khokhlov, K. O.

2014-11-01

The aim of this study was to design a device for explosives detection. The study design is based on excited steady-state luminescence quenching registration. Sensor's material luminescence intensity reduction occurs due to an interaction of explosives vapours contained in the air. The decrease rate of the luminescence intensity indicates the concentration of vapours. To study the luminescent properties of the sensor element, its luminescence spectra excited by photons with energies in the range 280 - 425 nm were measured. The excitation photoluminescence spectra for luminescence bands of the sensor element were also measured. Excitation source was light emitting diode (375 nm) and luminescent signal receiver was a photodiode (430 - 650 nm) in device designed. The device is operated under control of a program. The algorithm provides multiple operating modes (configuration, calibration, measurement etc.). Thus this device is referred to the class of devices with increased sensitivity to the explosives vapors. The advantages of device are autonomic power, small weight and sizes, simplicity of device operation for measurements.

Excited States and Luminescent Properties of UO 2F 2 and Its Solvated Complexes in Aqueous Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Jing; Wang, Zheming; Pan, Duoqiang

2014-07-21

The electronic absorption and emission spectra of free UO 2F 2 and its water solvated complexes below 32 000 cm –1 are investigated at the levels of ab initio CASPT2 and CCSD(T) with inclusion of scalar relativistic and spin–orbit coupling effects. The influence of the water coordination on the electronic spectra of UO 2F 2 is explored by investigating the excited states of solvated complexes (H 2O) nUO 2F 2 (n = 1–3). In these uranyl complexes, water coordination is found to have appreciable influence on the 3Δ (Ω = 1 g) character of the luminescent state and on themore » electronic spectral shape. The simulated luminescence spectral curves based on the calculated spectral parameters of (H 2O) nUO 2F 2 from CCSD(T) approach agree well with experimental spectra in aqueous solution at both near-liquid-helium temperature and room temperature. The possible luminescence spectra of free UO 2F 2 in gas phase are predicted on the basis of CASPT2 and CCSD(T) results, respectively, by considering three symmetric vibration modes. Finally, the effect of competition between spin–orbit coupling and ligand field repulsion on the luminescent state properties is discussed.« less

Long-lived room temperature deep-red/near-IR emissive intraligand triplet excited state (3IL) of naphthalimide in cyclometalated platinum(II) complexes and its application in upconversion.

PubMed

Wu, Wenting; Guo, Huimin; Wu, Wanhua; Ji, Shaomin; Zhao, Jianzhang

2011-11-21

[C(^)NPt(acac)] (C(^)N = cyclometalating ligand; acac = acetylacetonato) complexes in which the naphthalimide (NI) moiety is directly cyclometalated (NI as the C donor of the C-Pt bond) were synthesized. With 4-pyrazolylnaphthalimide, isomers with five-membered (Pt-2) and six-membered (Pt-3) chelate rings were obtained. With 4-pyridinylnaphthalimide, only the complex with a five-membered chelate ring (Pt-4) was isolated. A model complex with 1-phenylpyrazole as the C(^)N ligand was prepared (Pt-1). Strong absorption of visible light (ε = 21,900 M(-1) cm(-1) at 443 nm for Pt-3) and room temperature (RT) phosphorescence at 630 nm (Pt-2 and Pt-3) or 674 nm (Pt-4) were observed. Long-lived phosphorescences were observed for Pt-2 (τ(P) = 12.8 μs) and Pt-3 (τ(P) = 61.9 μs). Pt-1 is nonphosphorescent at RT in solution because of the acac-localized T(1) excited state [based on density functional theory (DFT) calculations and spin density analysis], but a structured emission band centered at 415 nm was observed at 77 K. Time-resolved transient absorption spectra and spin density analysis indicated a NI-localized intraligand triplet excited state ((3)IL) for complexes Pt-2, Pt-3, and Pt-4. DFT calculations on the transient absorption spectra (T(1) → T(n) transitions, n > 1) also support the (3)IL assignment of the T(1) excited states of Pt-2, Pt-3, and Pt-4. The complexes were used as triplet sensitizers for triplet-triplet-annihilation (TTA) based upconversion, and the results show that Pt-3 is an efficient sensitizer with an upconversion quantum yield of up to 14.1%, despite its low phosphorescence quantum yield of 5.2%. Thus, we propose that the sensitizer molecules at the triplet excited state that are otherwise nonphosphorescent were involved in the TTA upconversion process, indicating that weakly phosphorescent or nonphosphorescent transition-metal complexes can be used as triplet sensitizers for TTA upconversion.

Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra

USDA-ARS?s Scientific Manuscript database

Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...

Unusual x-ray excited luminescence spectra of NiO suggest self-trapping of the d-d charge-transfer exciton

NASA Astrophysics Data System (ADS)

Sokolov, V. I.; Pustovarov, V. A.; Churmanov, V. N.; Ivanov, V. Yu.; Gruzdev, N. B.; Sokolov, P. S.; Baranov, A. N.; Moskvin, A. S.

2012-09-01

Luminescence spectra of NiO have been investigated under vacuum ultraviolet (VUV) and soft x-ray (XUV) excitation (DESY, Hamburg). Photoluminescence (PL) spectra show broad emission violet and green bands centered at about 3.2 and 2.6 eV, respectively. The PL excitation (PLE) spectral evolution and lifetime measurements reveal that the two mechanisms with short and long decay times, attributed to the d(eg)-d(eg) and p(π)-d charge transfer (CT) transitions in the range 4-6 eV, respectively, are responsible for the observed emissions. The XUV excitation makes it possible to avoid the predominant role of the surface effects in luminescence and reveals a bulk violet luminescence with a puzzling well-isolated doublet of very narrow lines. These lines with close energies near 3.3 eV are attributed to recombination transitions in the self-trapped d-d CT excitons formed by the coupled Jahn-Teller Ni+ and Ni3+ centers. The conclusion is supported by a comparative analysis of the luminescence spectra for NiO and solid solution NixZn1-xO and by a comprehensive cluster model assignment of different p-d and d-d CT transitions and their relaxation channels. Our paper shows that the time-resolved luminescence measurements provide an instructive tool for the elucidation of the p-d and d-d CT excitations and their relaxation in 3d oxides.

Synchronous luminescence spectroscopic characterization of blood elements of normal and patients with cervical cancer

NASA Astrophysics Data System (ADS)

Muthuvelu, K.; Shanmugam, Sivabalan; Koteeswaran, Dornadula; Srinivasan, S.; Venkatesan, P.; Aruna, Prakasarao; Ganesan, Singaravelu

2011-03-01

In this study the diagnostic potential of synchronous luminescence spectroscopy (SLS) technique for the characterization of normal and different pathological condition of cervix viz., moderately differentiated squamous cell carcinoma (MDSCC), poorly differentiated squamous cell carcinoma (PDSCC) and well differentiated squamous cell carcinoma (WDSSC). Synchronous fluorescence spectra were measured for 70 abnormal cases and 30 normal subjects. Characteristic, highly resolved peaks and significant spectral differences between normal and MDSCC, PDSCC and WDSCC cervical blood formed elements were obtained. The synchronous luminescence spectra of formed elements of normal and abnormal cervical cancer patients were subjected to statistical analysis. Synchronous luminescence spectroscopy provides 90% sensitivity and 92.6% specificity.

Structure and intense UV up-conversion emissions in RE3+-doped sol-gel glass-ceramics containing KYF4 nanocrystals

NASA Astrophysics Data System (ADS)

Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.; del-Castillo, J.

2013-12-01

Transparent nano-glass-ceramics containing KYF4 nanocrystals were successfully obtained by the sol-gel method, doped with Eu3+ and co-doped with Yb3+ and Tm3+ ions. Precipitation of cubic KYF4 nanocrystals was confirmed by X-ray diffraction and high-resolution transmission electron microscope images. Excitation and emission spectra let us to discern between ions into KYF4 nanocrystals and those remaining in a glassy environment, supplemented with time-resolved photoluminescence decays, that also clearly reveal differences between local environments. Unusual high-energy up-conversion emissions in the UV range were obtained in Yb3+-Tm3+ co-doped samples, and involved mechanisms were discussed. The intensity of these high-energy emissions was analyzed as a function of Yb3+ concentration, heat treatment temperature of precursor sol-gel glasses and pump power, determining the optimum values for potential optical applications as highly efficient UV up-conversion materials in UV solid-state lasers.

Long wavelength identification of microcalcifications in breast cancer tissue using a quantum cascade laser and upconversion detection

NASA Astrophysics Data System (ADS)

Tseng, Y. P.; Bouzy, P.; Stone, N.; Pedersen, C.; Tidemand-Lichtenberg, P.

2018-02-01

Spectral imaging in the long-wave infrared regime has great potential for medical diagnostics. Breast cancer is the most common cancer amongst females in the US. The pathological features and the occurrence of the microcalcifications are still poorly understood. However, two types of microcalcifications have been identified as unique biomarkers: type I consisting of calcium oxalate (benign lesions) and type II composed of hydroxyapatite (benign or invasive lesions). In this study, we propose a new approach based on vibrational spectroscopy that is non-destructive, label-free and chemically specific for breast cancer detection. Long-wave infrared spectroscopy combining quantum cascade lasers (QCL) and upconversion detection, offer to improve signal-to-noise ratios compared to standard long-wave infrared spectroscopy. We demonstrated long-wave identification of synthetic samples of carbonated hydroxyapatite and of microcalcification in breast cancer tissue using upconversion detection. Absorbance spectra and upconverted images of in situ breast cancer biopsy are compared with that of Fourier-transform infrared (FTIR) spectroscopy.

Interference-enhanced infrared-to-visible upconversion in solid-state thin films sensitized by colloidal nanocrystals

NASA Astrophysics Data System (ADS)

Wu, Mengfei; Jean, Joel; Bulović, Vladimir; Baldo, Marc A.

2017-05-01

Infrared-to-visible photon upconversion has potential applications in photovoltaics, sensing, and bioimaging. We demonstrate a solid-state thin-film device that utilizes sensitized triplet-triplet exciton annihilation, converting infrared photons absorbed by colloidal lead sulfide nanocrystals (NCs) into visible photons emitted from a luminescent dopant in rubrene at low incident light intensities. A typical bilayer device consisting of a monolayer of NCs and a doped film of rubrene is limited by low infrared absorption in the thin NC film. Here, we augment the bilayer with an optical spacer layer and a silver-film back reflector, resulting in interference effects that enhance the optical field and thus the absorption in the NC film. The interference-enhanced device shows an order-of-magnitude increase in the upconverted emission at the wavelength of λ = 610 nm when excited at λ = 980 nm. At incident light intensities above 1.1 W/cm2, the device attains maximum efficiency, converting (1.6 ± 0.2)% of absorbed infrared photons into higher-energy singlet excitons in rubrene.

Intranuclear biophotonics by smart design of nuclear-targeting photo-/radio-sensitizers co-loaded upconversion nanoparticles.

PubMed

Fan, Wenpei; Shen, Bo; Bu, Wenbo; Zheng, Xiangpeng; He, Qianjun; Cui, Zhaowen; Ni, Dalong; Zhao, Kuaile; Zhang, Shengjian; Shi, Jianlin

2015-11-01

Biophotonic technology that uses light and ionizing radiation for positioned cancer therapy is a holy grail in the field of biomedicine because it can overcome the systemic toxicity and adverse side effects of conventional chemotherapy. However, the existing biophotonic techniques fail to achieve the satisfactory treatment efficacy, which remains a big challenge for clinical implementation. Herein, we develop a novel theranostic technique of "intranuclear biophotonics" by the smart design of a nuclear-targeting biophotonic system based on photo-/radio-sensitizers covalently co-loaded upconversion nanoparticles. These nuclear-targeting biophotonic agents can not only generate a great deal of multiple cytotoxic reactive oxygen species in the nucleus by making full use of NIR/X-ray irradiation, but also produce greatly enhanced intranuclear synergetic radio-/photodynamic therapeutic effects under the magnetic/luminescent bimodal imaging guidance, which may achieve the optimal efficacy in treating radio-resistant tumors. We anticipate that the highly effective intranuclear biophotonics will contribute significantly to the development of biophotonic techniques and open new perspectives for a variety of cancer theranostic applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

A fruitful demonstration in sensors based on upconversion luminescence of Yb3+/Er3+codoped Sb2O3-WO3-Li2O (SWL) glass-ceramic

NASA Astrophysics Data System (ADS)

Prasad Sukul, Prasenjit; Kumar, Kaushal

2016-07-01

In this article, erbium and ytterbium doped lithium tungsten antimonate (Yb3+/Er3+:Sb2O3-WO3-Li2O) glass-ceramics (GC) is synthesized and its novel applications in temperature sensing and detection of latent fingerprints is studied. It is also estimated that this material could be useful as a solar cell concentrator. The upconversion emission studies on Yb3+/Er3+:SWL glass-ceramics have shown intense green emission at 525 nm (2H11/2 → 4I15/2) & 545 nm (4s3/2 → 4I15/2). The variation of UC intensities with external temperature have shown a well-fashioned pattern, which suggests that the 2H11/2 and 4S3/2 levels of Er3+ ion are thermally coupled and can act as a temperature sensor in the 300-500 K temperature range. Dry powder of Yb3+/Er3+:SWL glass-ceramic is used to develop latent fingerprint with high contrast in green color on glass slide.

Boosting the down-shifting luminescence of rare-earth nanocrystals for biological imaging beyond 1500 nm.

PubMed

Zhong, Yeteng; Ma, Zhuoran; Zhu, Shoujun; Yue, Jingying; Zhang, Mingxi; Antaris, Alexander L; Yuan, Jie; Cui, Ran; Wan, Hao; Zhou, Ying; Wang, Weizhi; Huang, Ngan F; Luo, Jian; Hu, Zhiyuan; Dai, Hongjie

2017-09-29

In vivo fluorescence imaging in the near-infrared region between 1500-1700 nm (NIR-IIb window) affords high spatial resolution, deep-tissue penetration, and diminished auto-fluorescence due to the suppressed scattering of long-wavelength photons and large fluorophore Stokes shifts. However, very few NIR-IIb fluorescent probes exist currently. Here, we report the synthesis of a down-conversion luminescent rare-earth nanocrystal with cerium doping (Er/Ce co-doped NaYbF 4 nanocrystal core with an inert NaYF 4 shell). Ce doping is found to suppress the up-conversion pathway while boosting down-conversion by ~9-fold to produce bright 1550 nm luminescence under 980 nm excitation. Optimization of the inert shell coating surrounding the core and hydrophilic surface functionalization minimize the luminescence quenching effect by water. The resulting biocompatible, bright 1550 nm emitting nanoparticles enable fast in vivo imaging of blood vasculature in the mouse brain and hindlimb in the NIR-IIb window with short exposure time of 20 ms for rare-earth based probes.Fluorescence imaging in the near-infrared window between 1500-1700 nm (NIR-IIb window) offers superior spatial resolution and tissue penetration depth, but few NIR-IIb probes exist. Here, the authors synthesize rare earth down-converting nanocrystals as promising fluorescent probes for in vivo imaging in this spectral region.

Origin of near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+)co-doped fluorotellurite glasses under different excitations.

PubMed

Huang, Feifei; Liu, Xueqiang; Ma, Yaoyao; Kang, Shuai; Hu, Lili; Chen, Danping

2015-02-04

We report the near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+) co-doped fluorotellurite glasses under 980, 1550 and 800 nm excitations, respectively. Using a 980 nm laser diode pump, enhanced 1.5 and 2.7 μm emissions from Er(3+):I13/2→(4)I15/2 and I11/2→(4)I13/2 transitions are observed, in which Yb(3+) ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb(3+) can also be used as an acceptor and intensive upconversion luminescence of around 1000 nm is achieved from Er(3+):I11/2→(4)I15/2 and Yb(3+): F5/2→(4)F7/2 transitions using 1550 nm excitation. In addition, the luminescence properties and variation trendency by 800 nm excitation is similar to that using 1550 nm excitation. The optimum Er(3+) and Yb(3+) ion ratio is 1:1.5 and excess Yb(3+) ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er(3+)/Yb(3+) co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells.

Origin of near to middle infrared luminescence and energy transfer process of Er3+/Yb3+co-doped fluorotellurite glasses under different excitations

PubMed Central

Huang, Feifei; Liu, Xueqiang; Ma, Yaoyao; Kang, Shuai; Hu, Lili; Chen, Danping

2015-01-01

We report the near to middle infrared luminescence and energy transfer process of Er3+/Yb3+ co-doped fluorotellurite glasses under 980, 1550 and 800 nm excitations, respectively. Using a 980 nm laser diode pump, enhanced 1.5 and 2.7 μm emissions from Er3+:I13/2→4I15/2 and I11/2→4I13/2 transitions are observed, in which Yb3+ ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb3+ can also be used as an acceptor and intensive upconversion luminescence of around 1000 nm is achieved from Er3+:I11/2→4I15/2 and Yb3+: F5/2→4F7/2 transitions using 1550 nm excitation. In addition, the luminescence properties and variation trendency by 800 nm excitation is similar to that using 1550 nm excitation. The optimum Er3+ and Yb3+ ion ratio is 1:1.5 and excess Yb3+ ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er3+/Yb3+ co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells. PMID:25648651

Enhanced red emission of 808 nm excited upconversion nanoparticles by optimizing the composition of shell for efficient generation of singlet oxygen

NASA Astrophysics Data System (ADS)

Liu, Jinxue; Zhang, Tingbin; Song, Xiaoyan; Xing, Jinfeng

2018-01-01

With the aim to enhance the upconversion luminescence (UCL) intensity, much attention was paid to reduce the energy-back transfer from Er3+ ions to Nd3+ ions by constructing various kinds of multilayer upconversion nanoparticles (UCNPs). However, the energy-back transfer was difficult to be completely eliminated. Also, the thick shell of multilayer UCNPs is not favourable for effective Förster resonance energy transfer (FRET) in photodynamic therapy (PDT) system. Herein, an effective and facile method was applied to prepare UCNPs by optimizing the composition to largely enhance the red emission (at 660 nm) for efficient generation of singlet oxygen (1O2). In detail, the concentrations of Nd3+ ions and Yb3+ ions doped in the sensitizing shell were systematically researched to balance the energy back-transfer and the light harvest ability. The optimal emission and a relatively high Red/Green (R/G) ratio of NaYF4:Yb,Er,Nd@NaYF4:Yb0.1Nd0.2 UCNPs were obtained simultaneously. Furthermore, the emission under 980 nm excitation demonstrated the energy back-transfer from Er3+ to Yb3+ ions was also notable which was largely ignored previously. Then, UCNPs were encapsulated into mesoporous silica shell, and the photosensitizer Chlorin e6 (Ce6) was covalently conjugated to form a non-leaking nanoplatform. The efficiency of 1O2 generation obviously increased with the enhanced emission of UCNPs.

Temperature and pressure variations of d-d luminescence band maxima of bis(pyridylalkenolato)palladium(II) complexes with different ligand substituents: opposite-signed trends.

PubMed

Poirier, Stéphanie; Czympiel, Lisa; Bélanger-Desmarais, Nicolas; Mathur, Sanjay; Reber, Christian

2016-04-21

Luminescence spectra of two d(8)-configured bis(pyridylalkenolato)palladium(ii) complexes, [Pd{PyCHC(C3F7)O}2] and [Pd{PyCHC(CH3)O}2], are presented at variable temperature and pressure. Bands are assigned as d-d transitions. The heptafluoropropyl and methyl substituents on the ligands have different steric demands, influencing luminescence spectra. Broad bands with maxima at approximately 12 700 cm(-1) (790 nm) for ligands with heptafluoropropyl substituents and 12,100 cm(-1) (830 nm) for ligands with methyl substituents and widths of approximately 2100 cm(-1) for both complexes are observed at 80 K. Quenching of the luminescence is observed as temperature increases. The maxima of [Pd{PyCHC(C3F7)O}2] show a shift of -0.9 ± 0.1 cm(-1) K(-1) due to broadening of the spectra to lower energy. The luminescence maxima of [Pd{PyCHC(CH3)O}2] shift in the opposite direction by +7.2 ± 0.7 cm(-1) K(-1). Shifts with different signs are also obtained from variable-pressure luminescence spectra, with values of +13 ± 2 cm(-1) kbar(-1) and -15 ± 7 cm(-1) kbar(-1) for [Pd{PyCHC(C3F7)O}2] and [Pd{PyCHC(CH3)O}2], respectively. The pressure-induced decrease is unusual and likely caused by intermolecular interactions involving the palladium(ii) center and a vinylic proton of a neighboring complex.

The manifestation of optical centers in UV-Vis absorption and luminescence spectra of white blood human cells

NASA Astrophysics Data System (ADS)

Terent'yeva, Yu G.; Yashchuk, V. M.; Zaika, L. A.; Snitserova, O. M.; Losytsky, M. Yu

2016-12-01

A white blood human cells spectral investigation is presented. The aim of this series of experiments was to obtain and analyze the absorption and luminescence (fluorescence and phosphorescence) spectra at room temperature and at 78 K of newly isolated white blood human cells and their organelles. As a result the optical centers and possible biochemical components that form the studied spectra where identified. Also the differences between the spectra of abnormal cells (B-cell chronic lymphocytic leukemia BCLL) and normal ones were studied for the whole cells and individual organelles.

Luminescence in Conjugated Molecular Materials under Sub-bandgap Excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

So, Franky

2014-05-08

Light emission in semiconductors occurs when they are under optical and electrical excitation with energy larger than the bandgap energy. In some low-dimensional semiconductor heterostructure systems, this thermodynamic limit can be violated due to radiative Auger recombination (AR), a process in which the sub-bandgap energy released from a recombined electron-hole pair is transferred to a third particle leading to radiative band-to-band recombination.1 Thus far, photoluminescence up-conversion phenomenon has been observed in some low dimensional semiconductor systems, and the effect is very weak and it can only be observed at low temperatures. Recently, we discovered that efficient electroluminescence in poly[2-methoxy-5-(2’-ethylhexyloxy)-1, phenylenevinylene]more » (MEH-PPV) polymer light-emitting devices (PLEDs) at drive voltages below its bandgap voltage could be observed when a ZnO nanoparticles (NPs) electron injection layer was inserted between the polymer and the aluminum electrode. Specifically, emitted photons with energy of 2.13 eV can be detected at operating voltages as low as 1.2 V at room temperature. Based on these data, we propose that the sub-bandgap turn-on in the MEH-PPV device is due to an Auger-assisted energy up-conversion process. The significance of this discovery is three-fold. First, radiative recombination occurs at operating voltages below the thermodynamic bandgap voltage. This process can significantly reduce the device operating voltage. For example, the current density of the device with the ZnO NC layer is almost two orders of magnitude higher than that of the device without the NC layer. Second, a reactive metal is no longer needed for the cathode. Third, this electroluminescence up-conversion process can be applied to inorganic semiconductors systems as well and their operation voltages of inorganic LEDs can be reduced to about half of the bandgap energy. Based on our initial data, we propose that the sub-bandgap turn-on in MEH-PPV devices is due to Auger-assisted energy up-conversion process. Specifically, we propose that the up-conversion process is due to charge accumulation at the polymer/NPs interface. This model requires that holes should be the dominant carriers in the polymer and the polymer/ZnO NCs heterojunction should be a type II alignment. In order to determine the mechanism of the up-conversion process, we will characterize devices fabricated using polymers with different carrier transporting properties to determine whether hole accumulation at the polymer/nanocrystals is required. Likewise, we will also use NPs with different electronic structures to fabricate devices to determine how electron accumulation affects the up-conversion process. Finally, we will measure quantitatively the interface charge accumulation by electroabsorption and correlate the results with the up-conversion photoluminescence efficiency measurements under an applied electric field.« less

Luminescence Properties of RDX and HMX

DTIC Science & Technology

1975-08-01

AD-AO15 538 LUMINESCENCE PROPERTIES OF RDX AND HMX Paul L. Marinkas Picatinny Arsenal Dover, New Jersey August 1975 DISTRIBUTED BY: National...Technical Information Service U. S. DEPARTMENT OF COMMERCE • i 289106. TECHNICAL REPORT 4840 LUMINESCENCE PROPERTIES, OF RDX AND HMX PAULL. MARINKAS -’-I...yields Charge transfer HMX Phosphorescence Reflectance spectra Circular dichroism Lifetimes Photodecomposition RDX Doping Luminescence Polynitramines

Defect specific luminescence dead layers in CdS and CdSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenberg, R. A.

CdS and CdSe are often used in optoelectronic devices whose effectiveness is may be dictated by defects in the near surface region. Luminescence is one of the main tools for studying such defects. The energy dependence of the x-ray excited optical luminescence (XEOL) spectra of these materials enables the extraction of the depth dependence of the defect distribution. Normal and time-gated XEOL spectra were obtained from these materials in the energy range 600 to 1500 eV. Here, we find that the results can best be understood in terms of a luminescence dead layer whose width depends on the position ofmore » the defect level in the band gap.« less

Defect specific luminescence dead layers in CdS and CdSe

DOE PAGES

Rosenberg, R. A.

2017-04-28

CdS and CdSe are often used in optoelectronic devices whose effectiveness is may be dictated by defects in the near surface region. Luminescence is one of the main tools for studying such defects. The energy dependence of the x-ray excited optical luminescence (XEOL) spectra of these materials enables the extraction of the depth dependence of the defect distribution. Normal and time-gated XEOL spectra were obtained from these materials in the energy range 600 to 1500 eV. Here, we find that the results can best be understood in terms of a luminescence dead layer whose width depends on the position ofmore » the defect level in the band gap.« less

Spectral Characterization of a Novel Luminescent Organogel

ERIC Educational Resources Information Center

Waguespack, Yan; White, Shawn R.

2007-01-01

The spectroscopic-based luminescence experiments were designed to expose the students to various concepts of single-triplet excited states, electron spin, vibrational relaxation, fluorescence-phosphorescence lifetimes and quenching. The students were able to learn about luminescence spectra of the gel and have the experience of synthesizing a…

High quantum-yield phosphors via quantum splitting and upconversion

NASA Astrophysics Data System (ADS)

Jeong, Joayoung

The Gd3+ ion has been used to induce quantum splitting in luminescent materials by using cross-relaxation energy transfer (CRET). In Nd:LiGdF4, quantum splitting results from a two-step CRET between Gd3+ and Nd3+, first involving a transition 6G→6I on Gd3+ and an excitation within the 4f3 configuration of Nd3+ followed by a second CRET that brings Gd3+ to 6P7/2. The excited Nd3+ ion rapidly relaxes nonradiatively to the emitting 4F3/2. The excited Gd3+ ion then transfers its energy back to Nd3+, which gives rise to the second photon. The result is a quantum yield of 1.05 +/- 0.35 with emission in the NIR following excitation at 175 nm. GdF3:Pr3+, Eu 3+ also exhibits quantum splitting, but only at very low concentration of Pr3+ (0.3%) and Eu3+ (0.2%), resulting in a quantum yield of approximately 20% under 160-nm excitation. Host intrinsic emission via a self-trapped exciton (STE) was also examined as a means to sensitize Gd3+ emission. The material ScPO4:Gd 3+ exhibits a high absolute quantum yield of 0.9 +/- 0.2 under 170-nm excitation, demonstrating a potentially new and efficient pathway for exciting quantum splitting phosphors. Single crystals of the material GdZrF7 were grown, and its structure was established via single-crystal X-ray diffraction methods. Doped samples of GdZrF7:Yb3+, Er3+ exhibit bright up-conversion luminescence with light output that is up to twice that of a commercial material based on the host Gd2O2S. When doped with Eu3+, the fluoride also emits a nearly white color under vacuum ultraviolet excitation with an absolute quantum yield near 0.9. The new compound Gd4.67(SiO4)3S was synthesized and studied. The structure was established via single-crystal X-ray methods, and the luminescence of Tb3+ samples was investigated.

Synthesis of magnetic and upconversion nanocapsules as multifunctional drug delivery system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Shanshan; Chen, Yinyin; Liu, Bei

Multifunctional hollow nanocapsules with magnetic and upconversion luminescence properties were synthesized. Hollow Fe{sub 3}O{sub 4}@SiO{sub 2} was firstly prepared by using rodlike β-FeOOH as the template followed by silica coating, calcinations and reduction. Then Fe{sub 3}O{sub 4}@SiO{sub 2}@α-NaYF{sub 4}:Yb{sup 3+},Er{sup 3+} nanocapsules (FeSiUCNP) were synthesized by the hydrothermal transformation of the Y(Yb{sup 3+}, Er{sup 3+})(OH)CO{sub 3} (YOC) deposited onto the surface of nanocapsules through a urea-assisted homogeneous precipitation method. The hollow nanocapsules with porous structure provide space and entrance for the drug molecules. Due to the outside shell of α-NaYF{sub 4}:Yb{sup 3+}, Er{sup 3+}, the nanomaterial shows upconverting red emissionmore » upon 980 nm NIR-light excitation. Moreover, the nanocomposites with hollow magnetite core exhibit a high relaxivity with r{sub 2} value of 183 mM{sup −1} s{sup −1}, which reveal the potential as T{sub 2}-weighted contrast agents for magnetic resonance imaging (MRI). The as-prepared nanocapsules can be performed as anti-cancer drug carriers for investigation of drug loading/release properties, which demonstrated a sustained drug release pattern and a comparable cytotoxicity with free doxorubicin (DOX). The multifunctional nanocapsules incorporated upconverting luminescence, T{sub 2}-weighted MRI imaging and drug targeting delivery modalities have great potential for theranostic applications in cancer treatment. - Graphical abstract: Multifunctional hollow nanocapsules with upconverting luminescence, T{sub 2}-weighted MRI imaging and drug targeting delivery modalities were synthesized for cancer treatment. - Highlights: • Multifunctional porous Fe{sub 3}O{sub 4}@SiO{sub 2}@α-NaYF{sub 4}:Yb{sup 3+},Er{sup 3+} nanocapsules were synthesized. • The nanocapsules show upconverting red emission upon 980 nm NIR-light excitation. • The nanocapsules exihibit potential as T{sub 2}-weighted contrast agents for MRI. • The DOX loaded nanocapsules demonstrated a comparable cytotoxicity with free DOX.« less

Aptamer biosensor for Salmonella typhimurium detection based on luminescence energy transfer from Mn2 +-doped NaYF4:Yb, Tm upconverting nanoparticles to gold nanorods

NASA Astrophysics Data System (ADS)

Cheng, Keyi; Zhang, Jianguo; Zhang, Liping; Wang, Lun; Chen, Hongqi

2017-01-01

A highly sensitive luminescent bioassay for the detection of Salmonella typhimurium was fabricated using Mn2 +-doped NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) as the donor and gold nanorods (Au NRs) as the acceptor and utilizing an energy transfer (LET) system. Mn2 +-doped NaYF4:Yb,Tm UCNPs with a strong emission peak at 807 nm were obtained by changing the doped ion ratio. Carboxyl-terminated Mn2 +-doped NaYF4:Yb,Tm UCNPs were coupled with S. typhimurium aptamers, which were employed to capture and concentrate S. typhimurium. The electrostatic interactions shorten the distance between the negatively charged donor and the positively charged acceptor, which results in luminescence quenching. The added S. typhimurium leads to the restoration of luminescence due to the formation of UCNPs-aptamers-S. typhimurium, which repels the UCNPs-aptamers from the Au NRs. The LET system does not occur because of the nonexistence of the luminescence emission band of Mn2 +-doped NaYF4:Yb,Tm UCNPs, which had large spectral overlap with the absorption band of Au NRs. Under optimal conditions, the linear range of detecting S. typhimurium was 12 to 5 × 105 cfu/mL (R = 0.99). The limit of detection for S. typhimurium was as low as 11 cfu/mL in an aqueous buffer. The measurement of S. typhimurium in milk samples was satisfied in accordance with the plate-counting method, suggesting that the proposed method was of practical value in the application of food security.

Photoluminescence of Porous Silicon-Zinc Oxide Hybrid structures

NASA Astrophysics Data System (ADS)

Olenych, I. B.; Monastyrskii, L. S.; Luchechko, A. P.

2017-03-01

Arrays of ZnO nanostructures, which are optically transparent in the visible range, were grown on the surface of porous silicon by electrochemical deposition. Photoluminescence excitation and emission spectra of the obtained hybrid structures were investigated in 220-450 and 400-800 nm regions, respectively. It is established that multicolor emission is formed by combining the luminescence bands of porous silicon and zinc oxide. The possibility of controlling the photoluminescence spectra by changing the excitation energy is demonstrated. It is revealed that thermal annealing has an effect on the luminescent properties of porous silicon/zinc oxide hybrid structures. Thermal processing at 500°C leads to a sharp decrease of long-wavelength luminescence associated with porous silicon and to an increase of short-wavelength luminescence intensity related to zinc oxide.

Latent fingermark detection for NaYF4:Er3+/Yb3+ upconversion phosphor synthesized by thermal decomposition route

NASA Astrophysics Data System (ADS)

Maurya, S. K.; Tiwari, S. P.; Kumar, A.; Kumar, K.

2018-04-01

The synthesis and spectroscopy of the upconverting nanoparticles, cubic NaYF4:Er3+/Yb3+ phosphor is developed for latent fingermark detection. The cubic phase of NaYF4: Er3+/Yb3+ phosphor is synthesized by thermal decomposition method using trifluoroacetate precursor with coordinating ligand octadecene and oleic acid in a mixture of technical grade. The synthesized samples showed intense green emission using 976 nm diode laser as an excitation source. Because of excellent property of luminescence in green regime the sample is used to detect the latent fingermark on a porous glass surface.

Mechanisms of optical losses in the 5D4 and 5D3 levels in Tb3+ doped low silica calcium aluminosilicate glasses

NASA Astrophysics Data System (ADS)

dos Santos, J. F. M.; Terra, I. A. A.; Astrath, N. G. C.; Guimarães, F. B.; Baesso, M. L.; Nunes, L. A. O.; Catunda, T.

2015-02-01

Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb3+-doped low silica calcium aluminosilicate glasses are analyzed for UV (λexc = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb3+ concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5-15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb3+ concentrations. Cooperative upconversion from a pair of excited ions (5D3:5D3 or 5D3:5D4) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.

Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure.

PubMed

Sun, Chunyan; Ping, Hong; Zhang, Minwei; Li, Hongkun; Guan, Fengrui

2011-11-01

Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln(3+)). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes have been investigated in this contribution. Ce(4+)-SO(3)(2-) in acidic conditions was taken as the CL system and sensitized CL intensities of Tb(3+)-FQ and Eu(3+)-FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb(3+)-FQ complexes show characteristic peaks of Tb(3+) at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb(3+)-ENX, Tb(3+)-NFLX, Tb(3+)-LMFX and Tb(3+)-FLRX display relatively strong emission intensity compared with Tb(3+)-OFLX, Tb(3+)-RFX, Tb(3+)-GFLX and Tb(3+)-SPFX. Quite weak peaks with unique characters of Eu(3+) at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu(3+)-ENX, but no notable sensitized luminescence and CL of Eu(3+) could be observed when Eu(3+) is added into other FQ. The distinct differences on emission intensity of Tb(3+)-FQ and Eu(3+)-FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln(3+). The different sensitized luminescence and CL signals among Tb(3+)-FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results. Copyright © 2011 Elsevier B.V. All rights reserved.

Exonuclease III-Assisted Upconversion Resonance Energy Transfer in a Wash-Free Suspension DNA Assay.

PubMed

Chen, Yinghui; Duong, Hien T T; Wen, Shihui; Mi, Chao; Zhou, Yingzhu; Shimoni, Olga; Valenzuela, Stella M; Jin, Dayong

2018-01-02

Sensitivity is the key in optical detection of low-abundant analytes, such as circulating RNA or DNA. The enzyme Exonuclease III (Exo III) is a useful tool in this regard; its ability to recycle target DNA molecules results in markedly improved detection sensitivity. Lower limits of detection may be further achieved if the detection background of autofluorescence can be removed. Here we report an ultrasensitive and specific method to quantify trace amounts of DNA analytes in a wash-free suspension assay. In the presence of target DNA, the Exo III recycles the target DNA by selectively digesting the dye-tagged sequence-matched probe DNA strand only, so that the amount of free dye removed from the probe DNA is proportional to the number of target DNAs. Remaining intact probe DNAs are then bound onto upconversion nanoparticles (energy donor), which allows for upconversion luminescence resonance energy transfer (LRET) that can be used to quantify the difference between the free dye and tagged dye (energy acceptor). This scheme simply avoids both autofluorescence under infrared excitation and many tedious washing steps, as the free dye molecules are physically located away from the nanoparticle surface, and as such they remain "dark" in suspension. Compared to alternative approaches requiring enzyme-assisted amplification on the nanoparticle surface, introduction of probe DNAs onto nanoparticles only after DNA hybridization and signal amplification steps effectively avoids steric hindrance. Via this approach, we have achieved a detection limit of 15 pM in LRET assays of human immunodeficiency viral DNA.

Construction of Hierarchical Polymer Brushes on Upconversion Nanoparticles via NIR-Light-Initiated RAFT Polymerization.

PubMed

Xie, Zhongxi; Deng, Xiaoran; Liu, Bei; Huang, Shanshan; Ma, Pingan; Hou, Zhiyao; Cheng, Ziyong; Lin, Jun; Luan, Shifang

2017-09-13

Photoinduced reversible addition-fragmentation chain transfer (RAFT) polymerization generally adopts high-energy ultraviolet (UV) or blue light. In combination with photoredox catalyst, the excitation light wavelength was extended to the visible and even near-infrared (NIR) region for photoinduced electron transfer RAFT polymerization. In this report, we introduce for the first time a surface NIR-light-initiated RAFT polymerization on upconversion nanoparticles (UCNPs) without adding any photocatalyst and construct a functional inorganic core/polymer shell nanohybrid for application in cancer theranostics. The multilayer core-shell UCNPs (NaYF 4 :Yb/Tm@NaYbF 4 :Gd@NaNdF 4 :Yb@NaYF 4 ), with surface anchorings of chain transfer agents, can serve as efficient NIR-to-UV light transducers for initiating the RAFT polymerization. A hierarchical double block copolymer brush, consisting of poly(acrylic acid) (PAA) and poly(oligo(ethylene oxide)methacrylate-co-2-(2-methoxy-ethoxy)ethyl methacrylate) (PEG for short), was grafted from the surface in sequence. The targeting arginine-glycine-aspartic (RGD) peptide was modified at the end of the copolymer through the trithiolcarbonate end group. After loading of doxorubicin, the UCNPs@PAA-b-PEG-RGD exhibited an enhanced U87MG cancer cell uptake efficiency and cytotoxicity. Besides, the unique upconversion luminescence of the nanohybrids was used for the autofluoresence-free cell imaging and labeling. Therefore, our strategy verified that UCNPs could efficiently activate RAFT polymerization by NIR photoirradiation and construct the complex nanohybrids, exhibiting prospective biomedical applications due to the low phototoxicity and deep penetration of NIR light.

Lanthanide-doped NaScF4 nanoprobes: crystal structure, optical spectroscopy and biodetection.

PubMed

Ai, Yu; Tu, Datao; Zheng, Wei; Liu, Yongsheng; Kong, Jintao; Hu, Ping; Chen, Zhuo; Huang, Mingdong; Chen, Xueyuan

2013-07-21

Trivalent lanthanide ions (Ln(3+))-doped inorganic nanoparticles (NPs) as potential luminescent bioprobes have been attracting tremendous interest because of their unique upconversion (UC) and downconversion (DC) luminescence properties. NaScF4, as an important host material, has been rarely reported and its crystal structure remains unclear. Herein, based on the single crystal X-ray diffraction, the space group of NaScF4 crystals was determined to be P31 containing multiple sites of Sc(3+) with crystallographic site symmetry of C1, which was verified by high-resolution photoluminescence spectroscopy of Eu(3+) at low temperature (10 K). Furthermore, monodisperse and size-controllable NaScF4:Ln(3+) NPs were synthesized via a facile thermal decomposition method. The biotinylated NaScF4:Er(3+)/Yb(3+) NPs were demonstrated for their applications as a heterogeneous UC luminescence bioprobe to detect avidin with a detection limit of 180 pM. After bioconjugation with amino-terminal fragment (ATF) of urokinase plasminogen activator (uPA), NaScF4:Ln(3+) NPs also exhibited specific recognition of cancer cells overexpressed with uPA receptor (uPAR, an important marker of tumor biology and metastasis), showing great potentials in tumor-targeted bioimaging.

Development of luminescent pH sensor films for monitoring bacterial growth through tissue.

PubMed

Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J; DesJardins, John D; Anker, Jeffrey N

2014-02-01

Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SrAl2O4:Eu2+ (1%) luminescence under UV, VUV and electron beam excitation

NASA Astrophysics Data System (ADS)

Nazarov, M.; Mammadova, S.; Spassky, D.; Vielhauer, S.; Abdullayeva, S.; Huseynov, A.; Jabbarov, R.

2018-01-01

This paper reports the luminescence properties of nanosized SrAl2O4:Eu2+ (1%) phosphors. The samples were prepared by combustion method at 600 °C, followed by annealing of the resultant combustion ash at 1000 °C in a reductive (Ar + H2) atmosphere. X-ray diffraction (XRD), photo luminescence (PL) and cathodoluminescence (CL) analysis and thermal stimulated luminescence (TSL) method were applied to characterize the phosphor. For the first time a peak at 375 nm was observed in CL spectra of SrAl2O4:Eu2+ (1%) nanophosphors. Luminescence excitation spectra analysis have shown that this peak is related to crystal defects. Also in TSL curve one strong peak was observed in the region above room temperature (T = 325 K), which is attributed to lattice defects, namely oxygen vacancies. A green LED was fabricated by the combination of the SrAl2O4:Eu2+ (1%) nanosized phosphor and a 365 nm UV InGaN chip.

Variation of M···H-C Interactions in Square-Planar Complexes of Nickel(II), Palladium(II), and Platinum(II) Probed by Luminescence Spectroscopy and X-ray Diffraction at Variable Pressure.

PubMed

Poirier, Stéphanie; Lynn, Hudson; Reber, Christian; Tailleur, Elodie; Marchivie, Mathieu; Guionneau, Philippe; Probert, Michael R

2018-06-12

Luminescence spectra of isoelectronic square-planar d 8 complexes with 3d, 4d, and 5d metal centers show d-d luminescence with an energetic order different from that of the spectrochemical series, indicating that additional structural effects, such as different ligand-metal-ligand angles, are important factors. Variable-pressure luminescence spectra of square-planar nickel(II), palladium(II), and platinum(II) complexes with dimethyldithiocarbamate ({CH 3 } 2 DTC) ligands and their deuterated analogues show unexpected variations of the shifts of their maxima. High-resolution crystal structures and crystal structures at variable pressure for [Pt{(CH 3 ) 2 DTC} 2 ] indicate that intermolecular M···H-C interactions are at the origin of these different shifts.

Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

PubMed Central

Hao, Shuwei; Chen, Guanying; Yang, Chunhui

2013-01-01

Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

Effect of B2O3 on luminescence of erbium doped tellurite glasses.

PubMed

Shen, Xiang; Nie, Qiuhua; Xu, Tiefeng; Dai, Shixun; Wang, Xunsi

2007-02-01

The B2O3 was introduced into the Er3+ doped TeO2-ZnO-Na2O glass to increase the phonon energy of the host. The effect of B2O3 on the non-radiative rate of the 4I11/2-->4I13/2 transition of Er3+, the lifetime of the 4I11/2 and 4I13/2 levels, the green and red upconversion emissions intensity, and the 4I13/2-->4I15/2 emission intensity was discussed. The results show that the phonon energy of boro-tellurite glass is close to that of germanate glass and is quite smaller than that of borate glass. The lifetime of 4I11/2 level and the upconversion emissions decrease with increasing B2O3 concentration. The higher OH group concentration presented in the boro-tellurite glass may shorten the lifetime of 4I13/2 level and also reduce the quantum efficiency of 4I13/2-->4I15/2 emission. The future dehydrating procedures are suggested to enhance the efficiency of amplification at 1.5 microm band.

Determination of effective mass of heavy hole from phonon-assisted excitonic luminescence spectra in ZnO

NASA Astrophysics Data System (ADS)

Shi, S. L.; Xu, S. J.

2011-03-01

Longitudinal optical (LO) phonon-assisted luminescence spectra of free excitons in high-quality ZnO crystal were investigated both experimentally and theoretically. By using the rigorous Segall-Mahan model based on the Green's function, good agreement between the experimental emission spectra involving one or two LO phonons and theoretical spectra can be achieved when only one adjustable parameter (effective mass of heavy hole) was adopted. This leads to determination of the heavy-hole effective mass mh⊥ = (0.8 m0 and mh∥ = 5.0 m0) in ZnO. Influence of anisotropic effective masses of heavy holes on the phonon sidebands is also discussed.

Spectroscopic behavior of composition dependent Dy3+ doped alkali fluoroborophosphate glasses

NASA Astrophysics Data System (ADS)

Raj, V. Anthony; Maheshvaran, K.; D'Silva, A. Josuva; Rayappan, I. Arul

2018-04-01

A new series of Dy3+ doped Alkali fluoroborophosphate glasses were prepared following conventional melt quenching technique and characterized using optical absorption and luminescence measurements. The nature of the metal-ligand bonding and the electronic band structure has been investigated using the absorption spectra. The Judd-Oflet (JO) intensity parameters (Ω2, Ω4 and Ω6) were evaluated and the experimental oscillator strength values were also calculated. The luminescence spectra exhibit two visible bands 4F9/2→6H15/2 (Blue) and 4F9/2→6H13/2 (Yellow) respectively. The radiative properties such as peak wavelength and effective band width for the emission transition were calculated. The yellow to blue (Y/B) ratios and color coordinates have been calculated from the luminescence spectra and the utility of the present glasses for white LED applications.

Spectral luminescence analysis of amniotic fluid

NASA Astrophysics Data System (ADS)

Slobozhanina, Ekaterina I.; Kozlova, Nataly M.; Kasko, Leonid P.; Mamontova, Marina V.; Chernitsky, Eugene A.

1997-12-01

It is shown that the amniotic fluid has intensive ultra-violet luminescence caused by proteins. Along with it amniotic fluid radiated in the field of 380 - 650 nm with maxima at 430 - 450 nm and 520 - 560 nm. The first peak of luminescence ((lambda) exc equals 350 nm; (lambda) em equals 430 - 440 nm) is caused (most probably) by the presence in amniotic fluid of some hormones, NADH2 and NADPH2. A more long-wave component ((lambda) exc equals 460 nm; (lambda) em equals 520 - 560 nm) is most likely connected with the presence in amniotic fluid pigments (bilirubin connected with protein and other). It is shown that intensity and maximum of ultra-violet luminescence spectra of amniotic fluid in normality and at pathology are identical. However both emission spectra and excitation spectra of long-wave ((lambda) greater than 450 nm) luminescence of amniotic fluid from pregnant women with such prenatal abnormal developments of a fetus as anencephaly and spina bifida are too long-wave region in comparison with the norm. Results of research testify that spectral luminescent analysis of amniotic fluid can be used for screening of malformations of the neural tube. It is very difficult for a practical obstetrician to reveal pregnant women with a high risk of congenital malformations of the fetus. Apart from ultrasonic examination, cytogenetic examination of amniotic fluid and defumination of concentrations of alpha-fetoprotein and acetylcholin-esterases in the amniotic fluid and blood plasma are the most widely used diagnostic approaches. However, biochemical and cytogenetic diagnostic methods are time-consuming. In the present work spectral luminescence properties of the amniotic fluid are investigated to determine spectral parameters that can be used to reveal pregnant women with a high risk of congenital malformations of their offsprings.

Boron difluoride dibenzoylmethane derivatives: Electronic structure and luminescence

NASA Astrophysics Data System (ADS)

Tikhonov, Sergey A.; Vovna, Vitaliy I.; Osmushko, Ivan S.; Fedorenko, Elena V.; Mirochnik, Anatoliy G.

2018-01-01

Electronic structure and optical properties of boron difluoride dibenzoylmethanate and four of its derivatives have been studied by X-ray photoelectron spectroscopy, absorption and luminescence spectroscopy and quantum chemistry (DFT, TDDFT). The relative quantum luminescence yields have been revealed to correlate with charge transfers of HOMO-LUMO transitions, energy barriers of aromatic substituents rotation and the lifetime of excited states in the investigated complexes. The bathochromic shift of intensive bands in the optical spectra has been observed to occur when the functional groups are introduced into p-positions of phenyl cycles due to destabilizing HOMO levels. Calculated energy intervals between electronic levels correlate well with XPS spectra structure of valence and core electrons.

Selective emission and luminescence of Er{sub 2}O{sub 3} under intense laser excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchenko, V M; Studenikin, M I; Iskhakova, L D

2013-09-30

The microstructure of Er{sub 2}O{sub 3} polycrystals synthesised by laser heating is studied. The synthesis of erbium silicate (Er{sub 2}SiO{sub 5}) layers was observed upon interaction of Er{sub 2}O{sub 3} and SiO{sub 2} melts. The dependences of the selective emission (SE) and luminescence spectra of Er{sub 2}O{sub 3} polycrystals in the range 200 – 1700 nm on the intensity of laser-thermal (at the wavelength λ = 10.6 μm) and resonant laser (λ ≈ 975 nm) excitation are investigated. The emission of heated Er{sub 2}O{sub 3} polycrystals arises as a result of multiphonon relaxation of absorbed energy and is a superpositionmore » of the SE at the electronic-vibrational transitions of Er{sup 3+} ions and the thermal radiation of the crystal lattice. The shape of the SE spectra of Er{sub 2}O{sub 3} polycrystals in the range 400 – 1700 nm almost does not change upon laser-thermal heating from 300 to 1500 K and subsequent cooling and corresponds to the absorption spectra of Er{sup 3+} ions. With increasing temperature, the thermal radiation intensity increases faster than the SE intensity, and the shape of the Er{sub 2}O{sub 3} spectrum becomes closer to the calculated spectrum of a blackbody. The anti-Stokes luminescence spectra of Er{sup 3+} ions formed under intense laser excitation of the {sup 4}I{sub 11/2} level are explained by additional SE caused by heating of the crystal matrix due to the Stokes losses. A difference between the SE and luminescence spectra is observed at low intensities of resonant laser excitation and low temperatures, when only the Stokes luminescence occurs. The temperature dependences of the SE and luminescence spectra of Er{sub 2}O{sub 3} upon laser excitation testify to the fundamental role played by the interaction of the electronic f-shell of Er{sup 3+} ions with crystal lattice vibrations in the processes of multiphonon radiative and nonradiative relaxation. The laser-thermal synthesis is promising for inprocess variation of the chemical composition of rare-earth samples. (interaction of laser radiation with matter)« less

Temperature dependence of the ratio of intensities of up-conversion fluorescence bands of YVO4 and YGdVO4 crystals and lead fluoride nano glass ceramics activated with erbium ions

NASA Astrophysics Data System (ADS)

Varaksa, Yu. A.; Sinitsyn, G. V.; Khodasevich, M. A.; Aseev, V. A.; Kolobkova, E. V.; Yasyukevich, A. S.

2015-01-01

Up-conversion fluorescence spectra of YVO4 and YGdVO4 crystals and lead fluoride nano glass ceramics coactivated with erbium and ytterbium ions have been studied in the wavelength range of 520-560 nm under 967-nm pumping. The ratio of intensities of fluorescence bands in the ranges of 520-530 and 540-550 nm has been measured in the temperature range of from room temperature to 150°C. It is shown that the considered materials can be used for preparing a sensing element of optical fluorescent temperature sensors; the sensitivity of measuring the temperature of nano glass-ceramics can be close to that of crystal samples.

Resonant inelastic x-ray scattering and UV-VUV luminescence at the Be 1s edge in BeO.

PubMed

Kikas, A; Käämbre, T; Kooser, K; Kuusik, I; Kisand, V; Nõmmiste, E; Kirm, M; Feldbach, E; Ivanov, V; Pustovarov, V; Martinson, I

2010-09-22

We carried out a combined study of UV-VUV luminescence and resonant x-ray emission from BeO single crystals with incident photon energies in the vicinity of the Be 1s absorption edge. The x-ray emission spectra show that at the Be 1s photoabsorption edge the lattice relaxation processes in the excitation site take place already on the timescale of the radiative decay of the core excitation. Comparison of the x-ray emission and the luminescence spectra indicates that the maximum energy loss of the process of lattice relaxation during the decay of inner-shell holes is similar to the loss that occurs in the self-trapping process of valence excitons. The possible decay channels of core excitations have been discussed and the mechanism for the creation of 5.2 eV luminescence at the photoabsorption resonances has been suggested.

Influence of silver and copper doping on luminescent properties of zinc-phosphate glasses after x-ray irradiation

NASA Astrophysics Data System (ADS)

Murashov, Alexander A.; Sidorov, Alexander I.; Shakhverdov, Teimur A.; Stolyarchuk, Maxim V.

2017-11-01

It is shown, experimentally, that in silver- and copper-containing zinc-phosphate glasses, metal molecular clusters are formed during the glass synthesis. X-ray irradiation of these glasses led to the considerable increase of its luminescence in visible spectral range. This effect is caused by the transformation of the charged metal molecular clusters into the neutral state. Luminescence and excitation spectra of the glass, doped with silver and copper simultaneously, change significantly in comparison with the spectra of glasses doped with one metal. The reason for this can be the formation of hybrid AgnCum molecular clusters. The computer simulation of the structure and optical properties of such clusters by the time-dependent density functional theory method is presented. It is shown that the optimal luminescent material for photonics application, in comparison with other studied materials, is glass, containing hybrid molecular clusters.

Time-resolved spectroscopy and optical gain of silica-based fibers co-doped with Bi, Al and/or Ge, P, and Ti

NASA Astrophysics Data System (ADS)

Firstov, S. V.; Bufetov, I. A.; Khopin, V. F.; Umnikov, A. A.; Guryanov, A. N.; Dianov, E. M.

2009-04-01

The optical properties of optical fibers based on silica glass doped with bismuth and co-doped with aluminum oxides and/or germanium, phosphorus, and titanium oxides are studied. The optical loss and luminescence spectra of optical fibers substantially depend on the core composition. The gain spectra of single-mode optical fibers are measured in the IR range. It is demonstrated that the phosphorus-germanium-silicate optical fiber doped with bismuth exhibits a broad gain band (1270-1520 nm) when pumped at a wavelength of 1230 nm. It is also shown that the bismuth-aluminosilicate optical fibers additionally doped with Ge or Ti at about 1 at % have the gain spectra that are significantly narrower than the IR luminescence spectra (in contrast to the fibers that do not contain Ge and Ti). The intensity decay curves of the IR luminescence in such fibers indicate the presence of both short-lived (with the lifetime τ≤4 μs) and long-lived (τ ˜ 1 ms) energy levels in the bismuth active centers.

Complex study on photoluminescence properties of YAG:Ce,Gd phosphors

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Ju, Yangyang; Stepanov, S. A.; Soschin, N. M.

2017-05-01

Luminescence characteristics of gadolinium co-doped yttrium aluminium garnet doped with cerium phosphors were studied. In this work, powder X-ray diffraction (XRD) spectra, elemental composition analyses, excitation and emission spectra, conversion efficiency of emission phosphor, corresponding (CIE) chromaticity colour coordinates and pulsed photoluminescence decay kinetic curves were investigated, all the measurements were performed at room temperature. The properties of the phosphors were studied by comparing the composition of the phosphors and their luminescent properties.

Photoinduced Effects in the ZnO Luminescence Spectra

NASA Astrophysics Data System (ADS)

Akopyan, I. Kh.; Labzovskaya, M. E.; Novikov, B. V.; Lisachenko, A. A.; Serov, A. Yu.; Filosofov, N. G.

2018-02-01

The effect of intense UV irradiation on the photoluminescence (PL) spectra of ZnO powders and nanocrystalline films obtained by atomic layer deposition (ALD) was investigated. At room temperature, the behavior of the spectra under continuous UV irradiation in multiple vacuum-atmosphere cycles was studied. The changes in the intensities of exciton radiation and radiation in the "green" band region, associated with the phenomena of oxygen photodesorption and photoadsorption, are discussed. In the temperature range of 5-300 K, the effect of strong UV irradiation on the near-edge luminescence spectrum of ZnO films was studied. The nature of a new line arising in the photoluminescence spectra of an irradiated film in the region of emission of bound excitons is discussed.

Luminescence performance of Eu{sup 3+} doped lead free zinc phosphate glasses for red emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasad, V. Reddy; Babu, S.; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com

2016-05-06

Luminescence performance of zinc phosphate glasses containing Eu{sup 3+} ion with the chemical compositions (60-x)NH{sub 4}H{sub 2}PO{sub 4}-20ZnO-10BaF{sub 2}-10NaF-x Eu{sub 2}O{sub 3} (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. The Fourier Transform Infrared Spectroscopy (FT-IR) shows several vibrations bands. Luminescence spectra of these glasses exhibit characteristic emission of Eu{sup 3+} ion with an intense and most prominent red emission (614 nm) which is attributed to {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. Judd-Ofelt (Ω{sub 2}, Ω{sub 4}) parameters have been evaluated from the luminescence intensity ratios of {sup 5}D{sub 0}→{sup 7}F{sub J} (where J = 2 and 4)more » to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition as well as absorption spectra under different constraints. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu{sup 3+} doped glasses.« less

Site-specific incorporation of uranyl carbonate species at the calcite surface

NASA Astrophysics Data System (ADS)

Reeder, Richard J.; Elzinga, Evert J.; Tait, C. Drew; Rector, K. D.; Donohoe, Robert J.; Morris, David E.

2004-12-01

Spatially resolved luminescence spectra from U(VI) co-precipitated at the (101¯4) growth surface of synthetic calcite single crystals confirm heterogeneous incorporation corresponding to the distribution of structurally non-equivalent steps composing the vicinal surfaces of spiral growth hillocks. Spectral structure from U(VI) luminescence at the "-" vicinal regions and featureless, weak luminescence at the "+" vicinal regions are consistent with previously reported observations of enrichment at the former sites during calcite growth. Luminescence spectra differ between the non-equivalent regions of the crystal, with the spectral features from the "-" vicinal region corresponding to those observed in bulk calcite samples. Subtle spectral shifts are observed from U(VI) co-precipitated with microcrystalline calcite synthesized by a different method, and all of the U(VI)-calcite sample spectra differ significantly from that of U(VI) co-precipitated with aragonite. The step-selective incorporation of U(VI) can be explained by a proposed model in which the allowed orientation for adsorption of the dominant calcium uranyl triscarbonate species is controlled by the atomic arrangement at step edges. Differences in the tilt angles of carbonate groups between non-equivalent growth steps favor adsorption of the calcium uranyl triscarbonate species at "-" steps, as observed in experiments.

Spectral characterization and white light generation by yttrium silicate nanopowders undoped and doped with Ytterbium(III) at different concentrations when excited by a laser diode at 975 nm

NASA Astrophysics Data System (ADS)

Cinkaya, Hatun; Eryurek, Gonul; Bilir, Gokhan; Collins, John; Di Bartolo, Baldassare

2017-01-01

We have studied nanophosphors of yttrium silicate (YSO) undoped and doped with different concentration of ytterbium (Yb3+) synthesized by using the sol-gel method. Structural and luminescence properties of the nanophosphors were studied experimentally by using different analytical techniques. For the structural analysis, we performed X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectrometry (EDS) measurements. Upconversion (UC) and the white light (WL) emission properties were investigated by using the near infrared cw laser excitation of 975 nm. The spectral properties have been found to depend on several physical parameters.

Up-conversion routines of Er{sup 3+}–Yb{sup 3+} doped Y{sub 6}O{sub 5}F{sub 8} and YOF phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Sangmoon, E-mail: spark@silla.ac.kr; Yang, Wonseok; Park, Chu-Young

2015-11-15

Highlights: • Single-phase optical materials of Y{sub 6}O{sub 5}F{sub 8}:Er and YOF:Er were prepared. • Effective spectral converting properties were observed in Y{sub 6}O{sub 5}F{sub 8}:Er,Yb. • 980 nm diode laser was irradiated for up-converting analysis. • A multi-photon process in the phosphors was investigated. - Abstract: Optical materials composed of a Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} (p = 0.001–0.1, q = 0.005–0.1) solid solution with Y{sub 0.99}Er{sub 0.01}OF were prepared via a solid-state reaction using excess NH{sub 4}F flux at 950 °C for 30 min. X-ray diffraction patterns of Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} and Y{sub 0.99}Er{submore » 0.01}OF were compared upon altering the synthesis temperature and the molar ratio of the NH{sub 4}F flux to the Y{sup 3+} (Er{sup 3+}, Yb{sup 3+}) ions. The effective spectral-conversion properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} ions in Y{sub 6}O{sub 5}F{sub 8} phosphors were monitored during excitation with a 980 nm wavelength diode-laser. Selection of appropriate Er{sup 3+} and/or Yb{sup 3+} concentrations in the Y{sub 6}O{sub 5}F{sub 8} structure led to achievement of the desired up-conversion emission, from the green to the red regions of the spectra. Furthermore, the mechanism of up-conversion in the phosphors was described by an energy-level schematic. Up-conversion emission spectra and the dependence of the emission intensity on pump power (between 193 and 310 mW) in the Y{sub 6(0.995−q)}Er{sub 0.03}Yb{sub 6q}O{sub 5}F{sub 8} phosphors were also investigated.« less

Role of the stimulated radiation of Yb3+ ions in the formation of luminescence of the Y0.8Yb0.2F3:Tm3+ solid solution

NASA Astrophysics Data System (ADS)

Mikheev, A. V.; Kazakov, B. N.

2015-09-01

A new mechanism has been proposed for the transfer of the energy of exciting laser radiation through the donor subsystem (Yb3+) to acceptors (Tm3+), which induces multiphoton transitions in the acceptor subsystem. The coherence of the induced radiation of donors is of key importance in this mechanism. An analytical dependence of the intensity of the up-conversion luminescence of Tm3+ (1G4 → 3H6) ions in the Y0.8Yb0.2F3:Tm3+ system on the pump power at the steady-state excitation by 934-nm infrared radiation of a laser diode has been obtained using the mathematical technique of the theory of Poisson processes. In contrast to known mechanisms, this dependence approximates the experimental dependence well in a wide power range (200-1200 mW). The proposed model is applicable for any system where the energy of pump radiation is transferred to acceptors through the subsystem of donor ions.

Controllable upconversion luminescence and temperature sensing behavior in NaGdF4:Yb3+/Ho3+/Ce3+ nano-phosphors

NASA Astrophysics Data System (ADS)

Pang, Tao; Wang, Jiajun

2018-01-01

The hexagonal NaGdF4:Yb3+/Ho3+/Ce3+ nano-phosphors are synthesized by a hydrothermal method. Under 980 nm excitation, the phosphor emits green, red and far-red light in the visible wavelength region, corresponding to the 5S2/5F4 → 5I8, 5F5 → 5I8 and 5S2/5F4 → 5I7 transitions of Ho3+ ions, respectively. When adjusting the Ce3+ concentration from 0% to 16%, the dominant wavelength shifts ˜43 nm toward the longer wavelength. Two cross-relaxation processes between Ho3+ and Ce3+ are responsible for the change in chromaticity. Also, the ability of the Ce3+ concentration to regulate the luminescence color depends on the pumping power and temperature of samples. More interestingly, the phosphors are potentially applicable as the optical thermometric materials. In the case of 16% Ce3+ doping, the maximum sensitivity (0.1446 K-1) about 4-35 times as high as the reported values of several typical thermometric materials is obtained.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santos, J. F. M. dos; Terra, I. A. A.; Nunes, L. A. O.

Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb{sup 3+}-doped low silica calcium aluminosilicate glasses are analyzed for UV (λ{sub exc} = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb{sup 3+} concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5–15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two ordersmore » of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb{sup 3+} concentrations. Cooperative upconversion from a pair of excited ions ({sup 5}D{sub 3}:{sup 5}D{sub 3} or {sup 5}D{sub 3}:{sup 5}D{sub 4}) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.« less

A study of the effect of lithium oxide on the spectral properties of potassium-aluminoborate glass activated by chromium ions

NASA Astrophysics Data System (ADS)

Babkina, A. N.; Gorbachev, A. D.; Zyryanova, K. S.; Nikonorov, N. V.; Nuryev, R. K.; Stepanov, S. A.

2017-09-01

The results of designing and studying of potassium-aluminoborate glass activated by chromium and lithium ions are discussed. Changes in the absorption and luminescence spectra of glass after the isothermal treatment are demonstrated. X-ray diffraction data showed the presence of Li(Al7B4O17) and Cr2O3 nanocrystals with an average size of 20 and 15 nm, respectively. Analysis of the luminescence spectra showed that the Cr3+ ions are in a crystalline environment. The luminescence quantum yield was 20-50%, which indicates the prospects for using such materials as a basis for fiber amplifiers in information transmission systems and laser biomedical technologies.

Optical Spectroscopy and Photophysics of Single Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Brus, Louis

2006-03-01

We explore the fundamental nature and dynamics of excited electronic states in SWNT. Psec luminescence and photobleaching dynamics of SWNTs in micellar solution show that non-radiative Auger recombination is extremely fast. At low pH, nanotube surface endoperoxides protonate and introduce holes that quench the luminescence. At higher concentration these holes also bleach the band gap optical absorption. Near infrared two photon luminescence excitation spectra quantitatively reveal the importance of excitons. In order to characterize excited states in both metallic and semiconducting SWNTs at the single-tube level, we detect white-light Rayleigh scattering from individual tubes suspended over an open slit in a substrate. Diagnostic spectra with high signal to noise are obtained in just a few minutes.

A novel upconversion@polydopamine core@shell nanoparticle based aptameric biosensor for biosensing and imaging of cytochrome c inside living cells.

PubMed

Ma, Lina; Liu, Fuyao; Lei, Zhen; Wang, Zhenxin

2017-01-15

Herein, a novel upconversion@polydopamine core@shell nanoparticle (termed as UCNP@PDA NP) -based aptameric biosensor has been fabricated for the quantitative analysis of cytochrome c (Cyt c) inside living cells, which comprises an UCNP@PDA NP, acting as an internal reference and fluorescence quenching agent, and Cy3 modified aptamer enabling ratiometric quantitative Cyt c measurement. After the hybridization of Cy3 labeled aptamer with amino-terminated single DNA on the UCNP@PDA NP surface (termed as UCNP@PDA@AP), the fluorescence of Cy3 can be efficiently quenched by the PDA shell. With the spontaneous cellular uptake of UCNP@PDA@AP, the Cyt c aptamer dissociates from UCNP@PDA NP surface through formation of aptamer-Cyt c complex, resulting in concomitant activation of the Cy3 fluorescence. High amount of Cyt c leads to high fluorescence emission, enabling direct visualization/measurement of the Cyt c by fluorescence microscopy/spectroscopy. The steady upconversion luminescent (UCL) signals can be employed not only for intracellular imaging, but also as an internal reference for evaluating intracellular Cyt c amount using the ratio of fluorescence intensity of Cy3 with the UCL intensity of UCNP. The UCNP@PDA@AP shows a reasonable detection limit (20nM) and large dynamic range (50nM to 10μM, which covers the literature reported values (1-10μM) for cytosolic Cyt c in apoptotic cells) for detecting Cyt c in buffer with excellent selectivity. In addition, the UCNP@PDA@AP has been successfully used to monitor etoposide induced intracellular releasing of Cyt c, providing the possibility for cell-based screening of apoptosis-inducing drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

Excited-State Structure of Oligothiophene Dendrimers: Computational and Experimental Study

DTIC Science & Technology

2010-01-01

REPORT Excited-State Structure of Oligothiophene Dendrimers : Computational and Experimental Study 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: The...nature of one and two-photon absorption enhancement in a series of oligothiophene dendrimers , recently proposed for applications in entangled photon...upconversion measurements). The linear absorption spectra exhibit a red shift of the absorption maxima and broadening as a function of dendrimer generations

Luminescent and thermochromic properties of tellurium(IV) halide complexes with cesium

NASA Astrophysics Data System (ADS)

Sedakova, T. V.; Mirochnik, A. G.

2016-02-01

The spectral-luminescent and thermochromic properties of complex compounds of the composition Cs2TeHal6 (Hal = Cl, Br, I) are studied. The interrelation between the geometric structure and spectral-luminescent properties is studied using the example on complex compounds of tellurium(IV) halides with cesium. The Stokes shift and the luminescence intensity of Te(IV) ions with island octahedral coordination are found to depend on the position of the A band in the luminescence excitation spectra, the diffuse reflection, and the energy of the luminescent 3 P 1 → 1 S 0 transition of the tellurium(IV) ion. The maximum luminescence intensity and the minimum Stokes shift at 77 and 300 K are observed for Cs2TeCl6. The geometrical and electronic factors responsible for luminescence intensification in Te(IV) complexes under study are analyzed.

Y2O3:Yb,Er@mSiO2-CuxS double-shelled hollow spheres for enhanced chemo-/photothermal anti-cancer therapy and dual-modal imaging

NASA Astrophysics Data System (ADS)

Yang, Dan; Yang, Guixin; Wang, Xingmei; Lv, Ruichan; Gai, Shili; He, Fei; Gulzar, Arif; Yang, Piaoping

2015-07-01

Multifunctional composites have gained significant interest due to their unique properties which show potential in biological imaging and therapeutics. However, the design of an efficient combination of multiple diagnostic and therapeutic modes is still a challenge. In this contribution, Y2O3:Yb,Er@mSiO2 double-shelled hollow spheres (DSHSs) with up-conversion fluorescence have been successfully prepared through a facile integrated sacrifice template method, followed by a calcination process. It is found that the double-shelled structure with large specific surface area and uniform shape is composed of an inner shell of luminescent Y2O3:Yb,Er and an outer mesoporous silica shell. Ultra small CuxS nanoparticles (about 2.5 nm) served as photothermal agents, and a chemotherapeutic agent (doxorubicin, DOX) was then attached onto the surface of mesoporous silica, forming a DOX-DSHS-CuxS composite. The composite exhibits high anti-cancer efficacy due to the synergistic photothermal therapy (PTT) induced by the attached CuxS nanoparticles and the enhanced chemotherapy promoted by the heat from the CuxS-based PTT when irradiated by 980 nm near-infrared (NIR) light. Moreover, the composite shows excellent in vitro and in vivo X-ray computed tomography (CT) and up-conversion fluorescence (UCL) imaging properties owing to the doped rare earth ions, thus making it possible to achieve the target of imaging-guided synergistic therapy.Multifunctional composites have gained significant interest due to their unique properties which show potential in biological imaging and therapeutics. However, the design of an efficient combination of multiple diagnostic and therapeutic modes is still a challenge. In this contribution, Y2O3:Yb,Er@mSiO2 double-shelled hollow spheres (DSHSs) with up-conversion fluorescence have been successfully prepared through a facile integrated sacrifice template method, followed by a calcination process. It is found that the double-shelled structure with large specific surface area and uniform shape is composed of an inner shell of luminescent Y2O3:Yb,Er and an outer mesoporous silica shell. Ultra small CuxS nanoparticles (about 2.5 nm) served as photothermal agents, and a chemotherapeutic agent (doxorubicin, DOX) was then attached onto the surface of mesoporous silica, forming a DOX-DSHS-CuxS composite. The composite exhibits high anti-cancer efficacy due to the synergistic photothermal therapy (PTT) induced by the attached CuxS nanoparticles and the enhanced chemotherapy promoted by the heat from the CuxS-based PTT when irradiated by 980 nm near-infrared (NIR) light. Moreover, the composite shows excellent in vitro and in vivo X-ray computed tomography (CT) and up-conversion fluorescence (UCL) imaging properties owing to the doped rare earth ions, thus making it possible to achieve the target of imaging-guided synergistic therapy. Electronic supplementary information (ESI) available: XRD patterns, zeta potential and FT-IR spectra of the samples obtained in different steps. N2 adsorption/desorption isotherm and the pore size distribution of Y2O3:Yb,Er@mSiO2-CuxS. Confocal images of HeLa cancer cells dyed with calcein AM and propidium iodide co-stained cells after treatment of Y2O3:Yb,Er@mSiO2-CuxS without or with 980 nm laser irradiation. CLSM images of HeLa cells incubated with DOX-Y2O3:Yb,Er@mSiO2-NH2-FA-CuxS-PEG and DOX-Y2O3:Yb,Er@mSiO2-NH2-CuxS-PEG for different times. The digital photographs of the H22 tumor-bearing Balb/c mice injected in situ with DOX-Y2O3:Yb,Er@mSiO2-NH2-FA-CuxS-PEG and DOX-Y2O3:Yb,Er@mSiO2-NH2-CuxS-PEG and the corresponding tumor sizes. See DOI: 10.1039/c5nr02269j

Remote activation and detection of up-converted luminescence via surface plasmon polaritons propagating in a silver nanowire.

PubMed

Prymaczek, A; Cwierzona, M; Grzelak, J; Kowalska, D; Nyk, M; Mackowski, S; Piatkowski, D

2018-06-27

In this paper, we demonstrate remote activation and detection of the 2-photon up-conversion luminescence via surface plasmon polaritons propagating in a long silver nanowire. The hybrid nanostructure was assembled by locally depositing a submicron droplet of nanocrystal-containing colloidal solution on one of the ends of the metallic nanowire. When - using a classic confocal microscope - the second end of the nanowire, without the nanocrystals, is illuminated with infrared laser light, we observe strong emission from the same end. Therefore, it indicates that surface plasmon polaritons activated with infrared light at the second end of the nanowire propagate along it and can excite nanocrystals in the droplet at the opposite end. Subsequently, the excited nanocrystals up-convert the energy and by launching surface plasmon polaritons can guide the up-converted luminescence back to the starting point. The emergence of this effect is much more pronounced for a laser polarized along the nanowire. The spectral and temporal character of this emission reveals strong interactions between surface plasmon polaritons and electronic states of the nanocrystals. The details of local and non-local aspects of the effects of remote excitation and guiding of energy in a silver nanowire are elucidated using a unique experimental setup, based on two microscope objectives for spatial separation and control of both excitation and emission beams.

Multifunctional hydroxyapatite/Na(Y/Gd)F4:Yb3+,Er3+ composite fibers for drug delivery and dual modal imaging.

PubMed

Liu, Min; Liu, Hui; Sun, Shufen; Li, Xuejiao; Zhou, Yanmin; Hou, Zhiyao; Lin, Jun

2014-02-04

Porous hydroxyapatite (HAp) composite fibers functionalized with up-conversion (UC) luminescent and magnetic Na(Y/Gd)F4:Yb(3+),Er(3+) nanocrystals (NCs) have been fabricated via electrospinning. After transferring hydrophobic oleic acid-capped Na(Y/Gd)F4:Yb(3+),Er(3+) NCs into aqueous solution, these water-dispersible NCs were dispersed into precursor electrospun solution containing CTAB. Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers were fabricated by the high temperature treatment of the electrospun Na(Y/Gd)F4:Yb(3+),Er(3+) NCs decorated precursor fibers. The biocompatibility test on MC 3T3-E1 cells using MTT assay shows that the HAp composite fibers have negligible cytotoxity, which reveals the HAp composite fibers could be a drug carrier for drug delivery. Because the contrast brightening is enhanced at increased concentrations of Gd(3+), the HAp composite fibers can serve as T1 magnetic resonance imaging contrast agents. In addition, the composites uptaken by MC 3T3-E1 cells present the UC luminescent emission of Er(3+) under the excitation of a 980 nm near-infrared laser. The above findings reveal Na(Y/Gd)F4:Yb(3+),Er(3+)@HAp composite fibers have potential applications in drug storage/release and magnetic resonance/UC luminescence imaging.

Luminescence in Sr2MgAl22O36:Eu2+ phosphor

NASA Astrophysics Data System (ADS)

Tawalare, P. K.; Bhatkar, V. B.; Talewar, R. A.; Joshi, C. P.; Moharil, S. V.

2018-05-01

New results on luminescence of Eu2+ are reported in Sr2MgAl22O36 host prepared by combustion synthesis. Different emission and excitation spectra are observed for Eu2+ ions occupying two crystallographically non-equivalent sites.

High pressure luminescence spectra of CaMoO4:Ln3+ (Ln = Pr, Tb)

NASA Astrophysics Data System (ADS)

Mahlik, S.; Behrendt, M.; Grinberg, M.; Cavalli, E.; Bettinelli, M.

2013-03-01

Photoluminescence spectra and luminescence kinetics of pure CaMoO4 and CaMoO4 doped with Ln3+ (Ln = Pr or Tb) are presented. The spectra were obtained at high hydrostatic pressure up to 240 kbar applied in a diamond anvil cell. At ambient pressure undoped and doped samples exhibit a broad band emission extending between 380 and 700 nm with a maximum at 520 nm attributed to the {{MoO}}_{4}^{2-} luminescence. CaMoO4 doped with Pr3+ or Tb3+ additionally yields narrow emission lines related to f-f transitions. The undoped CaMoO4 crystal was characterized by a strong MoO{}_{4}^{2-} emission up to 240 kbar. In the cases of CaMoO4:Pr3+ and CaMoO4:Tb3+, high hydrostatic pressure caused quenching of Pr3+ and Tb3+ emission, and this effect was accompanied by a strong shortening of the luminescence lifetime. In doped samples, CaMoO4:Pr3+ and CaMoO4:Tb3+, quenching of the emission band attributed to {{MoO}}_{4}^{2-} was also observed, and at pressure above 130 kbar this luminescence was totally quenched. The effects mentioned above were related to the influence of the praseodymium (terbium) trapped exciton PTE (ITE—impurity trapped exciton) on the efficiency of the Pr3+ (Tb3+) and {{MoO}}_{4}^{2-} emissions.

Enhanced photo-activated luminescence for screening polychlorobiphenyls (PCBs) and other related chlorinated compounds

DOEpatents

Vo-Dinh, Tuan

1994-01-01

The presence of polychlorinated biphenyls and other chlorinated compounds in a sample is determined by treating the sample with a photo-activator and then exposing the treated sample to a UV light source. The UV light produces a photo-product complex, which is subsequently excited with UV light to cause luminescence of the complex. The luminescence is detected and characteristics of the luminescence spectra are used to determine the presence of chlorinated compounds and also the quantity of the chlorine in the compounds

Enhanced photo-activated luminescence for screening polychlorobiphenyls (PCBs) and other related chlorinated compounds

DOEpatents

Vo-Dinh, Tuan

1993-01-01

The presence of polychlorinated biphenyls and other chlorinated compounds in a sample is determined by treating the sample with a photo-activator and then exposing the treated sample to a UV light source. The UV light produces a photo-product complex, which is subsequently excited with UV light to cause luminescence of the complex. The luminescence is detected and characteristics of the luminescence spectra are used to determine the presence of chlorinated compounds and also the quantity of the chlorine in the compounds.

Enhanced photo-activated luminescence for screening polychlorobiphenyls (PCBs) and other related chlorinated compounds

DOEpatents

Vo-Dinh, T.

1994-06-07

The presence of polychlorinated biphenyls and other chlorinated compounds in a sample is determined by treating the sample with a photo-activator and then exposing the treated sample to a UV light source. The UV light produces a photo-product complex, which is subsequently excited with UV light to cause luminescence of the complex. The luminescence is detected and characteristics of the luminescence spectra are used to determine the presence of chlorinated compounds and also the quantity of the chlorine in the compounds. 14 figs.

Enhanced photo-activated luminescence for screening polychlorobiphenyls (PCBs) and other related chlorinated compounds

DOEpatents

Tuan Vodinh.

1993-12-21

The presence of polychlorinated biphenyls and other chlorinated compounds in a sample is determined by treating the sample with a photo-activator and then exposing the treated sample to a UV light source. The UV light produces a photo-product complex, which is subsequently excited with UV light to cause luminescence of the complex. The luminescence is detected and characteristics of the luminescence spectra are used to determine the presence of chlorinated compounds and also the quantity of the chlorine in the compounds. 14 figures.

Luminescent hybrid materials based on (8-hydroxyquinoline)-substituted metal-organic complexes and lead-borate glasses

NASA Astrophysics Data System (ADS)

Petrova, Olga B.; Anurova, Maria O.; Akkuzina, Alina A.; Saifutyarov, Rasim R.; Ermolaeva, Ekaterina V.; Avetisov, Roman I.; Khomyakov, Andrew V.; Taydakov, Ilya V.; Avetissov, Igor Ch.

2017-07-01

Novel luminescent organic-inorganic hybrid materials based on 8-hydroxyquinoline metal complexes (Liq, Kq, Naq, Rbq, Mgq2, Srq2, Znq2, Scq3, Alq3, Gaq3, and Inq3) have been synthesized by a high temperature exchange reaction with 80PbF2-20B2O3 inorganic low-melting glass. The mechanical and optical properties, transmission spectra, emission an excitation photoluminescence, and luminescence kinetic of hybrid materials were studied. All hybrid materials showed a wide luminescence band in the range 400-700 nm.

Dual-color upconversion fluorescence and aptamer-functionalized magnetic nanoparticles-based bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus.

PubMed

Duan, Nuo; Wu, Shijia; Zhu, Changqing; Ma, Xiaoyuan; Wang, Zhouping; Yu, Ye; Jiang, Yuan

2012-04-20

A sensitive luminescent bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus was developed using aptamer-conjugated magnetic nanoparticles (MNPs) for both recognition and concentration elements and using upconversion nanoparticles (UCNPs) as highly sensitive dual-color labels. The bioassay system was fabricated by immobilizing aptamer 1 and aptamer 2 onto the surface of MNPs, which were employed to capture and concentrate S. Typhimurium and S. aureus. NaY(0.78)F(4):Yb(0.2),Tm(0.02) UCNPs modified aptamer 1 and NaY(0.28)F(4):Yb(0.70),Er(0.02) UCNPs modified aptamer 2 further were bond onto the captured bacteria surface to form sandwich-type complexes. Under optimal conditions, the correlation between the concentration of S. Typhimurium and the luminescent signal was found to be linear within the range of 10(1)-10(5) cfu mL(-1) (R(2)=0.9964), and the signal was in the range of 10(1)-10(5) cfu mL(-1) (R(2)=0.9936) for S. aureus. The limits of detection of the developed method were found to be 5 and 8 cfu mL(-1) for S. Typhimurium and S. aureus, respectively. The ability of the bioassay to detect S. Typhimurium and S. aureus in real water samples was also investigated, and the results were compared to the experimental results from the plate-counting methods. Improved by the magnetic separation and concentration effect of MNPs, the high sensitivity of UCNPs, and the different emission lines of Yb/Er- and Yb/Tm-doped NaYF(4) UCNPs excited by a 980 nm laser, the present method performs with both high sensitivity and selectivity for the two different types of bacteria. Copyright © 2012 Elsevier B.V. All rights reserved.

Up-conversion monodispersed spheres of NaYF4:Yb3+/Er3+: green and red emission tailoring mediated by heating temperature, and greatly enhanced luminescence by Mn2+ doping.

PubMed

Zhu, Qi; Song, Caiyun; Li, Xiaodong; Sun, Xudong; Li, Ji-Guang

2018-04-09

Submicron sized, monodispersed spheres of Mn2+, Yb3+/Er3+ and Mn2+/Yb3+/Er3+ doped α-NaYF4 were easily autoclaved from mixed solutions of the component nitrates and ammonium fluoride (NH4F), in the presence of EDTA-2Na. Detailed characterizations of the resultant phosphors were obtained using XRD, Raman spectroscopy, FE-SEM, HR-TEM, STEM, PLE/PL spectroscopy, and fluorescence decay analysis. Finer structure and better crystal perfection was observed at a higher calcination temperature, and the spherical shape and excellent dispersion of the original particles was retained at temperatures up to 600 °C. Under the 980 nm infrared excitation, the Yb3+/Er3+-doped sample (calcined at 400 °C) exhibits a stronger green emission centered at ∼524 nm (2H11/2 → 4I15/2 transition of Er3+) and a weaker red emission centered at ∼657 nm (4F9/2 → 4I15/2 transition of Er3+). A 200 °C increase in the temperature from 400 °C to 600 °C resulted in the dominant red emission originating from the 4F9/2 → 4I15/2 transition of Er3+, instead of the previously dominant green one. Mn2+ doping induced a remarkable more enhanced intensity at ∼657 nm and ∼667 nm (red emission area) than that at ∼524 nm and ∼546 nm (green emission area), because of the non-radiative energy transfer between Mn2+ and Er3+. However, a poor thermal stability was induced by Mn2+ doping. The observed upconversion luminescence of the samples calcined at 400 °C and 600 °C followed the two photon process and the four photon process, respectively.

Tuning into single-band red upconversion luminescence in Yb(3+)/Ho(3+) activated nano-glass-ceramics through Ce(3+) doping.

PubMed

Chen, Daqin; Zhou, Yang; Wan, Zhongyi; Ji, Zhenguo; Huang, Ping

2015-03-28

Yb(3+)/Ho(3+) activated glass ceramics containing β-YF3 nanocrystals were successfully fabricated. The green ((5)S2/(5)F4→(5)I8) upconversion emission is dominant in the glass ceramics and is about 160 times stronger than that of the precursor glass, resulting from the partition of lanthanide activators into a low-phonon-energy crystalline lattice and the subsequent low probability of multi-phonon nonradiative relaxation from the (5)S2/(5)F4 and (5)I6 states to the lower ones. Upon the introduction of Ce(3+) ions into nano-glass-ceramics, two efficient cross-relaxation processes between Ho(3+) and Ce(3+), i.e., Ho(3+):(5)S2/(5)F4 + Ce(3+):(2)F5/2→Ho(3+):(5)F5 + Ce(3+):(2)F7/2 and Ho(3+):(5)I6 + Ce(3+):(2)F5/2→Ho(3+):(5)I7 + Ce(3+):(2)F7/2, are demonstrated to greatly suppress the population of the green-emitting (5)S2/(5)F4 state and to enhance the population of the red-emitting (5)F5 one, leading to the intense single-band red UC radiation of Ho(3+).

Synthesis and characterization of α-NaYF{sub 4}: Yb, Er nanoparticles by reverse microemulsion method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunaseelan, M.; Senthilselvan, J., E-mail: jsselvan@hotmail.com

2016-05-06

A simple and cost effective reverse microemulsion system was newly designed to synthesis NaYF{sub 4}:20%Yb,2%Er upconverting luminescent nanoparticles. XRD results confirms the cubic structure of NaYF{sub 4} nanophosphor in the as prepared condition without any other impurity phases. The as-prepared sample itself having highly crystalline nanoparticle with well dispersed uniform morphology is the advantage of this reverse microemulsion process. HRTEM images of as prepared and calcined samples revealed spherical nanoclusters morphology with size of ~210 nm and ~245 nm respectively. The characteristic absorption wavelength that occurs at 980 nm due to transition of energy levels {sup 2}F{sub 5/2} to {sup 2}F{sub 7/2} formore » Yb{sup 3+} rare earth ion in as prepared and calcined upconversion nanoparticle confirms the presence of Yb{sup 3+} by UV-Visible spectroscopy which can act as a sensitizer for photonic upconversion. Therefore the absorption at NIR region and emission spectrum at visible region suggests that NaYF{sub 4}:20%Yb,2%Er is suitable for upcoversion process, due to its optical property and chemical stability this material also be useful for bio imaging applications.« less

Recent Advances in Upconversion Nanoparticles-Based Multifunctional Nanocomposites for Combined Cancer Therapy.

PubMed

Tian, Gan; Zhang, Xiao; Gu, Zhanjun; Zhao, Yuliang

2015-12-16

Lanthanide-doped upconversion nanoparticles (UCNPs) have the ability to generate ultraviolet or visible emissions under continuous-wave near-infrared (NIR) excitation. Utilizing this special luminescence property, UCNPs are approved as a new generation of contrast agents in optical imaging with deep tissue-penetration ability and high signal-to-noise ratio. The integration of UCNPs with other functional moieties can endow them with highly enriched functionalities for imaging-guided cancer therapy, which makes composites based on UCNPs emerge as a new class of theranostic agents in biomedicine. Here, recent progress in combined cancer therapy using functional nanocomposites based on UCNPs is reviewed. Combined therapy referring to the co-delivery of two or more therapeutic agents or a combination of different treatments is becoming more popular in clinical treatment of cancer because it generates synergistic anti-cancer effects, reduces individual drug-related toxicity and suppresses multi-drug resistance through different mechanisms of action. Here, the recent advances of combined therapy contributed by UCNPs-based nanocomposites on two main branches are reviewed: i) photodynamic therapy and ii) chemotherapy, which are the two most widely adopted therapies of UCNPs-based composites. The future prospects and challenges in this emerging field will be also discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescent silver(I) tert-butylethynide compounds with nicotinic/isonicotinic acid as ligands

NASA Astrophysics Data System (ADS)

Xie, Yi-Ming; Fan, Yue-Yue; Lin, Fu-Lin; Hu, Ting; Liu, Jia; Lu, Can-Zhong

2017-12-01

Solvothermal reaction of tBuC≡CAg, AgBF4 and nicotinic/isonicotinic acid in acetonitrile afforded two new silver(I) tert-butylethynide double salts, namely [(tBuC≡CAg)(AgL1)3] (HL1 = nicotinic acid) (1) and [(tBuC≡CAg)(AgL1)2] (HL2 = isonicotinic acid) (2). These compounds have been characterized by elemental analysis, infrared spectra, single-crystal X-ray analysis, X-ray powder diffraction, thermogravimetric analysis, UV-visible absorption spectra, and luminescent measurement. 1 exhibits a two-dimensional coordination network, and 2 features a three-dimensional coordination architecture. Luminescence measurements indicate that 1 shows a fluorescent emission band centered at 568 nm, and 2 exhibits an intense emission maximum at 550 nm and a shoulder peak at 436 nm.

Listening to Chemical Materials: Determination of the Photophysical Parameters by Photoacoustic Spectroscopy

NASA Astrophysics Data System (ADS)

Yang, Y. T.; Zhang, S. Y.; Liu, X. J.

2012-11-01

Recently, photoacoustic (PA) spectroscopy has emerged as a valuable tool for the study of various kinds of materials. Herein, we present the results of PA spectral studies of chemical materials. First, the PA study on luminescent materials in condensed states is reported. Combining with the luminescence technique, the energy transfer efficiency and the intrinsic luminescence quantum yield are determined for a europium (III) complex in the glassy state, smectic A phase, and the isotropic liquid. Second, neodymium (III) compounds with l-glycine, l-phenylalanine, and l-tryptophan are synthesized and their PA spectra are reported. The nephelauxetic ratio and Sinha parameter are calculated based on the PA spectra. The environmental effect on the f-f transitions of the neodymium(III) ion is also studied.

Ytterbium-porphyrins as a new class of the luminescent labels

NASA Astrophysics Data System (ADS)

Tsvirko, M.; Korovin, Yu; Rusakova, N.

2007-08-01

New complexes of ytterbium with asymmetric porphyrins containing substituents in β-positions and hydrophobic meso-(monophenyl-p-oxypropyl)triphenylporphyrin (OPP) were obtained and characterized by elemental analysis, IR, UV-Vis absorption and luminescence spectroscopy. Electronic absorption, luminescence and luminescence excitation spectra of these complexes were studied at 295 K in DMF solutions and in the water-lecithin medium. The 4f-luminescence of ytterbium-porphyrins in the near infrared (IR) spectral region (λmax = 980 nm) is observed under excitation in Soret band (400-430 nm). The effect of substituent in porphyrin macroring on the 4f-luminescent properties was also investigated. The conjugates of these compounds with protein molecules - bovine serum albumin (BSA) were investigated as well. These compounds are interesting at the initial stage of diagnostics of tumor tissues as IR-luminescent probes due to their spectral-luminescent characteristics and some biochemical properties.

Influence of processing conditions on point defects and luminescence centers in ZnO

NASA Astrophysics Data System (ADS)

Zhong, J.; Kitai, A. H.; Mascher, P.

1993-12-01

Positron lifetime spectroscopy and cathodoluminescence were employed to study luminescence centers in ZnO. The samples were high-purity polycrystalline ceramics sintered at temperatures ranging from 800 to 1400 C for 2 to 40 h. Scanning electron microscopy shows that as annealing temperatures and/or times increase, the average grain size increases and can reach 30 micron for samples sintered at 1200 C. At the same time, the positron bulk lifetime approaches theoretically estimated single-crystal values, while the integrated luminescence intensity increase significantly. A further increase of the sintering temperature beyond 1200 C results in a decrease in the luminescence intensity, in good agreement with the only weak luminescence observed in single-crystalline material. The positron lifetime spectra clearly show the existence of the dominant vacancy-type defect, most likely a complex involving V(sub Zn), or the divacancy, V(sub Zn)V(sub O), independent of sample thermal history. The concentration of this center steadily decreases with increasing sintering temperatures. It is concluded that the yellow luminescence centers are related to charged zinc vacancies trapped in the grain boundary regions. We propose that the observed broadness of the spectra likely originates from the modification of the electronic configuration of the luminescence centers due to their complex environment. A direct connection between the positron and the luminescence results could not be established; instead, they appear to reflect two relatively independent aspects of the samples. It could be shown, however, that positron annihilation measurements can be used effectively to monitor the evolution of the microstructure of the samples, in good agreement with scanning electron micrographs.

Rare-Earth Ion-Host Lattice Interactions: 15. Analysis of the Spectra of Nd3+ in Gd3Sc2Ga3O12.

DTIC Science & Technology

1984-05-01

Luminescence of Cr3+ Ions in Gadolinium Gallium and Gadolinium Scandium Gallium Garnet CT’stals, Soy. J. Quant. Electron. 12 (1982), 1124. 6M. Dutoit, J. C...Shcherbakov, Absolute Quantum Efficiency of the Luminescence of Cr3+ Ions in Gadolinium Gallium and Gadolinium Scandium Gallium Garnet Crystals, Soy. J...HDL Project: 324332 19. KEY WORDS (Continue on reverse side it necessary end Identify by block number) Rare earth Mixed garnet Spectra Laser Judd-Ofelt

Electro-Optical Properties of Polymer Blends: Lasing, Electroluminescence and Photophysics

DTIC Science & Technology

2007-02-01

34- Phenylenevinylene" (Cirpan/Rathnayake/Lahti/Karasz) 16. Chem. Mater.: "Single-Molecule and Bulk Luminescence Studies of the Green Emission Band in 2,7- Bis...providing emission from the triplet state with a 100% theoretical yield. These electronic transitions of lanthanides result from different electronic...referred to above. Luminescence spectra and luminescence decays were recorded with a Thermo Laser Science pulsed nitrogen laser ( Aem =3 3 7 .1 nm; < 4 ns

[USE OF LASER RAMAN-LUMINESCENT TECHNOLOGIES FOR EVALUATION OF QUALITY OF MEAT PRODUCTS AND DETERMINATION OF THE DEGREE OF THEIR BACTERIAL CONTAMINATION].

PubMed

Kukushkin, V I; Satusheva, E V; Aleksandrov, M T; Morozova, O A; Pashkov, E P; Ambartsumyan, O A; Amosova, V A

2015-01-01

Determination of the effect of microorganisms on spoilage of meat products during various temperature regimes of storage by integral indexes of luminescent lines in their spectra and development of an algorithm of microorganism indication by an express method using laser Raman-luminescent spectroscopy. Minced meat from beef and pork was used. Determination of quantity of mesophilic aerobic and opportunistic-anaerobic microorganisms was carried out by serial 10-fold dilutions with subsequent parallel seeding into Rida count total 24 plates and Petri dishes with 5% blood agar. Sample study was carried out in luminescent software-hardware complex Enspectr L405 (a variant of Enspectr M software-hardware complexes). Meat spoilage was established to be caused to a large degree by Pseudomonas genus (P. fluorescens, P. putida, P. fragi et al.) bacterial growth. Raman-luminescent spectra of bacteria that compose microflora, characterizing and accompanying beef and pork spoilage, were measured and recorded into a database. The results obtained will allow to use this technique in the future for both express-indication and differentiation of microorganisms and express-evaluation of quality of meat products at all stages of their manufacturing, storage, transport and realization.

Multimodal emissions from Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate glass: Upconversion, downshifting and quantum cutting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahadur, A.; Yadav, R.S.; Yadav, R.V.

This paper reports the optical properties of Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method. The absorption spectrum of the Yb{sup 3+} doped LB glass contains intense NIR band centered at 976 nm due to {sup 2}F{sub 7/2}→{sup 2}F{sub 5/2} transition. The emission spectra of the prepared glasses have been monitored on excitation with 266, 355 and 976 nm. The Yb{sup 3+} doped glass emits a broad NIR band centered at 976 nm whereas the Tb{sup 3+} doped glass gives off visible bands on excitations with 266 and 355 nm. When the Tb{sup 3+} andmore » Yb{sup 3+} ions are co-doped together, the emission intensity in the visible region decreases whereas it increases in the NIR region significantly. The increase in the emission intensity in the NIR region is due to efficient cooperative energy transfer (CET) from Tb{sup 3+} to Yb{sup 3+} ions. The quantum cutting efficiency for Tb{sup 3+}/Yb{sup 3+} co-doped glass has been calculated and compared for 266 and 355 nm excitations. The quantum cutting efficiency is larger for 355 nm excitation (137%). The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass also emits upconverted visible bands on excitation with 976 nm. The mechanisms involved in the energy transfer have been discussed using schematic energy level diagram. The Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may be used in the optical devices and in solar cell for solar spectral conversion and behaves as a multi-modal photo-luminescent material. - Graphical abstract: The Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method emits upconverted visible emissions through upconversion CET from Yb{sup 3+} to Tb{sup 3+} ions and quantum cutting emissions through downconversion CET from Tb{sup 3+} to Yb{sup 3+} ions. Therefore, the Tb{sup 3+}/Yb{sup 3+} co-doped LB glass may find applications in optical devices and solar cell and behaves as a multi-modal photo-luminescent material. - Highlights: • The Tb{sup 3+}/Yb{sup 3+} co-doped lithium borate (LB) glass prepared by melt quench method. • The Tb{sup 3+}/Yb{sup 3+} co-doped glass gives QC emissions upon 266 and 355 nm excitations. • The Tb{sup 3+}/Yb{sup 3+} co-doped glass also emits intense green color on excitation with 976 nm. • The quantum cutting efficiency is larger for 355 nm excitation (137%). • The Tb{sup 3+}/Yb{sup 3+} co-doped glass may be used in solar cell and display devices.« less

Study of broadband near-infrared emission in Tm3+-Er3+ codoped TeO2-WO3-PbO glasses.

PubMed

Balda, R; Fernández, J; Fernández-Navarro, J M

2009-05-25

In this work, we report the near-infrared emission properties of Tm(3+)-Er(3+) codoped tellurite TeO(2)-WO(3)-PbO glasses under 794 nm excitation. A broad emission from 1350 to 1750 nm corresponding to the Tm(3+) and Er(3+) emissions is observed. The full width at half-maximum of this broadband increases with increasing [Tm]/[Er] concentration ratio up to a value of ~ 160 nm. The energy transfer between Tm(3+) and Er(3+) ions is evidenced by both the temporal behavior of the near-infrared luminescence and the effect of Tm3+ codoping on the visible upconversion of Er(3+) ions.

Visible luminescence of dysprosium ions in oxyhalide lead borate glasses.

PubMed

Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A

2011-08-15

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions. Copyright © 2010 Elsevier B.V. All rights reserved.

EPR, optical absorption and luminescence studies of Cr3+-doped antimony phosphate glasses

NASA Astrophysics Data System (ADS)

De Vicente, F. S.; Santos, F. A.; Simões, B. S.; Dias, S. T.; Siu Li, M.

2014-12-01

Antimony phosphate glasses (SbPO) doped with 3 and 6 mol% of Cr3+ were studied by Electron Paramagnetic Resonance (EPR), UV-VIS optical absorption and luminescence spectroscopy. The EPR spectra of Cr3+-doped glasses showed two principal resonance signals with effective g values at g = 5.11 and g = 1.97. UV-VIS optical absorption spectra of SbPO:Cr3+ presented four characteristics bands at 457, 641, 675, and 705 nm related to the transitions from 4A2(F) to 4T1(F), 4T2(F), 2T1(G), and 2E(G), respectively, of Cr3+ ions in octahedral symmetry. Optical absorption spectra of SbPO:Cr3+ allowed evaluating the crystalline field Dq, Racah parameters (B and C) and Dq/B. The calculated value of Dq/B = 2.48 indicates that Cr3+ ions in SbPO glasses are in strong ligand field sites. The optical band gap for SbPO and SbPO:Cr3+ were evaluated from the UV optical absorption edges. Luminescence measurements of pure and Cr3+-doped glasses excited with 350 nm revealed weak emission bands from 400 to 600 nm due to the 3P1 → 1S0 electronic transition from Sb3+ ions. Cr3+-doped glasses excited with 415 nm presented Cr3+ characteristic luminescence spectra composed by two broad bands, one band centered at 645 nm (2E → 4A2) and another intense band from 700 to 850 nm (4T2 → 4A2).

Cathodoluminescence study of one-dimensional free-standing widegap-semiconductor nanostructures: GaN nanotubes, Si3N4 nanobelts and ZnS/Si nanowires.

PubMed

Sekiguchi, Takashi; Hu, Junqing; Bando, Yoshio

2004-01-01

Luminescence properties of one-dimensional free-standing widegap-semiconductor nanostructures were characterized by means of cathodoluminescence (CL). GaN nanopipes, alpha-Si3N4 nanobelts and ZnS/Si nanowires were fabricated by a catalyst-free method, namely grown in an induction furnace from powders. After the observation of morphology by scanning electron microscopy as well as the confirmation of their crystal structures by transmission electron microscopy, their CL spectra and images were observed. The CL spectra mapping as well as the monochromatic CL imaging revealed the variation of the luminescence spectra of different nanowires as well as that along a single wire. These results revealed the optical features of nanostructures.

Structural and optical properties of thermal decomposition assisted Gd2O3:Ho(3+)/Yb(3+) upconversion phosphor annealed at different temperatures.

PubMed

Kumar, A; Tiwari, S P; Kumar, K; Rai, V K

2016-10-05

The infrared to visible upconversion fluorescent nanoparticles of Ho(3+)/Yb(3+) codoped Gd2O3 phosphor is synthesized via thermal decomposition route. The as-synthesized sample was annealed at 800, 1000 and 1200°C for 3h and then structural and optical properties were studied. The Rietveld refinement of X-ray diffraction (XRD) data was analyzed to probe the effect of Ho(3+)/Yb(3+) dopant on the structural parameters of Gd2O3 host. The upconversion emission spectra of as-synthesized and annealed samples are compared using 980nm diode laser excitation and five emission bands noticed at 490, 539, 550, 667 and 757nm corresponding to the (5)F3→(5)I8, (5)F4→(5)I8, (5)S2→(5)I8,(5)F5→(5)I8 and (5)I4→(5)I8 manifolds, respectively. The local temperature induced by laser light is also calculated. The fluorescence intensity ratio (FIR) of two thermally coupled transitions (5)F4→(5)I8 and (5)S2→(5)I8 is plotted against the sample temperature and sensor sensitivity of sample is calculated. Copyright © 2016 Elsevier B.V. All rights reserved.

Method bacterial endospore quantification using lanthanide dipicolinate luminescence

NASA Technical Reports Server (NTRS)

Venkateswaran, Kasthuri J. (Inventor); Kirby, James Patrick (Inventor); Ponce, Adrian (Inventor)

2007-01-01

A lanthanide is combined with a medium to be tested for endospores. The dipicolinic acid released from the endospores binds the lanthanides, which have distinctive emission (i.e., luminescence) spectra, and are detected using photoluminescence. The concentration of spores is determined by preparing a calibration curve generated from photoluminescence spectra of lanthanide complex mixed with spores of a known concentration. A lanthanide complex is used as the analysis reagent, and is comprised of lanthanide ions bound to multidentate ligands that increase the dipicolinic acid binding constant through a cooperative binding effect with respect to lanthanide chloride. The resulting combined effect of increasing the binding constant and eliminating coordinated water and multiple equilibria increase the sensitivity of the endospore assay by an estimated three to four orders of magnitude over prior art of endospore detection based on lanthanide luminescence.

Luminescence Properties of Surface Radiation-Induced Defects in Lithium Fluoride

NASA Astrophysics Data System (ADS)

Voitovich, A. P.; Kalinov, V. S.; Martynovich, E. F.; Novikov, A. N.; Runets, L. P.; Stupak, A. P.

2013-11-01

Luminescence and luminescence excitation spectra are recorded for surface radiation-induced defects in lithium fluoride at temperatures of 77 and 293 K. The presence of three bands with relatively small intensity differences is a distinctive feature of the excitation spectrum. These bands are found to belong to the same type of defects. The positions of the peaks and the widths of the absorption and luminescence bands for these defects are determined. The luminescence decay time is measured. All the measured characteristics of these surface defects differ from those of previously known defects induced by radiation in the bulk of the crystals. It is found that the luminescence of surface defects in an ensemble of nanocrystals with different orientations is not polarized. The number of anion vacancies in the surface defects is estimated using the polarization measurements. It is shown that radiative scattering distorts the intensity ratios of the luminescence excitation bands located in different spectral regions.

A color-tunable luminescent material with functionalized graphitic carbon nitride as multifunctional supports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Jiutian; Cao, Yudong; Fan, Hai

2015-12-15

A color-tunable luminescent material was prepared based on the composition of functionalized graphitic carbon nitride (g-C{sub 3}N{sub 4}) and europium (III). The functionalized g-C{sub 3}N{sub 4} layers not only behave as multifunctional supports including ligand coordinated with europium (III) and a support structure for the formation of the luminescent material, but exhibit excitation wavelength-dependent luminescence, thus the energy transfer between the functionalized g-C{sub 3}N{sub 4} and europium (III) can match very well by controlling the emission wavelength of functionalized g-C{sub 3}N{sub 4}. The as-prepared materials was comprehensively characterized via X-ray photoelectron spectroscopy, Fourier Transform Infrared spectroscopy, X-ray scattering techniques, Ultravioletmore » and Visible spectrophotometer, fluorescence spectrophotometer, thermogravimetric analysis, etc. The luminescent material exhibits multi-color emissions which are consistent with the characteristic emissions of europium (III) and functionalized g-C{sub 3}N{sub 4}, and the photoluminescence quality and density of the europium (III) can be greatly enhanced. The brilliant optical properties of the materials make them suiting for multipurpose applications in practical fields. - Graphical abstract: Schematic illustration of the synthesis and basic composition of the luminescent material. Inset figures were luminescence emission spectra of g-C{sub 3}N{sub 4} (A), europium (III) complex (a) and luminescent material (b) with the same concentration in (B) (K{sub ex}=350 nm) and photographs of (left) H{sub 2}O and (right) the H{sub 2}O dispersion of luminescence emission spectra under 350 nm UV radiation. The energy transfer in the luminescent material matchs very well and it exhibits multi-color emissions simultaneously. The enhanced photoluminescence quality and density of the europium (III) makes them suiting for multipurpose applications in practical fields. - Highlights: • Luminescent material exhibits multi-color emissions when excited by single wavelength. • The energy trsnsfer between functionalized g-C{sub 3}N{sub 4} and europium matches very vell. • Functionalized g-C{sub 3}N{sub 4} exhibits excitation wavelength-depengdent bright blue luminescence. • Functionalized g-C{sub 3}N{sub 4} layer provided as multifunctional supports.« less

Spectroscopic investigation of zinc tellurite glasses doped with Yb(3+) and Er(3+) ions.

PubMed

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-05

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80-x-y) TeO2+(0.20) ZnO+xEr2O3+yYb2O3 (x=0, y=0; x=0.004, y=0; x=0, y=0.05 and x=0.004, y=0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er(3+) glasses as erbium doped fiber amplifiers at 1.55μm in infrared emission region. Copyright © 2016 Elsevier B.V. All rights reserved.

Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

NASA Astrophysics Data System (ADS)

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-01

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

Synthesis and influence of ultrasonic treatment on luminescence of Mn incorporated ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Cadis, A.-I.; Muresan, L. E.; Perhaita, I.; Munteanu, V.; Karabulut, Y.; Garcia Guinea, J.; Canimoglu, A.; Ayvacikli, M.; Can, N.

2017-10-01

Manganese (Mn) doping of ZnS phosphors was achieved by precipitation method using different ultrasound (US) maturation times. The structural and luminescence properties of the samples were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL), and cathodoluminescence (CL). The real amount of manganese incorporated in ZnS lattice was calculated based on ICP-OES results. According with XRD patterns, the phase structure of ZnS:Mn samples is cubic. EDS spectra reveal deviations of the Mn dopant concentration from the target composition. Both 300 K PL and CL emission spectra of the Mn doped ZnS phosphors display intense orange emission at 590 and 600 nm, respectively, which is characteristic emission of Mn ion corresponding to a 4T1→6A1 transition. Both PL and CL spectra confirmed manganese is substitutionally incorporated into the ZnS host as Mn2+. However, it is suggested that the origin of broad blue emission around 400 nm appeared in CL is due to the radiative recombination at deep level defect states in the ZnS. The ultrasound treatment at first enhances the luminescent intensity by ∼3 times in comparison with samples prepared by classical way. This study gives rise to an optimization guideline, which is extremely demanded for the development of new luminescent materials.

Selective laser spectroscopy of molecules and ions in solids: a history, fundamentals and applications

NASA Astrophysics Data System (ADS)

Sapozhnikov, Michael

2018-03-01

A history of the development of selective laser spectroscopy is presented, beginning with a pioneering work by Yu. V. Denisov and V. A. Kizel in 1967, who were the first to demonstrate the possibility of removing the inhomogeneous broadening of luminescence spectra of impurity ions in glasses upon monochromatic resonance excitation. Selective excitation of optical centers can be achieved due to existence of zero-phonon transitions corresponding to narrow homogeneous zero-phonon lines in the spectra of impurity centers in solids, which are hidden in broad inhomogeneous optical bands upon usual nonselective excitation. The fundamentals of zero-phonon transition spectroscopy are considered and the mechanism of removing the inhomogeneous broadening of optical spectra of ions and molecules in crystals and amorphous solids under selective laser excitation of luminescence and persistent hole burning in absorption spectra is presented in detail. Various applications of selective laser spectroscopy for fundamental and applied studies are discussed.

Absorption, fluorescence and second harmonic generation in Cr3+-doped BiB3O6 glasses

NASA Astrophysics Data System (ADS)

Kuznik, W.; Fuks-Janczarek, I.; Wojciechowski, A.; Kityk, I. V.; Kiisk, V.; Majchrowski, A.; Jaroszewicz, L. R.; Brik, M. G.; Nagy, G. U. L.

2015-06-01

Synthesis, spectral properties and photoinduced nonlinear optical effects of chromium-doped BiB3O6 glass are studied in the present paper. Absorption, excitation and time resolved luminescence spectra are presented and luminescence decay behavior is discussed. Detailed analysis of the obtained spectra (assignment of the most prominent spectral features in terms of the corresponding Cr3+ energy levels, crystal field strength Dq, Racah parameters B and C) was performed. A weak photostimulated second harmonic generation signal was found to increase drastically due to poling by proton implantation in the investigated sample.

Convenient determination of luminescence quantum yield using a combined electronic absorption and emission spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prakash, John; Mishra, Ashok Kumar

2016-01-15

It is possible to measure luminescence quantum yield in a facile way, by designing an optical spectrometer capable of obtaining electronic absorption as well as luminescence spectra, with a setup that uses the same light source and detector for both the spectral measurements. Employment of a single light source and single detector enables use of the same correction factor profile for spectral corrections. A suitable instrumental scaling factor is used for adjusting spectral losses.

Crystal structure, electronic structure, and photoluminescent properties of SrMoO{sub 4}:Tb{sup 3+} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Sung Wook; Moon, Byung Kee; Jeong, Jung Hyun, E-mail: jhjeong@pknu.ac.kr

2015-10-15

Highlights: • SrMoO{sub 4}:Tb{sup 3+} phosphor samples were synthesized at different temperatures. • The crystal and electronic structures, and luminescence properties were studied. • The excitation peak shifts to red with increasing the sintering temperature. • The luminescence mechanism of SrMoO{sub 4}:Tb{sup 3+} was suggested. - Abstract: The experimental and theoretical studies of the optical properties of SrMoO{sub 4}:Tb{sup 3+} phosphors were carried out. The structural, optical, and electronical properties of the phosphors were systematically studied. The phosphor samples were crystallized at different temperatures via a sol–gel method. Excitation spectra of SrMoO{sub 4}:Tb{sup 3+} powder samples exhibited gradual red shiftmore » and luminescent intensity changed with increasing the sintering temperature. Such spectral changes depend strongly on the crystallographic properties such as lattice parameters and crystallinity. The shift of the excitation spectra is mainly ascribed to the covalent bond interaction between Mo−O bonds. An energy band model was demonstrated to describe the luminescence mechanism in the material.« less

Growth and luminescent properties of Yb:YAG and Ca co-doped Yb:YAG ultrafast scintillation crystals

NASA Astrophysics Data System (ADS)

Zhu, Maodong; Qi, Hongji; Pan, Mingyan; Hou, Qing; Jiang, Benxue; Jin, Yaxue; Han, Hetong; Song, Zhaohui; Zhang, Hui

2018-05-01

In this work, Yb-doped Y3Al5O12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb0.1Y0.9)3Al5O12 and (Ca0.001Yb0.1Y0.899)3Al5O12, respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV-Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

PubMed Central

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-01-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 → 2I15/2 and 4S3/2 → 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K−1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

NASA Astrophysics Data System (ADS)

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-02-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

Bifunctional NaYF4:Er3+/Yb3+ submicron rods, implemented in quantum dot sensitized solar cell(Conference Presentation)

NASA Astrophysics Data System (ADS)

Guerrero, J. Pablo; Cerdán Pasarán, Andrea; López-Luke, Tzarara; Ramachari, D.; Esparza, Diego; De la Rosa Cruz, Elder; Romero Arellano, Victor Hugo

2016-09-01

In this work are presented the results obtained with solar cells sensitized with quantum dots of cadmium sulphide (CdS) incorporating luminescent materials (NaYF4:Yb/Er). The study revealed that through using a bifunctional layer of NaYF4:Yb/Er submicron rods, the infrared radiation is absorbed in 980nm to generate luminescence in the visible region to 530nm, under the UP-conversion process, in the same way simultaneously, NaYF4:Yb/Er layer causes scattering toward the quantum dots, the emission and scattering generated by this material is reabsorbed by the QD-CdS, and these in turn are absorbing in its range of solar radiation absorption, Thus generates an increase in the electron injection into the semiconductor of TiO2. The results of a cell incorporating NaYF4: Yb/Er at 0.07M shown photoconversion efficiencies of 3.39% improving efficiency with respect to the reference solar cell without using NaYF4: Yb/Er of 1.99%. The obtained values of current and voltage showed a strong dependence of the percentage of NaYF4 Yb/Er, and the mechanism of incorporation of this material.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method.

PubMed

Gavrilović, Tamara V; Jovanović, Dragana J; Lojpur, Vesna; Dramićanin, Miroslav D

2014-02-27

Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

The luminescence of nanoscale Y2Si2O7:Eu3+ materials.

PubMed

Lu, Shaozhe; Zhang, Jishen; Zhang, Jiahua

2010-03-01

The Y2Si2O7:Eu3+ sample was prepared with the sol-gel method. The Y2O3:EU3 was dispersed in SiO2, and the complex Y2Si2O7:Eu3+ particles were synthesized at high annealing temperature. The sample consisted of nearly spherical particles with an average size about 60 nm. The ultraviolet excitation spectra and emission spectra were measured. The sample excited by short ultraviolet light showed strongly red luminescence and fine monochromaticity. The luminescence was strongest from the 5D0 --> 7F2 electric dipole transition located at 611 nm. The excitation spectra of Y2Si2O7:Eu3+ excited with ultraviolet lights showed that the peak of the Eu(3+)-O2- charge transition band located at about 240 nm. During monitoring of different emission peaks of 5D0 --> 7F2, the charge transition band in the excitation spectra shifted, and the relative intensity of emission spectra changed obviously under the excitation of different ultraviolet wavelengths. These results confirmed that the Eu3+ could be excited with ultraviolet radiation of different wavelengths. At low temperature, using Eu3+ ions as fluorescence probes, we monitored the emission peaks of 5D0 --> 7F1 and 5D0 --> 7F2 transitions and measured the excitation spectra of 7F0 --> 5D0, 5D0 --> 7F1, and 5D0 --> 7F2 site-selective excitation spectra. These results indicated that Eu3+ ions are located in different local environments in the Y2Si2O7 host.

Intervalence charge transfer luminescence: Interplay between anomalous and 5d − 4f emissions in Yb-doped fluorite-type crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barandiarán, Zoila, E-mail: zoila.barandiaran@uam.es; Seijo, Luis; Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid

2014-12-21

In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb{sup 2+}-doped CaF{sub 2} and SrF{sub 2}, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f{sup 14}–1A{sub 1g}→ 4f{sup 13}({sup 2}F{sub 7/2})5de{sub g}–1T{submore » 1u} absorption in the Yb{sup 2+} part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb{sup 3+} moiety is in the higher 4f{sup 13}({sup 2}F{sub 5/2}) multiplet. The Yb{sup 2+}–Yb{sup 3+} → Yb{sup 3+}–Yb{sup 2+} IVCT emission consists of an Yb{sup 2+} 5de{sub g} → Yb{sup 3+} 4f{sub 7/2} charge transfer accompanied by a 4f{sub 7/2} → 4f{sub 5/2} deexcitation within the Yb{sup 2+} 4f{sup 13} subshell: [{sup 2}F{sub 5/2}5de{sub g},{sup 2}F{sub 7/2}] → [{sup 2}F{sub 7/2},4f{sup 14}]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF{sub 2}, SrF{sub 2}, BaF{sub 2}, and SrCl{sub 2}: the presence of IVCT luminescence in Yb-doped CaF{sub 2} and SrF{sub 2}; its coexistence with regular 5d-4f emission in SrF{sub 2}; its absence in BaF{sub 2} and SrCl{sub 2}; the quenching of all emissions in BaF{sub 2}; and the presence of additional 5d–4f emissions in SrCl{sub 2} which are absent in SrF{sub 2}. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb{sup 2+}-doped CaF{sub 2} and SrF{sub 2}, the appearance of Yb{sup 2+} 4f–5d absorption bands in the excitation spectra of the IR Yb{sup 3+} emission in partly reduced CaF{sub 2}:Yb{sup 3+} samples, and to identify the broadband observed in the excitation spectrum of the so far called anomalous emission of SrF{sub 2}:Yb{sup 2+} as an IVCT absorption, which corresponds to an Yb{sup 2+} 4f{sub 5/2} → Yb{sup 3+} 4f{sub 7/2} electron transfer.« less

Solid-state surface luminescence of polycyclic aromatic hydrocarbons adsorbed on cellulose diacetate matrices

NASA Astrophysics Data System (ADS)

Rogacheva, Svetlana M.; Shipovskaya, Anna B.; Volkova, Elena V.; Khurshudyan, Grachia N.; Suska-Malawska, Malgorzata; Gubina, Tamara I.

2018-04-01

The spectral-kinetic characteristics of luminescence of 17 polycyclic aromatic hydrocarbons (PAH) sorbed from a "water-organic solvent" medium on cellulose diacetate (CDA) matrices were studied. A significant increase in the fluorescence signal on the CDA matrix was observed for 13 PAHs in comparison with aqueous solutions. The highest detection sensitivity was found for pyrene, benzo(a)pyrene, and benzo(k)fluoranthene. The fluorescence spectra of two PAH indicator pairs (anthracene-phenanthrene and pyrene-fluoranthene) used to control toxicant emission sources were studied with the simultaneous presence of isomers in the analyte, depending on the excitation wavelength. For both isomer pairs, it has been found that the spectra of their solid-state luminescence overlap insignificantly, the characteristic peaks do not coincide and do not overlap, the sensitivities of detection are close to each other, which makes it possible to consider this technique as promising to control PAH contamination sources.

Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites

NASA Technical Reports Server (NTRS)

Coyne, L. M.; Costanzo, P. M.; Theng, B. K.

1989-01-01

Luminescence, induced by dehydration and by wetting with hydrazine and unsymmetrically substituted hydrazine, and related ESR spectra have been observed from several kaolinites, synthetically hydrated kaolinites, and metahalloysites. The amine-wetting luminescence results suggest that intercalation, not a chemiluminescence reaction, is the luminescence trigger. Correlation between hydration-induced luminescence and g = 2 ESR signals associated with O(-)-centres in several natural halloysites, and concurrent diminution of the intensity of both these signal types as a function of aging in two 8.4 angstroms synthetically hydrated, kaolinites, confirm a previously-reported relationship between the luminescence induced by dehydration and in the presence of O(-)-centres (holes, i.e., electron vacancies) in the tetrahedral sheet. Furthermore, the ESR spectra of the 8.4 angstroms hydrate showed a concurrent change in the line shape of the g = 4 signal from a shape usually associated with structural Fe in an ordered kaolinite, to a simpler one typically observed in more disordered kaolinite, halloysite, and montmorillonite. Either structural Fe centres and the O(-)-centres interact, or both are subject to factors previously associated with degree of order. The results question the long-term stability of the 8.4 angstroms hydrate, although XRD does not indicate interlayer collapse over this period. Complex inter-relationships are shown between intercalation, stored energy, structural Fe, and the degree of hydration which may be reflected in catalytic as well as spectroscopic properties of the clays.

A multifunctional probe for ICP-MS determination and multimodal imaging of cancer cells.

PubMed

Yang, Bin; Zhang, Yuan; Chen, Beibei; He, Man; Yin, Xiao; Wang, Han; Li, Xiaoting; Hu, Bin

2017-10-15

Inductively coupled plasma-mass spectrometry (ICP-MS) based bioassay and multimodal imaging have attracted increasing attention in the current development of cancer research and theranostics. Herein, a sensitive, simple, timesaving, and reliable immunoassay for cancer cells counting and dual-modal imaging was proposed by using ICP-MS detection and down-conversion fluorescence (FL)/upconversion luminescence (UCL) with the aid of a multifunctional probe for the first time. The probe consisted of a recognition unit of goat anti-mouse IgG to label the anti-EpCAM antibody attached cells, a fluorescent dye (Cy3) moiety for FL imaging as well as upconversion nanoparticles (UCNPs) tag for both ICP-MS quantification and UCL imaging of cancer cells. Under the optimized conditions, an excellent linearity and sensitivity were achieved owing to the signal amplification effect of nanoparticles and low spectral interference. Accordingly, a limit of detection (3σ) of 1×10 2 HepG2 cells and a relative standard deviation of 7.1% for seven replicate determinations of 1×10 3 HepG2 cells were obtained. This work proposed a method to employ UCNPs with highly integrated functionalities enabling us not only to count but also to see the cancer cells, opening a promising avenue for biological research and clinical theranostics. Copyright © 2017 Elsevier B.V. All rights reserved.

Bench-scale evaluation of water disinfection by visible-to-UVC upconversion under high-intensity irradiation.

PubMed

Cates, Ezra L; Kim, Jae-Hong

2015-12-01

The feasibility of applying visible-to-UVC upconversion (UC) luminescence to enhance the kinetics of solar water disinfection was evaluated using Lu7O5F9:Pr(3+) ceramics incorporated into a solar reactor containing E. coli suspensions. Inactivation was assessed in batch conditions using both laser and lens-concentrated sunlight excitation conditions. Under 840-mW argon laser excitation, the UC efficiency was estimated to be 1 order of magnitude greater than previously reported under lamp excitation and UVC emitted by the reactors resulted in 3.6-log inactivation in 20 min. However, experiments using ~1500 mW of concentrated natural sunlight showed no additional inactivation that could be attributed to UC within the timescale studied. Due to the fundamental and practical limitations of solar focusing, the optical concentration ratio employed herein prevented the excitation beam from achieving the power densities required to attain UC efficiencies comparable to the laser experiments. We also observed that the high intensity of both the laser and sunlight induced rapid photoreactivation by the bacteria, which detracted from net disinfection performance. The results suggest that current UC materials perform inadequately for environmental application; nonetheless, valuable qualitative and quantitative insight was gained that more explicitly defines materials development goals and considerations for application of UC to environmental technology. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous observation of up/down conversion photoluminescence and colossal permittivity properties in (Er+Nb) co-doped TiO2 materials

NASA Astrophysics Data System (ADS)

Tse, Mei-Yan; Tsang, Ming-Kiu; Wong, Yuen-Ting; Chan, Yi-Lok; Hao, Jianhua

2016-07-01

We have investigated the optical and dielectric properties of rutile TiO2 doped with Nb and Er, i.e., (Er0.5Nb0.5)xTi1-xO2. The up/downconversion photoluminescence was observed in the visible and near-infrared region from the materials under 980 nm laser diode excitation. The upconversion emissions are attributed to the energy transfer between Er ions in the excited states. Moreover, the dielectric measurements indicate that the fabricated materials simultaneously present colossal permittivity properties with relatively low dielectric loss. Our work demonstrates the coexistence of both interesting luminescence and attractive dielectric characteristics in (Er+Nb) co-doped TiO2, showing the potential for multifunctional applications.

Multicolor Upconversion Nanoparticles for Protein Conjugation

PubMed Central

Wilhelm, Stefan; Hirsch, Thomas; Patterson, Wendy M.; Scheucher, Elisabeth; Mayr, Torsten; Wolfbeis, Otto S.

2013-01-01

We describe the preparation of monodisperse, lanthanide-doped hexagonal-phase NaYF4 upconverting luminescent nanoparticles for protein conjugation. Their core was coated with a silica shell which then was modified with a poly(ethylene glycol) spacer and N-hydroxysuccinimide ester groups. The nanoparticles were characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and dynamic light scattering. The N-hydroxysuccinimide ester functionalization renders them highly reactive towards amine nucleophiles (e.g., proteins). We show that such particles can be conjugated to proteins. The protein-reactive UCLNPs and their conjugates to streptavidin and bovine serum albumin display multicolor emissions upon 980-nm continuous wave laser excitation. Surface plasmon resonance studies were carried out to prove bioconjugation and to compare the affinity of the particles for proteins immobilized on a thin gold film. PMID:23606910

Luminescent and triboluminescent properties of europium(III) complex with cinnamic acid

NASA Astrophysics Data System (ADS)

Kalinovskaya, I. V.; Mirochnik, A. G.; Nagornyi, I. G.

2014-10-01

An intensely emitting crystalline europium(III) complex with cinnamic acid [Eu(Cin)3] n and exhibiting triboluminescent properties is synthesized. It is established that the measured photo- and triboluminescence spectra are identical for the above polymeric non-centrosymmetric complex and are determined by the characteristic f-f luminescence of the europium(III) ion.

Synchrotron generated X-ray Excited Optical Luminescence (XEOL) from Quartz

NASA Astrophysics Data System (ADS)

King, Georgina; Finch, Adrian; Robinson, Ruth

2010-05-01

Quartz is the preferred mineral for optically stimulated luminescence (OSL) dating, due to its well constrained behaviour as a radiation dosimeter. However, despite the plethora of successful quartz OSL applications, no solution has been found to the problem that some quartz luminesce more brightly than others, which has limited the application of OSL in certain settings. This has been addressed through examination of the luminescence emission using a variety of excitation techniques and emission spectroscopy. X-ray Excited Optical Luminescence (XEOL) is luminescence excited by x-rays produced by a synchrotron. XEOL analyses were conducted upon a suite of quartz samples at Diamond, Great Britain, which had previously been analysed with Ionoluminescence (IL), at Sussex University. The samples were selected to include quartz of both poor and excellent OSL sensitivities. Therefore, two Scottish glacial outwash samples prepared at St Andrews, and a calibration quartz sample, prepared at the Risø National Laboratory in Denmark were analysed for these properties respectively. The XEOL emission spectra comprised three major emissions at 3.32, 3.81 and 4.05 eV, and one weaker emission at 1.94 eV in all samples. The calibration quartz sample had the most intense emission by an order of magnitude. Throughout increased exposure to x-rays, the intensity of the UV emission reduced, and an increase in the red (1.94 eV) emission was recorded. The derived XEOL spectra complement the IL spectra obtained previously. The IL spectra were dominated by only two broad emissions at 3.2-3.1 eV and 1.8-1.7 eV. However, throughout the IL experiments a dose dependent effect was also observed, whereby the UV emission was depleted to the benefit of the red with increasing exposure. Furthermore the gradient of the power law relationship between the UV and red emission change with dose is similar for both the IL and XEOL data: at -1.15 and -1.05 respectively for calibration quartz, when plotted on a log-log scale. IL and XEOL are complimentary techniques, as although the radiation dose rate of XEOL is three orders of magnitude greater than that of IL, the total experimental administered dose is similar. This contrast in dose rate is caused by the significant variation is dose per carrier for each technique. Within IL each ion delivers 1E-01 J whereas each photon delivers 1E-15 J in XEOL. It is the much greater flux of photons relative to ions, which makes XEOL the more energetic mode of analysis. Thus these complimentary techniques enable investigation of radiation dose rate, as well as cumulative dose effects. The observed variations in the XEOL and IL derived emission spectra are therefore attributed to the differences in radiation dose rate. The radiation sensitivity of the quartz emission may provide an explanation for the varied luminescence response of different quartz. The quartz luminescence emission thus may not just record the most recent period of irradiation, but rather its entire radiation history.

An efficient ionoluminescence analysis of turquoise gemstone as a weakly luminescent mineral.

PubMed

Nikbakht, T; Kakuee, O; Lamehi-Rachti, M

2017-05-15

The unique ionization pattern of MeV-energy ion beam is applied for efficient luminescence analysis of a collection of natural turquoise samples. The considerable penetration depth of tens of micrometer and enhancement of energy deposition with depth, suggests ionoluminescence as an appropriate technique for studying weakly luminescent minerals. Herein, the luminescence induced in deeper parts of turquoise samples is extracted through their relatively transparent adjacent host stones. The resulting intense spectra reveal the vibrational structure of the broad green luminescence band of turquoise which probably originates from O 2 - centers. Moreover, owing to the applied ionoluminescence approach, red and blue luminescence bands of turquoise were observed which can be ascribed to Fe 3+ ions and UO 2 2+ centers respectively. The elemental information of the samples is provided using micro-PIXE analysis technique. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-Assembled Upconversion Nanoparticle Clusters for NIR-controlled Drug Release and Synergistic Therapy after Conjugation with Gold Nanoparticles.

PubMed

Cai, Huijuan; Shen, Tingting; Kirillov, Alexander M; Zhang, Yu; Shan, Changfu; Li, Xiang; Liu, Weisheng; Tang, Yu

2017-05-01

Fabricated three-dimensional (3D) upconversion nanoclusters (abbreviated as EBSUCNPs) are obtained via an emulsion-based bottom-up self-assembly of NaGdF 4 :Yb/Er@NaGdF 4 nanoparticles (abbreviated as UCNPs), which comprise a NaGdF 4 :Yb/Er core and a NaGdF 4 shell. The EBSUCNPs were then coated with a thin mesoporous amino-functionalized SiO 2 shell (resulting in EBSUCNPs@SiO 2 precursor) and further conjugated with gold nanoparticles to give the novel EBSUCNPs@SiO 2 @Au material. Finally, EBSUCNPs@SiO 2 @Au was applied as a biocompatible and efficient drug carrier for doxorubicin (DOX), thus giving rise to a multifunctional EBSUCNPs@SiO 2 -DOX@Au nanocomposite. This final material, EBSUCNPs@SiO 2 -DOX@Au, and the precursor nanoparticles, EBSUCNPs@SiO 2 @Au, were both fully characterized and their luminescence was investigated in detail. In addition, the drug release properties and photothermal effects of EBSUCNPs@SiO 2 -DOX@Au were also discussed. Interestingly, when under NIR irradiation, an increasing DOX release was achieved owing to the thermal effect of the Au NPs after absorbing the green light from the upconversion nanoclusters based on the fluorescence resonance energy transfer (FRET) effect. Thus, a near-infrared (NIR)-controlled "on-off" pattern of drug release behavior can be achieved. Moreover, compared with a single therapy method, the assembled nanocomposites exhibit a good synergistic therapy against cancer cells that combines chemotherapy with photothermal therapy. In addition, the in vitro fluorescence microscopy images of EBSUCNPs@SiO 2 -DOX@Au show a higher enhancement in the red region due to the loading of DOX molecules with respect to EBSUCNPs@SiO 2 @Au. Therefore, this novel multifunctional 3D cluster architecture can be used in the biomedical field after modification and may pave a new way in other application areas of UCNPs clusters.

Growth, spectroscopy and continuous-wave laser performance of Nd3+:LiLu0.65Y0.35F4 crystal

NASA Astrophysics Data System (ADS)

Demesh, M. P.; Kurilchik, S. V.; Gusakova, N. V.; Yasukevich, A. S.; Kisel, V. E.; Nizamutdinov, A. S.; Marisov, M. M.; Aglyamov, R. D.; Korableva, S. L.; Naumov, A. K.; Semashko, V. V.; Kuleshov, N. V.

2018-04-01

A mixed fluoride crystal of LiLu0.65Y0.35F4 doped with Nd3+ ions was grown by the Bridgman-Stockbarger method. Polarized absorption and luminescence spectra as well as luminescence lifetime were measured at room temperature. Emission probabilities, branching ratios and radiative lifetime were studied within the Judd-Ofelt theory and the emission cross section spectra were calculated. Efficient continuous wave laser operation was demonstrated with the crystal. A maximum output power of 7.7 W and slope efficiency of 60% were achieved at 1047 nm for the TEM00 mode.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

Structural and luminescence studies on Dy3+ doped lead boro-telluro-phosphate glasses

NASA Astrophysics Data System (ADS)

Selvi, S.; Venkataiah, G.; Arunkumar, S.; Muralidharan, G.; Marimuthu, K.

2014-12-01

This paper reports results obtained on the structural and luminescence properties of Dy3+doped lead boro-telluro-phosphate glasses prepared following the melt quenching technique. FTIR spectra exhibit the presence of B-O vibrations, P-O-P symmetric vibrations and Te-O stretching modes of TeO3 and TeO6 units. The metal-ligand bond was identified through UV-vis-NIR absorption spectra and to determine the band tailing parameter, direct and indirect band gap energy of the prepared glasses. The Judd-Ofelt (JO) intensity parameters (Ω2, Ω4 and Ω6), experimental and theoretical oscillator strengths were also determined and reported. Luminescence measurements were made to determine the transition probability (A), stimulated emission cross-section (σPE) and branching ratio (βR) for the transitions that include 4F9/2→6H11/2, 6H13/2 and 6H15/2 bands. The effect of Dy3+ ion concentration on the intensity ratio of yellow to blue emission bands has also been studied and reported. The lifetime corresponding to the 4F9/2 level of the title glasses has been found to decrease with the increase in Dy3+ ion concentration. The chromaticity coordinates (x,y) have been estimated from the luminescence spectra and the suitability of title glasses for white light applications has been analyzed using CIE chromaticity diagram. The variation of optical properties with the concentration of dysprosium oxide content in the glasses have been studied and reported.

Physical, structural and luminescence investigation of Eu3+-doped lithium-gadolinium bismuth-borate glasses for LEDs

NASA Astrophysics Data System (ADS)

Zaman, F.; Rooh, G.; Srisittipokakun, N.; Wongdeeying, C.; Kim, H. J.; Kaewkhao, J.

2018-06-01

The aim of the current report is to fabricate Eu3+-doped glasses with the chemical composition of 50Li2O-15Gd2O3-5Bi2O3-(30-x)B2O3-xEu2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%), with the help of conventional melt quenching technique. The fabricated glasses have been studied with help of physical, structural and luminescence properties for application of LEDs. The structural properties were investigated by XRD and FTIR spectra. Physical properties have been measured. Direct and indirect optical energy band gap (Eg) have been calculated and found to be increasing with Eu2O3 concentration. Luminescence spectra have been observed from photo and radioluminescence spectra and found in good agreement with each other, however the concentration quenching was not determined for the samples. The high-covalence and asymmetric nature was confirmed from Photoluminescence emission and RL emission transition as well as from the higher values of luminescence intensity ratio. The JO parameters have been found for the better performance of lasing materials. The lifetime's data have been found to be decreasing from 1.64 to 1.50 ms, which is the confirmation of energy transfer in Eu3+ ions through cross relaxations. From the calculated properties it has been suggested that the present glass samples might be good for red-light emitting devices.

A clear effect of charge compensation through Na+ co-doping on the luminescence spectra and decay kinetics of Nd3+-doped CaAl4O7

NASA Astrophysics Data System (ADS)

Puchalska, M.; Watras, A.

2016-06-01

We present a detailed analysis of luminescence behavior of singly Nd3+ doped and Nd3+, Na+ co-doped calcium aluminates powders: Ca1-xNdxAl4O7 and Ca1-2xNdxNaxAl4O7 (x=0.001-0.1). Relatively intense Nd3+ luminescence in IR region corresponding to typical 4F3/2→4IJ (J=9/2-13/2) transitions with maximum located at about 1079 nm was obtained in all samples on direct excitation into f-f levels. The effect of dopant concentration and charge compensation by co-doping with Na+ ions on morphology and optical properties were studied. The results show that both, the Nd3+ concentration and the alkali metal co-doping affected the optical properties but had no influence on the powders morphology. The studies of luminescence spectra (298 and 77 K) in a function of dopant concentration showed an increasing distortion of the local symmetry of Nd3+with raising activator content due to certain defects created in the crystal lattice. On the other hand Na+ addition led to significant narrowing of absorption and luminescence bands and also a reduction of the number of their components, showing smaller disturbance of Nd3+ ions local symmetries. Consequently, charge compensated by Na+ co-doping materials showed significantly enhanced Nd3+ luminescence. The decrease of emission intensity and luminescence lifetimes with increase of activator concentration was attributed mainly to phonon-assisted cross-relaxation processes between Nd3+ ions. Analysis with Inokuti-Hirayama model indicated dipole-dipole mechanism of ion-ion interaction. Na+ addition led to much smaller concentration quenching due to smaller clustering of dopant ions in CaAl4O7 lattice.

Near Infrared Quantum Cutting Luminescence of Er3+/Tm3+ Ion Pairs in a Telluride Glass.

PubMed

Chen, Xiaobo; Li, Song; Hu, Lili; Wang, Kezhi; Zhao, Guoying; He, Lizhu; Liu, Jinying; Yu, Chunlei; Tao, Jingfu; Lin, Wei; Yang, Guojian; Salamo, Gregory J

2017-05-16

The multiphoton near-infrared, quantum cutting luminescence in Er 3+ /Tm 3+ co-doped telluride glass was studied. We found that the near-infrared 1800-nm luminescence intensity of (A) Er 3+ (8%)Tm 3+ (0.5%):telluride glass was approximately 4.4 to 19.5 times larger than that of (B) Tm 3+ (0.5%):telluride glass, and approximately 5.0 times larger than that of (C) Er 3+ (0.5%):telluride glass. Additionally, the infrared excitation spectra of the 1800 nm luminescence, as well as the visible excitation spectra of the 522 nm and 652 nm luminescence, of (A) Er 3+ (8%)Tm 3+ (0.5%):telluride glass are very similar to those of Er 3+ ions in (C) Er 3+ (0.5%):telluride glass, with respect to the shapes of their excitation spectral waveforms and peak wavelengths. Moreover, we found that there is a strong spectral overlap and energy transfer between the infrared luminescence of Er 3+ donor ions and the infrared absorption of Tm 3+ acceptor ions. The efficiency of this energy transfer { 4 I 13/2 (Er 3+ ) →  4 I 15/2 (Er 3+ ), 3 H 6 (Tm 3+ ) →  3 F 4 (Tm 3+ )} between the Er 3+ and Tm 3+ ions is approximately 69.8%. Therefore, we can conclude that the observed behaviour is an interesting multiphoton, near-infrared, quantum cutting luminescence phenomenon that occurs in novel Er 3+ -Tm 3+ ion pairs. These findings are significant for the development of next-generation environmentally friendly germanium solar cells, and near-to-mid infrared (1.8-2.0 μm) lasers pumped by GaN light emitting diodes.

Photoanisotropic properties of luminescence media for polarization holography based on new-type dyes

NASA Astrophysics Data System (ADS)

Shaverdova, V. G.; Petrova, S. S.; Purtseladze, A. L.; Tarasashvili, V. I.; Obolashvili, N. Z.

2017-09-01

The luminescence polarization properties of new recording media obtained by directed synthesis—disulfochlorides of luminescent dyes (homologues of 1,7-diamino-3,9-dihydrodibenzo-[1,2,3de:4,5,6- d'e']diquinoline-2.8-dione (1,5-diaminoanthradipyridone) series), with the general structure (ClSO2)2-1,5-di-AAP-di-R—are investigated. Polarized photoluminescence spectra are recorded, and spectral dependences of the degree of anisotropy of phosphor on its chemical structure at different acidities of the medium are plotted.

Optical characterization of Nd (3+):AgBr.

PubMed

Bunimovich, D; Nagli, L; Katzir, A

1997-10-20

The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment.

The origin of 2.7 eV blue luminescence band in zirconium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perevalov, T. V., E-mail: timson@isp.nsc.ru; Zhuravlev, K. S.; Gritsenko, V. A.

2014-12-28

The luminescence spectra of non-stoichiometric zirconium oxide film series with different oxygen vacancies' concentrations show the blue photoluminescence band centered near a 2.7 eV peak. There is a broad band at 5.2 eV in the luminescence excitation spectrum for blue emission. The ab-initio quantum-chemical calculation gives a peak in the optical absorption at 5.1 eV for the oxygen vacancy in cubic ZrO{sub 2}. It was concluded that the 2.7 eV blue luminescence excited near 5.2 eV in a zirconium oxide film is associated with the oxygen vacancy.

Luminescence and Excitation Spectra of U 3+ doped RbY 2 Cl 7 Single Crystals

DOE PAGES

Karbowiak, M.; Murdoch, K.; Drożdżyński, J.; ...

1996-08-01

Uranium(3+) doped single crystals of RbY 2 Cl 7 with a uranium concentration of 0.05% and 0.2% were grown by the Bridgman-Stockbarger method using RbU 2 Cl 7 as the doping substance. Polished plates of ca. 5 mm in diameter were used for measurements of luminescence and excitation spectra. And since the U 3+ ions occupy two somewhat different site symmetries, a splitting of all observed f-f bands was observed. Furthermore, the analysis of the spectra enabled definitively an assignment of 22 crystal field bands for both site symmetries as well as the total crystal field splitting of the groundmore » level, equal to 473 cm -1 and 567 cm -1 for the first and second site symmetry, respectively.« less

Optical population of gerade and ungerade iodine ion-pair states via MI2 vdW complexes of valence states correlating with the third dissociation limit, M = I2, Xe

NASA Astrophysics Data System (ADS)

Lukashov, S. S.; Poretsky, S. A.; Pravilov, A. M.

2012-05-01

The results of measurements and analysis of excitation spectra of the λlum = 2350 Ǻ luminescence corresponding to I2(D0+u → X0+g) transition as well as luminescence at λlum = 3400 Ǻ, where I2(D'2g → A'2u and/or β1g → A1u) transitions occur, observed after three-step, λ1 + λf + λ1, λ1 = 5321-5508.2 Ǻ, λf = 10644.0 Ǻ, laser excitation of pure iodine vapour and I2 + Xe mixtures at room temperature are presented. Luminescence spectra in the λlum = 2200-3500 Ǻ spectral range are also analyzed. We discuss three alternative mechanisms of optical population of the IP states. In our opinion, the mechanism including the MI2, M = I2, Xe, complexes is the most probable at least in the λ1 ≈ 5321-5480 Ǻ, λ1 ≈ 5508 Ǻ spectral ranges and for population of the states which luminescence occur at λlum ≈ 3400 Ǻ.

In 0.35Ga 0.65P light-emitting diodes grown by gas-source MBE

NASA Astrophysics Data System (ADS)

Masselink, W. Ted; Zachau, Martin

1993-02-01

This paper describes the growth and optical characteristics of In yGa 1- yP with 0.3< y<0.5, and the LED operation of p-i-n structures in the same materials system. The InGaP is grown using gas-source molecular beam epitaxy (GSMBE). The non-lattice-matched In yGa 1- yP grown on GaAs using GSMBE has a specularly smooth surface morphology through the use of unique strained-layer superlattice (SLS) buffer. We have measured the luminescence, luminescence excitation, and Raman spectra of these undoped films and observe strong excitonic luminescence over the entire composition range investigated. The band gap derived from the luminescence excitation spectra corresponds to that of a fully relaxed InGaP film with no residual strain, which is confirmed by the Raman measurements. Light-emitting diodes with peak (300 K) emission centered at less than 590 nm have been fabricated from p-i-n junctions in In 0.35Ga 0.65P. This alloy is close to that with the largest direct band gap in the In yGa 1- y P system and has lattice mismatch from the GaAs substrate of 1%.

Spectra- and temperature-dependent dynamics of directly end-pumped holmium lasers

NASA Astrophysics Data System (ADS)

Ji, Encai; Shen, Yijie; Nie, Mingming; Fu, Xing; Liu, Qiang

2017-04-01

We develop a theoretical model with high accuracy for directly end-pumped Ho3+ laser system considering the influences of ground-state depletion, energy transfer up-conversion, temperature-dependent cross sections, and pump spectra shift. The heat generation in our model is precisely evaluated by calculating the transition rates of non-radiation relaxation processes among manifolds and in-band relaxation processes based on a detailed analysis of energy levels structure of holmium ions. A spatial dynamic thermal iteration method, just developed by our group, is applied to describe the coupled influences between spatial thermal effects and pump spectra. This model is verified to both adapt to the narrow-band good beam-quality pumped case and the broad-band bad beam-quality pumped case, which is in accordance with our previous reported experimental results.

Frenkel-exciton decomposition analysis of circular dichroism and circularly polarized luminescence for multichromophoric systems.

PubMed

Shiraogawa, Takafumi; Ehara, Masahiro; Jurinovich, Sandro; Cupellini, Lorenzo; Mennucci, Benedetta

2018-06-15

Recently, a method to calculate the absorption and circular dichroism (CD) spectra based on the exciton coupling has been developed. In this work, the method was utilized for the decomposition of the CD and circularly polarized luminescence (CPL) spectra of a multichromophoric system into chromophore contributions for recently developed through-space conjugated oligomers. The method which has been implemented using rotatory strength in the velocity form and therefore it is gauge-invariant, enables us to evaluate the contribution from each chromophoric unit and locally excited state to the CD and CPL spectra of the total system. The excitonic calculations suitably reproduce the full calculations of the system, as well as the experimental results. We demonstrate that the interactions between electric transition dipole moments of adjacent chromophoric units are crucial in the CD and CPL spectra of the multichromophoric systems, while the interactions between electric and magnetic transition dipole moments are not negligible. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Inorganic photosensitizer coupled Gd-based upconversion luminescent nanocomposites for in vivo magnetic resonance imaging and near-infrared-responsive photodynamic therapy in cancers.

PubMed

Zhang, Ling'e; Zeng, Leyong; Pan, Yuanwei; Luo, Song; Ren, Wenzhi; Gong, An; Ma, Xuehua; Liang, Hongze; Lu, Guangming; Wu, Aiguo

2015-03-01

Inorganic photosensitizer coupled Gd-based upconversion luminescent (UCL) nanocomposites have potential application for both magnetic resonance imaging (MRI) and photodynamic therapy (PDT) of cancers using the light stability and biocompatibility of TiO2 inorganic photosensitizer. However, TiO2 inorganic photosensitizer could only be excited by ultraviolet (UV) light, which was harmful and weakly penetrable in tissues. In this work, folic acid (FA)-targeted NaGdF4:Yb/Tm@SiO2@TiO2 nanocomposites (FA-Gd-Si-Ti NPs) were constructed and synthesized for both in vivo MRI and near infrared (NIR)-responsive inorganic PDT, in which TiO2 component could be excited by NIR light due to the UCL performance of NaGdF4:Yb/Tm component converting NIR to UV light. The results showed the as-prepared FA-Gd-Si-Ti NPs had good biocompatibility in vitro and in vivo. Moreover, MR study indicated that FA-Gd-Si-Ti NPs were good T1-weighted MRI contrast agents with high longitudinal relaxivity (r1) of 4.53 mm(-1) s(-1), also in vivo MRI of nude mice showed "bright" signal in MCF-7 tumor. Under the irradiation of 980 nm laser at the power density of 0.6 W/cm(2) for 20 min, the viability of HeLa and MCF-7 cells incubated with FA-Gd-Si-Ti NPs could decrease from about 90 % to 35 % and 31%, respectively. Furthermore, in vivo PDT of MCF-7 tumor-bearing nude mice model showed that the inhibition ratio of tumors injected with FA-Gd-Si-Ti NPs reached up to 88.6% after 2-week treatment, compared with that of nude mice in control group. Based on the deep penetration of NIR light and the good biocompatibility of TiO2 inorganic photosensitizer, the as-prepared FA-Gd-Si-Ti NPs could have potential applications in both MRI and NIR-responsive PDT of cancers in deep tissues. Copyright © 2014 Elsevier Ltd. All rights reserved.

Y{sub 2}O{sub 3}:Yb/Er nanotubes: Layer-by-layer assembly on carbon-nanotube templates and their upconversion luminescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Weishi; Shen, Jianfeng; Wan, Lei

2012-11-15

Graphical abstract: Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer assembly on carbon nanotubes templates followed by a subsequent heat treatment process. The as-prepared Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission corresponding to the {sup 4}F{sub 9/2}–{sup 4}I{sub 15/2} transition of the Er{sup 3+} ions under excitation at 980 nm. Display Omitted Highlights: ► Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized. ► CNTs were used as templates for Y{sub 2}O{sub 3}:Yb/Er nanotubes. ► LBL assembly and calcination were used for preparation of Y{sub 2}O{sub 3}:Yb/Er nanotubes. ► The as-preparedmore » Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission. -- Abstract: Well-shaped Y{sub 2}O{sub 3}:Yb/Er nanotubes have been successfully synthesized on a large scale via layer-by-layer (LBL) assembly on carbon nanotubes (CNTs) templates followed by a subsequent heat treatment process. The crystal structure, element analysis, morphology and upconversion luminescence properties were characterized. XRD results demonstrate that the diffraction peaks of the samples calcinated at 800 °C or above can be indexed to the pure cubic phase of Y{sub 2}O{sub 3}. SEM images indicate that a large quantity of uniform and rough nanotubes with diameters of about 30–60 nm can be observed. The as-prepared Y{sub 2}O{sub 3}:Yb/Er nanotubes show a strong red emission corresponding to the {sup 4}F{sub 9/2}–{sup 4}I{sub 15/2} transition of the Er{sup 3+} ions under excitation at 980 nm, which have potential applications in such fields as nanoscale devices, molecular catalysts, nanobiotechnology, photonics and optoelectronics.« less

Up-conversion white light of Tm 3+/Er 3+/Yb 3+ tri-doped CaF 2 phosphors

NASA Astrophysics Data System (ADS)

Cao, Chunyan; Qin, Weiping; Zhang, Jisen; Wang, Yan; Wang, Guofeng; Wei, Guodong; Zhu, Peifen; Wang, Lili; Jin, Longzhen

2008-03-01

Tm3+/Er3+/Yb3+ tri-doped CaF2 phosphors were synthesized using a hydrothermal method. The phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and up-conversion (UC) emission spectra. After annealing, the phosphors emitted white light under a 980 nm continuous wave diode laser (CW LD 2 W) excitation. As the excitation power density changed in the range of 20-260 W/cm2, the chromaticity coordinates of the UC light of the phosphor Ca0.885Tm0.005Er0.01Yb0.1F2 fell well in the white region of the 1931 CIE diagram. For the proportion of red, green and blue (RGB) in white light is strict, key factors for achieving UC white light, such as host materials, rare earth ions doping concentrations, annealing temperatures, as well as the excitation power densities, were investigated and discussed.

Optical thermometry through infrared excited green upconversion in monoclinic phase Gd2(MoO4)3:Yb3+/Er3+ phosphor

NASA Astrophysics Data System (ADS)

Xu, Weijiang; Li, Dongyu; Hao, Haoyue; Song, Yinglin; Wang, Yuxiao; Zhang, Xueru

2018-04-01

Monoclinic phase Gd2(MoO4)3: Yb3+/Er3+ phosphor is synthesized via a simple sol-gel method. The XRD result reveals that the phosphor possesses monoclinic structure with space group C2/c(15). Under the excitation of a 980 nm laser, its emission spectra shows remarkably intense green and negligible red emissions, which are all two-photon process. By investigating effect of temperature on green emission of the sample, the competition between the thermal agitation and non-radiative relaxation of 2H11/2 level can be found, which is verified by the measurement of lifetime. In addition, the sensitivity of optical thermometry is studied based on the fluorescence intensity ratio technique through infrared excited green upconversion. The maximum sensitivity is found to be about 0.02574 K-1 at 510.2 K, suggesting that the phosphor can be used as an excellent material for optical temperature sensing.

Orbital surveys of solar stimulated luminescence

NASA Astrophysics Data System (ADS)

Hemphill, W. R.; Theisen, A. F.; Tyson, R. M.; Granata, J. S.

The Fraunhofer line discriminator (FLD) is an electro-optical device for imaging natural and manmade materials which have been stimulated to luminesce by the sun. An airborne FLD has been used to detect geochemically stressed vegetation, drought-stressed agricultural crops, industrial and residential pollution effluents, marine oil seeps, phosphate rock, uranium-bearing sandstone, and bioluminescent ocean plankton. Three-dimensional perspective plots of excitation and emission spectra, measured with a laboratory spectrometer, graphically depict similarities and differences in luminescence properties between sample materials. The laboratory data also include luminescence intensities at six Fraunhofer lines in the visible and near-infrared regions of the electromagnetic spectrum. Both the airborne and laboratory data suggest the feasibility of delineating and monitoring at least some of these luminescing materials from orbital altitude, such as a test flight aboard the Space Shuttle using an improved third-generation FLD.

Study of coal and graphite specimens by means of Raman and cathodoluminescence.

PubMed

Kostova, Irena; Tormo, Laura; Crespo-Feo, Elena; Garcia-Guinea, Javier

2012-06-01

The weak luminescence shown by coals has been attributed to accessorial minerals and poly-nuclear aromatic hydrocarbons, such as exinite, vitrinite or inertinite, while the luminescence quenching has been found in asphaltenes produced by coal hydrogenation or in pyridine extracts. Nowadays, the spatial resolution and the improved luminescence efficiency of the modern spectrometers allow some details of the luminescent emission centers to be explained. We have selected museum historical coal specimens with different rank, i.e., peat, lignite, sub-bituminous, bituminous, and anthracite to be analyzed by their spectra from cathodoluminescence probe (CL) of an environmental scanning electron microscopy (ESEM), with an energy dispersive spectrometry analyzer (EDS). Additional analytical controls were also performed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Raman spectrometries. We conclude that coals may display different luminescence emission features coming from several different sources, as follows: (i) broadband of intense luminescence from polynuclear aromatic hydrocarbons, (ii) weakly visible broadband luminescence attributed to band-tail states caused by variations in the energy gap of individual sp(2) carbon clusters, which are different in size and/or shape, (iii) silicate impurities causing the common luminescence peak at 325 nm observed in coals. This peak is due to non-bridging oxygen hole centres (≡Si-O·) probably generated by precursor Si-O-C species formed by ≡Si-O· defects and carbon atoms; (iv) a 710 nm CL emission commonly detected also in wood and ivory, which has been correlated with hydrocarbon groups of chlorophyll or lignine. Coals are very complex rocks, composed by both organic and inorganic phases with variable and complex spectra. More analyses are necessary and carbonaceous standards of graphite, silicon carbide, stuffed carbon silica and diamond at variable experimental conditions have to be developed. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of nanostructuring on luminescence properties of SrS:Ce,Sm phosphor: An experimental and phenomenological study

NASA Astrophysics Data System (ADS)

Yazdanmehr, Mohsen; Sadeghi, Hossein; Tehrani, Masoud Kavosh; Hashemifar, Seyed Javad; Mahdavi, Mohammad

2018-01-01

In this work, we employ various experimental techniques to illustrate the effects of nanostructuring on improvement of the luminescence properties of the polycrystalline SrS co-activated by cerium and samarium dopants (SrS : Ce , Sm). The nano and microstructure SrS : Ce , Sm powders were synthesized by the co-precipitation and solid state diffusion methods, respectively, followed by the spark plasma sintering (SPS) process to densify powders into pellet shape. It is observed that the photo-luminescence (PL), radio-luminescence (RL), and optically stimulated luminescence (OSL) emission intensity of the nanostructure samples are significantly improved with respect to the microstructure samples. Moreover, by using an accurate photomultiplier tube, we measured the CW-OSL decay curves of the samples to demonstrate much higher and faster sensitivity of the nanostructure SrS : Ce , Sm for in-flight and online OSL radiation dosimetry. The obtained absorption and emission spectra are used for phenomenology of the electronic band structure of the SrS : Ce , Sm micro and nano-phosphors inside the band gap. The proposed phenomenological electronic structures are then used to clarify the role of Ce3+ and Sm3+ localized energy levels in the luminescence properties of the nano and microstructure samples. It is argued that electronic transitions from the 2T2g state of Ce3+ and the 4G5/2 state of Sm3+ have strong contribution to the PL and RL emission spectra, while in the OSL mechanism, the Sm3+ 4G5/2 state is mainly responsible for electrons trapping.

Magnetic upconverting fluorescent NaGdF4:Ln3+ and iron-oxide@NaGdF4:Ln3+ nanoparticles

NASA Astrophysics Data System (ADS)

Shrivastava, Navadeep; Rocha, Uéslen; Muraca, Diego; Jacinto, Carlos; Moreno, Sergio; Vargas, J. M.; Sharma, S. K.

2018-05-01

Microwave assisted solvothermal method has been employed to synthesize multifunctional upconverting β-NaGdF4:Ln3+ and magnetic-upconverting Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (Ln = Yb and Er) nanoparticles. The powder x-ray diffraction data confirms the hexagonal structure of NaGdF4:Ln3+ and high resolution transmission electron microscopy shows the formation of rod shaped NaGdF4:Ln3+ (˜ 20 nm) and ovoid shaped Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (˜ 15 nm) nanoparticles. The magnetic hysteresis at 300 K for β-NaGdF4:Ln3+ demonstrates paramagnetic features, whereas iron-oxide@β-NaGdF4:Ln3+ exhibits superparamagnetic behavior along with a linear component at large applied field due to paramagnetic NaGdF4 matrix. Both nanoparticle samples provide an excellent green emitting [(2H11/2, 4S3/2)→4I15/2 (˜ 540 nm)] upconversion luminescence emission under excitation at 980 nm. The energy migration between Yb and Er in NaGdF4 matrix has been explored from 300-800 nm. Intensity variation of blue, green and red lines and the observed luminescence quenching due to the presence of Fe3O4/γ-Fe2O3 in the composite has been proposed. These kinds of materials contain magnetic and luminescence characteristics into single nanoparticle open new possibility for bioimaging applications.

The deformation stimulated luminescence in KCl, KBr and KI crystals

NASA Astrophysics Data System (ADS)

Shunkeyev, K.; Sergeyev, D.; Drozdowski, W.; Brylev, K.; Myasnikova, L.; Barmina, A.; Zhanturina, N.; Sagimbaeva, Sh; Aimaganbetova, Z.

2017-05-01

Currently, strengthening of the intensity of luminescence in alkali halide crystals (AHC) at lattice symmetry lowering is discussed as a promising direction for the development of scintillation detectors [1-3]. In this regard, for the study of anion excitons and radiation defects in the AHC anion sublattice at deformation, the crystals with the same sizes of cations and different sizes of anions were chosen. In the X-ray spectra of KCl at 10 K, the luminescence at 3.88 eV; 3.05 eV and 2.3 eV is clearly visible. The luminescence at 3.05 eV corresponds to the tunneling recharge [F*, H]. Luminescence at 3.88 eV is quenched in the region of thermal destruction of F‧-centers and characterizes tunneling recharge of F‧, VK-centers. In KCl at 90 K, the luminescence of self-trapped excitons (STE) is completely absent. In KBr at deformation not only STE luminescence, but also deformation stimulated luminescence at 3.58 eV were recorded, the last one corresponds to tunneling recharge of F‧, VK-centers. In KI crystal at 10 K and 90 K at deformation, only STE luminescence is enhanced. There are no deformation luminescence bands in KI compares with KBr and KCl crystals.

Effect of annealing on structural and luminescence properties of Eu3+ doped NaYF4 phosphor

NASA Astrophysics Data System (ADS)

Pathak, Trilok K.; Kumar, Ashwini; Swart, H. C.; Kroon, R. E.

2018-04-01

Eu3+ doped NaYF4 phosphors have been synthesized by the combustion method. The effect of annealing on the structural, morphological and luminescence properties has been investigated. X-ray diffraction analysis revealed that the Eu3+ doped NaYF4 phosphors consisted of mixed phases: α-phase and β-phase which were affected by the annealing of the phosphor. The surface morphology showed a significant change with annealing in the Eu3+ doped NaYF4 phosphors. The elemental mapping and energy dispersive X-ray spectroscopy spectra proved the formation of the desired materials. The photoluminescence spectra illustrated the optical properties of Eu3+ in the as-prepared and annealed Eu3+ doped NaYF4 phosphors. The intensity of the peaks 5D0 → 7F2 and 5D0 → 7F1 varied in as-prepared and annealed samples. The lifetime of the Eu3+ luminescence at 615 nm was also weakly affected by the Eu3+ doping and annealing temperature.

Theoretical tuning of the firefly bioluminescence spectra by the modification of oxyluciferin

NASA Astrophysics Data System (ADS)

Cheng, Yuan-Yuan; Zhu, Jia; Liu, Ya-Jun

2014-01-01

Extending the firefly bioluminescence is of practical significance for the improved visualization of living cells and the development of a multicolor reporter. Tuning the color of bioluminescence in fireflies mainly involves the modification of luciferase and luciferin. In this Letter, we theoretically studied the emission spectra of 9 firefly oxyluciferin analogs in the gas phase and in solutions. Three density functionals, including B3LYP, CAM-B3LYP and M06-2X, were employed to theoretically predict the efficiently luminescent analogs. The reliable functionals for calculating the targeted systems were suggested. The luminescence efficiency, solvent effects, and substituent effects are discussed based on the calculated results.

Adaption of synchronously scanned luminescence spectroscopy to organic-rich fluid inclusion microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musgrave, J.A.; Carey, R.G.; Janecky, D.R.

1994-06-01

The instrumentation, the luminescence microprobe, and synchronously scanned luminescence spectroscopy technique described here can be used to classify microliter quantities of oil such as those in fluid inclusions in cements from petroleum reservoirs. It is primarily constructed to obtain synchronously scanned luminescence spectra from microscopic sized samples to characterize the organic classes of compounds that predominate. At present no other technique can so readily analyze a single oil-bearing fluid inclusion. The data collected from the technique are pertinent to evaluating systems and providing quantitative data for solving problems in oil migration and maturation determinations, oil-to-oil and oil-to-source correlations, oil degradation,more » and episodes and chemistry of cementation.« less

Photoluminescence Characteristics of Yag:Ce, Gd Based Phosphors with Different Prehistories

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Soshchin, N. P.; Yang yang, Yu; Stepanov, S. A.; Lisitsyna, L. A.; Tulegenova, A. T.; Abdullin, Kh. A.

2017-09-01

Luminescence characteristics of yttrium-aluminum garnet based phosphor samples differed by their elemental composition and prehistory of synthesis are studied. The morphology, structure, and elemental composition of phosphor samples, their excitation and emission spectra, efficiency of phosphor conversion of chip emission, and kinetics of luminescence decay are measured. The emission characteristics of phosphors are compared with their structural properties and elemental composition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikhlina, Ya. A.; Bolotin, B. M., E-mail: bolotin70@yandex.ru; Uzhinov, B. M., E-mail: uzhinov@light.chem.msu.ru

In view of the dramatic difference in the spectral-luminescence properties of {alpha}-(p-chlorobenzoyl)-4-diethylaminocinnamonitrile and {alpha}-ethoxycarbonyl-4-diethylaminocinnamonitrile in solutions and in the crystalline state, X-ray diffraction analysis has been applied to study crystals of these compounds. The intermolecular C-H...N and C-H...O hydrogen bonds are found to contribute to the quinoidization of molecules, which leads to a bathochromic shift in the absorption and fluorescence spectra. A spectral-luminescence study of the aforementioned compounds has revealed that the solvent temperature and polarity affect the position of absorption and luminescence peaks: a decrease in these parameters causes a hypsochromic shift.

Vectorial photoinduced energy transfer between boron-dipyrromethene (Bodipy) chromophores across a fluorene bridge.

PubMed

Puntoriero, Fausto; Nastasi, Francesco; Campagna, Sebastiano; Bura, Thomas; Ziessel, Raymond

2010-08-02

A series of novel multichromophoric, luminescent compounds has been prepared, and their absorption spectra, luminescence properties (both at 77 K in rigid matrix and at 298 K in fluid solution), and photoinduced intercomponent energy-transfer processes have been studied. The series contains two new multichromophoric systems 1 and 2, each one containing two different boron-dipyrromethene (Bodipy) subunits and one bridging fluorene species, and two fluorene-Bodipy bichromophoric species, 6 and 7. Three monochromophoric compounds, 3, 4, and 5, used as precursors in the synthetic process, were also fully characterized. The absorption spectra of the multichromophoric compounds are roughly the summation of the absorption spectra of their individual components, thus demonstrating the supramolecular nature of the assemblies. Luminescence studies show that quantitative energy transfer occurs in 6 and 7 from the fluorene chromophore to the Bodipy dyes. Luminescence studies, complemented by transient-absorption spectroscopy studies, also indicate that efficient inter-Bodipy energy transfer across the rigid fluorene spacer takes place in 1 and 2, with rate constants, evaluated by several experimental methods, between 2.0 and 7.0 x 10(9) s(-1). Such an inter-Bodipy energy transfer appears to be governed by the Förster mechanism. By taking advantage of the presence of various protonable sites in the substituents of the lower-energy Bodipy subunit of 1 and 2, the effect of protonation on the energy-transfer rates has also been investigated. The results suggest that control of energy-transfer rate and efficiency of inter-Bodipy energy transfer in this type of systems can be achieved by an external, reversible input.

Accurate thermometry based on the red and green fluorescence intensity ratio in NaYF₄: Yb, Er nanocrystals for bioapplication.

PubMed

Liu, Lixin; Qin, Feng; Lv, Tianquan; Zhang, Zhiguo; Cao, Wenwu

2016-10-15

A biological temperature measurement method based on the fluorescence intensity ratio (FIR) was developed to reduce uncertainty. The upconversion luminescence of NaYF₄:Yb, Er nanocrystals was studied as a function of temperature around the physiologically relevant range of 300-330 K. We found that the green-green FIR Fe and red-green FIR (I₆₆₀/I₅₄₀) varied linearly as temperature increased. The thermometric uncertainties using the two FIRs were discussed and were determined to be almost constant at 0.6 and 0.09 K for green-green and red-green, respectively. The lower thermometric uncertainty comes from the intense signal-to-noise ratio of the measured FIRs owing to their comparable fluorescence intensities.

Ce3+/Yb3+/Er3+ triply doped bismuth borosilicate glass: a potential fiber material for broadband near-infrared fiber amplifiers

PubMed Central

Chu, Yushi; Ren, Jing; Zhang, Jianzhong; Peng, Gangding; Yang, Jun; Wang, Pengfei; Yuan, Libo

2016-01-01

Erbium doped bismuth borosilicate (BBS) glasses, possessing the broadest 1.55 μm near infrared (NIR) emission band among oxide glasses, stand out as excellent fiber material for optical fiber amplifiers. In this work, we demonstrate that both broadened and enhanced NIR emission of Er3+ can be obtained by sensibly combining the effects such as mixed glass former effect, phonon-assisted energy transfer (PAET) and de-excitation effect induced by codopant. Specially, by codoping CeO2 in a controlled manner, it leads to not only much improved optical quality of the glasses, enhanced NIR emission, but also significantly suppressed energy transfer up-conversion (ETU) luminescence which is detrimental to the NIR emission. Cerium incorporated in the glasses exists overwhelmingly as the trivalent oxidation state Ce3+ and its effects on the luminescence properties of Er3+ are discussed. Judd-Ofelt analysis is used to evaluate gain amplification of the glasses. The result indicates that Ce3+/Yb3+/Er3+ triply doped BBS glasses are promising candidate for erbium doped fiber amplifiers. The strategy described here can be readily extended to other rare-earth ions (REs) to improve the performance of REs doped fiber lasers and amplifiers. PMID:27646191

Preparation and effect of thermal treatment on Gd2O3:SiO2 nanocomposite

NASA Astrophysics Data System (ADS)

Ahlawat, Rachna

2015-04-01

Rare earth oxides have been extensively investigated due to their fascinating properties such as enhanced luminescence efficiency, lower lasing threshold, high-performance luminescent devices, drug-carrying vehicle, contrast agent in magnetic resonance imaging (MRI), up-conversion materials, catalysts and time-resolved fluorescence (TRF) labels for biological detection etc. Nanocomposites of silica gadolinium oxide have been successfully synthesized by sol-gel process using hydrochloric acid as a catalyst. Gd(NO3)3ṡ6H2O and tetraethyl orthosilicate (TEOS) were used as precursors to obtain powdered form of gadolinum oxide:silica (Gd2O3:SiO2) composite. The powdered samples having 2.8 mol% Gd2O3 were annealed at 500°C and 900°C temperature for 6 h and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effect of annealing on the phase evolution of the composite system has been discussed in detail. It was found that the sintering of gadolinium precursor plays a pivotal role to obtain crystalline phase of Gd2O3. Cubic phase of gadolinium oxide was developed for annealed sample at 900°C (6 h) with an average grain size 12 nm.

High sensitivity of gold nanoparticles co-doped with Gd2O3 mesoporous silica nanocomposite to nasopharyngeal carcinoma cells

NASA Astrophysics Data System (ADS)

Wang, Hui; Zhang, Songjin; Tian, Xiumei; Liu, Chufeng; Zhang, Lei; Hu, Wenyong; Shao, Yuanzhi; Li, Li

2016-10-01

Nanoprobes for combined optical and magnetic resonance imaging have tremendous potential in early cancer diagnosis. Gold nanoparticles (AuNPs) co-doped with Gd2O3 mesoporous silica nanocomposite (Au/Gd@MCM-41) can produce pronounced contrast enhancement for T1 weighted image in magnetic resonance imaging (MRI). Here, we show the remarkably high sensitivity of Au/Gd@MCM-41 to the human poorly differentiated nasopharyngeal carcinoma (NPC) cell line (CNE-2) using fluorescence lifetime imaging (FLIM). The upconversion luminescences from CNE-2 and the normal nasopharyngeal (NP) cells (NP69) after uptake of Au/Gd@MCM-41 show the characteristic of two-photon-induced-radiative recombination of the AuNPs. The presence of the Gd3+ ion induces a much shorter luminescence lifetime in CNE-2 cells. The interaction between AuNPs and Gd3+ ion clearly enhances the optical sensitivity of Au/Gd@MCM-41 to CNE-2. Furthermore, the difference in the autofluorescence between CNE-2 and NP69 cells can be efficiently demonstrated by the emission lifetimes of Au/Gd@MCM-41 through the Forster energy transfers from the endogenous fluorophores to AuNPs. The results suggest that Au/Gd@MCM-41 may impart high optical resolution for the FLIM imaging that differentiates normal and high-grade precancers.

Spectroscopy and excitation dynamics of the trivalent lanthanides Tm(3+) and Ho(3+) in LiYF4

NASA Technical Reports Server (NTRS)

Walsh, Brian M.

1995-01-01

A detailed study of the spectroscopy and excitation dynamics Tm3+ and Ho3+ in yttrium lithium fluoride, LiYF4 (YLF), has been done. Absorption spectroscopy is utilized in the Judd-Ofelt theory to determine radiative transition rates of spontaneous emission. Luminescence spectroscopy is studied under cw diode laser excitation at 785nm. The effect of dopant ion concentration and excitation power on the observed luminescence are considered in these measurements. An analysis of these measurements have been used to determine channels of energy transfer between Tm3+ and Ho3+ ions. The temporal response of Tm and Ho in singly and co-doped YLF to pulsed laser excitation with a Ti:Al2O3 laser and a CoMgF2 laser turned to various wavelengths have also been studied. The energy transfer mechanisms of cross relaxation, upconversion, and resonant energy transfer between Tm3+ and Ho3+ ions have been modeled, and the model parameters extracted by a fitting procedure to the measured temporal response curves. Rate equation approaches to modeling are presented that result in predictions of rate constants for energy transfer processes, as well as more conventional approaches to modeling such as the Forster-Dexter models, which give the interaction strengths in terms of microscopic interaction parameters.

Upconversion induced enhancement of dye sensitized solar cells based on core-shell structured β-NaYF4:Er3+, Yb3+@SiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Zhou, Ziyao; Wang, Jiahong; Nan, Fan; Bu, Chenghao; Yu, Zhenhua; Liu, Wei; Guo, Shishang; Hu, Hao; Zhao, Xing-Zhong

2014-01-01

Upconversion materials have been employed as energy relay materials in dye sensitized solar cells (DSCs) to broaden the range of light absorption. However, the origin of the enhancements can be induced by both upconversion and size-dependent light scattering effects. To clarify the role of the upconversion material in the photoelectrode of DSCs, an upconversion induced device was realized here, which has the size-dependent light scattering effect eliminated via the application of NaYF4:Er3+, Yb3+@SiO2 upconversion nanoparticles (β-NYEY@SiO2 UCNPs). An enhancement of 6% in efficiency was observed for the device. This demonstration provided an insight into the possible further employment of upconversion in DSCs.Upconversion materials have been employed as energy relay materials in dye sensitized solar cells (DSCs) to broaden the range of light absorption. However, the origin of the enhancements can be induced by both upconversion and size-dependent light scattering effects. To clarify the role of the upconversion material in the photoelectrode of DSCs, an upconversion induced device was realized here, which has the size-dependent light scattering effect eliminated via the application of NaYF4:Er3+, Yb3+@SiO2 upconversion nanoparticles (β-NYEY@SiO2 UCNPs). An enhancement of 6% in efficiency was observed for the device. This demonstration provided an insight into the possible further employment of upconversion in DSCs. Electronic supplementary information (ESI) available: Details of preparations and characterizations; the TEM images, EDX measurements, XRD measurements and upconversion emission spectrum of bared β-NYEY nanocrystals; SEM and AFM images of the photoelectrode with different concentrations of β-NYEY nanocrystals; J-V characteristics, EIS measurements and fitted EIS parameters of the DSCs based on five different photoelectrodes. See DOI: 10.1039/c3nr04315k

Luminescence of CdSe/ZnS quantum dots infiltrated into an opal matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruzintsev, A. N.; Emelchenko, G. A.; Masalov, V. M.

The effect of the photonic band gap in the photonic crystal, the synthesized SiO{sub 2} opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and themore » luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide.« less

Self-trapping of the d- d charge transfer exciton in bulk NiO evidenced by X-ray excited luminescence

NASA Astrophysics Data System (ADS)

Sokolov, V. I.; Pustovarov, V. A.; Churmanov, V. N.; Ivanov, V. Yu.; Gruzdev, N. B.; Sokolov, P. S.; Baranov, A. N.; Moskvin, A. S.

2012-07-01

Soft X-ray (XUV) excitation did make it possible to avoid the predominant role of the surface effects in luminescence of NiO and revealed a bulk luminescence with a puzzling well isolated doublet of very narrow lines with close energies near 3.3 eV which is assigned to recombination transitions in self-trapped d- d charge transfer (CT) excitons formed by coupled Jahn-Teller Ni+ and Ni3+ centers. The conclusion is supported both by a comparative analysis of the CT luminescence spectra for NiO and solid solutions Ni x Zn1 - x O, and by a comprehensive cluster model assignment of different p- d and d- d CT transitions, their relaxation channels. To the best of our knowledge, it is the first observation of the luminescence due to self-trapped d- d CT excitons.

Role of the chemical substitution on the luminescence properties of solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} (0 ≤ x ≤1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taoufyq, A.; Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir; CEA, DEN, Département d'Etudes des Réacteurs, Service de Physique Expérimentale, Laboratoire Dosimétrie Capteurs Instrumentation, 13108 Saint-Paul-lez-Durance

2015-10-15

Highlights: • Luminescence can be modified by chemical substitution in solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4}. • The various emission spectra (charge transfer) were obtained under X-ray excitation. • Scheelite or wolframite solid solutions presented two types of emission spectra. • A luminescence component depended on cadmium substitution in each solid solution. • A component was only characteristic of oxyanion symmetry in each solid solution. - Abstract: We have investigated the chemical substitution effects on the luminescence properties under X-ray excitation of the solid solutions Ca{sub (1−x)}Cd{sub (x)}WO{sub 4} with 0 ≤ x ≤ 1. Two types of wide spectralmore » bands, associated with scheelite-type or wolframite-type solid solutions, have been observed at room temperature. We decomposed each spectral band into several spectral components characterized by energies and intensities varying with composition x. One Gaussian component was characterized by an energy decreasing regularly with the composition x, while the other Gaussian component was only related to the tetrahedral or octahedral configurations of tungstate groups WO{sub 4}{sup 2−} or WO{sub 6}{sup 6−}. The luminescence intensities exhibited minimum values in the composition range x < 0.5 corresponding to scheelite-type structures, then, they regularly increased for cadmium compositions x > 0.5 corresponding to wolframite-type structures.« less

Spectroscopic, structural and in vitro cytotoxicity evaluation of luminescent, lanthanide doped core@shell nanomaterials GdVO4:Eu(3+)5%@SiO2@NH2.

PubMed

Szczeszak, Agata; Ekner-Grzyb, Anna; Runowski, Marcin; Szutkowski, Kosma; Mrówczyńska, Lucyna; Kaźmierczak, Zuzanna; Grzyb, Tomasz; Dąbrowska, Krystyna; Giersig, Michael; Lis, Stefan

2016-11-01

The luminescent GdVO4:Eu(3+)5%@SiO2@NH2 core@shell nanomaterials were obtained via co-precipitation method, followed by hydrolysis and co-condensation of silane derivatives: tetraethyl orthosilicate and 3-aminopropyltriethoxysilane. Their effect on human erythrocytes sedimentation and on proliferation of human lung microvascular endothelial cells was examined and discussed. The luminescent nanoparticles were synthesized in the presence of polyacrylic acid or glycerin in order to minimalize the agglomeration and excessive growth of nanostructures. Surface coating with amine functionalized silica shell improved their biocompatibility, facilitated further organic conjugation and protected the internal core. Magnetic measurements revealed an enhanced T1-relaxivity for the synthesized GdVO4:Eu(3+)5% nanostructures. Structure, morphology and average grain size of the obtained nanomaterials were determined by X-ray diffraction, transmission electron microscopy and dynamic light scattering analysis. The qualitative elemental composition of the nanomaterials was established using energy-dispersive X-ray spectroscopy. The spectroscopic characteristic of red emitting core@shell nanophosphors was completed by measuring luminescence spectra and decays. The emission spectra revealed characteristic bands of Eu(3+) ions related to the transitions (5)D0-(7)F0,1,2,3,4 and (5)D1-(7)F1. The luminescence lifetimes consisted of two components, associated with the presence of Eu(3+) ions located at the surface of the crystallites and in the bulk. Copyright © 2016 Elsevier Inc. All rights reserved.

Transition Metal-Involved Photon Upconversion.

PubMed

Ye, Shi; Song, En-Hai; Zhang, Qin-Yuan

2016-12-01

Upconversion (UC) luminescence of lanthanide ions (Ln 3+ ) has been extensively investigated for several decades and is a constant research hotspot owing to its fundamental significance and widespread applications. In contrast to the multiple and fixed UC emissions of Ln 3+ , transition metal (TM) ions, e.g., Mn 2+ , usually possess a single broadband emission due to its 3 d 5 electronic configuration. Wavelength-tuneable single UC emission can be achieved in some TM ion-activated systems ascribed to the susceptibility of d electrons to the chemical environment, which is appealing in molecular sensing and lighting. Moreover, the UC emissions of Ln 3+ can be modulated by TM ions (specifically d -block element ions with unfilled d orbitals), which benefits from the specific metastable energy levels of Ln 3+ owing to the well-shielded 4 f electrons and tuneable energy levels of the TM ions. The electric versatility of d 0 ion-containing hosts ( d 0 normally viewed as charged anion groups, such as MoO 6 6- and TiO 4 4- ) may also have a strong influence on the electric dipole transition of Ln 3+ , resulting in multifunctional properties of modulated UC emission and electrical behaviour, such as ferroelectricity and oxide-ion conductivity. This review focuses on recent advances in the room temperature (RT) UC of TM ions, the UC of Ln 3+ tuned by TM or d 0 ions, and the UC of d 0 ion-centred groups, as well as their potential applications in bioimaging, solar cells and multifunctional devices.

Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

NASA Astrophysics Data System (ADS)

Hazarika, Deepshikha; Karak, Niranjan

2016-07-01

In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO2) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO2 and nanohybrid of TiO2 in presence of CD (CD/TiO2) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO2, CD@TiO2 and CD/TiO2 were examined by Fourier transform infrared (FTIR), UV-vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO2 nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO2 were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO2 exhibited the most promising photocatalytic degradation of organic pollutants like benzene and phenol as well as an anthrogenic pesticide under sunlight.

Transition Metal‐Involved Photon Upconversion

PubMed Central

Song, En‐Hai

2016-01-01

Upconversion (UC) luminescence of lanthanide ions (Ln3+) has been extensively investigated for several decades and is a constant research hotspot owing to its fundamental significance and widespread applications. In contrast to the multiple and fixed UC emissions of Ln3+, transition metal (TM) ions, e.g., Mn2+, usually possess a single broadband emission due to its 3d 5 electronic configuration. Wavelength‐tuneable single UC emission can be achieved in some TM ion‐activated systems ascribed to the susceptibility of d electrons to the chemical environment, which is appealing in molecular sensing and lighting. Moreover, the UC emissions of Ln3+ can be modulated by TM ions (specifically d‐block element ions with unfilled d orbitals), which benefits from the specific metastable energy levels of Ln3+ owing to the well‐shielded 4f electrons and tuneable energy levels of the TM ions. The electric versatility of d 0 ion‐containing hosts (d 0 normally viewed as charged anion groups, such as MoO6 6‐ and TiO4 4‐) may also have a strong influence on the electric dipole transition of Ln3+, resulting in multifunctional properties of modulated UC emission and electrical behaviour, such as ferroelectricity and oxide‐ion conductivity. This review focuses on recent advances in the room temperature (RT) UC of TM ions, the UC of Ln3+ tuned by TM or d 0 ions, and the UC of d 0 ion‐centred groups, as well as their potential applications in bioimaging, solar cells and multifunctional devices. PMID:27981015

Photon up-conversion increases biomass yield in Chlorella vulgaris.

PubMed

Menon, Kavya R; Jose, Steffi; Suraishkumar, Gadi K

2014-12-01

Photon up-conversion, a process whereby lower energy radiations are converted to higher energy levels via the use of appropriate phosphor systems, was employed as a novel strategy for improving microalgal growth and lipid productivity. Photon up-conversion enables the utilization of regions of the solar spectrum, beyond the typical photosynthetically active radiation, that are usually wasted or are damaging to the algae. The effects of up-conversion of red light by two distinct sets of up-conversion phosphors were studied in the model microalgae Chlorella vulgaris. Up-conversion by set 1 phosphors led to a 2.85 fold increase in biomass concentration and a 3.2 fold increase in specific growth rate of the microalgae. While up-conversion by set 2 phosphors resulted in a 30% increase in biomass and 12% increase in specific intracellular neutral lipid, while the specific growth rates were comparable to that of the control. Furthermore, up-conversion resulted in higher levels of specific intracellular reactive oxygen species in C. vulgaris. Up-conversion of red light (654 nm) was shown to improve biomass yields in C. vulgaris. In principle, up-conversion can be used to increase the utilization range of the electromagnetic spectrum for improved cultivation of photosynthetic systems such as plants, algae, and microalgae. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

X-ray luminescence imaging of water, air, and tissue phantoms

NASA Astrophysics Data System (ADS)

Lun, Michael C.; Li, Changqing

2018-02-01

X-ray luminescence computed tomography (XLCT) is an emerging hybrid molecular imaging modality. In XLCT, high energy x-ray photons excite phosphors emitting optical photons for tomographic image reconstruction. During XLCT, the optical signal obtained is thought to only originate from the embedded phosphor particles. However, numerous studies have reported other sources of optical photons such as in air, water, and tissue that are generated from ionization. These sources of optical photons will provide background noise and will limit the molecular sensitivity of XLCT imaging. In this study, using a water-cooled electron multiplying charge-coupled device (EMCCD) camera, we performed luminescence imaging of water, air, and several tissue mimicking phantoms including one embedded with a target containing 0.01 mg/mL of europium-doped gadolinium oxysulfide (GOS:Eu3+) particles during x-ray irradiation using a focused x-ray beam with energy less than the Cerenkov radiation threshold. In addition, a spectrograph was used to measure the x-ray luminescence spectrum. The phantom embedded with the GOS:Eu3+ target displayed the greatest luminescence intensity, followed by the tissue phantom, and finally the water phantom. Our results indicate that the x-ray luminescence intensity from a background phantom is equivalent to a GOS:Eu3+ concentration of 0.8 μg/mL. We also found a 3-fold difference in the radioluminescence intensity between liquid water and air. From the measurements of the emission spectra, we found that water produced a broad spectrum and that a tissue-mimicking phantom made from Intralipid had a different x-ray emission spectrum than one made with TiO2 and India ink. The measured spectra suggest that it is better to use Intralipid instead if TiO2 as optical scatterer for future XLCT imaging.

The sensitized luminescence of manganese-activated calcite

USGS Publications Warehouse

Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.

1947-01-01

Synthetic manganese-activated calcites are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural calcites is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural calcites to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".

Characterization of the proton irradiation induced luminescence of materials and application in radiation oncology dosimetry

NASA Astrophysics Data System (ADS)

Darafsheh, Arash; Zhang, Rongxiao; Kassaee, Alireza; Finlay, Jarod C.

2018-03-01

Visible light generated as the result of interaction of ionizing radiation with matter can be used for radiation therapy quality assurance. In this work, we characterized the visible light observed during proton irradiation of poly(methyl methacrylate) (PMMA) and silica glass fiber materials by performing luminescence spectroscopy. The spectra of the luminescence signal from PMMA and silica glass fibers during proton irradiation showed continuous spectra whose shape were different from that expected from Čerenkov radiation, indicating that Čerenkov radiation cannot be the responsible radioluminescence signal. The luminescence signal from each material showed a Bragg peak pattern and their corresponding proton ranges are in agreement with measurements performed by a standard ion chamber. The spectrum of the silica showed two peaks at 460 and 650 nm stem from the point defects of the silica: oxygen deficiency centers (ODC) and non-bridging oxygen hole centers (NBOHC), respectively. The spectrum of the PMMA fiber showed a continuous spectrum with a peak at 410 nm whose origin is connected with the fluorescence of the PMMA material. Our results are of interest for various applications based on imaging radioluminescent signal in proton therapy and will inform on the design of high-resolution fiber probes for proton therapy dosimetry.

Optical population of iodine molecule ion-pair states via MI2 vdW complexes, M = I2, Xe, of valence states correlating with the third, I(2 P 1/2) + I(2 P 1/2), dissociation limit

NASA Astrophysics Data System (ADS)

Lukashov, S. S.; Poretsky, S. A.; Pravilov, A. M.; Khadikova, E. I.; Shevchenko, E. V.

2010-10-01

The first results of measurements and analysis of excitation spectra of the λlum = 3250 Å luminescence corresponding to I2( D0{/u +} → X0{/g +}) transition as well as luminescence at λlum = 3400 Å, where I2( D'2 g → A'2 u and/or β1 g → A1 u ) transitions occur, observed after three-step, λ1 + λ f + λ1, λ1 = 5321-5508.2 Å, λ f = 10644.0 Å, laser excitation of pure iodine vapour and I2 + Xe mixtures at room temperature via MI2 vdW complexes, M = I2, Xe, of the I2(0{/g +}, 1 u ( bb)) valence states correlating with the third, I(2 P 1/2) + I(2 P 1/2) (I2( bb)), dissociation limit are presented. Luminescence spectra in the λlum = 2200-3500 Å spectral range are also analyzed. Strong luminescence from the I2(D) and, probably, I2(D' and β) states is observed. We discuss three alternative mechanisms of optical population of the IP state. In our opinion, the mechanism including the MI2 complexes is the most probable.

Lanthanum lead boro-tellurite glasses doped with samarium trioxide for luminescent devices application

NASA Astrophysics Data System (ADS)

Madhu, A.; Eraiah, B.

2018-04-01

Boro-tellurite based glasses (10La2O3-(20-x) TeO2-30PbO-40B2O3-xSm2O3) (x = 0, 0.5, 1.0 and 2.0 mol %) doped with different concentrations of Sm3+ ions has been investigated. The optical properties have been studied through spectroscopic measurements such as absorption and luminescence. Absorption spectra reveals nine peaks due to 6H5/2→6P3/2, 4I3/2+4F5/2+4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, and 6H13/2 transitions. Luminescence spectra under the excitation of 403 nm display four emission bands due to 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of Sm3+ ions. Among them 6H7/2 bright orange -red is more intense which proves that the present glasses are potential candidates for luminescent device applications in visible range as well as optical fibre communication since its refractive index is 1.65 high compared to other glasses.

Infrared upconversion for astronomy

NASA Technical Reports Server (NTRS)

Boyd, R. W.

1977-01-01

The basic theory of upconversion is presented, along with a brief historical summary of upconversion techniques. Upconverters were used in astronomical studies, but have met with only modest success. Upconversion will become a useful detection method for astronomy only if substantial but perhaps forseeable, improvements can be realized.

Synthesis and luminescent properties of Sr3Al2O5Cl2: Eu2+, Dy3+ rod-like nanocrystals

NASA Astrophysics Data System (ADS)

Wang, Zhengliang; Zhang, Qiuhan; Rong, Meizhu; Tan, Huiying; Wang, Qin; Zhou, Qiang; Chen, Guo

2016-08-01

White long afterglow phosphor with nano-rods, Sr3Al2O5Cl2: Eu2+, Dy3+, has been successfully synthesized by the solid state reaction. Their structure, morphology, scanning electron microscopy, luminescent properties and long afterglow properties were investigated by X-ray diffraction, transmission electron microscopy luminescence spectra and the luminescence decay curve. The obtained phosphor Sr3Al2O5Cl2: Eu2+, Dy3+ exhibits two broad emission bands, which are located at ∼445 nm and ∼590 nm, respectively. White light can be observed from this phosphor with appropriate CIE values (x = 0.357, y = 0.332). The white afterglow duration of this phosphor is about 0.5 h (>0.35 mcd/m2).

Radioluminescence response of germanosilicate optical fibres

NASA Astrophysics Data System (ADS)

Khanlary, M. R.; Townsend, P. D.; Townsend, J. E.

1993-07-01

X-ray irradiation of germanosilicate optical fibres simultaneously produces signals from both the core and substrate and so the radioluminescence spectra record the defect structure of both regions. The data provide evidence for the presence of dopants and trace impurities, as well as intrinsic defects formed by thermal and radiation processing. Examples of the changes in spectra or luminescence sensitivity with radiation dose, the influence of fibre pulling conditions and post irradiation heating are noted. The temperature dependence of the radioluminescence is reported. Whilst most of the intrinsic defects produce broad emission bands, rare earth dopants show line features. However, line features have also been noted for Al doped fibres. Such studies of fibre luminescence offer a sensitive monitor of changes in the structure of the glass network.

Use of Isobestic and Isoemission Points in Absorption and Luminescence Spectra for Study of the Transformation of Radiation Defects in Lithium Fluoride

NASA Astrophysics Data System (ADS)

Voitovich, A. P.; Kalinov, V. S.; Stupak, A. P.; Runets, L. P.

2015-03-01

Isobestic and isoemission points are recorded in the combined absorption and luminescence spectra of two types of radiation defects involved in complex processes consisting of several simultaneous parallel and sequential reactions. These points are observed if a constant sum of two terms, each formed by the product of the concentration of the corresponding defect and a characteristic integral coefficient associated with it, is conserved. The complicated processes involved in the transformation of radiation defects in lithium fluoride are studied using these points. It is found that the ratio of the changes in the concentrations of one of the components and the reaction product remains constant in the course of several simultaneous reactions.

Using lead chalcogenide nanocrystals as spin mixers: a perspective on near-infrared-to-visible upconversion.

PubMed

Nienhaus, Lea; Wu, Mengfei; Bulović, Vladimir; Baldo, Marc A; Bawendi, Moungi G

2018-03-01

The process of upconversion leads to emission of photons higher in energy than the incident photons. Near-infrared-to-visible upconversion, in particular, shows promise in sub-bandgap sensitization of silicon and other optoelectronic materials, resulting in potential applications ranging from photovoltaics that exceed the Shockley-Queisser limit to infrared imaging. A feasible mechanism for near-infrared-to-visible upconversion is triplet-triplet annihilation (TTA) sensitized by colloidal nanocrystals (NCs). Here, the long lifetime of spin-triplet excitons in the organic materials that undergo TTA makes upconversion possible under incoherent excitation at relatively low photon fluxes. Since this process relies on optically inactive triplet states, semiconductor NCs are utilized as efficient spin mixers, absorbing the incident light and sensitizing the triplet states of the TTA material. The state-of-the-art system uses rubrene with a triplet energy of 1.14 eV as the TTA medium, and thus allows upconversion of light with photon energies above ∼1.1 eV. In this perspective, we review the field of lead sulfide (PbS) NC-sensitized near-infrared-to-visible upconversion, discuss solution-based upconversion, and highlight progress made on solid-state upconversion devices.

Near-Infrared to Visible Organic Upconversion Devices Based on Organic Light-Emitting Field Effect Transistors.

PubMed

Li, Dongwei; Hu, Yongsheng; Zhang, Nan; Lv, Ying; Lin, Jie; Guo, Xiaoyang; Fan, Yi; Luo, Jinsong; Liu, Xingyuan

2017-10-18

The near-infrared (NIR) to visible upconversion devices have attracted great attention because of their potential applications in the fields of night vision, medical imaging, and military security. Herein, a novel all-organic upconversion device architecture has been first proposed and developed by incorporating a NIR absorption layer between the carrier transport layer and the emission layer in heterostructured organic light-emitting field effect transistors (OLEFETs). The as-prepared devices show a typical photon-to-photon upconversion efficiency as high as 7% (maximum of 28.7% under low incident NIR power intensity) and millisecond-scale response time, which are the highest upconversion efficiency and one of the fastest response time among organic upconversion devices as referred to the previous reports up to now. The high upconversion performance mainly originates from the gain mechanism of field-effect transistor structures and the unique advantage of OLEFETs to balance between the photodetection and light emission. Meanwhile, the strategy of OLEFETs also offers the advantage of high integration so that no extra OLED is needed in the organic upconversion devices. The results would pave way for low-cost, flexible and portable organic upconversion devices with high efficiency and simplified processing.

Thiazole derivative-modified upconversion nanoparticles for Hg2+ detection in living cells

NASA Astrophysics Data System (ADS)

Gu, Bin; Zhou, Yi; Zhang, Xiao; Liu, Xiaowang; Zhang, Yuhai; Marks, Robert; Zhang, Hua; Liu, Xiaogang; Zhang, Qichun

2015-12-01

Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems.Mercury ion (Hg2+) is an extremely toxic ion, which will accumulate in human bodies and cause severe nervous system damage. Therefore, the sensitive and efficient monitoring of Hg2+ in human bodies is of great importance. Upconversion nanoparticle (UCNPs) based nano probes exhibit no autofluorescence, deep penetration depth and chemical stability in biological samples, as well as a large anti-stokes shift. In this study, we have developed thiazole-derivative-functionalized UCNPs, and employed an upconversion emission intensity ratio of 540 nm to 803 nm (I540/I803) as a ratiometric signal to detect Hg2+ in living cells showing excellent photo stability and high selectivity. Our nano probe was characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). The low cytotoxicity of our probe was confirmed by an MTT assay and the UCL test in HeLa cells was carried out by confocal microscopy. Our results demonstrated that organic-dye-functionalized UCNPs should be a good strategy for detecting toxic metal ions when studying cellular biosystems. Electronic supplementary information (ESI) available: NMR, MALDI-TOF MS spectra, etc. See DOI: 10.1039/c5nr05286f

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lecointre, A., E-mail: lecointre.aurelie@gmail.com; Bessière, A., E-mail: aurelie-bessiere@chimie-paristech.fr; Department of Physics, Goa University, Taleigao Plateau, Goa 403 206

Highlights: ► Long-lasting phosphorescence of CaMgSi{sub 2}O{sub 6}:Mn is studied for bioimaging application. ► CaMgSi{sub 2}O{sub 6}:Mn yields orange and red luminescence of Mn{sup II}{sub Ca} and Mn{sup II}{sub Mg}, respectively. ► Red Mn{sup II}{sub Mg} emission dominates long-lasting phosphorescence spectra. ► Mn mainly substitutes Mg. ► Mn{sup II}{sub Mg} plays the role of hole trap in the persistent luminescence mechanism. - Abstract: Materials with red long-lasting phosphorescence, such as Mn{sup II}-doped diopsides, can be used for small animal in vivo imaging. CaMgSi{sub 2}O{sub 6}:Mn powders with various amounts of Mn were prepared by sol–gel to investigate their long-lasting phosphorescencemore » mechanism. X-ray diffraction, X-ray absorption fine and near-edge structure and electron paramagnetic resonance showed that manganese is quantitatively introduced in the structure as Mn{sup II}. Most of the Mn doping ions substitute Mg and possess a highly elongated octahedral environment. While photoluminescence and X-ray excited optical luminescence spectra show both orange (585 nm) and red (685 nm) {sup 4}T{sub 1} ({sup 4}G) → {sup 6}A{sub 1} ({sup 6}S) emission of Mn{sup II}{sub Ca} and Mn{sup II}{sub Mg}, respectively, Mn{sup II}{sub Mg} red emission dominates long-lasting phosphorescence and thermally stimulated luminescence spectra. These results point to Mn{sup II}{sub Mg} as the preferential hole trap and recombination center in the long-lasting phosphorescence mechanism. An intense persistent red emission suitable for in vivo imaging probes is obtained for the highest nominal Mn content (7.5%)« less

Influence of the morphology of ZnO nanostructures on luminescent and photovoltaic properties

NASA Astrophysics Data System (ADS)

Ibrayev, N. Kh.; Ilyassov, B. R.; Afanasyev, D. A.

2017-03-01

Arrays of ZnO nanorods and nanoplates are synthesized by the hydrothermal and electrochemical methods, respectively. The photoluminescence spectra indicate that the nanoplates have a more defective structure than the nanorods. The obtained ZnO nanostructures are used as the basis to construct dye-sensitized solar cells. The influence of morphology and defectiveness of ZnO nanostructures on the luminescent and photovoltaic properties of the cells is studied.

Energy-gap reduction in heavily doped silicon: Causes and consequences

NASA Astrophysics Data System (ADS)

Pantelides, Sokrates T.; Selloni, Annabella; Car, Roberto

1985-02-01

The authors review briefly the existing theoretical treatments of the various effects that contribute to the reduction of the energy gap in heavily doped Si, namely electron-electron and electron-impurity interactions and the effect of disorder in the impurity distribution. They then turn to the longstanding question why energy-gap reductions extracted from three different types of experiments have persistently produced values with substantial discrepancies, making it impossible to compare with theoretical values. First, they demonstrate that a meaningful comparison between theory and experiment can indeed be made if theoretical calculations are carried out for actual quantities that experiments measure, e.g. luminescence spectra, as recently done by Selloni and Pantelides. Then, they demonstrate that, independent of any theoretical calculations, the optical absorption spectra are fully consistent with the luminescence spectra and that the discrepancies in the energy-gap reductions extracted from the two sets of spectra are caused entirely by the curve-fitting procedures used in analyzing optical-absorption data. Finally, they show explicitly that, as already believed by many authors, energy-gap reductions extracted from electrical measurements on transistors do not correspond to true gap reductions. They identify two corrections that must be added to the values extracted from the electrical data in order to arrive at the true gap reductions and show that the resulting values are in good overall agreement with luminescence and absorption data. They, therefore, demonstrate that the observed reduction in emitter injection efficiency in bipolar transistors is not strictly due to a gap reduction, as generally believed, but to three very different effects.

New Data On The Cathodoluminescence Of White Marbles: Interpretation Of Peaks And Relationships To Weathering

NASA Astrophysics Data System (ADS)

Garcia-Guinea, J.; Crespo-Feo, E.; Correcher, V.; Iordanidis, A.; Charalampides, G.; Karamitrou-Mentessidi, G.

This work focus on the Thermoluminescence (TL), the Spatially Resolved Spectral Cathodoluminescence (CL) and Raman spectroscopy (Raman) of white marble specimens collected from the archaeological park of Aiani (Greece) and from patterns of Iceland calcite and Macael marble for comparison purposes. The spectra CL were measured with a high sensitivity cathodoluminescence spectrometer MonoCL3 of Gatan (UK) attached to an FEI-ESEM microscope (CL-ESEM). The experimental set of spectra CL curves of Aiani white marbles suggest that the blue band is more resistant to weathering in comparison with the red band which drops down easily under weathering. The comparison among CL spectra of CaCO3 patterns give a slight difference between the small 330 nm peak, detected in marble and not observed in the monocrystal pattern of Iceland calcite. The Backscattering Electron Dispersed (BSED) images of the white marble are similar to the CL monochromatic plots at 330 nm which highlight the surfaces with remarkable clarity, suggesting a CL emission-defect associated to the marble crystal interfaces, such as protons or hydroxyls. Conversely, the 395 nm monochromatic mapping depicts a CL image emitting from bulk and not from interfaces attributable to point defects or cationic activators in Ca2+ positions. The blue band of the spectra luminescence of marble is composed by several peaks associated to very different types of luminescent defects. This statement is not inconsequential since in archaeological TL dating of marbles the regenerated luminescence in the blue region of the spectrum is a serious difficulty and further research on this topic is necessary.

Formation of Ag nanoparticles and enhancement of Tb3+ luminescence in Tb and Ag co-doped lithium-lanthanum-aluminosilicate glass

NASA Astrophysics Data System (ADS)

Piasecki, Patryk; Piasecki, Ashley; Pan, Zhengda; Mu, Richard; Morgan, Steven H.

2010-12-01

Tb3+ and Ag co-doped glass nano-composites were synthesized in a glass matrix Li2O-LaF3-Al2O3-SiO2 (LLAS) by a melt-quench technique. The growth of Ag nanoparticles (NPs) was controlled by a thermal annealing process. A broad absorption band peaking at about 420 nm was observed due to surface plasmon resonance (SPR) of Ag NPs. The intensity of this band grows with increasing annealing time. The transmission electron microscopic image (TEM) reveals the formation of Ag NPs in glass matrix. Photoluminescence (PL) emission and excitation spectra were measured for glass samples with different Ag concentrations and different annealing times. Plasmon enhanced Tb3+ luminescence was observed at certain excitation wavelength regions. Luminescence quenching was also observed for samples with high Ag concentration and longer annealing time. Our luminescence results suggest that there are two competitive effects, enhancement and quenching, acting on Tb3+ luminescence in the presence of Ag NPs. The enhancement of Tb3+ luminescence is mainly attributed to local field effects due to SPR. The quenching of luminescence suggests an energy transfer from Tb3+ ions to Ag NPs.

Low-level luminescence as a method of detecting the UV influence on biological systems

NASA Astrophysics Data System (ADS)

Mei, Wei-Ping; Popp, Fritz A.

1995-02-01

It is well known that low-level luminescence is correlated to many physiological and biological parameters, e.g. cell cycle, temperature, oxidation- and UV-stress. We report some new approaches on low-level luminescence measurements and UV influence on different biological systems. One example concerns yeast cultures, which show an increasing intensity of luminescence after UV-treatment with a maximum after 1.5 h. Investigations on normal human fibroblasts and keratinocytes display different longtime kinetics: The former show no changes of the luminescence in time, the latter an increase that reaches the maximum after 9 h. The time-dependent spectral measurement on xeroderma pigmentosum after UV-treatment displays a time-shift of the action-spectra shifting the maximum from 400 nm to 420 nm in 12 h. Some results on neutrophils reveals spectral UV influence on respiratory burst and the cellular repair system. The results on human skin display spectral changes of low-level luminescence after UV-treatment. These results provide a useful tool of analyzing UV influence on human skin.

Photoluminescence analysis of Ce3+:Zn2SiO4 & Li++ Ce3+:Zn2SiO4: phosphors by a sol-gel method

NASA Astrophysics Data System (ADS)

Babu, B. Chandra; Vandana, C. Sai; Guravamma, J.; Rudramadevi, B. Hemalatha; Buddhudu, S.

2015-06-01

Here, we report on the development and photoluminescence analysis of Zn2SiO4, Ce3+:Zn2SiO4 & Li+ + Ce3+: Zn2SiO4 novel powder phosphors prepared by a sol-gel technique. The total amount of Ce3+ ions was kept constant in this experiment at 0.05 mol% total doping. The excitation and emission spectra of undoped (Zn2SiO4) and Ce3+ doped Zn2SiO4 and 0.05 mol% Li+ co-doped samples have been investigated. Cerium doped Zn2SiO4 powder phosphors had broad blue emission corresponding to the 2D3/2→2FJ transition at 443nm. Stable green-yellow-red emission has been observed from Zn2SiO4 host matrix and also we have been observed the enhanced luminescence of Li+ co-doped Zn2SiO4:Ce3+. Excitation and emission spectra of these blue luminescent phosphors have been analyzed in evaluating their potential as luminescent screen coating phosphors.

Thermally stimulated luminescence properties of BaY2F8 : Ce crystals

NASA Astrophysics Data System (ADS)

Vedda, A.; Martini, M.; di Martino, D.; Sani, E.; Toncelli, A.; Tonelli, M.

Wavelength resolved thermally stimulated luminescence (TSL) measurements were performed on BaY2 F-8 :1.8 mol% Ce crystals after X-ray irradiation at 10 K and at 300 K, in order to obtain preliminary information about both trap levels and recombination centres. After irradiation at 10 K, the TSL glow curve shows the presence of a strong peak at 50 K, together with additional structures at approximately 20 and 170 K. The TSL spectrum is dominated by the characteristic doublet emission due to transitions from the lowest energy level of the 5d configuration to the spin-orbit split F-2 ground state of Ce3+ . Above RT, the glow curve exhibits a peak at 60 degreesC, whose spectrum is again dominated by Ce3+ emission. The TSL emission is in accordance with radio-luminescence (RL) spectra performed in the 10-300 K region. Moreover, RL spectra at temperatures lower than 200 K display an additional weak high energy band at around 4.5 eV assigned to host lattice transitions.

Effect of solid-phase amorphization on the spectral characteristics of europium-doped gadolinium molybdate

NASA Astrophysics Data System (ADS)

Shmurak, S. Z.; Kiselev, A. P.; Kurmasheva, D. M.; Red'Kin, B. S.; Sinitsyn, V. V.

2010-05-01

A method is proposed for detecting spectral characteristics of optically inactive molybdates of rare-earth elements by their doping with rare-earth ions whose luminescence lies in the transparency region of all structural modifications of the sample. Gadolinium molybdate is chosen as the object of investigations, while europium ions are used as an optically active and structurally sensitive admixture. It is shown that after the action of a high pressure under which gadolinium molybdate passes to the amorphous state, the spectral characteristics of Gd1.99Eu0.01(MoO4)3 (GMO:Eu) change radically; namely, considerable line broadening is observed in the luminescence spectra and the luminescence excitation spectra, while the long-wave threshold of optical absorption is shifted considerably (by approximately 1.1 eV) towards lower energies. It is found that by changing the structural state of GMO:Eu by solid-state amorphization followed by annealing, the spectral characteristics of the sample can be purposefully changed. This is extremely important for solving the urgent problem of designing high-efficiency light-emitting diodes producing “white” light.

Influence of MO/MF2 modifiers (M = Ca, Sr, Ba) on spectroscopic properties of Eu3+ ions in germanate and borate glasses

NASA Astrophysics Data System (ADS)

Zur, Lidia; Janek, Joanna; Pietrasik, Ewa; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

2016-11-01

Series of Eu3+-doped lead-free germanate and borate glasses were synthesized. The MO glass modifiers (M = Ca, Sr or Ba) were partially or totally substituted by MF2 in chemical composition. In contrast to samples modified by CaO/CaF2 or SrO/SrF2, the germanate glass samples containing BaO and/or BaF2 are fully amorphous, while the lead-free borate glasses are fully amorphous, independently from glass modifiers. Effect of glass modifiers on spectroscopic properties of Eu3+ were systematically investigated. For that reason, excitation and emission spectra of Eu3+ ions in examined systems were registered. Based on the emission spectra, ratio of integrated luminescence intensity of the 5D0 → 7F2 transition to that of the 5D0 → 7F1 transition (R factor) was calculated. Moreover, the luminescence decay curves were collected and the luminescence lifetimes of the 5D0 excited state of Eu3+ ions were determined in function of MF2 concentration.

Five chiral Cd(II) complexes with dual chiral components: Effect of positional isomerism, luminescence and SHG response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Lin, E-mail: lcheng@seu.edu.cn; Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, Southeast University, Nanjing 211189; Wang, Jun

2015-01-15

Five chiral Cd(II) complexes with dual chiral components have been synthesized by using a series of (1R,2R)–N{sup 1},N{sup 2}-bis(pyridinylmethyl)cyclohexane-1,2-diamine ligands with different N-positions of pyridyl rings and Cd(NO{sub 3}){sub 2}. The circular dichroism (CD) spectra and second-harmonic generation (SHG) efficiency measurements confirmed that they are of structural chirality in the bulk samples. The luminescent properties indicated that they may have potential applications as optical materials. The formation of discrete mononuclear and binuclear complexes, and one-dimensional chains may be attributed to positional isomerism of the ligands. - Graphical abstract: Five chiral Cd(II) complexes with dual chiral components have been synthesized bymore » using a series of chiral ligands with different N-positions of pyridyl rings. - Highlights: • Five chiral Cd(II) complexes with dual chiral components have been synthesized. • CD spectra and SHG efficiency of the bulk samples have been measured. • The complexes display luminescent properties.« less