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Sample records for induced luminescence characterisation

  1. Laser Induced Blue Luminescence Phenomenon

    NASA Astrophysics Data System (ADS)

    Zhu, Haiyong; Duan, Yanmin; Zhang, Ge; Zhang, Yaoju; Yang, Fugui

    2011-09-01

    Laser induced strange blue luminescence in several Raman crystals has been investigated. The blue luminescence at about 473 nm has the characteristic of no orientation and only produced in the crystal where the fundament laser oscillated. The experimental results show that the blue luminescence must result from the fundamental laser around 1.0 µm rather than Stokes-shifting. The spectrum detected is similar for different crystals. This blue luminescence is obviously strange and inconsistent with traditional luminescence theories, which maybe a brand-new luminescence theory.

  2. Spectrometer for cluster ion beam induced luminescence

    SciTech Connect

    Ryuto, H. Sakata, A.; Takeuchi, M.; Takaoka, G. H.; Musumeci, F.

    2015-02-15

    A spectrometer to detect the ultra-weak luminescence originated by the collision of cluster ions on the surfaces of solid materials was constructed. This spectrometer consists of 11 photomultipliers with band-pass interference filters that can detect the luminescence within the wavelength ranging from 300 to 700 nm and of a photomultiplier without filter. The calibration of the detection system was performed using the photons emitted from a strontium aluminate fluorescent tape and from a high temperature tungsten filament. Preliminary measurements show the ability of this spectrometer to detect the cluster ion beam induced luminescence.

  3. The characterisation by luminescence spectroscopy of uranium(VI) incorporated into zeolites and aluminas

    NASA Astrophysics Data System (ADS)

    Azenha, M. E. D. G.; da Graça Miguel, M.; Formosinho, S. J.; Burrows, H. D.

    2001-05-01

    Luminescence spectroscopy of solids at 77 K has been used to characterise the uranium(VI) species incorporated into α-alumina, γ-alumina and zeolites Y and ZSM-20 by adsorption from solution and into ZSM-5 by chemical synthesis. With uranyl adsorbed from nitrate solutions onto α- and γ-aluminas, the luminescence measurements show the dominant uranium species is schoepite, UO 3· xH 2O, in agreement with results from X-ray diffraction and Raman spectroscopy. With uranyl acetate, there are indications that a crystalline acetate species is also present. With zeolite-Y and ZSM-20, the main species is a dimer. In addition, some monomeric [UO 2(H 2O) 5] 2+ is also present. With ZSM-5, although this is not observed in X-ray diffraction, the luminescence spectrum shows the presence of a species, similar to the schoepite seen with the aluminas. It is suggested that this may be due both to closely related polymeric species, and to uranyl anions, such as [UO 2(OH) 4] 2- and [UO 2(OH) 3] -.

  4. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  5. Mixing frequency induces [WO4]2- generating blue luminescence

    NASA Astrophysics Data System (ADS)

    Xia, Zhongchao; Yang, Fugui

    2014-02-01

    In the process of investigating end-pumped continuous intra-cavity Raman laser, a strong blue luminescence at wavelength 473 nm (nanometer) in pure [XO4]2- (X = W, Y, …) has been observed. This luminescence is strange and inconsistent with the traditional single up-conversion luminescence theory, scintillation theory. Basing on the optics theory and scintillation crystal theory, we suggest a "mixing frequency inducing blue emission" mechanism to explain the phenomenon. The mixing wavelength 473.4 nm with the four wavelengths of 808, 890, 912, and 1.064 nm stimulates and induces the blue emission of the [WO4]2-. The mechanism is in good harmony with the experiment.

  6. Ion beam induced luminescence analysis of painting pigments

    NASA Astrophysics Data System (ADS)

    Quaranta, A.; Salomon, J.; Dran, J. C.; Tonezzer, M.; Della Mea, G.

    2007-01-01

    Ion beam induced luminescence (IBIL) has been exploited for the first time in the analysis of inorganic painting pigments. The elemental constituents of the different compounds have been determined by particle induced X-ray emission (PIXE). The acquisition time of each spectrum ranges from 100 ms to a few seconds, depending on the luminescence intensity. The luminescence features are fingerprints of the different compounds, thus identifying the provenience of pigments of the same nominal composition. Organic varnish layers do not affect the IBIL features, allowing the identification of pigments, like lapis-lazuli, whose identification with PIXE is hindered by the varnish. IBIL proved to be a technique complementary to PIXE in the archeometry and cultural heritage analysis fields.

  7. Ion beam induced luminescence: Relevance to radiation induced bystander effects

    NASA Astrophysics Data System (ADS)

    Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.

    2012-10-01

    The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

  8. Characterization of dehydration-induced luminescence of kaolinite

    NASA Technical Reports Server (NTRS)

    Lahav, N.; Coyne, L.; Lawless, J. G.

    1985-01-01

    The dehydration-induced luminescence of a colloidal kaolinite is investigated experimentally, with particular attention given to the effect of various treatments on the luminescence characteristics. It is found that the total photon count of the emitted light is linearly related to the film thickness up to a thickness of 30 microns; mechanical stress in the form of grinding increases the photon output and produces extensive changes in the emission kinetics. A direct check of the emission wavelength dependence (by using color filters) indicates that roughly 75 percent of the emission occurs in the wavelength range below 410 nm. It is also found that incorporation of fluorescent molecules into the kaolinite paste increases the photon output and may indicate the transfer of ultraviolet photons to the fluorescent probe.

  9. Characteristics of laser-induced luminescence in poly(paraphenylene)

    NASA Astrophysics Data System (ADS)

    Jin, Changqin; Lu, Shaozhe; Su, Xi A.; Liu, Xing J.

    1992-02-01

    Under laser inducement, we have observed steady state photoluminescence from poly(paraphenylene) and transient photoliininescence from PPP in nanosecond time regime for the first time. PPP samples studied were produced using the Kovacic method. The experimental results indicate that the lininescence spectra are well-resolved. The peaks are rather sharp and located at 4340Å(100K), 4332Å(50K), 4318Å(8.5K) (transient state) and 4309Å, 4575Å (steady state). The luminescence spectra have been discussed by using the lattice relaxation process. The lifetime of the luminescence of PPP was measured. The decay curve of PPP is found to have a double exponential form with a lifetime of 7.47 ns and 5.13 ns. The decay kinetics was interpreted by the interchain recombination of photoexcited polaron pairs. The decay kinetics of photoinduced absorption between a few nanoseconds and a few microseconds is mainly due to the interchain recombination of the photoexcited polaron pairs and exhibits the radiative luminescence after relaxation.

  10. Spectrographic studies: Electron induced luminescence in optical materials

    NASA Technical Reports Server (NTRS)

    Romanko, J.; Miles, J. K.; Cheever, P. R.

    1971-01-01

    The spectral luminescence induced in UV grade sapphire, MgF2 and LiF2, three fused silicas, and three Corning glasses, by 1/2, 1, 2, and 3 MeV electrons was recorded. In the wavelength range from the LiF UV cutoff to the near visible, a plane-grating spectrograph with photographic recording at resolutions of 0.8 and 1.6 nm was utilized. Qualitative results based on relative density tracings of seven of the nine materials obtained from preliminary plates are given.

  11. Synthesis, characterisation, optical and luminescence properties of CoAl{sub 2}O{sub 4}

    SciTech Connect

    Agilandeswari, K.; Kumar, A. Ruban

    2015-06-24

    Solid state method has been used as an efficient method to synthesize blue pigment CoAl{sub 2}O{sub 4} at a temperature of 800°C. The products were characterized by powder X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectroscopy (DRS) and luminescent spectroscopy. X-ray diffraction pattern confirmed the formation of single phase CoAl{sub 2}O{sub 4}. Optical properties of CoAl{sub 2}O{sub 4} ceramic shows an energy band gap in the range of 3.10eV. The emission spectra of spinel CoAl{sub 2}O{sub 4} in the visible region confirmed the presence of tetrahedral coordinated Co{sup 2+} ions.

  12. Space-radiation-induced Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas; Lee, Kerry

    2008-01-01

    We report on the results of a study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon's surface when there is no sunlight and Earthshine. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to design orbiting instrumentation for measuring various components of the space-radiation-induced photon luminescence present on the Moon.

  13. Characterisation of energy response of Al2O3:C optically stimulated luminescent dosemeters (OSLDs) using cavity theory

    PubMed Central

    Scarboro, S. B.; Kry, S. F.

    2013-01-01

    Aluminium oxide (Al2O3:C) is a common material used in optically stimulated luminescent dosemeters (OSLDs). OSLDs have a known energy dependence, which can impact on the accuracy of dose measurements, especially for lower photon energies, where the dosemeter can overrespond by a factor of 3–4. The purpose of this work was to characterise the response of Al2O3:C using cavity theory and to evaluate the applicability of this approach for polyenergetic photon beams. The cavity theory energy response showed good agreement (within 2 %) with the corresponding measured values. A comparison with measured values reported in the literature for low-energy polyenergetic spectra showed more varied agreement (within 6 % on average). The discrepancy between these results is attributed to differences in the raw photon energy spectra used to calculate the energy response. Analysis of the impact of the photon energy spectra versus the mean photon energy showed improved accuracy if the energy response was determined using the entire photon spectrum rather than the mean photon energy. If not accounted for, the overresponse due to photon energy could introduce substantial inaccuracy in dose measurement using OSLDs, and the results of this study indicate that cavity theory may be used to determine the response with reasonable accuracy. PMID:22653437

  14. GCR-Induced Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Lee, K. T.; Wilson, T. L.

    2008-01-01

    It is shown that the Moon has a ubiquitous photon luminescence induced by Galactic cosmic-rays (GCRs), using the Monte Carlo particle-physics program FLUKA. Both the fluence and the flux of the radiation can be determined by this method, but only the fluence will be presented here. This is in addition to thermal radiation emitted due to the Moon s internal temperature and radioactivity. This study is a follow-up to an earlier discussion [1] that addressed several misconceptions regarding Moonshine in the Earth-Moon system (Figure 1) and predicted this effect. There also exists a related x-ray fluorescence induced by solar energetic particles (SEPs, <350 MeV) and solar photons at lower x-ray energies, although this latter fluorescence was studied on Apollo 15 and 16 [2- 5], Lunar Prospector [6], and even EGRET [7].

  15. In situ variations of carrier decay and proton induced luminescence characteristics in polycrystalline CdS

    NASA Astrophysics Data System (ADS)

    Gaubas, E.; Brytavskyi, I.; Ceponis, T.; Jasiunas, A.; Kalesinskas, V.; Kovalevskij, V.; Meskauskaite, D.; Pavlov, J.; Remeikis, V.; Tamulaitis, G.; Tekorius, A.

    2014-06-01

    Evolution of the microwave-probed photoconductivity transients and of the proton induced luminescence has simultaneously been examined in polycrystalline CdS layers evaporated in vacuum during exposure to a 1.6 MeV proton beam. The decrease of the intensity of luminescence peaked at 510 and 709 nm wavelengths and of values of the effective carrier lifetime has been correlated in dependence of proton irradiation fluence. The defect introduction rate has been evaluated by the comparative analysis of the laser and proton beam induced luminescence. The difference of a carrier pair generation mechanism inherent for light and for a proton beam has been revealed.

  16. In situ variations of carrier decay and proton induced luminescence characteristics in polycrystalline CdS

    SciTech Connect

    Gaubas, E. Ceponis, T.; Jasiunas, A.; Kalesinskas, V.; Meskauskaite, D.; Pavlov, J.; Tamulaitis, G.; Tekorius, A.; Brytavskyi, I.; Kovalevskij, V.; Remeikis, V.

    2014-06-28

    Evolution of the microwave-probed photoconductivity transients and of the proton induced luminescence has simultaneously been examined in polycrystalline CdS layers evaporated in vacuum during exposure to a 1.6 MeV proton beam. The decrease of the intensity of luminescence peaked at 510 and 709 nm wavelengths and of values of the effective carrier lifetime has been correlated in dependence of proton irradiation fluence. The defect introduction rate has been evaluated by the comparative analysis of the laser and proton beam induced luminescence. The difference of a carrier pair generation mechanism inherent for light and for a proton beam has been revealed.

  17. Luminescence from pigments and resins for oil paintings induced by laser excitation

    NASA Astrophysics Data System (ADS)

    Borgia, Ilaria; Fantoni, Roberta; Flamini, Chiara; Di Palma, Tonia M.; Giardini Guidoni, Anna; Mele, Aldo

    1998-05-01

    The present work reports results of an extensive study of laser induced luminescence by tripled Nd:YAG laser ( λ=355 nm) of a few most common painting materials, namely, natural and synthetic pigments and resins. The luminescence spectra have been analyzed by an Optical Multichannel Analyzer (OMA III). Luminescence time decay has been measured by a Streak camera or by the OMA III. Pigments and resins show characteristic emission spectra with bands peaking in the visible. The decay ranges from less than 1 ns up to 700 μs for pigments and for resins. The mechanism of excitation and relaxation leading to luminescence is discussed for the various materials. Oil colour specimens have been irradiated by a UV KrF laser ( λ=248 nm). Luminescence photographs have been detected by an intensified charge coupled device (ICCD) camera at different time delays.

  18. Room-temperature luminescence from kaolin induced by organic amines

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Kloepping, R.; Pollack, G.

    1984-01-01

    Several new, room-temperature luminescent phenomena, resulting from the interaction of kaolin and various amino compounds, have been observed. The emission of light from kaolin pastes (treated with quinoline, pyridine, hydrazine, monoethanolamine, n-butylamine, and piperidine) was shown to decay monotonically over a period of hours to days. More light was released by a given amino compound after it was dried and purified. Hydrazine, in addition to the monotonically decaying photon release, produces delayed pulses of light with peak emission wavelength of 365 nm which last between several hours and several days. These photon bursts are acutely sensitive to the initial dryness of the hydrazine, both in the number of bursts and the integrated photon output. The amount of light and the capacity of the kaolin to produce the delayed burst appeared to be strongly dependent on preliminary heating and on gamma-irradiation, analogous to the dehydration-induced light pulse previously reported from the Ames Research Center. A small, delayed burst of photons occurred when piperidine and n-butylamine were removed by evaporation into an H2SO4 reservoir.

  19. Characterisation of estuarine intertidal macroalgae by laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Gameiro, Carla; Utkin, Andrei B.; Cartaxana, Paulo

    2015-12-01

    The article reports the application of laser-induced fluorescence (LIF) for the assessment of macroalgae communities of estuarine intertidal areas. The method was applied for the characterisation of fifteen intertidal macroalgae species of the Tagus estuary, Portugal, and adjacent coastal area. Three bands characterised the LIF spectra of red macroalgae with emission maxima in the ranges 577-583 nm, 621-642 nm and 705-731 nm. Green and brown macroalgae showed one emission maximum in the red region (687-690 nm) and/or one in the far-red region (726-732 nm). Characteristics of LIF emission spectra were determined by differences in the main fluorescing pigments: phycoerythrin, phycocyanin and chlorophyll a (Chl a). In the green and brown macroalgae groups, the relative significance of the two emission maxima seems to be related to the thickness of the photosynthetic layer. In thick macroalgae, like Codium tomentosum or Fucus vesiculosus, the contribution of the far-red emission fluorescence peak was more significant, most probably due to re-absorption of the emitted red Chl a fluorescence within the dense photosynthetic layer. Similarly, an increase in the number of layers of the thin-blade green macroalgae Ulva rigida caused a shift to longer wavelengths of the red emission maximum and the development of a fluorescence peak at the far-red region. Water loss from Ulva's algal tissue also led to a decrease in the red/far-red Chl fluorescence ratio (F685/F735), indicating an increase in the density of chloroplasts in the shrinking macroalgal tissue during low tide exposure.

  20. Luminescence modulations of rhenium tricarbonyl complexes induced by structural variations.

    PubMed

    Bertrand, Hélène C; Clède, Sylvain; Guillot, Régis; Lambert, François; Policar, Clotilde

    2014-06-16

    Octahedral d(6) low-spin Re(I) tricarbonyl complexes are of considerable interest as noninvasive imaging probes and have been deeply studied owing to their biological stability, low toxicity, large Stokes shifts, and long luminescence lifetimes. We reported recently the bimodal IR and luminescence imaging of a Re(I) tricarbonyl complex with a Pyta ligand (4-(2-pyridyl)-1,2,3-triazole) in cells and labeled such metal-carbonyl complexes SCoMPIs for single-core multimodal probes for imaging. Re(I) tricarbonyl complexes have unique photophysical properties allowing for their unequivocal detection in cells but also present some weaknesses such as a very low luminescence quantum yield in aqueous medium. Further optimizations would thus be desirable. We therefore developed new Re(I) tricarbonyl complexes prepared from different ancillary ligands. Complexes with benzothiadiazole-triazole ligands show interesting luminescent quantum yields in acetonitrile and may constitute valuable luminescent metal complexes in organic media. A series of complexes with bidentate 1-(2-quinolinyl)-1,2,3-triazole (Taquin) and 1-(2-pyridyl)-1,2,3-triazole (Tapy) ligands bearing various 4-substituted alkyl side chains has been designed and synthesized with efficient procedures. Their photophysical properties have been characterized in acetonitrile and in a H2O/DMSO (98/2) mixture and compared with those of the parent Quinta- and Pyta-based complexes. Tapy complexes bearing long alkyl chains show impressive enhancement of their luminescent properties relative to the parent Pyta complex. Theoretical calculations have been performed to further characterize this new class of rhenium tricarbonyl complexes. Preliminary cellular imaging studies in MDA-MB231 breast cancer cells reveal a strong increase in the luminescence signal in cells incubated with the Tapy complex substituted with a C12 alkyl chain. This study points out the interesting potential of the Tapy ligand in coordination chemistry

  1. The influence of the crystal structure on aggregation-induced luminescence of derivatives of aminobenzoic acid

    NASA Astrophysics Data System (ADS)

    Nosova, D. A.; Zarochentseva, E. P.; Vysotskaya, S. O.; Klemesheva, N. A.; Korotkov, V. I.

    2014-12-01

    The luminescence of three derivatives of 2-(phenylamino)-benzoic acid (N-phenylanthranilic, mefenamic, and niflumic acids) in benzene solution, in the polycrystalline state, and in the hexamethylbenzene matrix is studied. In the crystalline state, these compounds exhibit intense aggregation-induced luminescence. An increase in luminescence is also observed in the impurity crystal. The hexamethylbenzene crystal lattice restricts the mobility of molecules, thus ensuring the rigidity of the molecular structure of acids, which decreases the efficiency of nonradiative electron energy degradation. The main reason for the increase in the luminescence intensity in the case of fixation in a crystalline matrix is the formation of intramolecular hydrogen bonds and dimers of acid molecules.

  2. Fast reconstruction of a bounded ultrasonic beam using acoustically induced piezo-luminescence

    SciTech Connect

    Kersemans, Mathias Lammens, Nicolas; Degrieck, Joris; Van Paepegem, Wim; Smet, Philippe F.

    2015-12-07

    We report on the conversion of ultrasound into light by the process of piezo-luminescence in epoxy with embedded BaSi{sub 2}O{sub 2}N{sub 2}:Eu as active component. We exploit this acoustically induced piezo-luminescence to visualize several cross-sectional slices of the radiation field of an ultrasonic piston transducer (f = 3.3 MHz) in both the near-field and the far-field. Simply combining multiple slices then leads to a fast representation of the 3D spatial radiation field. We have confronted the luminescent results with both scanning hydrophone experiments and digital acoustic holography results, and obtained a good correlation between the different approaches.

  3. Investigation of radiation-induced free radicals and luminescence properties in fresh pomegranate fruits.

    PubMed

    Shahbaz, Hafiz M; Akram, Kashif; Ahn, Jae-Jun; Kwon, Joong-Ho

    2013-05-01

    Radiation-induced free radicals and luminescence properties were investigated in γ-irradiated (0-3 kGy) pomegranate ( Punica granatum L.) fruits. Photostimulated luminescence (PSL) analysis showed limited applicability, and only 3 kGy-irradiated pomegranates showed positive PSL values (>5000 PCs). Thermoluminescence (TL) glow curve features, such as intensity and the presence of maximum glow peak in radiation-specific temperature range (150-250 °C), provided definite proof of irradiation, and the TL ratios (TL1/TL2) also confirmed the reliability of TL results. Scanning electron microscopy energy dispersive X-ray (SEM-EDX) analysis of the separated minerals showed that feldspar and quartz minerals were responsible for the luminescence properties. Radiation-induced cellulose radicals were detected in the seeds and rinds by ESR analysis. The ESR results were better in freeze-dried samples than in alcohol-extracted ones. A positive correlation was found between the ESR and TL signal intensities and irradiation doses; however, the most promising detection of the irradiation status was possible through TL analysis.

  4. Investigation of radiation-induced free radicals and luminescence properties in fresh pomegranate fruits.

    PubMed

    Shahbaz, Hafiz M; Akram, Kashif; Ahn, Jae-Jun; Kwon, Joong-Ho

    2013-05-01

    Radiation-induced free radicals and luminescence properties were investigated in γ-irradiated (0-3 kGy) pomegranate ( Punica granatum L.) fruits. Photostimulated luminescence (PSL) analysis showed limited applicability, and only 3 kGy-irradiated pomegranates showed positive PSL values (>5000 PCs). Thermoluminescence (TL) glow curve features, such as intensity and the presence of maximum glow peak in radiation-specific temperature range (150-250 °C), provided definite proof of irradiation, and the TL ratios (TL1/TL2) also confirmed the reliability of TL results. Scanning electron microscopy energy dispersive X-ray (SEM-EDX) analysis of the separated minerals showed that feldspar and quartz minerals were responsible for the luminescence properties. Radiation-induced cellulose radicals were detected in the seeds and rinds by ESR analysis. The ESR results were better in freeze-dried samples than in alcohol-extracted ones. A positive correlation was found between the ESR and TL signal intensities and irradiation doses; however, the most promising detection of the irradiation status was possible through TL analysis. PMID:23565691

  5. Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter.

    PubMed

    Cao, Xu; Li, Yang; Zhan, Yonghua; Chen, Xueli; Kang, Fei; Wang, Jing; Liang, Jimin

    2016-01-01

    Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image. PMID:27648450

  6. Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter

    PubMed Central

    Li, Yang; Zhan, Yonghua; Kang, Fei; Wang, Jing

    2016-01-01

    Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image.

  7. Removing Noises Induced by Gamma Radiation in Cerenkov Luminescence Imaging Using a Temporal Median Filter

    PubMed Central

    Li, Yang; Zhan, Yonghua; Kang, Fei; Wang, Jing

    2016-01-01

    Cerenkov luminescence imaging (CLI) can provide information of medical radionuclides used in nuclear imaging based on Cerenkov radiation, which makes it possible for optical means to image clinical radionuclide labeled probes. However, the exceptionally weak Cerenkov luminescence (CL) from Cerenkov radiation is susceptible to lots of impulse noises introduced by high energy gamma rays generating from the decays of radionuclides. In this work, a temporal median filter is proposed to remove this kind of impulse noises. Unlike traditional CLI collecting a single CL image with long exposure time and smoothing it using median filter, the proposed method captures a temporal sequence of CL images with shorter exposure time and employs a temporal median filter to smooth a temporal sequence of pixels. Results of in vivo experiments demonstrated that the proposed temporal median method can effectively remove random pulse noises induced by gamma radiation and achieve a robust CLI image. PMID:27648450

  8. Induced circularly polarized luminescence arising from anion or protein binding to racemic emissive lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Carr, Rachel; Puckrin, Robert; McMahon, Brian K.; Pal, Robert; Parker, David; Pålsson, Lars-Olof

    2014-06-01

    A circularly polarized luminescence (CPL) spectrometer has been built and used to study the binding interaction of lactate and four different proteins with racemic EuIII and TbIII complexes in aqueous solution. Lactate binding gives rise to strong induced CPL spectra, and the observed emission dissymmetry factors vary linearly with enantiomeric composition. Particularly strong induced TbIII CPL also characterizes the binding interaction of alpha-1-acid glycoprotein with a dissociation constant, Kd, of 2.5 μM.

  9. Luminescent osmium(ii) bi-1,2,3-triazol-4-yl complexes: photophysical characterisation and application in light-emitting electrochemical cells.

    PubMed

    Ross, Daniel A W; Scattergood, Paul A; Babaei, Azin; Pertegás, Antonio; Bolink, Henk J; Elliott, Paul I P

    2016-05-01

    The series of osmium(ii) complexes [Os(bpy)3-n(btz)n][PF6]2 (bpy = 2,2'-bipyridyl, btz = 1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl, n = 0, n = 1, n = 2, n = 3), have been prepared and characterised. The progressive replacement of bpy by btz leads to blue-shifted UV-visible electronic absorption spectra, indicative of btz perturbation of the successively destabilised bpy-centred LUMO. For , a dramatic blue-shift relative to the absorption profile for is observed, indicative of the much higher energy LUMO of the btz ligand over that of bpy, mirroring previously reported data on analogous ruthenium(ii) complexes. Unlike the previously reported ruthenium systems, heteroleptic complexes and display intense emission in the far-red/near-infrared (λmax = 724 and 713 nm respectively in aerated acetonitrile at RT) as a consequence of higher lying, and hence less thermally accessible, (3)MC states. This assertion is supported by ground state DFT calculations which show that the dσ* orbitals of to are destabilised by between 0.60 and 0.79 eV relative to their Ru(ii) analogues. The homoleptic complex appears to display extremely weak room temperature emission, but on cooling to 77 K the complex exhibits highly intense blue emission with λmax 444 nm. As complexes to display room temperature luminescent emission and readily reversible Os(ii)/(iii) redox couples, light-emitting electrochemical cell (LEC) devices were fabricated. All LECs display electroluminescent emission in the deep-red/near-IR (λmax = 695 to 730 nm). Whilst devices based on and show inferior current density and luminance than LECs based on , the device utilising shows the highest external quantum efficiency at 0.3%. PMID:27055067

  10. Luminescence of rhodamine B doped in silica films by evaporation-induced self-assembly

    NASA Astrophysics Data System (ADS)

    Yao, Lanfang; Lu, Fengqin; Yue, Chunxiao; Xie, Fujiang; Guan, Feifei

    2008-02-01

    Rhodamine B was embedded in a matrix of mesoporous silica films by the sol-gel method. A precursor sol containing tetraethoxysilane, ethanol, surfactant cetyltrimethylammonium bromide (CTAB), water, rhodamine B and acid catalyst was prepared by sol-gel. Depositing the precursor sol on a substrate wherein evaporation of solvent and water causes the formation of mesostructured films on the substrate surface by evaporation-induced self- assembly process. The nanocomposites films were obtained by embedded rhodamine B in the pores of mesoporous silica films. The mesoporous film was characterized by XRD and TEM, UV-VIS-NIR. The luminescence was measured and a red shift in the peak of the luminescence spectra compared with rhodamine B in the film and rhodamine B in water was observed, which may be interpreted as reflecting a decrease in the dipole moment of the exited molecule. The results show the luminescence action of rhodamine B in nanopores approach to single molecule's. This relates to the restriction of nanopores to organic molecules. The degree of aggregation decreases for the mesoporous silica films may be regarded as a hydroxylic, relatively polar environment, less polar than water although controversy still exists on the role of water in causing aggregation.

  11. Iron-induced luminescence as a method for assessing lipid peroxidation of frozen-thawed goat spermatozoa.

    PubMed

    Gogol, P; Wierzchoś-Hilczer, A; Cegła, M

    2007-07-01

    Freezing/thawing procedures induce enhanced reactive oxygen species (ROS) formation in mammalian sperm and these ROS may be a cause for the decrease in sperm function following cryopreservation. In the present study, we used a chemiluminescence method to detect ROS-induced damage in goat spermatozoa. Iron-induced luminescence of fresh and frozen/thawed sperm cells was assessed using a luminometer. It was shown that the freezing/thawing procedure had a significant effect on some luminescence parameters. Semen freezing significantly increased the values of integral, peak max, T.half (rise) and T.max (peak) parameters. A significant correlation was observed between the percentage of motile spermatozoa and integral, peak max and T.half (rise) parameters. In conclusion, the results of the present study indicate that measurement of induced luminescence can be an alternative, sensitive and relatively simple method for assessing the effect of cryopreservation on oxidative damage to spermatozoa. PMID:22444748

  12. Spectral analysis of photo-induced delayed luminescence from human skin in vivo

    NASA Astrophysics Data System (ADS)

    Musumeci, Francesco; Lanzanò, Luca; Privitera, Simona; Tudisco, Salvatore; Scordino, Agata

    2007-07-01

    The UVA induced Delayed Luminescence (DL), has been measured in vivo in the forearm skin of some healthy volunteers of different sex and age during several periods of the year. An innovative instrument able to detect, in single photon counting mode, the spectrum and the time trend of the DL emission has been used. The measured differences in the time trends of the spectral components may be related to the sex and the age. The potential development of a new analysis technique based on this phenomenon is discussed.

  13. GCR-induced Photon Luminescence of the Moon: The Moon as a CR Detector

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Lee, Kerry; Andersen, Vic

    2007-01-01

    We report on the results of a preliminary study of the GCR-induced photon luminescence of the Moon using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) in FLUKA to determine the photon fluence when there is no sunshine or Earthshine. From the photon fluence we derive the energy spectrum which can be utilized to design an orbiting optical instrument for measuring the GCR-induced luminescence. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of its radiogenic constituents lying in the surface and interior. Also, we investigate transient optical flashes from high-energy CRs impacting the lunar surface (boulders and regolith). The goal is to determine to what extent the Moon could be used as a rudimentary CR detector. Meteor impacts on the Moon have been observed for centuries to generate such flashes, so why not CRs?

  14. Assembly-Induced Enhancement of Cu Nanoclusters Luminescence with Mechanochromic Property.

    PubMed

    Wu, Zhennan; Liu, Jiale; Gao, Yang; Liu, Huiwen; Li, Tingting; Zou, Haoyang; Wang, Zhigang; Zhang, Kai; Wang, Yue; Zhang, Hao; Yang, Bai

    2015-10-14

    Metal nanoclusters (NCs) as a new class of phosphors have attracted a great deal of interest owing to their unique electronic structure and subsequently molecule-like optical properties. However, limited successes have been achieved in producing the NCs with excellent luminescent performance. In this paper, we demonstrate the significant luminescence intensity enhancement of 1-dodecanethiol (DT)-capped Cu NCs via self-assembly strategy. By forming compact and ordered assemblies, the original nonluminescent Cu NCs exhibit strong emission. The flexibility of self-assembly allows to further control the polymorphism of Cu NCs assemblies, and hence the emission properties. Comparative structural and optical analysis of the polymorphic NCs assemblies permits to establish a relationship between the compactness of assemblies and the emission. First, high compactness reinforces the cuprophilic Cu(I)···Cu(I) interaction of inter- and intra-NCs, and meanwhile, suppresses intramolecular vibration and rotation of the capping ligand of DT, thus enhancing the emission intensity of Cu NCs. Second, as to the emission energy that depends on the distance of Cu(I)···Cu(I), the improved compactness increases average Cu(I)···Cu(I) distance by inducing additional inter-NCs cuprophilic interaction, and therewith leads to the blue shift of NCs emission. Attributing to the assembly mediated structural polymorphism, the NCs assemblies exhibit distinct mechanochromic and thermochromic luminescent properties. Metal NCs-based white light-emitting diodes are further fabricated by employing the NCs assemblies with blue-green, yellow, and red emissions as phosphors. PMID:26397821

  15. Sensitive detection of PDT-induced cell damages with luminescent oxygen nanosensors

    NASA Astrophysics Data System (ADS)

    Ma, Hong-Ru; Peng, Hong-shang; You, Fang-tian; Ping, Jian-tao; Zhou, Chao; Guo, Lan-ying

    2016-09-01

    In this work luminescent nanosensors specifically created for intracellular oxygen (ic-O2) were utilized to assess photodynamic therapy (PDT) -induced cell damages. Firstly, ic-O2 was demonstrated to be consumed much faster than extracellular O2 with respective O2 nanosensors. Using the ic-O2 nanosensors, PDT-treated cells with different degree of impairment were then resolved according to the oxygen consumption rate (OCR). The evolving trend of cytotoxicity derived from OCRs was in agreement with cell viability obtained from 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Moreover, the direct damage of PDT on cell mitochondria was successfully detected by monitoring respiration instantly after PDT treatment, which is actually beyond the scope of MTT assay. These results suggest that fluorescence sensing of ic-O2-associated cell respiration is promising and even may become a standardized method, complementary to MTT assay, to evaluate PDT-induced cytotoxicity.

  16. Time Evolution of Radiation-Induced Luminescence in Terbium-Doped Silicate Glass

    NASA Technical Reports Server (NTRS)

    West, Michael S.; Winfree, William P.

    1996-01-01

    A study was made on two commercially available terbium-doped silicate glasses. There is an increased interest in silicate glasses doped with rare-earth ions for use in high-energy particle detection and radiographic applications. These glasses are of interest due to the fact that they can be formed into small fiber sensors; a property that can be used to increase the spatial resolution of a detection system. Following absorption of radiation, the terbium ions become excited and then emit photons via 4f-4f electronic transitions as they relax back to the ground state. The lifetime of these transitions is on the order of milliseconds. A longer decay component lasting on the order of minutes has also been observed. While radiative transitions in the 4f shell of rare-earth ions are generally well understood by the Judd-Olfelt theory, the pr'esence of a longer luminescence decay component is not. Experimental evidence that the long decay component is due, in part, to the thermal release of trapped charge carriers will be presented. In addition, a theoretical model describing the time evolution of the radiation-induced luminescence will be presented.

  17. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy.

    PubMed

    Ji, J; Colosimo, A M; Anwand, W; Boatner, L A; Wagner, A; Stepanov, P S; Trinh, T T; Liedke, M O; Krause-Rehberg, R; Cowan, T E; Selim, F A

    2016-01-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials. PMID:27550235

  18. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    PubMed Central

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-01-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials. PMID:27550235

  19. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy.

    PubMed

    Ji, J; Colosimo, A M; Anwand, W; Boatner, L A; Wagner, A; Stepanov, P S; Trinh, T T; Liedke, M O; Krause-Rehberg, R; Cowan, T E; Selim, F A

    2016-08-23

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  20. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    NASA Astrophysics Data System (ADS)

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-08-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  1. X-ray Inducible Luminescence and Singlet Oxygen Sensitization by an Octahedral Molybdenum Cluster Compound: A New Class of Nanoscintillators.

    PubMed

    Kirakci, Kaplan; Kubát, Pavel; Fejfarová, Karla; Martinčík, Jiří; Nikl, Martin; Lang, Kamil

    2016-01-19

    Newly synthesized octahedral molybdenum cluster compound (n-Bu4N)2[Mo6I8(OOC-1-adamantane)6] revealed uncharted features applicable for the development of X-ray inducible luminescent materials and sensitizers of singlet oxygen, O2((1)Δg). The compound exhibits a red-NIR luminescence in the solid state and in solution (e.g., quantum yield of 0.76 in tetrahydrofuran) upon excitation by UV-vis light. The luminescence originating from the excited triplet states is quenched by molecular oxygen to produce O2((1)Δg) with a high quantum yield. Irradiation of the compound by X-rays generated a radioluminescence with the same emission spectrum as that obtained by UV-vis excitation. It proves the formation of the same excited triplet states regardless of the excitation source. By virtue of the described behavior, the compound is suggested as an efficient sensitizer of O2((1)Δg) upon X-ray excitation. The luminescence and radioluminescence properties were maintained upon embedding the compound in polystyrene films. In addition, polystyrene induced an enhancement of the radioluminescence intensity via energy transfer from the scintillating polymeric matrix. Sulfonated polystyrene nanofibers were used for the preparation of nanoparticles which form stable dispersions in water, while keeping intact the luminescence properties of the embedded compound over a long time period. Due to their small size and high oxygen diffusivity, these nanoparticles are suitable carriers of sensitizers of O2((1)Δg). The presented results define a new class of nanoscintillators with promising properties for X-ray inducible photodynamic therapy.

  2. Ligand Induced Circular Dichroism and Circularly Polarized Luminescence in CdSe Quantum Dots

    PubMed Central

    Tohgha, Urice; Deol, Kirandeep K.; Porter, Ashlin G.; Bartko, Samuel G.; Choi, Jung Kyu; Leonard, Brian M.; Varga, Krisztina; Kubelka, Jan; Muller, Gilles; Balaz, Milan

    2014-01-01

    Chiral thiol capping ligands L- and D-cysteines induced modular chiroptical properties in achiral cadmium selenide quantum dots (CdSe QDs). Cys-CdSe prepared from achiral oleic acid capped CdSe by post-synthetic ligand exchange displayed size-dependent electronic circular dichroism (CD) and circularly polarized luminescence (CPL). Opposite CPL signals were measured for the CdSe QDs capped with D- and L-cysteine. The CD profile and CD anisotropy varied with size of CdSe nanocrystals with largest anisotropy observed for CdSe nanoparticles of 4.4 nm. Magic angle spinning solid state NMR (MAS ssNMR) experiments suggested bidentate interaction between cysteine and the surface of CdSe. Density functional theory (DFT) calculations verified that attachment of L- and D-cysteine to the surface of model (CdSe)13 nanoclusters induces measurable opposite CD signals for the exitonic band of the nanocluster. The chirality was induced by the hybridization of highest occupied CdSe molecular orbitals with those of the chiral ligand. PMID:24200288

  3. Ligand induced circular dichroism and circularly polarized luminescence in CdSe quantum dots.

    PubMed

    Tohgha, Urice; Deol, Kirandeep K; Porter, Ashlin G; Bartko, Samuel G; Choi, Jung Kyu; Leonard, Brian M; Varga, Krisztina; Kubelka, Jan; Muller, Gilles; Balaz, Milan

    2013-12-23

    Chiral thiol capping ligands L- and D-cysteines induced modular chiroptical properties in achiral cadmium selenide quantum dots (CdSe QDs). Cys-CdSe prepared from achiral oleic acid capped CdSe by postsynthetic ligand exchange displayed size-dependent electronic circular dichroism (CD) and circularly polarized luminescence (CPL). Opposite CPL signals were measured for the CdSe QDs capped with D- and L-cysteine. The CD profile and CD anisotropy varied with size of CdSe nanocrystals with largest anisotropy observed for CdSe nanoparticles of 4.4 nm. Magic angle spinning solid state NMR (MAS ssNMR) experiments suggested bidentate interaction between cysteine and the surface of CdSe. Time Dependent Density Functional Theory (TDDFT) calculations verified that attachment of L- and D-cysteine to the surface of model (CdSe)13 nanoclusters induces measurable opposite CD signals for the exitonic band of the nanocluster. The origin of the induced chirality is consistent with the hybridization of highest occupied CdSe molecular orbitals with those of the chiral ligand.

  4. Delayed luminescence to monitor programmed cell death induced by berberine on thyroid cancer cells

    NASA Astrophysics Data System (ADS)

    Scordino, Agata; Campisi, Agata; Grasso, Rosaria; Bonfanti, Roberta; Gulino, Marisa; Iauk, Liliana; Parenti, Rosalba; Musumeci, Francesco

    2014-11-01

    Correlation between apoptosis and UVA-induced ultraweak photon emission delayed luminescence (DL) from tumor thyroid cell lines was investigated. In particular, the effects of berberine, an alkaloid that has been reported to have anticancer activities, on two cancer cell lines were studied. The FTC-133 and 8305C cell lines, as representative of follicular and anaplastic thyroid human cancer, respectively, were chosen. The results show that berberine is able to arrest cell cycle and activate apoptotic pathway as shown in both cell lines by deoxyribonucleic acid fragmentation, caspase-3 cleavage, p53 and p27 protein overexpression. In parallel, changes in DL spectral components after berberine treatment support the hypothesis that DL from human cells originates mainly from mitochondria, since berberine acts especially at the mitochondrial level. The decrease of DL blue component for both cell lines could be related to the decrease of intra-mitochondrial nicotinamide adenine dinucleotide and may be a hallmark of induced apoptosis. In contrast, the response in the red spectral range is different for the two cell lines and may be ascribed to a different iron homeostasis.

  5. Transient luminescence induced by electrical refilling of charge carrier traps of dislocation network at hydrophilically bonded Si wafers interface

    SciTech Connect

    Bondarenko, Anton; Vyvenko, Oleg

    2014-02-21

    Dislocation network (DN) at hydrophilically bonded Si wafers interface is placed in space charge region (SCR) of a Schottky diode at a depth of about 150 nm from Schottky electrode for simultaneous investigation of its electrical and luminescent properties. Our recently proposed pulsed traps refilling enhanced luminescence (Pulsed-TREL) technique based on the effect of transient luminescence induced by refilling of charge carrier traps with electrical pulses is further developed and used as a tool to establish DN energy levels responsible for D1 band of dislocation-related luminescence in Si (DRL). In present work we do theoretical analysis and simulation of traps refilling kinetics dependence on refilling pulse magnitude (Vp) in two levels model: shallow and deep. The influence of initial charge state of deep level on shallow level occupation-Vp dependence is discussed. Characteristic features predicted by simulations are used for Pulsed-TREL experimental results interpretation. We conclude that only shallow (∼0.1 eV from conduction and valence band) energetic levels in the band gap participate in D1 DRL.

  6. Femtosecond Laser-Induced Upconversion Luminescence in Rare-Earth Ions by Nonresonant Multiphoton Absorption.

    PubMed

    Yao, Yunhua; Xu, Cheng; Zheng, Ye; Yang, Chengshuai; Liu, Pei; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

    2016-07-21

    The upconversion luminescence of rare-earth ions has attracted considerable interest because of its important applications in photoelectric conversion, color display, laser device, multiplexed biolabeling, and security printing. Previous studies mainly explored the upconversion luminescence generation through excited state absorption, energy transfer upconversion, and photon avalanche under the continuous wave laser excitation. Here, we focus on the upconversion luminescence generation through a nonresonant multiphoton absorption by using the intense femtosecond pulsed laser excitation and study the upconversion luminescence intensity control by varying the femtosecond laser phase and polarization. We show that the upconversion luminescence of rare-earth ions under the intense femtosecond laser field excitation is easy to be obtained due to the nonresonant multiphoton absorption through the nonlinear interaction between light and matter, which is not available by the continuous wave laser excitation in previous works. We also show that the upconversion luminescence intensity can be effectively controlled by varying the femtosecond pulsed laser phase and polarization, which can open a new technological opportunity to generate and control the upconversion luminescence of rare-earth ions and also can be further extended to the relevant application areas. PMID:27367751

  7. Self-assembly of α-6T Molecule on Ag(100) and Related STM Induced Luminescence

    NASA Astrophysics Data System (ADS)

    Chen, Liu-guo; Zhang, Chao; Zhang, Rui; Dong, Zhen-chao

    2011-12-01

    We have investigated the self-assembly and light emission properties of organic α-sexithiophene (α-6T) molecules on Ag(100) under different coverage by scanning tunneling microscopy (STM). At very low coverage, the α-6T molecules form a unique enantiomer by grouping four molecules into a windmill supermolecular structure. As the coverage is increased, α-6T molecules tend to pack side by side into a denser stripe structure. Further increase of the coverage will lead to the layer-by-layer growth of molecules on Ag(100) with the lower-layer stripe pattern serving as a template. Molecular fluorescence for α-6T molecules on Ag(100) at a coverage of five monolayers has been detected by light excitations, which indicates a well decoupled electronic states for the top-layer α-6T molecules. However, the STM induced luminescent spectra for the same sample reveal only plasmonic-like emission. The absence of intramolecular fluorescence in this case suggests that the electronic decoupling is not a sufficient condition for generating photon emission from molecules. For intramolecular fluorescence to occur, the orientation of the dynamic dipole moment of molecules and the energy-level alignment at the molecule-metal interface are also important so that molecules can be effectively excited through efficient dipolar coupling with local plasmons and by injecting holes into the molecules.

  8. Insights on proximity effect and multiphoton induced luminescence from gold nanospheres in far field optical microscopy

    SciTech Connect

    Borglin, Johan; Guldbrand, Stina; Evenbratt, Hanne; Kirejev, Vladimir; Ericson, Marica B.; Grönbeck, Henrik

    2015-12-07

    Gold nanoparticles can be visualized in far-field multiphoton laser-scanning microscopy (MPM) based on the phenomena of multiphoton induced luminescence (MIL). This is of interest for biomedical applications, e.g., for cancer diagnostics, as MPM allows for working in the near-infrared (NIR) optical window of tissue. It is well known that the aggregation of particles causes a redshift of the plasmon resonance, but its implications for MIL applying far-field MPM should be further exploited. Here, we explore MIL from 10 nm gold nanospheres that are chemically deposited on glass substrates in controlled coverage gradients using MPM operating in NIR range. The substrates enable studies of MIL as a function of inter-particle distance and clustering. It was shown that MIL was only detected from areas on the substrates where the particle spacing was less than one particle diameter, or where the particles have aggregated. The results are interpreted in the context that the underlying physical phenomenon of MIL is a sequential two-photon absorption process, where the first event is driven by the plasmon resonance. It is evident that gold nanospheres in this size range have to be closely spaced or clustered to exhibit detectable MIL using far-field MPM operating in the NIR region.

  9. Hard X-ray-induced optical luminescence via biomolecule-directed metal clusters†

    PubMed Central

    Pratx, Guillem; Sun, Conroy; Sakamoto, Masanori; Ahmad, Moiz; Volotskova, Olga; Ong, Qunxiang; Teranishi, Toshiharu; Harada, Yoshie

    2014-01-01

    Here, we demonstrate that biomolecule-directed metal clusters are applicable in the study of hard X-ray excited optical luminescence, promising a new direction in the development of novel X-ray-activated imaging probes. PMID:24463467

  10. ZnO Luminescence and scintillation studied via photoexcitation, x-ray excitation, and gamma-induced positron spectroscopy"

    SciTech Connect

    Ji, C; Colosimo, A; Anwand, W; Boatner, Lynn A; Wagner, A; Stepanov, P S; Trinh, t t; Liedke, m o; Krause-Rehberg, R; Cowan, T E; Selim, F. A.

    2016-01-01

    Luminescence and scintillation in ZnO single crystals were measured by photoluminescence and X-ray-induced luminescence (XRIL). XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. The origin of green emission, the dominant trap emission in ZnO, was investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials or the surroundings. The measurements showed the absence of positron traps in the crystals and yielded a bulk positron lifetime value that is in complete agreement with the predicted theoretical value = thereby confirming the advantage of the GIPS method. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE.

  11. ZnO Luminescence and scintillation studied via photoexcitation, x-ray excitation, and gamma-induced positron spectroscopy"

    DOE PAGES

    Ji, C; Colosimo, A; Anwand, W; Boatner, Lynn A; Wagner, A; Stepanov, P S; Trinh, t t; Liedke, m o; Krause-Rehberg, R; Cowan, T E; et al

    2016-01-01

    Luminescence and scintillation in ZnO single crystals were measured by photoluminescence and X-ray-induced luminescence (XRIL). XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. The origin of green emission, the dominant trap emission in ZnO, was investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials or the surroundings. The measurements showed the absence of positron traps in the crystalsmore » and yielded a bulk positron lifetime value that is in complete agreement with the predicted theoretical value = thereby confirming the advantage of the GIPS method. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE.« less

  12. Defects in sodalite-group minerals determined from X-ray-induced luminescence

    NASA Astrophysics Data System (ADS)

    Finch, Adrian A.; Friis, Henrik; Maghrabi, Mufeed

    2016-07-01

    The luminescence spectra of a suite of natural sodium framework silicates including four different sodalite variants and tugtupite have been collected during X-ray irradiation as a function of temperature between 20 and 673 K. The origin of the emission bands observed in these samples is attributed to F-centres (360 nm), paramagnetic oxygen defects (400 and 450 nm), S2 - ions (620 nm) and tetrahedral Fe3+ (730 nm). Luminescence in the yellow (550 nm) is tentatively attributed to Mn2+, and red luminescence in Cr-rich pink sodalite is possibly from Cr3+ activation. Sudden reduction in luminescence intensities of emission centres was observed for all minerals in the 60-120 K range. Since it is common to all the sodalite-group minerals, we infer it is a feature of the aluminosilicate framework. Sodalite luminescence has responses from substitutions on the framework (e.g. paramagnetic oxygen defects, Fe3+) which give sodalite properties akin to other framework silicates such as feldspar and quartz. However, the presence of the sodalite cage containing anions (such as F-centres, S2 - ions) imparts additional properties akin to alkali halides. The possibility of coupling between Fe3+ and S2 - is discussed. The overall luminescence behaviour of sodalite group can be understood in terms of competition between these centre types.

  13. Osteogenic, stem cell and molecular characterisation of the human induced membrane from extremity bone defects

    PubMed Central

    Ode, G.; Hoelscher, G.; Ingram, J.; Bethea, S.; Bosse, M. J.

    2016-01-01

    Objectives The biomembrane (induced membrane) formed around polymethylmethacrylate (PMMA) spacers has value in clinical applications for bone defect reconstruction. Few studies have evaluated its cellular, molecular or stem cell features. Our objective was to characterise induced membrane morphology, molecular features and osteogenic stem cell characteristics. Methods Following Institutional Review Board approval, biomembrane specimens were obtained from 12 patient surgeries for management of segmental bony defects (mean patient age 40.7 years, standard deviation 14.4). Biomembranes from nine tibias and three femurs were processed for morphologic, molecular or stem cell analyses. Gene expression was determined using the Affymetrix GeneChip Operating Software (GCOS). Molecular analyses compared biomembrane gene expression patterns with a mineralising osteoblast culture, and gene expression in specimens with longer spacer duration (> 12 weeks) with specimens with shorter durations. Statistical analyses used the unpaired student t-test (two tailed; p < 0.05 was considered significant). Results Average PMMA spacer in vivo time was 11.9 weeks (six to 18). Trabecular bone was present in 33.3% of the biomembrane specimens; bone presence did not correlate with spacer duration. Biomembrane morphology showed high vascularity and collagen content and positive staining for the key bone forming regulators, bone morphogenetic protein 2 (BMP2) and runt-related transcription factor 2 (RUNX2). Positive differentiation of cultured biomembrane cells for osteogenesis was found in cells from patients with PMMA present for six to 17 weeks. Stem cell differentiation showed greater variability in pluripotency for osteogenic potential (70.0%) compared with chondrogenic or adipogenic potentials (100% and 90.0%, respectively). Significant upregulation of BMP2 and 6, numerous collagens, and bone gla protein was present in biomembrane compared with the cultured cell line. Biomembranes with

  14. Generation of cavitation luminescence by laser-induced exothermic chemical reaction

    SciTech Connect

    Jung Park, Han; Diebold, Gerald J.

    2013-08-14

    Absorption of high power laser radiation by aqueous carbon suspensions is known to result in the formation of highly compressed bubbles of hydrogen and carbon monoxide through the endothermic carbon-steam reaction. The bubbles expand rapidly, overreaching their equilibrium diameter, and then collapse tens to hundreds of microseconds after formation to give a flash of radiation. Here we report on the effects of laser-initiated exothermic chemical reaction on cavitation luminescence. Experiments with hydrogen peroxide added to colloidal carbon suspensions show that both the time of the light flash following the laser pulse and the intensity of luminescence increase with hydrogen peroxide concentration, indicating that large, highly energetic gas bubbles are produced. Additional experiments with colloidal carbon suspensions show the effects of high pressure on the luminescent intensity and its time of appearance following firing of the laser.

  15. Characterisation of antibody responses in pigs induced by recombinant oncosphere antigens from Taenia solium.

    PubMed

    Jayashi, César M; Gonzalez, Armando E; Castillo Neyra, Ricardo; Kyngdon, Craig T; Gauci, Charles G; Lightowlers, Marshall W

    2012-12-14

    Recombinant antigens cloned from the oncosphere life cycle stage of the cestode parasite Taenia solium (T. solium) have been proven to be effective as vaccines for protecting pigs against infections with T. solium. Previous studies have defined three different host protective oncosphere antigens, TSOL18, TSOL16 and TSOL45. In this study, we evaluated the potential for combining the antigens TSOL16 and TSOL18 as a practical vaccine. Firstly, in a laboratory trial, we compared the immunogenicity of the combined antigens (TSOL16/18) versus the immunogenicity of the antigens separately. Secondly, in a field trial, we tested the ability of the TSOL16/18 vaccine to induce detectable antibody responses in animals living under environmental stress and traditionally reared in areas where T. solium cysticercosis is endemic; and finally, we characterised the immune response of the study population. Pigs of 8-16 weeks of age were vaccinated with 200 μg each of TSOL16 and TSOL18, plus 5mg of Quil-A. Specific total IgG, IgG(1) and IgG(2) antibody responses induced by TSOL16 and TSOL18 were determined with ELISA. The immunogenicity of both antigens was retained in the combined TSOL16/18 vaccine. The combined vaccine TSOL16/18 induced detectable specific anti-TSOL18 antibody responses in 100% (113/113) and specific anti-TSOL16 in 99% (112/113) of the vaccinated animals measured at 2 weeks following the booster vaccination. From the two IgG antibody subtypes analysed we found there was stronger response to IgG(2).

  16. Towards the differentiation of non-treated and treated corundum minerals by ion-beam-induced luminescence and other complementary techniques.

    PubMed

    Calvo del Castillo, H; Deprez, N; Dupuis, T; Mathis, F; Deneckere, A; Vandenabeele, P; Calderón, T; Strivay, D

    2009-06-01

    Differentiation of treated and non-treated gemstones is a chief concern for major jewellery import companies. Low-quality corundum specimens coming from Asia appear to be often treated with heat, BeO or flux in order to enhance their properties as precious minerals. A set of corundum samples, rubies and sapphires from different origins, both treated and non-treated has been analysed at the Centre Européen d'Archéométrie, with ion-beam-induced luminescence (IBIL) and other complementary techniques such as Raman, proton-induced X-ray emission (PIXE), and proton-induced gamma-ray emission (PIGE). IBIL, also known as ionoluminescence, has been used before to detect impurities or defects inside synthetic materials and natural minerals; its use for the discrimination of gemstone simulants or synthetic analogues has been elsewhere discussed (Cavenago-Bignami Moneta, Gemología, Tomo I Piedras preciosas, perlas, corales, marfil. Ediciones Omega, Barcelona, 1991). PIXE has been frequently applied in the archaeometric field for material characterisation and provenance studies of minerals (Hughes, Ruby & sapphire. RWH Publishing, Fallbrook, 1997; Calvo del Castillo et al., Anal Bioanal Chem 387:869-878, 2007; Calligaro et al., NIM-B 189:320-327, 2002) and PIGE complements the elemental analysis by detecting light elements in these materials such as-and lighter than-sodium that cannot be identified with the PIXE technique (Sanchez et al., NIM-B 130:682-686, 1997; Emmett et al., Gems Gemology 39:84-135, 2003). The micro-Raman technique has also been used complementarily to ion beam analysis techniques for mineral characterisation (Novak et al., Appl Surf Sci 231-232:917-920, 2004). The aim of this study is to provide new means for systematic analysis of corundum gemstone-quality mineral, alternative to the traditional gemmologic methods; for this purpose, a Spanish jewellery import company supplied us with a number of natural corundum samples coming from different places

  17. Towards the differentiation of non-treated and treated corundum minerals by ion-beam-induced luminescence and other complementary techniques.

    PubMed

    Calvo del Castillo, H; Deprez, N; Dupuis, T; Mathis, F; Deneckere, A; Vandenabeele, P; Calderón, T; Strivay, D

    2009-06-01

    Differentiation of treated and non-treated gemstones is a chief concern for major jewellery import companies. Low-quality corundum specimens coming from Asia appear to be often treated with heat, BeO or flux in order to enhance their properties as precious minerals. A set of corundum samples, rubies and sapphires from different origins, both treated and non-treated has been analysed at the Centre Européen d'Archéométrie, with ion-beam-induced luminescence (IBIL) and other complementary techniques such as Raman, proton-induced X-ray emission (PIXE), and proton-induced gamma-ray emission (PIGE). IBIL, also known as ionoluminescence, has been used before to detect impurities or defects inside synthetic materials and natural minerals; its use for the discrimination of gemstone simulants or synthetic analogues has been elsewhere discussed (Cavenago-Bignami Moneta, Gemología, Tomo I Piedras preciosas, perlas, corales, marfil. Ediciones Omega, Barcelona, 1991). PIXE has been frequently applied in the archaeometric field for material characterisation and provenance studies of minerals (Hughes, Ruby & sapphire. RWH Publishing, Fallbrook, 1997; Calvo del Castillo et al., Anal Bioanal Chem 387:869-878, 2007; Calligaro et al., NIM-B 189:320-327, 2002) and PIGE complements the elemental analysis by detecting light elements in these materials such as-and lighter than-sodium that cannot be identified with the PIXE technique (Sanchez et al., NIM-B 130:682-686, 1997; Emmett et al., Gems Gemology 39:84-135, 2003). The micro-Raman technique has also been used complementarily to ion beam analysis techniques for mineral characterisation (Novak et al., Appl Surf Sci 231-232:917-920, 2004). The aim of this study is to provide new means for systematic analysis of corundum gemstone-quality mineral, alternative to the traditional gemmologic methods; for this purpose, a Spanish jewellery import company supplied us with a number of natural corundum samples coming from different places

  18. A high-content platform to characterise human induced pluripotent stem cell lines

    PubMed Central

    Leha, Andreas; Moens, Nathalie; Meleckyte, Ruta; Culley, Oliver J.; Gervasio, Mia K.; Kerz, Maximilian; Reimer, Andreas; Cain, Stuart A.; Streeter, Ian; Folarin, Amos; Stegle, Oliver; Kielty, Cay M.; Durbin, Richard; Watt, Fiona M.; Danovi, Davide

    2016-01-01

    Induced pluripotent stem cells (iPSCs) provide invaluable opportunities for future cell therapies as well as for studying human development, modelling diseases and discovering therapeutics. In order to realise the potential of iPSCs, it is crucial to comprehensively characterise cells generated from large cohorts of healthy and diseased individuals. The human iPSC initiative (HipSci) is assessing a large panel of cell lines to define cell phenotypes, dissect inter- and intra-line and donor variability and identify its key determinant components. Here we report the establishment of a high-content platform for phenotypic analysis of human iPSC lines. In the described assay, cells are dissociated and seeded as single cells onto 96-well plates coated with fibronectin at three different concentrations. This method allows assessment of cell number, proliferation, morphology and intercellular adhesion. Altogether, our strategy delivers robust quantification of phenotypic diversity within complex cell populations facilitating future identification of the genetic, biological and technical determinants of variance. Approaches such as the one described can be used to benchmark iPSCs from multiple donors and create novel platforms that can readily be tailored for disease modelling and drug discovery. PMID:26608109

  19. Characterisation of proton pump antibodies and stomach pathology in gastritis induced by neonatal immunisation without adjuvant.

    PubMed

    Greenwood, D L; Sentry, J W; Toh, B H

    2001-01-01

    It has previously been reported that neonatal BALB.D2 mice injected with native proton pump antigens without adjuvant develop an irreversible gastritis (Claeys et al, 1997). The ease of inititating gastritis in the neonate stands in contrast with the difficulty in initiating gastritis in adult mice that require repeated immunisation in adjuvant that is reversible following cessation of immunisation (Scarff et al, 1997). In view of these contrasting observations, we set out to ascertain whether we could confirm the observations in neonatal mice as well as further characterise the pathology and the autoantibody response. We found that neonatal gastritis-susceptible BALB/c mice (n=12), immunised with either pig or mouse gastric membranes in the absence of adjuvant, develop gastritis without circulating antibody to parietal cells detected by immunofluorescence, a hallmark of murine and human gastritis (Toh et al, 1997). However, mice immunized with pig gastric membranes (n=6) had circulating antibodies reactive by immunofluorescence to recombinant alpha and/or beta subunit of gastric H+/K+-ATPase expressed by insect cells (Sfalpha and Sfbeta). Four mice from this cohort with antibodies to Sfbeta also had reactivity to gastric H+/K+-ATPase by ELISA, and 3 immunoblotted the beta but not the alpha subunit of the ATPase. In the cohort of mice immunised with mouse gastric membranes (n=6), four produced antibodies reactive by immunofluorescence to Sfalpha, two of which were also reactive to Sfbeta and one developed antibodies detected by ELISA to gastric H+/K+-ATPase. However, no members of this cohort had antibodies reactive by immunoblotting to either the beta or alpha subunit of the ATPase. In all cases gastritic stomachs were characterised by areas deficient in ribosome-rich zymogenic cells and marked reductions in H+/K+-ATPase-positive parietal cells. Metaplasia detected by Maxwell stain, as clusters of mucus-producing cells throughout gastric units, were non

  20. Fluoride-induced reduction of Ag(I) cation leading to formation of silver mirrors and luminescent Ag-nanoparticles.

    PubMed

    Maity, Krishnendu; Panda, Dillip K; Lochner, Eric; Saha, Sourav

    2015-03-01

    In aprotic solvents, Lewis basic F(-) anion reduces Lewis acidic Ag(I) cation to Ag(0), forming metallic silver mirrors on the inner surfaces of reaction vessels and luminescent Ag-nanoparticles (AgNPs) in supernatant solutions, which emit blue light upon UV irradiation. The F(-)-induced formation of silver mirrors and AgNPs was confirmed through X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), fluorescence spectroscopy, and mass spectrometry, whereas the Ag(I)-induced oxidation of F(-) to Ḟ radical, followed by its conversion to HF2(-) via H-abstraction and H-bonding, was evident from (19)F NMR spectroscopy. This redox reaction is deactivated in water, as the reducing power of hydrated F(-) diminishes drastically. Less Lewis basic Cl(-), Br(-), and I(-) ions do not reduce Ag(I) to Ag(0), instead they can only form Ag(I) halide precipitates irrespective of protic or aprotic solvents. The Ag-coated surfaces, luminescent AgNPs, and Ḟ radicals produced by this unprecedented redox reaction could be exploited as electrodes, light-emitting materials, and radical initiators, respectively.

  1. Coordination-Induced Syntheses of Two Hybrid Framework Iodides: A Thermochromic Luminescent Thermometer.

    PubMed

    Zhang, Ren-Chun; Wang, Jun-Jie; Zhang, Jing-Chao; Wang, Meng-Qi; Sun, Min; Ding, Feng; Zhang, Dao-Jun; An, Yong-Lin

    2016-08-01

    Two new 3D hybrid framework iodides, Hmta[(Hmta)Ag4I4] (1; Hmta = hexamethylenetetramine) and [(Hmta)2Ag8I6]I2 (2), have been synthesized under solvothermal conditions. Compound 1 consists of a neutral 3D framework built up from alternation of the tetrahedral Ag4I4 unit and Hmta with dia-b topology. Compound 2 features a 3D cationic framework with flu topology, constructed by cationic [Ag8I6](2+) units linked with Hmta. Tetrahedral Hmta plays crucial structure-directing roles in the formation of these 3D frameworks with high symmetry. The temperature-dependent photoluminescent measurement reveals luminescent thermochromism of the compounds, the emission maximum of which shows a gradual blue shift with increasing temperature. The results indicate that 1 is a promising wavelength- and intensity-dependent luminescent thermometer applicable in two different temperature ranges. PMID:27438190

  2. In situ formation and characterisation of singly ionised atomic europium in rare gas matrices—Luminescence spectroscopy and MP2 calculations

    SciTech Connect

    Byrne, Owen; Davis, Barry; McCaffrey, John G.

    2015-02-07

    Irradiation of atomic europium isolated in the solid rare gases, with low intensity laser excitation of the y{sup 8}P←a{sup 8}S resonance transition at ca. 465 nm, is found to produce singly charged europium cations (Eu{sup +}) in large amounts in xenon and in smaller amounts in argon. Confirmation of the formation of matrix-isolated Eu{sup +} is obtained from characteristic absorption bands in the UV and in the visible spectral regions. The luminescence produced with excitation of the cation bands is presented in greatest detail for Eu/Xe and assigned. Excitation of the 4f{sup 7}({sup 8}S{sub 7/2})6p{sub 3/2} absorption bands of Eu{sup +} between 390 and 410 nm produces emission which is quite distinct from that resulting from excitation of the 4f{sup 7}({sup 8}S{sub 7/2})6p{sub 1/2} absorption (430 to 450 nm) features. The latter consists of narrow, resolved emission bands with Stokes shifts ten times smaller than the former. The observed spectral differences are discussed in relation to the different spatial symmetries of the p{sub 3/2} and p{sub 1/2} orbitals in these j-j coupled (7/2, 3/2){sub J} and the (7/2, 1/2){sub J} levels. Møller-Plesset calculations are conducted to obtain the molecular parameters of the neutral Eu-RG and cationic Eu{sup +}-RG diatomics (RG = Ar, Kr, Xe). From the short bond lengths and the strong binding energies obtained for the Eu{sup +}-RG species, these values suggest the isolation of the ion in small, possibly interstitial sites especially in xenon. In contrast, but consistent with previous work [O. Byrne and J. G. McCaffrey, J. Chem. Phys. 134, 124501 (2011)], the interaction potentials calculated herein for the Eu-RG diatomics suggest that the neutral Eu atom occupies tetra-vacancy (tv) and hexa-vacancy (hv) sites in the solid rare gas hosts. Possible reasons for the facile production of Eu{sup +} in the solid rare gases are discussed. The mechanism proposed is that atomic europium is also acting as an electron acceptor

  3. In situ formation and characterisation of singly ionised atomic europium in rare gas matrices—Luminescence spectroscopy and MP2 calculations

    NASA Astrophysics Data System (ADS)

    Byrne, Owen; Davis, Barry; McCaffrey, John G.

    2015-02-01

    Irradiation of atomic europium isolated in the solid rare gases, with low intensity laser excitation of the y8P←a8S resonance transition at ca. 465 nm, is found to produce singly charged europium cations (Eu+) in large amounts in xenon and in smaller amounts in argon. Confirmation of the formation of matrix-isolated Eu+ is obtained from characteristic absorption bands in the UV and in the visible spectral regions. The luminescence produced with excitation of the cation bands is presented in greatest detail for Eu/Xe and assigned. Excitation of the 4f7(8S7/2)6p3/2 absorption bands of Eu+ between 390 and 410 nm produces emission which is quite distinct from that resulting from excitation of the 4f7(8S7/2)6p1/2 absorption (430 to 450 nm) features. The latter consists of narrow, resolved emission bands with Stokes shifts ten times smaller than the former. The observed spectral differences are discussed in relation to the different spatial symmetries of the p3/2 and p1/2 orbitals in these j-j coupled (7/2, 3/2)J and the (7/2, 1/2)J levels. Møller-Plesset calculations are conducted to obtain the molecular parameters of the neutral Eu-RG and cationic Eu+-RG diatomics (RG = Ar, Kr, Xe). From the short bond lengths and the strong binding energies obtained for the Eu+-RG species, these values suggest the isolation of the ion in small, possibly interstitial sites especially in xenon. In contrast, but consistent with previous work [O. Byrne and J. G. McCaffrey, J. Chem. Phys. 134, 124501 (2011)], the interaction potentials calculated herein for the Eu-RG diatomics suggest that the neutral Eu atom occupies tetra-vacancy (tv) and hexa-vacancy (hv) sites in the solid rare gas hosts. Possible reasons for the facile production of Eu+ in the solid rare gases are discussed. The mechanism proposed is that atomic europium is also acting as an electron acceptor, providing a temporary trap for the ionised electron in the matrices.

  4. Protonation-induced red-coloured circularly polarized luminescence of [5]carbohelicene fused by benzimidazole.

    PubMed

    Sakai, Hayato; Kubota, Takako; Yuasa, Junpei; Araki, Yasuyuki; Sakanoue, Tomo; Takenobu, Taishi; Wada, Takehiko; Kawai, Tsuyoshi; Hasobe, Taku

    2016-07-12

    Benzimidazole-fused [5]carbohelicene ([5]HeliBI) was newly synthesized to examine the spectroscopic and chiroptical properties. The reversible protonation and deprotonation processes of [5]HeliBI were successfully investigated using (1)H NMR, absorption and fluorescence spectral measurements. We also confirmed the circularly polarized luminescence of protonated [5]HeliBI (H(+)-[5]HeliBI). This is the first observation of red-coloured CPL of a helicene derivative. PMID:27319321

  5. Luminescence nanothermometry

    NASA Astrophysics Data System (ADS)

    Jaque, Daniel; Vetrone, Fiorenzo

    2012-07-01

    The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed.The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed. This work was supported by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (Project S2009/MAT-1756), by the Spanish Ministerio de Educacion y Ciencia (MAT2010-16161) and by Caja Madrid Foundation.

  6. Preliminary results on time-resolved ion beam induced luminescence applied to the provenance study of lapis lazuli

    NASA Astrophysics Data System (ADS)

    Czelusniak, C.; Palla, L.; Massi, M.; Carraresi, L.; Giuntini, L.; Re, A.; Lo Giudice, A.; Pratesi, G.; Mazzinghi, A.; Ruberto, C.; Castelli, L.; Fedi, M. E.; Liccioli, L.; Gueli, A.; Mandò, P. A.; Taccetti, F.

    2016-03-01

    This work will present preliminary results concerning the use of time-resolved ion beam induced luminescence applied to provenance studies of lapis lazuli. Measurements were performed at the pulsed beam facility at LABEC laboratory in Florence. Lapis lazuli is a semi-precious gemstone, used as ornament since the early civilizations that can be found in few places on Earth. The importance of this work lies in understanding the origin of various samples of lapis lazuli, from which it may be possible to gain insight into trade routes from ancient times. The samples studied in this work originated from Chile, Afghanistan, Tajikistan, Myanmar, and Siberia. The stones were irradiated with 3 MeV protons and the resulting luminescence was detected by a photomultiplier tube, whose output was acquired using a sampling digitizer VME module (CAEN/V1720). Wavelength discrimination was performed at 430 nm utilizing a range of beam currents. The results showed that, by changing the beam current intensity, one can study different features of lapis lazuli, and this may aid in distinguishing lapis lazuli from different provenances.

  7. In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

    NASA Astrophysics Data System (ADS)

    Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

    2016-06-01

    Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

  8. Plasmon-induced enhancement of yellow-red luminescence in InGaN/Au nanocomposites

    SciTech Connect

    Belyaev, K. G. Usikova, A. A.; Jmerik, V. N.; Kop’ev, P. S.; Ivanov, S. V.; Toropov, A. A.; Brunkov, P. N.

    2015-02-15

    A significant (by up to a factor of 7) increase in the internal quantum efficiency of luminescence is achieved at room temperature in semiconductor-metal-insulator hybrid structures fabricated by the successive deposition of gold and Si{sub 3}N{sub 4} over an array of InGaN nanoblocks, grown by molecular-beam epitaxy. The observed effect can be accounted for by the resonant interaction of excitons localized in InGaN nanoblocks with localized surface-plasmon modes in gold intrusions embedded into InGaN and Si{sub 3}N{sub 4}.

  9. Charge trapping induced by plasma in alumina electrode surface investigated by thermoluminescence and optically stimulated luminescence

    SciTech Connect

    Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ligonzo, T.; Augelli, V.

    2009-02-02

    The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode. Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated luminescence. Comparison with similar results for traps created by other radiation sources clarifies the mechanisms regulating this effect. Alumina's trap energies are approximately 1 eV, and the traps remain active for several days after plasma exposure. These results could be important to keep dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir.

  10. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

    PubMed

    Zolotovskaya, S A; Tyrk, M A; Stalmashonak, A; Gillespie, W A; Abdolvand, A

    2016-10-28

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios. PMID:27658641

  11. Ag7+ ion induced modification of morphology, optical and luminescence behaviour of charge compensated CaMoO4 nanophosphor

    NASA Astrophysics Data System (ADS)

    Dutta, S.; Som, S.; Kunti, A. K.; Sharma, S. K.; Kumar, Vijay; Swart, H. C.; Visser, H. G.

    2016-10-01

    The present paper reports on the swift heavy ion (SHI) induced structural, optical and luminescence properties of CaMoO4:Dy3+/K+ nanophosphor synthesized via hydrothermal route. Herein 100 MeV Ag7+ ion beam was used varying fluence from 1 × 1011 to 1 × 1013 ions/cm2. The depth profile of the Ag7+ ions was estimated using SRIM code. XRD and FESEM results revealed the loss of crystallinity and reduction in particle size after SHI irradiations. The XPS technique confirmed the stability of oxidation states of the elements. Reflectance spectra exhibited a red shift in the absorption band, followed by a decrease in band gap. Decrease in the intensity of the photoluminescence peaks without any change in band positions was also obtained after ion irradiation. The thermoluminescence (TL) characteristics were discussed in detail, and the trapping parameter was calculated. The results were compared on the grounds of linear energy transfer of the irradiated ions.

  12. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass

    NASA Astrophysics Data System (ADS)

    Zolotovskaya, S. A.; Tyrk, M. A.; Stalmashonak, A.; Gillespie, W. A.; Abdolvand, A.

    2016-10-01

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs’ surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  13. Ion-Beam-Induced Luminescence Analysis as Diagnostic Tool for Microstructure Patterning on Diamond by Proton Beam Writing

    NASA Astrophysics Data System (ADS)

    Kada, Wataru; Yokoyama, Akihito; Koka, Masashi; Takano, Katsuyoshi; Satoh, Takahiro; Kamiya, Tomihiro

    2012-06-01

    An in situ diagnostics technique for proton beam writing (PBW) on chemical vapor deposition (CVD) diamond was newly established by developing a method of monochromatic ion-beam-induced luminescence (IBIL) analysis. As a compact optic system of IBIL analysis, a couple of optics including a monochromator and a photon counting photomultiplier were installed on the microbeam line of a 3 MV single-ended accelerator. Changes in the crystal structure of single-crystal CVD diamond were continuously monitored by observing the decay of IBIL at a wavelength related to them. Two-dimensional microscopy images of IBIL were also clearly visualized as patterns on diamond in the postprocess of PBW with the same experimental setup. The total fluence of the proton microbeam was well linked to the photon count of IBIL for the fabrication of micrometer-sized carbonized layers in the CVD diamond crystal.

  14. On second harmonic generation and multiphoton-absorption induced luminescence from laser-reshaped silver nanoparticles embedded in glass.

    PubMed

    Zolotovskaya, S A; Tyrk, M A; Stalmashonak, A; Gillespie, W A; Abdolvand, A

    2016-10-28

    Spherical silver nanoparticles (NPs) of 30 nm diameter embedded in soda-lime glass were uniformly reshaped (elongated) after irradiation by a linearly polarised 250 fs pulsed laser operating within the NPs' surface plasmon resonance band. We observed second harmonic generation (SHG) and multiphoton-absorption-induced luminescence (MAIL) in the embedded laser-reshaped NPs upon picosecond (10 ps) pulsed laser excitation at 1064 nm. A complementary study of SHG and MAIL was conducted in soda-lime glass containing embedded, mechanically-reshaped silver NPs of a similar elongation ratio (aspect ratio) to the laser-reshaped NPs. This supports the notion that the observed difference in SHG and MAIL in the studied nanocomposite systems is due to the shape modification mechanism. The discrete dipole approximation method was used to assess the absorption and scattering cross-sections of the reshaped NPs with different elongation ratios.

  15. SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator

    NASA Astrophysics Data System (ADS)

    Gardés, E.; Balanzat, E.; Ban-d'Etat, B.; Cassimi, A.; Durantel, F.; Grygiel, C.; Madi, T.; Monnet, I.; Ramillon, J.-M.; Ropars, F.; Lebius, H.

    2013-02-01

    We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/μm. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments.

  16. Capillary-force-induced formation of luminescent polystyrene/(rare-earth-doped nanoparticle) hybrid hollow spheres.

    PubMed

    Chen, Min; Xie, Lin; Li, Fuyou; Zhou, Shuxue; Wu, Limin

    2010-10-01

    This paper presents a "one-pot" procedure to synthesize polystyrene/(rare-earth-doped nanoparticles) (PS/REDNPs) hybrid hollow spheres via the in situ diffusion of organic core into inorganic shell under strong capillary force. In this approach, when carboxyl-capped PS colloids were deposited by different REDNPs in aqueous medium, such as LaF3:Eu3+, LaF3:Ce3+-Tb3+, and YVO4:Dy3+, PS/REDNPs inorganic-organic hybrid hollow spheres could be directly obtained via the in situ diffusion of core PS chains into the voids between rare-earth-doped nanoparticles through the strong capillary force. Not only is the synthetic procedure versatile and very simple, but also the obtained hybrid hollow spheres are hydrophilic and luminescent and could be directly used in chemical and biological fields.

  17. Size-induced effect on cathode luminescence spectra of CsI(Na) and CsI(Tl) crystals

    NASA Astrophysics Data System (ADS)

    Liu, Fang; Ouyang, XiaoPing; Liu, Bin; Liu, JinLiang; Chen, Liang; Zhang, ZhongBing; Zhang, XueBin; Feng, Yi

    2014-09-01

    We investigated the cathode luminescence characteristics of CsI(Na) and CsI(Tl) crystals by the spectrum and structure properties at room temperature. We fabricated three different sizes of CsI(Na) and CsI(Tl) crystals and measured their luminescence spectra under cathode rays. We found that CsI(Na) cathode luminescence peaks appear at 420 and 305 nm, and CsI(Tl) cathode luminescence peaks are 540 and 410 nm, the grain size affects CsI(Na) luminescence significantly, and the Na-related 420 nm luminescence intensified relatively when the average grain size reaches ˜20 μm, which becomes weak when the grain size is down to nano-scale. But the cathode luminescence spectra of CsI(Tl) crystals with different size have no obvious changes. Our explanations for these phenomena are that the different impurities in the same host material CsI lead to different luminescence mechanisms. These cathode luminescence characteristics indicate the suitability of CsI(Na) and CsI(Tl) crystals to match photomultiplier tube for large area crystal detector development.

  18. Bimetallic Au2 Cu6 Nanoclusters: Strong Luminescence Induced by the Aggregation of Copper(I) Complexes with Gold(0) Species.

    PubMed

    Kang, Xi; Wang, Shuxin; Song, Yongbo; Jin, Shan; Sun, Guodong; Yu, Haizhu; Zhu, Manzhou

    2016-03-01

    The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal nanoclusters. PMID:26890334

  19. Bimetallic Au2 Cu6 Nanoclusters: Strong Luminescence Induced by the Aggregation of Copper(I) Complexes with Gold(0) Species.

    PubMed

    Kang, Xi; Wang, Shuxin; Song, Yongbo; Jin, Shan; Sun, Guodong; Yu, Haizhu; Zhu, Manzhou

    2016-03-01

    The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal nanoclusters.

  20. Energy transfer induced improvement of luminescent efficiency and thermal stability in phosphate phosphor.

    PubMed

    Zhao, Yun; Lin, Chun Che; Wei, Yi; Chan, Ting-Shan; Li, Guogang

    2016-02-22

    Ce3+ and Eu2+/Tb3+/Mn2+ ions codoped Ca6BaP4O17 (CBPO) phosphors have been prepared via a high-temperature solid state reaction. The structural refinement indicates that the as-prepared phosphors crystallize in monoclinic phase (C2/m) and there are two Ca sites and one Ba site in host lattice. The doping ions are determined to occupy Ca sites and the emission of Ce3+ and Eu2+ ions at different Ca sites were identified and discussed. Since bright blue and yellow emissions were observed from Ce3+and Eu2+ ions monodoped CBPO under n-UV excitation, respectively. They were codoped into the CBPO for designing energy transfer from Ce3+ to Eu2+ to improve the luminescence efficiency of Eu2+. In addition, Tb3+ ions were added into the CBPO:Ce3+ system for realizing highly efficient green emission. The energy transfer mechanisms from Ce3+ to Eu2+/Tb3+ ions were discussed. Interestingly, the incorporation of Mn2+ ions into the CBPO:Ce3+ system enhanced the blue emission of Ce3+ ions due to the modification of crystal lattice. Finally, the thermal stability of CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors were investigated systematically and corresponding mechanisms were proposed. Based on these results, the as-prepared CBPO:Ce3+, Eu2+/Tb3+/Mn2+ phosphors can act as potential blue, yellow, green, and emission-tunable phosphors for n-UV based white LEDs. PMID:26907078

  1. Facile preparation and biological imaging of luminescent polymeric nanoprobes with aggregation-induced emission characteristics through Michael addition reaction.

    PubMed

    Lv, Qiulan; Wang, Ke; Xu, Dazhuang; Liu, Meiying; Wan, Qing; Huang, Hongye; Liang, Shangdong; Zhang, Xiaoyong; Wei, Yen

    2016-09-01

    Water dispersion aggregation-induced emission (AIE) dyes based nanomaterials have recently attracted increasing attention in the biomedical fields because of their unique optical properties, outstanding performance as imaging and therapeutic agents. The methods to conjugate hydrophilic polymers with AIE dyes to solve the hydrophobic nature of AIE dyes and makeS them widely used in biomedicine, which have been extensively explored and paid great effort previously. Although great advance has been made in the fabrication and biomedical applications of AIE-active polymeric nanoprobes, facile and efficient strategies for fabrication of biodegradable AIE-active nanoprobes are still high desirable. In this work, amphiphilic biodegradable fluorescent organic nanoparticles (PLL-TPE-O-E FONs) have been fabricated for the first time by conjugation of AIE dye tetraphenylethene acrylate (TPE-O-E) with Poly-l-Lysine (PLL) through a facile one-step Michael addition reaction, which was carried out under rather mild conditions, included air atmosphere, near room temperature and absent of metal catalysts or hazardous reagents. Due to the unique AIE properties, these amphiphilic copolymers tend to self-assemble into high luminescent water dispersible nanoparticles with size range from 400 to 600nm. Laser scanning microscope and cytotoxicity results revealed that PLL-TPE-O-E FONs can be internalized into cytoplasm with negative cytotoxicity, which implied that PLL-TPE-O-E FONs are promising for biological applications. PMID:27311129

  2. Time-evolving photo-induced changes of luminescent and spectral properties of PbS quantum dots sols

    NASA Astrophysics Data System (ADS)

    Evstropiev, S. K.; Kislyakov, I. M.; Bagrov, I. V.; Belousova, I. M.; Kiselev, V. M.

    2016-05-01

    Light irradiation influence on spectral and luminescent properties of PbS sol, stabilized by high-molecular polyvinylpyrrolidone, was studied as a time-evolving process. Uniform and stable for at least three months PbS/PVP suspensions were obtained with an average quantum dots size of 4 nm. Photoluminescent spectra of the suspensions showed wide intensive emission at 1000-1400 nm upon excitation by visible light. Luminescence intensities of all the suspensions demonstrate nonlinear dependences on the exciting radiation intensity. Experimental results show that light irradiation during luminescence measurements even with low excitation power density can significantly change luminescent and spectral properties of PbS quantum dots. The dependences found can be useful in preparation of a variety of quantum dots-containing photonics materials.

  3. Characterising the Geomorphic Response of a Tropical Mega-River to an Extreme, Cyclone Induced, Flood Event.

    NASA Astrophysics Data System (ADS)

    Hackney, C. R.; Leyland, J.; Darby, S. E.; Parsons, D. R.; Aalto, R. E.; Nicholas, A. P.; Best, J.

    2014-12-01

    Extreme events have the ability to induce extensive geomorphic change in fluvial systems as a result of elevated discharge levels, increased sediment transport capacity and associated changes in sheer stresses along channel boundaries. Understanding how rapid rises in water levels change flow structures and channel boundary roughness is key to understanding the relative significance of large events in terms of driving local and system wide geomorphic change. However, capturing the fluvial process dynamics in operation during such events is technically and logistically difficult, especially in the world's largest rivers. During September 2013, on the peak of the monsoon, a series of tropical cyclones induced a large flood event within the Mekong basin. At the peak of the flood wave, discharge measured ~60000 m3/s; the 11th largest flood on record. Pre and post event high resolution topographic surveys of parts of the bed and bank were captured using a combination of contiguous multibeam echo sounding (MBES) and terrestrial laser scanning (TLS) during the event. Simultaneously detailed measurements of cross sectional and near bank flow structure were acquired using an acoustic Doppler current profiler (aDcp). Together, these unique datasets can be used to characterise and assess the geomorphic impact of a cyclone induced extreme flood event on the Mekong. We show how flow structures in the near bank region evolve with stage during the extreme event and how the associated geomorphic response is modulated by the distinctive process dynamics of a mega-river.

  4. Electron beam induced coloration and luminescence in layered structure of WO{sub 3} thin films grown by pulsed dc magnetron sputtering

    SciTech Connect

    Karuppasamy, A.; Subrahmanyam, A.

    2007-06-01

    Tungsten oxide thin films have been deposited by pulsed dc magnetron sputtering of tungsten in argon and oxygen atmosphere. The as-deposited WO{sub 3} film is amorphous, highly transparent, and shows a layered structure along the edges. In addition, the optical properties of the as-deposited film show a steplike behavior of extinction coefficient. However, the electron beam irradiation (3.0 keV) of the as-deposited films results in crystallization, coloration (deep blue), and luminescence (intense red emission). The above changes in physical properties are attributed to the extraction of oxygen atoms from the sample and the structural modifications induced by electron bombardment. The present method of coloration and luminescence has a potential for fabricating high-density optical data storage device.

  5. Characterisation of a satellite RNA of Cucumber mosaic virus that induces chlorosis in Capsicum annuum.

    PubMed

    Choi, Seung-Kook; Jeon, Yong-Woon; Yoon, Ju-Yeon; Choi, Jang-Kyung

    2011-08-01

    The presence of Cucumber mosaic virus (CMV) satellite RNA dramatically changes symptoms on some hosts. A satellite RNA present in a strain of CMV (PepY-CMV) that induced chlorosis in pepper (Capsicum annuum) was shown to induce chlorosis in pepper in combination with another strain (Fny-CMV) that by itself induced a green mosaic symptom. The location of sequences within the PepY satellite RNA (PepY-satRNA) of CMV that conferred the ability to induce chlorosis on pepper plants were analyzed by exchanging sequence domains between cDNA clones of PepY-satRNA and an attenuated mosaic satellite RNA (Paf-satRNA), as well as site-directed mutagenesis of various clusters of the 22-nt sequence differences between the two satellite RNAs in the delimited central domain. The symptoms induced by site-directed mutants of PepY-satRNA and Paf-satRNA in the presence of Fny-CMV demonstrated an insertion within PepY-satRNA of 11 nt at positions 86-96 relative to Paf-satRNA determined the chlorosis-inducing phenotype. Within the chlorosis-inducing domain, deletion of nucleotides did not affect the satRNA replication but abolished the ability of PepY-satRNA to elicit chlorosis symptom. Conversely, a mutant satellite RNA derived from Paf-satRNA in which eleven nucleotides were inserted indicated that sequences of 11 nucleotides were found to be sufficient for chlorosis induction in pepper.

  6. Visible luminescence from laser-induced stain- and dry etched silicon

    SciTech Connect

    Dimova-Malinovska, D.; Tzolov, M.; Malinowski, N.

    1996-12-31

    Light emitting silicon has been prepared by Ar laser (514.5 nm) induced stain etching and Nd:YAG impulse (532 nm) laser irradiation in air. Photoluminescence (PL), IR and XPS spectra have been studied. The intensity and position of the PL depend on the power or the energy and the duration of laser beam treatment during the etching. Correlation between the PL and chemical bonding is discussed.

  7. Heat induced transformation of fossil mastodon ivory into turquoise 'odontolite'. Structural and elemental characterisation

    NASA Astrophysics Data System (ADS)

    Reiche, I.; Vignaud, C.; Menu, M.

    2000-10-01

    The present work deals with the structural and elemental analysis of turquoise mineral imitations as 'odontolite' or bone turquoise by transmission electron microscopy (TEM), scanning electron microscopy (SEM-EDX) and particle induced X-ray and γ-ray emission (PIXE-PIGE). The aim of the work is to evidence the former deliberate transformation of fossilised ivory by man in order to transform them into semi-precious stones. We show that the crystal structure of 'odontolite' artefacts consisting of fluorapatite (Ca 5(PO 4) 3F) corresponds to that of heated fossil mastodon ivory (12-15 million years old). Metallic traces detected by PIXE-PIGE in these 'odontolites' are discussed in order to explain their role for coloration. Other more greenish turquoise imitations have a bone-like structure and composition, and carbonate-hydroxylapatite. The presence of copper salts at the surface is responsible for their green coloration.

  8. Histological characterisation of the ethanol-induced microphthalmia phenotype in a chick embryo model system.

    PubMed

    Kennelly, Kevin; Brennan, Deirdre; Chummun, Kushal; Giles, Seamus

    2011-09-01

    The eye is a sensitive indicator of the teratogenic effects of ethanol with ophthalmic defects such as microphthalmia frequently observed in FAS children. In this study, we have optimised the chick-embryo model system to investigate ethanol-induced ocular defects. Injection of 20% ethanol (125μl) directly into the yolk sac of HH-stage 7 embryos resulted in an overall 30% incidence of eye anomalies including microphthalmia. Ocular measurements showed that this treatment regime caused a significant reduction in overall globe size. Histological examination of microphthalmic specimens revealed three subgroups: (1) all ocular structures developed but were significantly retarded compared to age matched controls, (2) the bi-layered optic cup developed but with no evidence of lens induction, and (3) the optic vesicle failed to invaginate but remained as a vesicular structure comprising of a single layer of retinal pigment cells with no evidence of a neuro-retinal cell layer or lens structure. Further analysis identified clusters of apoptotic bodies in the ventral telencephalon, a region responsible for the expression of important genes in ocular specification. These results support a growing body of evidence, indicating that ethanol targets inductive signals in early eye development involving lens formation and retinal ganglion cell differentiation. The possible involvement of Shh, Fgf8, Bmp4 and Pax6 is discussed in relation to these outcomes.

  9. Characterisation of TiO 2 deposited by photo-induced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Kaliwoh, Never; Zhang, Jun-Ying; Boyd, Ian W.

    2002-01-01

    We report the deposition of thin TiO 2 films on crystalline Si and quartz by photo-induced chemical vapour deposition (CVD) using UV excimer lamps employing a dielectric barrier discharge in krypton chloride (KrCl ∗) to provide intense narrow band radiation at λ=222 nm. The precursor used was titanium isopropoxide (TTIP). Films from around 20-510 nm in thickness with refractive indices from 2.20 to 2.54 were grown at temperatures between 50 and 350 °C. The higher refractive index values compare favourably with the value of 2.58 recorded for the bulk material. The measured deposition rate was around 50 nm/min at 350 °C. Fourier transform infrared spectroscopy (FTIR) revealed the presence of TiO 2 through the observation of a Ti-O absorption peak and the absence of OH in films deposited at 250-350 °C indicated relatively good quality films. The phase of films deposited at 200-350 °C was anatase as determined by X-ray diffraction.

  10. Colloidal luminescent silicon nanorods.

    PubMed

    Lu, Xiaotang; Hessel, Colin M; Yu, Yixuan; Bogart, Timothy D; Korgel, Brian A

    2013-07-10

    Silicon nanorods are grown by trisilane decomposition in hot squalane in the presence of tin (Sn) nanocrystals and dodecylamine. Sn induces solution-liquid-solid nanorod growth with dodecylamine serving as a stabilizing ligand. As-prepared nanorods do not luminesce, but etching with hydrofluoric acid to remove residual surface oxide followed by thermal hydrosilylation with 1-octadecene induces bright photoluminescence with quantum yields of 4-5%. X-ray photoelectron spectroscopy shows that the ligands prevent surface oxidation for months when stored in air. PMID:23731184

  11. Characterisation of stochastically-induced climate jumps to other histories paced by the astronomical forcing.

    NASA Astrophysics Data System (ADS)

    De Saedeleer, B.

    2012-04-01

    The mystery of ice ages induced by a varying incoming solar radiation has drawn ceaseless attention for several decades. A pleiad of paleoclimatic models has been developed in order to have a try at catching the underlying climate dynamics, and their validity is challenged by comparison with typical milestones in paleoclimatic records. In several published works, the astronomical forcing synchronises the climate to a unique climatic attracting trajectory representing the ice volume evolution. Other studies, though, reported multistability, i.e. the fact that several climatic attracting trajectories could coexist for some given set of parameters, in a deterministic framework. More importantly, it has been illustrated that additional disturbances may cause some 'jumps' from one trajectory to other ones in the climatic history over the last millions years of the Pleistocene. These stochastic effects hence indirectly affect the timing of the glacial inceptions and terminations. The jumping mechanism is closely linked to the widely spread hypothesis that the glacial-interglacial cycles could be primarily triggered by random internal climate variability. A conjecture has recently been made that these externally triggered jumps are the most likely when the temporary desynchronisation (positive largest local Lyapunov exponent) due to the loss of local stability coalesces with the weakening of the global stability due to the proximity to the basin boundary. No proof of this conjecture has however been provided sofar; it is precisely the aim of the present research to assess the conditions for such a jump to occur. We uncover the details of the underlying mechanisms by providing a systematic numerical study of the conditions under which these jumps are likely to occur. Extensive Monte Carlo experiments are performed in order to show that the jumps occur preferentially at specific times or locations in the phase space, for a given level of noise. We show how the most critical

  12. Condensation and salt-induced decondensation of DNA upon incorporation of a V-shaped luminescent [Ru2(bpy)4(mbpibH2)](4+).

    PubMed

    Gan, Gui-Lian; Chao, Hui; Cai, Xue-Ping; Jiang, Zhen-Shen; Li, Hong

    2013-12-01

    This paper first reports on the condensation of DNA to a tightly packed state induced by a V-shaped di-ruthenium(II) complex [Ru2(bpy)4(mbpibH2)]Cl4 (bpy=2,2'-bipyridine and mbpibH2=1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene), which binds to the groove of herring sperm DNA (hsDNA) with the binding constant of 2.0×10(7)M(-1) (0.05M NaCl, pH7.2). The di-Ru(II) complex is found to induce the condensation of both hsDNA to long chain-like particle clusters and originally circular plasmid pBR322 DNA to particulate structure under neutral conditions. More interestingly, the presence of NaCl has a significant impact on the condensation and decondensation of DNA upon incorporation of [Ru2(bpy)4(mbpibH2)](4+), representing tunable luminescence characteristics by NaCl. High salt concentration facilitates the decondensation of DNA-[Ru2(bpy)4(mbpibH2)](4+) adducts. The results from this study offer an effective method to control the condensation and decondensation of DNA upon incorporation of luminescent concentrators.

  13. Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

    NASA Astrophysics Data System (ADS)

    Novelli, A.; Hens, K.; Tatum Ernest, C.; Kubistin, D.; Regelin, E.; Elste, T.; Plass-Dülmer, C.; Martinez, M.; Lelieveld, J.; Harder, H.

    2014-10-01

    Atmospheric measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance of OH as an atmospheric oxidant has motivated a sustained effort leading to the development of a number of highly sensitive analytical techniques. Recent work has indicated that the laser-induced fluorescence of the OH molecules method based on the fluorescence assay by gas expansion technique (LIF-FAGE) for the measurement of atmospheric OH in some environments may be influenced by artificial OH generated within the instrument, and a chemical method to remove this interference was implemented in a LIF-FAGE system by Mao et al. (2012). While it is not clear whether other LIF-FAGE instruments suffer from the same interference, we have applied this method to our LIF-FAGE HORUS (Hydroxyl Radical Measurement Unit based on fluorescence Spectroscopy) system, and developed and deployed an inlet pre-injector (IPI) to determine the chemical zero level in the instrument via scavenging the ambient OH radical. We describe and characterise this technique in addition to its application at field sites in forested locations in Finland, Spain and Germany. Ambient measurements show that OH generated within the HORUS instrument is a non-negligible fraction of the total OH signal, which can comprise 30 to 80% during daytime and 60 to 100% during the night. The contribution of the background OH varied greatly between measurement sites and was likely related to the type and concentration of volatile organic compounds (VOCs) present at each particular location. Two inter-comparisons in contrasting environments between the HORUS instrument and two different chemical ionisation mass spectrometers (CIMS) are described to demonstrate the efficacy of IPI and the necessity of the chemical zeroing method for our LIF-FAGE instrument in such environments.

  14. Localization induced intense red upconversion luminescence in monodispersed K3ZrF7:Yb3+/Er3+ nanocrystals

    NASA Astrophysics Data System (ADS)

    Luo, Wenqin; Wu, Haiyan; Li, Bin

    2016-08-01

    There are increasing demands for upconversion (UC) nanocrystals since they are found to have important applications in the field of bio-imaging. Herein, novel monodispersed Yb3+/Er3+ co-doped K3ZrF7 nanocrystals with tunable sizes of 6-30 nm were prepared by high temperature co-precipitation method. Intense UC emission of Er3+ with large red to green ratio was obtained under the excitation of 980 nm-laser due to the cation localization effects. The UC luminescent lifetimes of 4S3/2 and 4F9/2 were determined to be 0.137 and 0.217 ms, respectively. At last, the possible upconversion mechanism was proposed basing on the pump power dependent UC luminescence experiments.

  15. Laser-induced generation of micrometer-sized luminescent patterns on rare-earth-doped amorphous films

    SciTech Connect

    Zanatta, A.R.; Ribeiro, C.T.M.

    2004-12-01

    Room-temperature photoluminescence has been achieved from rare-earth-doped amorphous (a-) GeN films. The samples were prepared by the radio-frequency-sputtering method, and light emission from the rare-earth (RE) centers was obtained after irradiating the films with a highly focused laser beam. As a result of this laser annealing procedure, almost circular holes with approximately 1-{mu}m diameter were produced on the surface of the a-GeN films. The area nearby these holes correspond to crystalline Ge and coincide with the regions, where relatively strong RE-related luminescence takes place. These laser-annealed areas can be easily and conveniently managed in order to generate different microscopic luminescent patterns. Depending on the RE ion employed, visible and near-infrared light emission were obtained from the patterns so produced. The development of these micrometer-sized luminescent centers, as well as their probable mechanisms of excitation-recombination, will be presented and discussed. The importance of the current experimental results to future technological applications such as microdevices, for example, will also be outlined.

  16. Piezochromic luminescence behaviors of two new benzothiazole-enamido boron difluoride complexes: intra- and inter-molecular effects induced by hydrostatic compression.

    PubMed

    Wang, Xiaoqing; Liu, Qingsong; Yan, Hui; Liu, Zhipeng; Yao, Mingguang; Zhang, Qingfu; Gong, Shuwen; He, Weijiang

    2015-05-01

    Two new propeller-shaped benzothiazole-enamide boron difluoride complexes exhibiting piezochromic luminescence upon mechanical grinding or hydrostatic compression were prepared. The two analogues displayed the red shift in luminescence under high pressure, while compound 2 with ICT effects showed a more sensitive piezochromic response at low pressure (<1.5 GPa). The different piezochromic luminescence behaviors of these compounds were investigated.

  17. Specific chiral sensing of amino acids using induced circularly polarized luminescence of bis(diimine)dicarboxylic acid europium(III) complexes.

    PubMed

    Okutani, Kazuhiro; Nozaki, Koichi; Iwamura, Munetaka

    2014-06-01

    The circularly polarized luminescence (CPL) from [Eu(pda)2](-) (pda = 1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(bda)2](-) (bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) in aqueous solutions containing various amino acids was investigated. The europium(III) complexes exhibited bright-red luminescence assignable to the f-f transition of the Eu(III) ion when irradiated with UV light. Although the luminescence was not circularly polarized in the solid state or in aqueous solutions, in accordance with the achiral crystal structure, the complexes exhibited detectable induced CPL (iCPL) in aqueous solutions containing chiral amino acids. In the presence of L-pyrrolidonecarboxylic acid, both [Eu(pda)2](-) and [Eu(bda)2](-) showed similar iCPL intensity (glum ∼ 0.03 for the (5)D0 → (7)F1 transition at 1 mol·dm(-3) of the amino acid). On the other hand, in the presence of L-histidine or L-arginine, [Eu(pda)2](-) exhibited intense CPL (glum ∼ 0.08 for the (5)D0 → (7)F1 transition at 0.10 mol·dm(-3) of the amino acid), whereas quite weak CPL was observed for [Eu(bda)2](-) under the same conditions (glum < 0.01). On the basis of analysis of the iCPL intensities in the presence of 12 amino acids, [Eu(pda)2](-) was found to be a good chiral CPL probe with high sensitivity (about 10(-2) mol·dm(-3)) and high selectivity for L-histidine at pH 3 and for L-arginine at pH 7. The mechanism of iCPL was evaluated by analysis of the fine structures in the luminescence spectra and the amino acid concentration dependence of glum. For the [Eu(pda)2](-)-histidine/arginine systems, the europium(III) complexes possess coordination structures similar to that in the crystal with slight distortion to form a chiral structure due to specific interaction with two zwitterionic amino acids. This mechanism was in stark contrast to that of the europium(III) complex-pyrrolidonecarboxylic acid system in which one amino acid coordinates to the Eu(III) ion to yield an achiral coordination

  18. Limitations and design considerations for donor–acceptor systems in luminescent solar concentrators: the effect of coupling-induced red-edge absorption

    NASA Astrophysics Data System (ADS)

    MacQueen, Rowan W.; Tayebjee, Murad J. Y.; Webb, James E. A.; Falber, Alexander; Thordarson, Pall; Schmidt, Timothy W.

    2016-06-01

    Luminescent solar concentrators (LSCs) use luminescence and waveguiding to concentrate photons within thin dielectric slabs for use in photovoltaic, lighting, and photobioreactor applications. Donor–acceptor systems of organic chromophores are widely used in LSCs to broaden the sunlight absorption range and attempt to reduce loss-inducing reabsorption by the emitting chromophore. We use raytrace simulations across a large parameter space to model the performance of LSCs containing two novel donor–acceptor trimers based on the perylene moiety. We find that under certain conditions, trimers outperform single-dye LSCs as expected. However, at higher concentrations, a slight increase in red-edge absorption by the trimers increases reabsorption and has a deleterious effect on LSC performance. This underscores the large effect that even small changes in the red edge can have, and may discourage the use of donor–acceptor schemes with high interchromophore coupling that promotes red-edge absorption. Finally, we show that for a LSC-PV pair, selecting a PV cell that is well-matched with the LSC emission spectrum has a large effect on the flux gain of the system, and that the systems studied here are well-matched to emerging PV technologies.

  19. Limitations and design considerations for donor-acceptor systems in luminescent solar concentrators: the effect of coupling-induced red-edge absorption

    NASA Astrophysics Data System (ADS)

    MacQueen, Rowan W.; Tayebjee, Murad J. Y.; Webb, James E. A.; Falber, Alexander; Thordarson, Pall; Schmidt, Timothy W.

    2016-06-01

    Luminescent solar concentrators (LSCs) use luminescence and waveguiding to concentrate photons within thin dielectric slabs for use in photovoltaic, lighting, and photobioreactor applications. Donor-acceptor systems of organic chromophores are widely used in LSCs to broaden the sunlight absorption range and attempt to reduce loss-inducing reabsorption by the emitting chromophore. We use raytrace simulations across a large parameter space to model the performance of LSCs containing two novel donor-acceptor trimers based on the perylene moiety. We find that under certain conditions, trimers outperform single-dye LSCs as expected. However, at higher concentrations, a slight increase in red-edge absorption by the trimers increases reabsorption and has a deleterious effect on LSC performance. This underscores the large effect that even small changes in the red edge can have, and may discourage the use of donor-acceptor schemes with high interchromophore coupling that promotes red-edge absorption. Finally, we show that for a LSC-PV pair, selecting a PV cell that is well-matched with the LSC emission spectrum has a large effect on the flux gain of the system, and that the systems studied here are well-matched to emerging PV technologies.

  20. Chiral Sensing of Various Amino Acids Using Induced Circularly Polarized Luminescence from Europium(III) Complexes of Phenanthroline Dicarboxylic Acid Derivatives.

    PubMed

    Uchida, Taka-Aki; Nozaki, Koichi; Iwamura, Munetaka

    2016-09-01

    Circularly polarized luminescence (CPL) was observed from [Eu(dppda)2 ](-) (dppda=4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(pzpda)2 ](-) (pzpda=pyrazino[2,3-f][1,10]phenanthroline-7,10-dicarboxylic acid) in aqueous solutions containing various amino acids. The selectivity of these complexes towards amino acids enabled them to be used as chiral sensors and their behavior was compared with that of [Eu(pda)2 ](-) (pda=1,10-phenanthroline-2,9-dicarboxylic acid). As these Eu(III) complexes have achiral D2d structures under ordinary conditions, there were no CPL signals in the emission assigned to f-f transitions. However, when the solutions contained particular amino acids they exhibited detectable CPL signals with glum values of about 0.1 (glum =CPL/2 TL; TL=total luminescence). On examining 13 amino acids with these three Eu(III) complexes, it was found that whether an amino acid induced a detectable CPL depended on the Eu(III) complex ligands. For example, when ornithine was used as a chiral agent, only [Eu(dppda)2 ](-) exhibited intense CPL in aqueous solutions of 10(-2)  mol dm(-3) . Steep amino acid concentration dependence suggested that CPL in [Eu(dppda)2 ](-) and [Eu(pzpda)2 ](-) was induced by the association of four or more amino acid molecules, whereas CPL in [Eu(pda)2 ](-) was induced by association of two arginine molecules.

  1. Chiral Sensing of Various Amino Acids Using Induced Circularly Polarized Luminescence from Europium(III) Complexes of Phenanthroline Dicarboxylic Acid Derivatives.

    PubMed

    Uchida, Taka-Aki; Nozaki, Koichi; Iwamura, Munetaka

    2016-09-01

    Circularly polarized luminescence (CPL) was observed from [Eu(dppda)2 ](-) (dppda=4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid) and [Eu(pzpda)2 ](-) (pzpda=pyrazino[2,3-f][1,10]phenanthroline-7,10-dicarboxylic acid) in aqueous solutions containing various amino acids. The selectivity of these complexes towards amino acids enabled them to be used as chiral sensors and their behavior was compared with that of [Eu(pda)2 ](-) (pda=1,10-phenanthroline-2,9-dicarboxylic acid). As these Eu(III) complexes have achiral D2d structures under ordinary conditions, there were no CPL signals in the emission assigned to f-f transitions. However, when the solutions contained particular amino acids they exhibited detectable CPL signals with glum values of about 0.1 (glum =CPL/2 TL; TL=total luminescence). On examining 13 amino acids with these three Eu(III) complexes, it was found that whether an amino acid induced a detectable CPL depended on the Eu(III) complex ligands. For example, when ornithine was used as a chiral agent, only [Eu(dppda)2 ](-) exhibited intense CPL in aqueous solutions of 10(-2)  mol dm(-3) . Steep amino acid concentration dependence suggested that CPL in [Eu(dppda)2 ](-) and [Eu(pzpda)2 ](-) was induced by the association of four or more amino acid molecules, whereas CPL in [Eu(pda)2 ](-) was induced by association of two arginine molecules. PMID:27380553

  2. Coherent detection of THz waves based on THz-induced time-resolved luminescence quenching in bulk gallium arsenide.

    PubMed

    Chu, Zheng; Liu, Jinsong; Wang, Kejia

    2012-05-01

    A kind of photoluminescence quenching, in which the time-resolved photoluminescence is modulated by a THz pulse, has been theoretically investigated by performing the ensemble Monte Carlo method in bulk gallium arsenide (GaAs) at room temperature. The quenching ratio could reach up to 50% under a strong THz field (100  kV/cm). The range in which luminescence quenching is linearly proportional to the THz field could be over 60  kV/cm. On the basis of these results, a principle for THz modulation and coherent detection is proposed.

  3. Luminescence induced by dehydration of kaolin - Association with electron-spin-active centers and with surface activity for dehydration-polymerization of glycine

    NASA Technical Reports Server (NTRS)

    Coyne, L.; Hovatter, W.; Sweeney, M.

    1983-01-01

    Experimental data concerning emission of light upon dehydration as a function of preheating and pre-gamma-irradiation are correlated with reported studies of electron-spin resonance (ESR) activity after similar pretreatments. The effect of these pretreatments on the kaolin-promoted incorporation of glycine into peptide oligomers in a wet/cold, hot/dry fluctuating environment is compared to their effect on the ESR and luminescent signals. The existence of spectroscopically active centers appears to be loosely anticorrelated with reaction yield; these yields are increased by increasing the overall energy content of the material. It is concluded that some part of the chemical yield is produced by a mechanism involving intrinsic, excited electronic states of the clay crystal lattice. These states may be derived from thermally, interfacially, and/or mechanically induced charge reorganization within interspersed energy levels in the band structure of the material.

  4. Silicon based light emitters utilizing radiation from dislocations; electric field induced shift of the dislocation-related luminescence

    NASA Astrophysics Data System (ADS)

    Arguirov, T.; Mchedlidze, T.; Kittler, M.; Reiche, M.; Wilhelm, T.; Hoang, T.; Holleman, J.; Schmitz, J.

    2009-05-01

    Dislocation rich regions can be controllably formed at a certain location inside a silicon wafer. We studied the light emission properties of such regions located in an electric field of a p-n junction under different excitation conditions. It was found that the luminescence spectra of the dislocations are significantly influenced by the presence of the junction. The dislocation-related luminescence peak position appears red-shifted due to the built-in electric field. A suppression of that field by photo-generation of carriers or by applying a forward bias voltage at the junction leads to a gradual decrease in the energy position of the peaks. The dependence of the peak position on the electric field was found to be a quadratic function, similar to that observed for semiconductor nanostructures. We show that the shift of the peak position is due to the Stark effect on dislocation-related excitonic states. The characteristic constant of the shift, obtained by fitting the data with the quadratic Stark effect equation, was 0.0186 meV/(kV/cm) 2. The observed effect opens new possibilities for integration of a silicon based light emitter, combining the radiation from dislocations with a Stark effect based modulator.

  5. A luminescent nisin biosensor

    NASA Astrophysics Data System (ADS)

    Immonen, Nina; Karp, Matti

    2006-02-01

    Nisin is a lantibiotic, an antibacterial peptide produced by certain Lactococcus lactis strains that kills or inhibits the growth of other bacteria. Nisin is widely used as a food preservative, and its long-time use suggests that it can be generally regarded as safe. We have developed a method for determining the amount of nisin in food samples that is based on luminescent biosensor bacteria. Bacterial luciferase operon luxABCDE was inserted into plasmid pNZ8048, and the construct was transformed by electroporation into Lc. lactis strain NZ9800, whose ability to produce nisin has been erased by deletion of the gene nisA. The operon luxABCDE has been modified to be functional in gram-positive bacteria to confer a bioluminescent phenotype without the requirement of adding an exogenous substrate. In the plasmid pNZ8048, the operon was placed under control of the nisin-inducible nisA promoter. The chromosomal nisRK genes of Lc. lactis NZ9800 allow it to sense nisin in the environment and relay this signal via signal transduction proteins NisK and NisR to initiate transcription from nisA promoter. In the case of our sensor bacteria, this leads to production of luciferase and, thus, luminescence that can be directly measured from living bacteria. Luminescence can be detected as early as within minutes of induction. The nisin assay described here provides a detection limit in the sub-picogram level per ml, and a linear area between 1 - 1000 pg/ml. The sensitivity of this assay exceeds the performance of all previously published methods.

  6. Photon Luminescence of the Moon

    NASA Technical Reports Server (NTRS)

    Wilson, T.L.; Lee, K.T.

    2009-01-01

    Luminescence is typically described as light emitted by objects at low temperatures, induced by chemical reactions, electrical energy, atomic interactions, or acoustical and mechanical stress. An example is photoluminescence created when photons (electromagnetic radiation) strike a substance and are absorbed, resulting in the emission of a resonant fluorescent or phosphorescent albedo. In planetary science, there exists X-ray fluorescence induced by sunlight absorbed by a regolith a property used to measure some of the chemical composition of the Moon s surface during the Apollo program. However, there exists an equally important phenomenon in planetary science which will be designated here as photon luminescence. It is not conventional photoluminescence because the incoming radiation that strikes the planetary surface is not photons but rather cosmic rays (CRs). Nevertheless, the result is the same: the generation of a photon albedo. In particular, Galactic CRs (GCRs) and solar energetic particles (SEPs) both induce a photon albedo that radiates from the surface of the Moon. Other particle albedos are generated as well, most of which are hazardous (e.g. neutrons). The photon luminescence or albedo of the lunar surface induced by GCRs and SEPs will be derived here, demonstrating that the Moon literally glows in the dark (when there is no sunlight or Earthshine). This extends earlier work on the same subject [1-4]. A side-by-side comparison of these two albedos and related mitigation measures will also be discussed.

  7. Electron beam induced green luminescence and degradation study of CaS:Ce nanocrystalline phosphors for FED applications

    NASA Astrophysics Data System (ADS)

    Kumar, Vinay; Mishra, Varun; Biggs, M. M.; Nagpure, I. M.; Ntwaeaborwa, O. M.; Terblans, J. J.; Swart, H. C.

    2010-01-01

    Green luminescence and degradation of Ce 3+ doped CaS nanocrystalline phosphors were studied with a 2 keV, 10 μA electron beam in an O 2 environment. The nanophosphors were synthesized by the co-precipitation method. The samples were characterized using X-ray diffraction, Transmission electron microscopy, Scanning electron microscopy/electron dispersive X-ray spectroscopy and Photoluminescence (PL) spectroscopy. Cubic CaS with an average particle size of 42 ± 2 nm was obtained. PL emission was observed at 507 nm and a shoulder at 560 nm with an excitation wavelength of 460 nm. Auger electron spectroscopy and Cathodoluminescence (CL) were used to monitor the changes in the surface composition of the CaS:Ce 3+ nanocrystalline phosphors during electron bombardment in an O 2 environment. The effect of different oxygen pressures ranging from 1 × 10 -8 to 1 × 10 -6 Torr on the CL intensity was also investigated. A CaSO 4 layer was observed on the surface after the electron beam degradation. The CL intensity was found to decrease up to 30% of its original intensity at 1 × 10 -6 Torr oxygen pressure after an electron dose of 50 C/cm 2. The formation of oxygen defects during electron bombardment may also be responsible for the decrease in CL intensity.

  8. Photosensitizer fluorescence and singlet oxygen luminescence as dosimetric predictors of topical 5-aminolevulinic acid photodynamic therapy induced clinical erythema

    PubMed Central

    Mallidi, Srivalleesha; Anbil, Sriram; Lee, Seonkyung; Manstein, Dieter; Elrington, Stefan; Kositratna, Garuna; Schoenfeld, David; Pogue, Brian; Davis, Steven J.; Hasan, Tayyaba

    2014-01-01

    Abstract. The need for patient-specific photodynamic therapy (PDT) in dermatologic and oncologic applications has triggered several studies that explore the utility of surrogate parameters as predictive reporters of treatment outcome. Although photosensitizer (PS) fluorescence, a widely used parameter, can be viewed as emission from several fluorescent states of the PS (e.g., minimally aggregated and monomeric), we suggest that singlet oxygen luminescence (SOL) indicates only the active PS component responsible for the PDT. Here, the ability of discrete PS fluorescence-based metrics (absolute and percent PS photobleaching and PS re-accumulation post-PDT) to predict the clinical phototoxic response (erythema) resulting from 5-aminolevulinic acid PDT was compared with discrete SOL (DSOL)-based metrics (DSOL counts pre-PDT and change in DSOL counts pre/post-PDT) in healthy human skin. Receiver operating characteristic curve (ROC) analyses demonstrated that absolute fluorescence photobleaching metric (AFPM) exhibited the highest area under the curve (AUC) of all tested parameters, including DSOL based metrics. The combination of dose-metrics did not yield better AUC than AFPM alone. Although sophisticated real-time SOL measurements may improve the clinical utility of SOL-based dosimetry, discrete PS fluorescence-based metrics are easy to implement, and our results suggest that AFPM may sufficiently predict the PDT outcomes and identify treatment nonresponders with high specificity in clinical contexts. PMID:24503639

  9. Defect-Related Luminescent Hydroxyapatite-Enhanced Osteogenic Differentiation of Bone Mesenchymal Stem Cells Via an ATP-Induced cAMP/PKA Pathway.

    PubMed

    Wang, Chao; Liu, Dandan; Zhang, Cuimiao; Sun, Jiadong; Feng, Weipei; Liang, Xing-Jie; Wang, Shuxiang; Zhang, Jinchao

    2016-05-11

    Novel defect-related hydroxyapatite (DHAP), which combines the advantages of HAP and defect-related luminescence, has the potential application in tissue engineering and biomedical area, because of its excellent capability of monitoring the osteogenic differentiation and material biodegradation. Although the extracellular mechanism of DHAP minerals and PO4(3-) functioning in osteogenic differentiation has been widely studied, the intracellular molecular mechanism through which PO4(3-) mediates osteogenesis of bone mesenchymal stem cells (BMSCs) is not clear. We examined a previously unknown molecular mechanism through which PO4(3-) promoted osteogenesis of BMSCs with an emphasis on adenosine-triphosphate (ATP)-induced cAMP/PKA pathway. Our studies showed that DHAP could be uptaken into lysosome, in which PO4(3-) was released from DHAP, because of the acid environment of lysosome. The released PO4(3-) interacted with ADP to form ATP, and then degraded into adenosine, an ATP metabolite, which interacted with A2b adenosine receptor to activate the cAMP/PKA pathway, resulting in the high expression of osteogenesis-related genes, such as Runx2, BMP-2, and OCN. These findings first revealed the function of ATP-metabolism in bone physiological homeostasis, which may be developed to cure bone metabolic diseases. PMID:27088570

  10. A Single 9-Colour Flow Cytometric Method to Characterise Major Leukocyte Populations in the Rat: Validation in a Model of LPS-Induced Pulmonary Inflammation.

    PubMed

    Barnett-Vanes, Ashton; Sharrock, Anna; Birrell, Mark A; Rankin, Sara

    2016-01-01

    The rat is a commonly used model for immunological investigation. Yet basic research and characterisation of leukocyte populations and sub-sets lags far behind murine research, with inconsistency on reported leukocyte markers and their overlap. These shortcomings limit the opportunity for more complex and advanced rat immunology research. In this study, we developed a robust 9-colour flow-cytometric protocol to elucidate the major blood and tissue rat leukocyte populations, and validated it in a model of LPS-induced pulmonary inflammation. Blood and tissues (lung, BALF, spleen, liver, bone marrow) from naïve Sprague-Dawley rats were collected and analysed by flow cytometry (FCM). Rats were exposed to aerosolised saline or LPS (1 mg/mL), at 3 and 24 hrs thereafter blood, lung and BALF were collected and analysed using FCM and ELISA. Neutrophils, two monocyte subsets, NK Cells, B Cells, CD4+, CD8+ T Cells and alveolar macrophages can be identified simultaneously across different tissues using a 9-colour panel. Neutrophils and monocytes can be distinguished based upon differential expression of CD43 and His48. Neutrophils and CD43Lo/His48Hi monocyte-macrophages are elevated in the lung at 3 and 24 hrs during LPS-induced pulmonary inflammation. This validated method for leukocyte enumeration will offer a platform for greater consistency in future rat immunology and inflammation research.

  11. Characterisation of the conformational changes in platelet factor 4 induced by polyanions: towards in vitro prediction of antigenicity.

    PubMed

    Brandt, S; Krauel, K; Gottschalk, K E; Renné, T; Helm, C A; Greinacher, A; Block, S

    2014-07-01

    Heparin-induced thrombocytopenia (HIT) is the most frequent drug-induced immune reaction affecting blood cells. Its antigen is formed when the chemokine platelet factor 4 (PF4) complexes with polyanions. By assessing polyanions of varying length and degree of sulfation using immunoassay and circular dichroism (CD)-spectroscopy, we show that PF4 structural changes resulting in antiparallel β-sheet content >30% make PF4/polyanion complexes antigenic. Further, we found that polyphosphates (polyP-55) induce antigenic changes on PF4, whereas fondaparinux does not. We provide a model suggesting that conformational changes exposing antigens on PF4/polyanion complexes occur in the hairpin involving AA 32-38, which form together with C-terminal AA (66-70) of the adjacent PF4 monomer a continuous patch on the PF4 tetramer surface, explaining why only tetrameric PF4 molecules express "HIT antigens". The correlation of antibody binding in immunoassays with PF4 structural changes provides the intriguing possibility that CD-spectroscopy could become the first antibody-independent, in vitro method to predict potential immunogenicity of drugs. CD-spectroscopy could identify compounds during preclinical drug development that induce PF4 structural changes correlated with antigenicity. The clinical relevance can then be specifically addressed during clinical trials. Whether these findings can be transferred to other endogenous proteins requires further studies.

  12. Size/morphology induced tunable luminescence in upconversion crystals: ultra-strong single-band emission and underlying mechanisms.

    PubMed

    Wang, Zhaofeng; Zeng, Songshan; Yu, Jingfang; Ji, Xiaoming; Zeng, Huidan; Xin, Shuangyu; Wang, Yuhua; Sun, Luyi

    2015-06-01

    In this work, we present a two-step method to controllably synthesize novel and highly efficient upconversion materials, Lu5O4F7:Er(3+),Yb(3+) nano/micro-crystals, and investigate their size/morphology induced tunable upconversion properties. In addition to the common phenomenon aroused by a surface quenching effect, direct experimental evidence for the regulation of phonon modes is obtained in nanoparticles. The findings in this work advance the existing mechanisms for the general explanation of size/morphology induced upconversion features. Because of the adjustment of phonon energy and density as well as the surface quenching effect, the biocompatible Lu5O4F7:Er(3+),Yb(3+) nanoparticles exhibit an ultra-strong single-band red upconversion, rendering them promising for biomedical applications.

  13. Luminescence properties of lustre decorated majolica

    NASA Astrophysics Data System (ADS)

    Galli, A.; Martini, M.; Sibilia, E.; Padeletti, G.; Fermo, P.

    Luminescence measurements have been performed on several Italian Renaissance ceramic shards produced in central Italy, as well as on some others from Hispano-Moresque and Fatimid periods. The aim of this study was the characterisation of the raw materials used to manufacture lustre decorated majolica. At first, the thermoluminescence (TL) dating of all ceramic bodies was performed, because the shards lacked sure chronological attribution, having been provided by private collectors, or found during emergency restoration works or archaeological surveys. To characterise the defects and the recombination centers of the different components of the ceramics (ceramic body, glaze, glaze, and lustre), radioluminescence (RL) measurements have been performed on samples representative of each historical period. The dating results are reported, as well as the preliminary RL results.

  14. Isolation and characterisation of Kasumi-1 human myeloid leukaemia cell line resistant to tumour necrosis factor alpha-induced apoptosis.

    PubMed Central

    Ido, M.; Hayashi, K.; Kato, S.; Ogawa, H.; Komada, Y.; Zhau, Y. W.; Zhang, X. L.; Sakurai, M.; Suzuki, K.

    1996-01-01

    Tumour necrosis factor (TNF)-alpha induces apoptosis in a human acute myeloid leukaemia cell line, Kasumi-1. To examine the role of protein phosphorylation in signal transduction of TNF-alpha-induced apoptosis, a variant cell line resistant to TNF-alpha was established by an intermittent challenge of Kasumi-1 cells with increasing concentrations of TNF-alpha for 6 months. The mechanism of resistance to TNF-alpha appears to be in the post-receptor pathway because expression of p55 TNF receptor in the variant cells is increased compared with that of the parental Kasumi-1 cells. In renaturation assays, TNF-alpha induced a rapid activation of different protein kinases of different molecular weights, including the 50 kDa protein kinase (PK50) followed by the 35 kDa protein kinase (PK35), in the parental Kasumi-1 cells. The dose-response of TNF-alpha required to activate PK50 and PK35 was closely related to concentrations of TNF-alpha that induced apoptosis. Treatment of Kasumi-1 cells with ceramide also activated PK35. In TNF-resistant variant cells, activation of PK35 in response to TNF-alpha or ceramide was practically nil. These findings suggest that activation of PK35 through the ceramide pathway may play an important role in signal transduction of TNF-alpha in the Kasumi-1 cell line, while the decreased activation of PK35 may explain the insensitivity of the variant cells towards TNF-alpha. Images Figure 3 Figure 4 Figure 5 Figure 6 PMID:8562342

  15. Argon-ion-induced formation of nanoporous GaSb layer: Microstructure, infrared luminescence, and vibrational properties

    SciTech Connect

    Datta, D. P.; Som, T.; Kanjilal, A.; Satpati, B.; Das, T. D.; Kanjilal, D.

    2014-07-21

    Room temperature implantation of 60 keV Ar{sup +}-ions in GaSb to the fluences of 7 × 10{sup 16} to 3 × 10{sup 18} ions cm{sup −2} is carried out at two incidence angles, viz 0° and 60°, leading to formation of a nanoporous layer. As the ion fluence increases, patches grow on the porous layer under normal ion implantation, whereas the porous layer gradually becomes embedded under a rough top surface for oblique incidence of ions. Grazing incidence x-ray diffraction and cross-sectional transmission electron microscopy studies reveal the existence of nanocrystallites embedded in the ion-beam amorphized GaSb matrix up to the highest fluence used in our experiment. Oxidation of the nanoporous layers becomes obvious from x-ray photoelectron spectroscopy and Raman mapping. The correlation of ion-beam induced structural modification with photoluminescence signals in the infrared region has further been studied, showing defect induced emission of additional peaks near the band edge of GaSb.

  16. Cd(II)-coordination framework: synthesis, anion-induced structural transformation, anion-responsive luminescence, and anion separation.

    PubMed

    Hou, Shan; Liu, Qi-Kui; Ma, Jian-Ping; Dong, Yu-Bin

    2013-03-18

    A series of Cd(II) coordination frameworks that are constructed from a new oxadiazole-bridged ligand 3,5-bis(3-pyridyl-3-(3'-methylphenyl)-1,3,4-oxadiazole (L) and CdX2 (X = NO3(-), Cl(-), Br(-), I(-), N3(-), and SCN(-)) were synthesized. The NO3(-) anion of the solid CdL2(NO3)2·2THF (1) is able to be quantitatively exchanged with Cl(-), Br(-), I(-), SCN(-), and N3(-) in the solid state. For Cl(-) and Br(-), the anion exchange resulted in a anion-induced structural transformation to form the structures of 2 and 3, respectively. In addition, the Cd(II) structure herein exhibits the anion-responsive photoluminescence, which could be a useful method to monitor the anion-exchange process. Notably, compound 1 can recognize and completely separate SCN(-)/N3(-) with similar geometry.

  17. Molecular characterisation of Ltchi7, a gene encoding a Class III endochitinase induced by drought stress in Lotus spp.

    PubMed

    Tapia, G; Morales-Quintana, L; Inostroza, L; Acuña, H

    2011-01-01

    Chitinases are enzymes that digest chitin molecules, present principally in insects and fungi. In plants, these enzymes play an important role in defence against pathogen attack, although they have also been described as induced by mechanical damage, ozone, heavy metals, cold, salinity, etc. Using an annealing control primer, we isolated a gene fragment whose translated sequence has high homology with a class III endochitinase. The gene, named Ltchi7, consisted of one ORF of 1005 bp, which codes for a peptide of 334 amino acids, including a deduced signal peptide of 27 amino acid that directs protein to the extracellular space. Phylogenetic analysis suggests that Ltchi7 is within a cluster that includes Sesbania rostrata, Medicago sativa and Glycine max class III endochitinases. This group is differentiated from other species of endochitinases by the presence of an additional extension in carboxy-terminal region. Moreover, in comparison with the majority of chitinases, Ltchi7 has two additional cysteine residues, which, according to 3D modelling studies, are very close. Gene expression analysis showed enhanced transcript abundance of this gene during drought stress in Lotus tenuis and Lotus japonicus, compared with growth under normal conditions. Furthermore, its expression is restricted to nodules and roots. Expression of this gene was also induced by salt stress, hydrogen peroxide and weakly with abscisic acid.

  18. Swift heavy ion induced structural and luminescence characterization of Y₂O₃:Eu³⁺ phosphor: a comparative study.

    PubMed

    Som, S; Sharma, S K; Lochab, S P

    2014-08-01

    We report a comparative study on structural and thermoluminescence modifications of Y2O3:Eu(3+) phosphor induced by 150 MeV Ni(7+), 120 MeV Ag(9+) and 110 MeV Au(8+) swift heavy ions (SHI) in the fluence range 1 × 10(11) to 1 × 10(13) ions/cm(2). X-Ray diffraction and transition electron microscopy studies confirm the loss of crystallinity of the phosphors after ion irradiation, which is greater in the case of Au ion irradiation. Structural refinement using the Rietveld method yields the various structural parameters of ion-irradiated phosphors. Thermoluminescence glow curves of ion-irradiated phosphors show a small shift in the position of the peaks, along with an increase in intensity with ion fluence. Stopping range of ions in Matter (SRIM) calculations were performed to correlate the change in thermoluminescence properties of various ion-irradiated phosphors. It shows that the defects created by 110 MeV Au(8+) ions are greater in number. Trapping parameters of ion-irradiated phosphors were calculated from thermoluminescence data using various glow curve analysis methods. PMID:24753140

  19. Optically stimulated luminescence dosimetry

    NASA Astrophysics Data System (ADS)

    McKeever, Stephen W. S.

    2001-09-01

    Models and the conceptual framework necessary for an understanding of optically stimulated luminescence (OSL) are described. Examples of various OSL readout schemes are described, along with examples of the use of OSL in radiation dosimetry.

  20. Advanced synchronous luminescence system

    DOEpatents

    Vo-Dinh, Tuan

    1997-01-01

    A method and apparatus for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition.

  1. Pulsed-Laser-Induced Simple Synthetic Route for Tb3Al5O12:Ce3+ Colloidal Nanocrystals and Their Luminescent Properties

    NASA Astrophysics Data System (ADS)

    Mhin, Sung Wook; Ryu, Jeong Ho; Kim, Kang Min; Park, Gyeong Seon; Ryu, Han Wool; Shim, Kwang Bo; Sasaki, Takeshi; Koshizaki, Naoto

    2009-08-01

    Cerium-doped Tb3Al5O12 (TAG:Ce3+) colloidal nanocrystals were synthesized by pulsed laser ablation (PLA) in de-ionized water and lauryl dimethylaminoacetic acid betain (LDA) aqueous solution for luminescent bio-labeling application. The influence of LDA molecules on the crystallinity, crystal morphology, crystallite size, and luminescent properties of the prepared TAG:Ce3+ colloidal nanocrystals was investigated in detail. When the LDA solution was used, smaller average crystallite size, narrower size distribution, and enhanced luminescence were observed. These characteristics were explained by the effective role of occupying the oxygen defects on the surface of TAG:Ce3+ colloidal nanocrystal because the amphoteric LDA molecules were attached by positively charged TAG:Ce3+ colloidal nanocrystals. The blue-shifted phenomena found in luminescent spectra of the TAG:Ce3+ colloidal nanocrystals could not be explained by previous crystal field theory. We discuss the 5d energy level of Ce3+ with decreased crystal size with a phenomenological model that explains the relationship between bond distance with 5d energy level of Ce3+ based on the concept of crystal field theory modified by covalency contribution.

  2. Pulsed-Laser-Induced Simple Synthetic Route for Tb(3)Al(5)O(12):Ce Colloidal Nanocrystals and Their Luminescent Properties.

    PubMed

    Mhin, Sung Wook; Ryu, Jeong Ho; Kim, Kang Min; Park, Gyeong Seon; Ryu, Han Wool; Shim, Kwang Bo; Sasaki, Takeshi; Koshizaki, Naoto

    2009-01-01

    Cerium-doped Tb(3)Al(5)O(12) (TAG:Ce(3+)) colloidal nanocrystals were synthesized by pulsed laser ablation (PLA) in de-ionized water and lauryl dimethylaminoacetic acid betain (LDA) aqueous solution for luminescent bio-labeling application. The influence of LDA molecules on the crystallinity, crystal morphology, crystallite size, and luminescent properties of the prepared TAG:Ce(3+) colloidal nanocrystals was investigated in detail. When the LDA solution was used, smaller average crystallite size, narrower size distribution, and enhanced luminescence were observed. These characteristics were explained by the effective role of occupying the oxygen defects on the surface of TAG:Ce(3+) colloidal nanocrystal because the amphoteric LDA molecules were attached by positively charged TAG:Ce(3+) colloidal nanocrystals. The blue-shifted phenomena found in luminescent spectra of the TAG:Ce(3+) colloidal nanocrystals could not be explained by previous crystal field theory. We discuss the 5d energy level of Ce(3+) with decreased crystal size with a phenomenological model that explains the relationship between bond distance with 5d energy level of Ce(3+) based on the concept of crystal field theory modified by covalency contribution. PMID:20596420

  3. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  4. Pickled luminescent silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Boukherroub, R.; Morin, S.; Wayner, D. D. M.; Lockwood, D. J.

    2001-05-01

    In freshly prepared porous Si, the newly exposed silicon-nanostructure surface is protected with a monolayer of hydrogen, which is very reactive and oxidizes in air leading to a loss of luminescence intensity and a degradation of the electronic properties. We report a surface passivation approach based on organic modification that stabilizes the luminescence. This novel 'pickling' process not only augments the desired optoelectronic properties, but also is adaptable to further chemical modification for integration into chemical and biophysical sensors.

  5. Characterisation of SalRAB a Salicylic Acid Inducible Positively Regulated Efflux System of Rhizobium leguminosarum bv viciae 3841

    PubMed Central

    Tett, Adrian J.; Karunakaran, Ramakrishnan; Poole, Philip S.

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants. PMID:25133394

  6. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841.

    PubMed

    Tett, Adrian J; Karunakaran, Ramakrishnan; Poole, Philip S

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants.

  7. Spectroscopic characterisation of the erbium impurity in crystalline semiconductors

    NASA Astrophysics Data System (ADS)

    Ammerlaan, C. A. J.

    2001-12-01

    A scheme for the numerical calculation of energy levels of rare-earth ions in a crystalline solid is presented. Stark fields of cubic, trigonal, tetragonal, orthorhombic and monoclinic symmetry are considered. As examples, optical luminescence spectra of erbium in the semiconductors zinc selenide and silicon are analysed. Based on the optical characterisation, the g tensors for Zeeman splitting in an applied magnetic field are predicted for the crystal-field ground states of these centres.

  8. Luminescence induite par un microscope à effet tunnel comme sonde nanophotonique

    NASA Astrophysics Data System (ADS)

    Silly, Fabien; Charra, Fabrice

    The luminescence of nanostructured systems can be excited highly locally by the tip of a Scanning Tunneling Microscope (STM). We first present briefly the principles of this STM-induced luminescence. Then we present a review of selected results in STM-induced luminescence from the point of view of nano-scale photonics. We illustrate various contrast mechanisms with different examples of nanostructured systems. To cite this article: F. Silly, F. Charra, C. R. Physique 3 (2002) 493-500.

  9. In-air broad beam ionoluminescence microscopy as a tool for rocks and stone artworks characterisation.

    PubMed

    Lo Giudice, Alessandro; Re, Alessandro; Angelici, Debora; Calusi, Silvia; Gelli, Nicla; Giuntini, Lorenzo; Massi, Mirko; Pratesi, Giovanni

    2012-07-01

    Broad beam ionoluminescence (IL) microscopy is a promising technique for the non-destructive characterisation of rocks and stone objects. Luminescence imaging by means of broad ion beams has been sporadically used by other authors but, to our knowledge, its potential has not yet been fully investigated, neither in geological science nor in other fields. The in-air broad beam IL microscope was developed and installed at the INFN-LABEC external microbeam in Florence. Similar to the cathodoluminescence (CL) microscope, the apparatus exploits a CCD colour camera collecting images (few square millimetres wide, with ~10-μm spatial resolution) of the luminescence emitted by the sample hit by a defocused megaelectron volt (MeV) proton beam. The main differences with the well-established and widespread CL are the possibility of working in air (no sampling or conductive coatings required) and the possibility of combining the analysis with microbeam analysis, such as, for example, μ-IL and μ-PIXE (particle-induced X-ray emission). To show the potential of the technique, IL images of thin sections of lapis lazuli are compared with those obtained by means of an in-vacuum cold CL. An application to the study of stone artworks is also reported. This technique and apparatus will provide a valuable help for interdisciplinary applications, e.g. in geological sciences and in the cultural heritage field. PMID:22644153

  10. In-air broad beam ionoluminescence microscopy as a tool for rocks and stone artworks characterisation.

    PubMed

    Lo Giudice, Alessandro; Re, Alessandro; Angelici, Debora; Calusi, Silvia; Gelli, Nicla; Giuntini, Lorenzo; Massi, Mirko; Pratesi, Giovanni

    2012-07-01

    Broad beam ionoluminescence (IL) microscopy is a promising technique for the non-destructive characterisation of rocks and stone objects. Luminescence imaging by means of broad ion beams has been sporadically used by other authors but, to our knowledge, its potential has not yet been fully investigated, neither in geological science nor in other fields. The in-air broad beam IL microscope was developed and installed at the INFN-LABEC external microbeam in Florence. Similar to the cathodoluminescence (CL) microscope, the apparatus exploits a CCD colour camera collecting images (few square millimetres wide, with ~10-μm spatial resolution) of the luminescence emitted by the sample hit by a defocused megaelectron volt (MeV) proton beam. The main differences with the well-established and widespread CL are the possibility of working in air (no sampling or conductive coatings required) and the possibility of combining the analysis with microbeam analysis, such as, for example, μ-IL and μ-PIXE (particle-induced X-ray emission). To show the potential of the technique, IL images of thin sections of lapis lazuli are compared with those obtained by means of an in-vacuum cold CL. An application to the study of stone artworks is also reported. This technique and apparatus will provide a valuable help for interdisciplinary applications, e.g. in geological sciences and in the cultural heritage field.

  11. Functional characterisation of UCP1 in the common carp: uncoupling activity in liver mitochondria and cold-induced expression in the brain.

    PubMed

    Jastroch, Martin; Buckingham, Julie A; Helwig, Michael; Klingenspor, Martin; Brand, Martin D

    2007-10-01

    Mammalian uncoupling protein 1 (UCP1) mediates nonshivering thermogenesis in brown adipose tissue. We previously reported on the presence of a UCP1 orthologue in ectothermic fish and observed downregulation of UCP1 gene expression in the liver of the common carp. Neither the function of UCP1, nor the mode of UCP1 activation is known in carp liver mitochondria. Here, we compared the proton conductance at 25 degrees C of liver mitochondria isolated from carp either maintained at 20 degrees C (warm-acclimated, WA) or exposed to 8 degrees C (cold-acclimated, CA) water temperature for 7-10 days. Liver mitochondria from WA carp had higher state four rates of oxygen consumption and greater proton conductance at high membrane potential. Liver mitochondria from WA, but not from CA, carp showed a strong increase in proton conductance when palmitate (or 4-hydroxy-trans-2-nonenal, HNE) was added, and this inducible proton conductance was prevented by addition of GDP. This fatty acid sensitive proton leak is likely due to the expression of UCP1 in the liver of WA carp. The observed biochemical properties of proton leak strongly suggest that carp UCP1 is a functional uncoupling protein with broadly the same activatory and inhibitory characteristics as mammalian UCP1. Significant UCP1 expression was also detected in our previous study in whole brain of the carp. We here observed a twofold increase of UCP1 mRNA in carp brain following cold exposure, suggesting a role of UCP1 in the thermal adaptation of brain metabolism. In situ hybridization located the UCP1 gene expression to the optic tectum responsible for visual system control, the descending trigeminal tract and the solitary tract. Taken together, this study characterises uncoupling protein activity in an ectotherm for the first time.

  12. The mensuration of delayed luminescence on ginseng

    NASA Astrophysics Data System (ADS)

    Xiang, Fenghua; Bai, Hua; Tang, Guoqing

    2008-12-01

    In this paper, the delayed luminescence of ginseng produced from two different areas was determined with the self built bioluminescence detecting system. And the attenuation curve of bioluminescence of the experimental samples were studied, before and after the samples extracted by 58% alcohol. We primarily gave out the parameters describing emitting characteristic. Using the method of optic induced bioluminescence, we also determined the weak luminescence emitting from the ginseng tuber, and find the intensity and decay time having obvious difference from skin and core, with these data we can distinguish the producing area and feature of the ginseng. In the experiment, the light-induce luminescence of the sample was menstruated, which has been infused by water and 58% alcohol; the difference between two kinds of samples which were infused and not infused has been delivered. In order to investigate the effect of excitation-light spectrum component to delayed luminescence of ginseng, a light filter witch allow a wavelength scope of 225nm~420nm pass through was installed between the light source and sample, keeping other work condition unchanged, the bioluminescence was also determined. For investigating the effect of extracting to emitting, the absorption spectrum of above samples ware studied, and the time-sequence of absorption spectrum was obtained. Based on the data obtained from our experiment, we analyzed the radiation mechanism of ginseng slice and tuber.

  13. Band-gap engineering by molecular mechanical strain-induced giant tuning of the luminescence in colloidal amorphous porous silicon nanostructures.

    PubMed

    Mughal, A; El Demellawi, J K; Chaieb, Sahraoui

    2014-12-14

    Nano-silicon is a nanostructured material in which quantum or spatial confinement is the origin of the material's luminescence. When nano-silicon is broken into colloidal crystalline nanoparticles, its luminescence can be tuned across the visible spectrum only when the sizes of the nanoparticles, which are obtained via painstaking filtration methods that are difficult to scale up because of low yield, vary. Bright and tunable colloidal amorphous porous silicon nanostructures have not yet been reported. In this letter, we report on a 100 nm modulation in the emission of freestanding colloidal amorphous porous silicon nanostructures via band-gap engineering. The mechanism responsible for this tunable modulation, which is independent of the size of the individual particles and their distribution, is the distortion of the molecular orbitals by a strained silicon-silicon bond angle. This mechanism is also responsible for the amorphous-to-crystalline transformation of silicon.

  14. Quantitative Luminescence Imaging System

    SciTech Connect

    Batishko, C.R.; Stahl, K.A.; Fecht, B.A.

    1992-12-31

    The goal of the MEASUREMENT OF CHEMILUMINESCENCE project is to develop and deliver a suite of imaging radiometric instruments for measuring spatial distributions of chemiluminescence. Envisioned deliverables include instruments working at the microscopic, macroscopic, and life-sized scales. Both laboratory and field portable instruments are envisioned. The project also includes development of phantoms as enclosures for the diazoluminomelanin (DALM) chemiluminescent chemistry. A suite of either phantoms in a variety of typical poses, or phantoms that could be adjusted to a variety of poses, is envisioned. These are to include small mammals (rats), mid-sized mammals (monkeys), and human body parts. A complete human phantom that can be posed is a long-term goal of the development. Taken together, the chemistry and instrumentation provide a means for imaging rf dosimetry based on chemiluminescence induced by the heat resulting from rf energy absorption. The first delivered instrument, the Quantitative Luminescence Imaging System (QLIS), resulted in a patent, and an R&D Magazine 1991 R&D 100 award, recognizing it as one of the 100 most significant technological developments of 1991. The current status of the project is that three systems have been delivered, several related studies have been conducted, two preliminary human hand phantoms have been delivered, system upgrades have been implemented, and calibrations have been maintained. Current development includes sensitivity improvements to the microscope-based system; extension of the large-scale (potentially life-sized targets) system to field portable applications; extension of the 2-D large-scale system to 3-D measurement; imminent delivery of a more refined human hand phantom and a rat phantom; rf, thermal and imaging subsystem integration; and continued calibration and upgrade support.

  15. Lunar luminescence measurements

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.

    1983-01-01

    Spectra of lunar sites obtained in June 1983 have been analyzed for residual luminescence using the spectral line depth technique. The results or three sites each at three wavelengths are presented. The sites observed were Mare Crisium, Kepler, and Aristarchus. In each case, the value quoted was based not only on the strong Fraunhofer line in the spectral range covered but also on from 11 to 21 weaker lines within 80 A of the strongest feature. These data do not support previous observations. The values given do not indicate a greatly reddened spectrum, and the luminescence spectrum of the mare site is not significantly different from the two young crater sites. These observations cannot be adequately explained by thermal luminescence, theories of direct excitation are also unable to explain the strength of the flux.

  16. Luminescent dendrimers. Recent advances.

    PubMed

    Balzani, Vincenzo; Ceroni, Paolo; Maestri, Mauro; Saudan, Christophe; Vicinelli, Veronica

    2003-01-01

    Luminescent dendrimers are currently attracting much attention since coupling luminescence and dendrimer research topics can lead to valuable new functions. Indeed, luminescence is a valuable tool to monitor both basic properties and possible applications (sensors, displays, lasers), and dendrimers are macromolecular compounds exhibiting a well-defined chemical structure with the possibility of containing selected chemical units in predetermined sites and of encapsulating ions or neutral molecules in their internal dynamic cavities. In this paper we will review recent advances in this field focusing our attention on their properties in fluid solution related to light harvesting, changing the "color" of light, sensing with signal amplification, quenching and sensitization processes, shielding effects, elucidation of dendritic structures and superstructures, and investigation of dendrimer rotation in solution. PMID:21132484

  17. Luminescent nanocrystal stress gauge

    PubMed Central

    Choi, Charina L.; Koski, Kristie J.; Olson, Andrew C. K.; Alivisatos, A. Paul

    2010-01-01

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe-CdS core-shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution. PMID:21098301

  18. Advanced synchronous luminescence system

    DOEpatents

    Vo-Dinh, T.

    1997-02-04

    A method and apparatus are disclosed for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition. 14 figs.

  19. CCD Luminescence Camera

    NASA Technical Reports Server (NTRS)

    Janesick, James R.; Elliott, Tom

    1987-01-01

    New diagnostic tool used to understand performance and failures of microelectronic devices. Microscope integrated to low-noise charge-coupled-device (CCD) camera to produce new instrument for analyzing performance and failures of microelectronics devices that emit infrared light during operation. CCD camera also used to indentify very clearly parts that have failed where luminescence typically found.

  20. Two bisthienylethene-Ir(III) complexes showing acid/base-induced structural transformation and on-off luminescence switching in solution.

    PubMed

    Cao, Deng-Ke; Hu, Jiong-Sheng; Li, Min-Qiang; Gong, Dan-Ping; Li, Xiao-Xiong; Ward, Michael D

    2015-12-28

    Complexes [Ir(dfppy)2(pbdtiH)](PF6)·2CHCl3 (1-H) and [Ir(dfppy)2(pbdti)] (1) were synthesized by the reaction of bisthienylethene pbdtiH and an [Ir(dfppy)2Cl]2 dimer under neutral and basic conditions, respectively. Thus, the {Ir(dfppy)2}(+) unit is coordinated by pbdtiH in 1-H, and by pbdti(-) in 1, which are confirmed by their crystal structures. The structures of 1-H and 1 could be interconverted in solution, upon alternately adding NEt3 and TFA, thus resulting in reversible luminescence switching between the on-state of 1-H and the off-state of 1 at room temperature. In addition, both 1-H and 1 show solid-state luminescence, with a broad emission at 534 nm and 525 nm, respectively. The free pbdtiH ligand shows photochromic behavior in CH2Cl2 solution. However, no photochromism has been observed in 1-H and 1, indicating that the coordination of the pbdtiH/pbdti(-) ligand to the {Ir(dfppy)2}(+) unit could suppress their photochromic behaviors.

  1. Electronic structure and luminescence center of blue luminescent carbon nanocrystals

    NASA Astrophysics Data System (ADS)

    Zhou, Jigang; Zhou, Xingtai; Li, Ruying; Sun, Xueliang; Ding, Zhifeng; Cutler, Jeffrey; Sham, Tsun-Kong

    2009-06-01

    The electronic structure and the origin of luminescence from blue luminescent carbon nanocrystals (CNC) have been investigated with X-ray absorption near-edge structures (XANES) and X-ray excited optical luminescence (XEOL). XANES shows that nitrogen has been incorporated into the carbon nanocrystals matrix (dominated by sp 2 carbon). XEOL from CNC is compared with that from natural diamond and previously reported CVD nanodiamond containing N impurities. The results reveal that N doping is almost certainly responsible for the blue luminescence in carbon nanocrystals. The implication of the results is discussed.

  2. Optically stimulated luminescence dosimetry

    NASA Astrophysics Data System (ADS)

    McKeever, Stephen W.

    1999-02-01

    Optically Stimulated Luminescence (OSL) dosimetry is attractive to the health physics and dosimetry community due to its all-optical character, fast data acquisition and the avoidance of heating the detector. Until recently there was no luminescent material sensitive enough to radiation, and at the same time suitable for stimulation with visible light, for use in this application. However, anion-deficient aluminum oxide doped with carbon (Al2O3:C) appears to be not only an extremely sensitive thermoluminescence (TL) material, but is also well-suited to OSL applications. Several OSL readout protocols have been suggested, including cw-OSL, pulsed OSL (POSL), and 'delayed' OSL (DOSL). The paper discusses the physical mechanisms that give rise to the OSL signals and the dependence of these signals upon absorbed dose. Example applications of the use of OSL from Al2O3:C in environmental radiation and ultraviolet-B dosimetry are discussed.

  3. Quantitative luminescence imaging system

    DOEpatents

    Erwin, David N.; Kiel, Johnathan L.; Batishko, Charles R.; Stahl, Kurt A.

    1990-01-01

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopie imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber.

  4. Quantitative luminescence imaging system

    DOEpatents

    Erwin, D.N.; Kiel, J.L.; Batishko, C.R.; Stahl, K.A.

    1990-08-14

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopic imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber. 22 figs.

  5. Influence of solution parameters on europium(III), α-Al2O3, and humic acid interactions: Macroscopic and time-resolved laser-induced luminescence data

    NASA Astrophysics Data System (ADS)

    Janot, Noémie; Benedetti, Marc F.; Reiller, Pascal E.

    2013-12-01

    Speciation of Eu(III) in the presence of purified Aldrich humic acid (PAHA) and/or α-Al2O3 has been studied by time-resolved luminescence spectroscopy as a function of pH, ionic strength and PAHA concentration. The comparisons of macroscopic and spectroscopic data (adsorption, spectra, and decay times analyses) between the ternary system, i.e., Eu(III)/PAHA/α-Al2O3, and the corresponding binary systems are comprehensively presented. As expected, results show almost no influence of ionic strength on Eu(III) adsorption onto α-Al2O3. However, in the binary Eu(III)/PAHA system, it is clearly shown that variations of electrolyte concentration, which modify PAHA conformation, influence the symmetry of the humic-bound Eu(III) at pH ⩾ 7. In the ternary system, adsorption of both Eu(III) and PAHA onto the surface decreases with ionic strength. At I = 0.01 M NaClO4, Eu(III) luminescence decay is much faster than at I = 0.1 M NaClO4. This is most likely due to the lower surface concentration of PAHA at lower ionic strength, leading to a less constrained environment for Eu(III) ions. At high pH, luminescence spectra are different at the two ionic strengths studied. Concerning the influence of PAHA concentration, spectroscopic results show that in the binary Eu(III)/PAHA system complete complexation of 1 μM Eu(III) is reached for 16 mgPAHA l-1 at pH 4, and for lower PAHA concentrations at higher pH. At the same PAHA concentration, asymmetry ratios are comparable between the binary Eu(III)/PAHA system and the ternary system between pH 4 and 7.7. This means that the presence of mineral surface has almost no influence on Eu(III) environment symmetry below pH 8; hence, under these acid to neutral pH conditions, the occurrence of Eu(III)-bridged humic surface complexes is not likely. In the ternary system, at different pH, luminescence decay times of Eu(III) increase with PAHA concentration. They are much higher in the ternary system than in the binary Eu(III)/PAHA system

  6. Luminescence properties of Si-containing porous matrix–PbS nanoparticle systems

    SciTech Connect

    Tarasov, S. A. Aleksandrova, O. A.; Lamkin, I. A.; Maksimov, A. I.; Maraeva, E. V.; Mikhailov, I. I.; Moshnikov, V. A.; Musikhin, S. F.; Nalimova, S. S.; Permyakov, N. V.; Spivak, Yu. M.; Travkin, P. G.

    2015-12-15

    The luminescence properties of systems that contain lead-sulfide nanoparticles deposited onto substrates fabricated from porous silicon, oxidized porous silicon, and porous (tin-oxide)–(silicon-oxide) layers are studied. It is shown that the structure and composition of the matrix induce a strong effect on the luminescence spectra of colloidal quantum dots, defining their emission wavelength.

  7. An Introduction to Luminescence in Inorganic Solids.

    ERIC Educational Resources Information Center

    DeLuca, John A.

    1980-01-01

    Introduces luminescence by characterizing phosphors, describing phosphor phenomena, presenting a configurational coordinate model of characteristic luminescence, and describing some commercial applications of phosphors. (CS)

  8. Neutron dosimetry using optically stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Miller, S. D.; Eschbach, P. A.

    1991-06-01

    The addition of thermoluminescent (TL) materials within hydrogenous matrices to detect neutron induced proton recoils for radiation dosimetry is a well known concept. Previous attempts to implement this technique have met with limited success, primarily due to the high temperatures required for TL readout and the low melting temperatures of hydrogen-rich plastics. Research in recent years PNL has produced a new Optically Stimulated Luminescence (OSL) technique known as the Cooled Optically Stimulated Luminescence (COSL) that offers, for the first time, the capability of performing extremely sensitive radiation dosimetry at low temperatures. In addition to its extreme sensitivity, the COSL technique offers multiple readout capability, limited fading in a one year period, and the capability of analyzing single grains within a hydrogenous matrix.

  9. Neutron dosimetry using optically stimulated luminescence

    SciTech Connect

    Miller, S.D.; Eschbach, P.A.

    1991-06-01

    The addition of thermoluminescent (TL) materials within hydrogenous matrices to detect neutron-induced proton recoils for radiation dosimetry is a well-known concept. Previous attempts to implement this technique have met with limited success, primarily due to the high temperatures required for TL readout and the low melting temperatures of hydrogen-rich plastics. Research in recent years at Pacific Northwest laboratories (PNL) has produced a new Optically Stimulated Luminescence (OSL) technique known as the Cooled Optically Stimulated Luminescence (COSL) that offers, for the first time, the capability of performing extremely sensitive radiation dosimetry at low temperatures. In addition to its extreme sensitivity, the COSL technique offers multiple readout capability, limited fading in a one-year period, and the capability of analyzing single grains within a hydrogenous matrix. 4 refs., 10 figs.

  10. Characterisation of dark current in novel Hg 1- xCd xTe mid-wavelength infrared photovoltaic detectors based on n-on-p junctions formed by plasma-induced type conversion

    NASA Astrophysics Data System (ADS)

    Rais, M. H.; Musca, C. A.; Antoszewski, J.; Dell, J. M.; Nener, B. D.; Faraone, L.

    2000-06-01

    This paper reports initial characterisation results for planar mid-wavelength infrared (MWIR) photodiodes fabricated using a novel reactive ion plasma-induced n-on-p junction formation technology on vacancy-doped p-type HgCdTe grown by LPE on CdZnTe substrates. The junction is formed without the need for post-implant annealing typically required by ion implantation junction formation techniques to repair damage or to move the junction away from damaged regions. The dark current and dynamic resistance, Rd, of the fabricated photodiodes have been characterised as a function of temperature. At 80 K, the zero-bias dynamic resistance-junction area product ( R0A) of the diodes is 4.6×10 7 Ω cm 2, with the devices being diffusion limited down to ˜135 K. Dynamic resistance has been measured for temperatures between 80 and 195 K and biases between -200 and +150 mV. Modelling of the observed dark current has been undertaken using three distinct mechanisms, diffusion, generation-recombination, and trap-assisted tunnelling. The results show that the plasma-induced junction formation technique can produce high-performance planar HgCdTe photodiodes. The dark current mechanisms found in these devices are similar to those found in diodes formed using conventional ion implantation techniques.

  11. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    SciTech Connect

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; Misewich, James A.; Wong, Stanislaus S.

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementary electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.

  12. Characterization of edible oils using total luminescence spectroscopy.

    PubMed

    Sikorska, E; Romaniuk, A; Khmelinskii, I V; Herance, R; Bourdelande, J L; Sikorski, M; Kozioł, J

    2004-01-01

    Total luminescence spectroscopy was used to characterise and differentiate edible oils and additionally, to control one of the major problems in the oil quality--the effect of thermal and photo-oxidation. We studied several vegetable oils available on the Polish market, including soybean, rapeseed, corn, sunflower, linseed and olive oils. Total luminescence spectroscopy measurements were performed using two different sample geometries: front-face for pure oil samples and right-angle for transparent samples, diluted in n-hexane. All the samples studied as n-hexane solutions exhibit an intense peak, which appears at 320 nm in emission and 290 nm in excitation, attributed to tocopherols. Some of the oils exhibit a second long-wavelength peak, appearing at 670 nm in emission and 405 nm in excitation, belonging to pigments of the chlorophyll group. Additional bands were present in the intermediate range of excitation and emission wavelengths; however, the compounds responsible for this emission were not identified. The front-face spectra for pure oils included chlorophyll peaks for most samples, and some additional peaks in the intermediate range, while the tocopherol peaks were comparatively less intense. The results presented demonstrate the capability of the total luminescence techniques to characterise and differentiate vegetable oil products, and additionally, to characterize the effect of thermal and photo-oxidation on such products. In the photo-oxidation experiments, special attention was paid to possible involvement of singlet oxygen. Experiments were done to monitor the highly specific O2(1delta(g)) --> O2(3sigma(g)-) singlet oxygen emission at 1270 nm. Thus, total luminescence spectroscopy presents an interesting alternative to time-consuming and expensive techniques such as gas or liquid chromatography, mass spectrometry and other methods requiring wet chemistry steps. PMID:15622857

  13. The application of photon, electron and proton induced X-ray analysis for the identification and characterisation of medieval silver coins

    NASA Astrophysics Data System (ADS)

    Linke, R.; Schreiner, M.; Demortier, G.

    2004-11-01

    Photons, electrons and protons beams applied to the scientific investigation of archaeological materials provide complementary information for characterising the state of preservation and the provenance of the objects. Investigations were carried out on medieval silver coins of the "Friesacher Pfennig" and the "Tiroler Kreuzer" from the Kunsthistorisches Museum Vienna and the Oesterreichische Nationalbank. Techniques employed were EDXRF, SEM/EDX and PIXE. By determining the trace elements of the alloys it was possible to assign coins to their mint. The results outline advantages and disadvantages of EDXRF, SEM/EDX and PIXE when applied to corroded objects.

  14. Making sense of lanthanide luminescence.

    PubMed

    Werts, Martinus H V

    2005-01-01

    The luminescence of trivalent lanthanide ions has found applications in lighting, lasers, optical telecommunications, medical diagnostics, and various other fields. This introductory review presents the basics of organic and inorganic luminescent materials containing lanthanide ions, their applications, and some recent developments. After a brief history of the discovery, purification and early spectroscopic studies of the lanthanides, the radiative and nonradiative transitions of the 4f electrons in lanthanide ions are discussed. Lanthanide-doped phosphors, glasses and crystals as well as luminescent lanthanide complexes with organic ligands receive attention with respect to their preparation and their applications. Finally, two recent developments in the field of luminescent materials are addressed: near-infrared luminescent lanthanide complexes and lanthanide-doped nano-particles.

  15. Boron clusters in luminescent materials.

    PubMed

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed. PMID:26574714

  16. Boron clusters in luminescent materials.

    PubMed

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.

  17. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N.; Corneillie, Todd M.; Xu, Jide

    2012-05-08

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  18. Luminescent macrocyclic lanthanide complexes

    DOEpatents

    Raymond, Kenneth N; Corneillie, Todd M; Xu, Jide

    2014-05-20

    The present invention provides a novel class of macrocyclic compounds as well as complexes formed between a metal (e.g., lanthanide) ion and the compounds of the invention. Preferred complexes exhibit high stability as well as high quantum yields of lanthanide ion luminescence in aqueous media without the need for secondary activating agents. Preferred compounds incorporate hydroxy-isophthalamide moieties within their macrocyclic structure and are characterized by surprisingly low, non-specific binding to a variety of polypeptides such as antibodies and proteins as well as high kinetic stability. These characteristics distinguish them from known, open-structured ligands.

  19. The effects of luminescent ruthenium(II) polypyridyl functionalized selenium nanoparticles on bFGF-induced angiogenesis and AKT/ERK signaling.

    PubMed

    Sun, Dongdong; Liu, Yanan; Yu, Qianqian; Zhou, Yanhui; Zhang, Rong; Chen, Xiaojia; Hong, An; Liu, Jie

    2013-01-01

    Anti-angiogenesis is an effective strategy for cancer treatment because uncontrolled tumor growth depends on tumor angiogenesis and sufficient blood supply. Thus, blocking angiogenesis could be a strategy to arrest tumor growth. The function and mechanism of luminescent ruthenium-modified selenium nanoparticles (Ru-SeNPs) in angiogenesis have not been elucidated to date. Here, we found that Ru-SeNPs significantly inhibited human umbilical vascular endothelial cell (HUVEC) proliferation, migration and tube formation. Ru-SeNPs was also tested in vivo in the chicken chorioallantoic membrane (CAM) assay and found to inhibit bFGF-treated CAMs development like suramin. Moreover, we showed that Ru-SeNPs inhibited the activations of FGFR1 and its downstream protein kinases, such ErK and AKT. Furthermore, by using fluorescence confocal microscopy and TEM imaging studies, we have demonstrated their cellular uptake and localization within the cytoplasm of HepG2 and HUVEC cells. These findings indicate that Ru-SeNPs inhibits angiogenesis and may be a viable drug candidate in anti-angiogenesis and anticancer therapies. PMID:23059005

  20. The nature of unusual luminescence in natural calcite, CaCO3

    SciTech Connect

    Gaft, M.; Nagli, L.; Panczer, G.; Waychunas, G.; Porat, N.

    2008-11-01

    The unusual luminescence of particular varieties of natural pink calcite (CaCO{sub 3}) samples was studied by laser-induced time-resolved luminescence spectroscopy at different temperatures. The luminescence is characterized by intense blue emission under short-wave UV lamp excitation with an extremely long decay time, accompanied by pink-orange luminescence under long wave UV excitation. Our investigation included optical absorption, natural thermostimulated luminescence (NTL) and Laser-Induced Breakdown Spectroscopy (LIBS) studies. Two luminescence centers were detected: a narrow violet band, with {lambda}{sub max} = 412 nm, {Delta} = 45 nm, two decay components of {tau}{sub 1} = 5 ns and {tau}{sub 2} = 7.2 ms, accompanied by very long afterglow, and an orange emission band with {lambda}{sub max} = 595 nm, {Delta} = 90 nm and {tau} = 5 ns. Both luminescence centers are thermally unstable with the blue emission disappearing after heating at 500 C, and the orange emission disappearing after heating at different temperatures starting from 230 C, although sometimes it is stable up to 500 C in different samples. Both centers have spectral-kinetic properties very unusual for mineral luminescence, which in combination with extremely low impurity concentrations, prevent their identification with specific impurity related emission. The most likely explanation of these observations may be the presence of radiation-induced luminescence centers. The long violet afterglow is evidently connected with trapped charge carrier liberation, with their subsequent migration through the valence band and ultimate recombination with a radiation-induced center responsible for the unusual violet luminescence.

  1. Enhanced radiation detectors using luminescent materials

    DOEpatents

    Vardeny, Zeev V.; Jeglinski, Stefan A.; Lane, Paul A.

    2001-01-01

    A radiation detecting device comprising a radiation sensing element, and a layer of luminescent material to expand the range of wavelengths over which the sensing element can efficiently detect radiation. The luminescent material being selected to absorb radiation at selected wavelengths, causing the luminescent material to luminesce, and the luminescent radiation being detected by the sensing element. Radiation sensing elements include photodiodes (singly and in arrays), CCD arrays, IR detectors and photomultiplier tubes. Luminescent materials include polymers, oligomers, copolymers and porphyrines, Luminescent layers include thin films, thicker layers, and liquid polymers.

  2. Luminescence resonance energy transfer

    SciTech Connect

    Selvin, P.R.; Rana, T.M.; Hearst, J.E. Lawrence Berkeley Lab., CA )

    1994-06-29

    Fluorescence resonance energy transfer (FRET), in which a fluorescent donor molecule transfers energy via a nonradiative dipole-dipole interaction to an acceptor molecule (which is usually a fluorescent molecule), is a standard spectroscopic technique for measuring distances in the 10-70 Angstrom range. We have used a luminescent europium chelate as donor and an organic dye, CY-5, as acceptor. This luminescence resonance energy transfer (LRET) has several advantages over the more conventional FRET. The distance at which 50% of the energy is transferred (R[sub 0]) is large, 70 [angstrom]; the donor lifetime is single exponential and long (0.63 ms in H[sub 2]O; 2.5 ms in D[sub 2]O), making lifetime measurements facile and highly accurate; the orientation dependence (k[sup 2]) of energy transfer is minimized by the donor's multiple electronic transitions and long lifetime, limiting uncertainty in the measured distance due to orientation effects to [+-]12% in the worst case; the sensitized emission of the acceptor can be measured with little or no interfering background, yielding a >50-fold improvement in signal to background over standard donor-acceptor pairs and enabling distances several times R[sub 0] to be measured. 13 refs., 4 figs.

  3. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region. PMID:26589210

  4. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

  5. Structural and luminescent properties of electron-irradiated silicon

    SciTech Connect

    Sobolev, N. A.; Loshachenko, A. S.; Aruev, P. N.; Kalyadin, A. E.; Shek, E. I.; Zabrodskiy, V. V.; Shtel'makh, K. F.; Vdovin, V. I.; Xiang, Luelue; Yang, Deren

    2014-02-21

    Structural defects induced by electron irradiation of p-Cz-Si wafers were identified. The influence of the annealing conditions in a chlorine-containing atmosphere on the structural and luminescent properties of the samples was examined. Light-emitting diodes based on electron-irradiated and high-temperature-annealed wafers were fabricated by a vapour-phase epitaxy technique and their luminescence properties were studied. A high-intensity dislocation-related D1 line was observed at 1.6 μm in the room-temperature electroluminescence spectrum.

  6. A double substitution induced Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) phosphor for w-LEDs: synthesis, structure, and luminescence properties.

    PubMed

    Li, Yang; Liu, Wenjing; Wang, Xicheng; Zhu, Ge; Wang, Chuang; Wang, Yuhua

    2015-08-01

    A double substitution induced blue-emitting phosphor Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) (CMAS:Eu(2+)) was successfully synthesized by a solid-state reaction process, and its structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of the CMAS matrix were analyzed and determined based on Rietveld refinements and Energy Dispersive Spectroscopy (EDS). The composition-optimized CMAS:Eu(2+) exhibited a strong blue light, centered at 446 nm upon excitation at 365 nm with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.144, 0.113). Under 380 nm excitation, the PL emission intensity area of the optimized phosphor was found to be 46.95% of that of the commercial BaMgAl10O17:Eu(2+) (BAM:Eu(2+)) phosphor and the quantum efficiency of the phosphor is 41.32%. The temperature-dependent PL studies have been investigated which show the thermal stability of the CMAS:Eu(2+) phosphor compared with that of the CaMgSi2O6:Eu(2+) (CMS:Eu(2+)) phosphor. PMID:26115078

  7. A double substitution induced Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) phosphor for w-LEDs: synthesis, structure, and luminescence properties.

    PubMed

    Li, Yang; Liu, Wenjing; Wang, Xicheng; Zhu, Ge; Wang, Chuang; Wang, Yuhua

    2015-08-01

    A double substitution induced blue-emitting phosphor Ca(Mg0.8, Al0.2)(Si1.8, Al0.2)O6:Eu(2+) (CMAS:Eu(2+)) was successfully synthesized by a solid-state reaction process, and its structure and luminescence properties were investigated in detail. The crystal structure and chemical composition of the CMAS matrix were analyzed and determined based on Rietveld refinements and Energy Dispersive Spectroscopy (EDS). The composition-optimized CMAS:Eu(2+) exhibited a strong blue light, centered at 446 nm upon excitation at 365 nm with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.144, 0.113). Under 380 nm excitation, the PL emission intensity area of the optimized phosphor was found to be 46.95% of that of the commercial BaMgAl10O17:Eu(2+) (BAM:Eu(2+)) phosphor and the quantum efficiency of the phosphor is 41.32%. The temperature-dependent PL studies have been investigated which show the thermal stability of the CMAS:Eu(2+) phosphor compared with that of the CaMgSi2O6:Eu(2+) (CMS:Eu(2+)) phosphor.

  8. Enhanced Luminescence of Lanthanides: Determination of Europium by Enhanced Luminescence

    NASA Astrophysics Data System (ADS)

    Jenkins, Amanda L.; Murray, George M.

    1998-02-01

    An experiment has been developed to teach the principles of molecular luminescence spectroscopy. This laboratory experiment is designed for upper-level undergraduates as a less toxic alternative to current fluorescence experiments. It combines elements of physical and inorganic as well as analytical chemistry. The experiment can be performed on a variety of rudimentary fluorescence instrumentation and still give good analytical figures of merit. The object of the experiment is to measure the luminescent enhancement that is achieved when a lanthanide such as Eu(III) or Tb(III) is complexed with appropriate organic ligands, in this case 2,6 pyridinedicarboxylic acid. The importance of pH on metal ion coordination is also explored via luminescence intensity. This approach provides several advantages over current luminescence experiments. These advantages include limited toxicity and flammability of the chemicals involved, a large luminescence linear dynamic range, and low detection limits (parts per trillion). These low detection limits, achieved using modest equipment, allow the determination of the europium concentration in a variety of samples, such as tap water. The narrow lanthanide luminescent bands also permit incorporation of qualitative analysis of a mixture of lanthanides.

  9. Probing structure-induced optical behavior in a new class of self-activated luminescent 0D/1D CaWO₄ metal oxide – CdSe nanocrystal composite heterostructures

    DOE PAGES

    Han, Jinkyu; McBean, Coray; Wang, Lei; Hoy, Jessica; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Sfeir, Matthew Y.; Fischer, Daniel A.; Taylor, Gordon T.; et al

    2015-01-30

    In this report, we synthesize and characterize the structural and optical properties of novel heterostructures composed of (i) semiconducting nanocrystalline CdSe quantum dot (QDs) coupled with (ii) both one and zero-dimensional (1D and 0D) motifs of self-activated luminescence CaWO₄ metal oxides. Specifically, ~4 nm CdSe QDs have been anchored onto (i) high-aspect ratio 1D nanowires, measuring ~230 nm in diameter and ~3 μm in length, as well as onto (ii) crystalline 0D nanoparticles (possessing an average diameter of ~ 80 nm) of CaWO₄ through the mediation of 3-mercaptopropionic acid (MPA) as a connecting linker. Composite formation was confirmed by complementarymore » electron microscopy and spectroscopy (i.e. IR and Raman) data. In terms of luminescent properties, our results show that our 1D and 0D heterostructures evince photoluminescence (PL) quenching and shortened PL lifetimes of CaWO₄ as compared with unbound CaWO₄. We propose that a photo-induced electron transfer process occurs from CaWO₄ to CdSe QDs, a scenario which has been confirmed by NEXAFS measurements and which highlights a decrease in the number of unoccupied orbitals in the conduction bands of CdSe QDs. By contrast, the PL signature and lifetimes of MPA-capped CdSe QDs within these heterostructures do not exhibit noticeable changes as compared with unbound MPA-capped CdSe QDs. The striking difference in optical behavior between CaWO₄ nanostructures and CdSe QDs within our heterostructures can be correlated with the relative positions of their conduction and valence energy band levels. In addition, the PL quenching behaviors for CaWO₄ within the heterostructure configuration were examined by systematically varying (i) the quantities and coverage densities of CdSe QDs as well as (ii) the intrinsic morphology (and by extension, the inherent crystallite size) of CaWO₄ itself.« less

  10. Studies of LSO:Tb radio-luminescence properties using white beam hard X-ray synchrotron irradiation

    NASA Astrophysics Data System (ADS)

    Cecilia, A.; Rack, A.; Pelliccia, D.; Douissard, P.-A.; Martin, T.; Couchaud, M.; Dupré, K.; Baumbach, T.

    A radio-luminescence set-up was installed at the synchrotron light source ANKA to characterise scintillators under the high X-ray photon flux density of white beam synchrotron radiation. The system allows for investigating the radio-luminescence spectrum of the material under study as well as analysing in situ changes of its scintillation behaviour (e.g. under heat load and/or intensive ionising radiation). In this work we applied the radio-luminescence set-up for investigating the radiation damage effects on the luminescence properties of a new kind of thin single crystal scintillator for high resolution X-ray imaging based on a layer of modified Lu2SiO5 grown by liquid phase epitaxy on a dedicated substrate within the framework of an EC project (SCINTAX).

  11. Confocal luminescence microscopy study of defect-domain wall interaction in lithium niobate and its application to light-induced domain engineering

    NASA Astrophysics Data System (ADS)

    Sandmann, Christian

    Understanding the mutual interaction of extrinsic and intrinsic defects with the ferroelectric domain walls of LiNbO3 is the key to achieve domain patterns on the sub-micron scale. For that reason the influence of domain inversion on the Er3+ defect was investigated in a detailed study, in which energetic shifts and changes in the intensity ratio of individual Er3+ sites were found. The results led to an improved model describing the Er3+ defect in LiNbO3 and to the introduction of a concept of an atomistic probe. This atomistic probe allows the determination of the orientation of the ferroelectric axis by means of optical spectroscopy and allows three-dimensional imaging of domain structures with high spatial resolution without topographic artifacts. For this purpose a confocal luminescence microscope was developed, adapted to allow investigation at low temperature and applied electric fields. Based on the concept of an atomistic probe, the interaction of Er and Ti dopants was investigated, and significant spectral broadening and line shifting were found. Calibrating these changes to the [Ti4+]-concentration allows imaging of [Ti4+]-profiles, as found in integrated optical devices. The [Ti4+]-concentration profile can be imaged without artifacts caused by topology, intensity fluctuations, or variations in the [Er3+]-concentration profile. A novel approach was introduced for directly writing ferroelectric domain patterns into LiNbO3 substrates using the confocal microscope to focus visible light from an argon ion laser to a diffraction limited spot. It was shown that space charge fields, created by light with a wavelength of 488nm, can reduce the external applied field needed for domain inversion by up to 30%. So far, structures with a period down to 8mum have been demonstrated. In-situ experiments during domain inversion demonstrated the possibility to monitor the domain inversion process in-situ with a temporal resolution of up to t = 7ms. It could be

  12. Luminescent screen composition and apparatus

    NASA Technical Reports Server (NTRS)

    Hilborn, E. H.

    1970-01-01

    Ultraviolet light projects photographically produced images on a screen composed of a mixture of linear and nonlinear phosphors whose spectral emissions are different. This allows the display of polychromatic luminescent images, which gives better discrimination of the objects being viewed.

  13. Quench-Shield Ratiometric Upconversion Luminescence Nanoplatform for Biosensing.

    PubMed

    Wu, Yong-Xiang; Zhang, Xiao-Bing; Zhang, Dai-Liang; Zhang, Cui-Cui; Li, Jun-Bin; Wu, Yuan; Song, Zhi-Ling; Yu, Ru-Qin; Tan, Weihong

    2016-02-01

    Upconversion nanoparticles (UCNPs) possess several unique features, but they suffer from surface quenching effects caused by the interaction between the UCNPs and fluorophore. Thus, the use of UCNPs for target-induced emission changes for biosensing and bioimaging has been challenging. In this work, fluorophore and UCNPs are effectively separated by a silica transition layer with a thickness of about 4 nm to diminish the surface quenching effect of the UCNPs, allowing a universal and efficient luminescence resonance energy transfer (LRET) ratiometric upconversion luminescence nanoplatform for biosensing applications. A pH-sensitive fluorescein derivative and Hg(2+)-sensitive rhodamine B were chosen as fluoroionphores to construct the LRET nanoprobes. Both showed satisfactory target-triggered ratiometric upconversion luminescence responses in both solution and live cells, indicating that this strategy may find wide applications in the design of nanoprobes for various biorelated targets. PMID:26744211

  14. Direct imaging of singlet oxygen luminescence generated in blood vessels during photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Lin, Lisheng; Lin, Huiyun; Chen, Defu; Chen, Longchao; Wang, Min; Xie, Shusen; Gu, Ying; Wilson, Brian C.; Li, Buhong

    2014-05-01

    Singlet oxygen (1O2) is commonly recognized to be a major phototoxic component for inducing the biological damage during photodynamic therapy (PDT). In this study, a novel configuration of a thermoelectrically-cooled near-infrared sensitive InGaAs camera was developed for imaging of photodynamically-generated 1O2 luminescence. The validation of 1O2 luminescence images for solution samples was performed with the model photosensitizer Rose Bengal (RB). Images of 1O2 luminescence generated in blood vessels in vivo in a well-controlled dorsal skinfold window chamber model were also recorded during PDT. This study demonstrated the capacity of the newly-developed imaging system for imaging of 1O2 luminescence, and the first reported images of 1O2 luminescence in blood vessels in vivo. This system has potential for elucidating the mechanisms of vascular targeted PDT.

  15. Interactions between bicarbonate, potassium, and magnesium, and sulfur-dependent induction of luminescence in Vibrio fischeri.

    PubMed

    Tabei, Yosuke; Era, Mariko; Ogawa, Akane; Morita, Hiroshi

    2012-06-01

    In spite of its central importance in research efforts, the relationship between seawater compounds and bacterial luminescence has not previously been investigated in detail. Thus, in this study, we investigated the effect of cations (Na(+) , K(+) , NH(4) (+) , Mg(2+) , and Ca(2+) ) and anions (Cl(-) , HCO(3) (-) , CO(3) (2-) , and NO(3) (-) ) on the induction of both inorganic (sulfate, sulfite, and thiosulfate) and organic (L-cysteine and L-cystine) sulfur-dependent luminescence in Vibrio fischeri. We found that HCO(3) (-) (bicarbonate) and CO(3) (2-) (carbonate), in the form of various compounds, had a stimulatory effect on sulfur-dependent luminescence. The luminescence induced by bicarbonate was further promoted by the addition of magnesium. Potassium also increased sulfur-dependent luminescence when sulfate or thiosulfate was supplied as the sole sulfur source, but not when sulfite, L-cysteine, or L-cystine was supplied. The positive effect of potassium was accelerated by the addition of magnesium and/or calcium. Furthermore, the additional supply of magnesium improved the induction of sulfite- or L-cysteine-dependent luminescence, but not the l-cystine-dependent type. These results suggest that sulfur-dependent luminescence of V. fischeri under nutrient-starved conditions is mainly controlled by bicarbonate, carbonate, and potassium. In addition, our results indicate that an additional supply of magnesium is effective for increasing V. fischeri luminescence. PMID:21953119

  16. Spectral reflectance change and luminescence of selected salts during 2-10 KeV proton bombardment - Implications for Io

    NASA Technical Reports Server (NTRS)

    Nelson, R. M.; Nash, D. B.

    1979-01-01

    Radiation damage and luminescence caused by magnetospheric charged particles have been suggested by several investigators as mechanisms that are capable of explaining some of the peculiar spectral/albedo features of Io. In the present paper, this possibility is pursued by measuring the UV-visual spectral reflectance and luminescent efficiency of several proposed Io surface constituents during 2 to 10 keV proton irradiation at room and low temperatures. The luminescence efficiencies of pure samples, studied in the laboratory, suggest that charged-particle induced luminescence from Io's surface might be observable by spacecraft such as Voyager when viewing Io's dark side.

  17. Measuring chronic toxicity using luminescent bacteria

    SciTech Connect

    Huynh, H.; Bulich, A.

    1994-12-31

    Bioassays using luminescent bacteria are routinely used to assess the acute toxicity of environmental samples. Two physiological characteristics of these test organisms, a short division cycle and the inducible luciferase pathway, provide functional attributes for measuring chronic toxicity. Freeze-dried luminescent bacteria, following inoculation into appropriate growth medium, initiate a series of reproductive cycles while inducing a complex series of metabolic pathways resulting in production of bioluminescence. Toxic chemicals or samples which inhibit any aspect of this reproductive cycle or induction of light production are detected in low concentrations. The development of this bioassay is based upon a detailed understanding of the growth requirements and biochemistry of this organism and the genetics of luciferase induction. A defined growth medium was developed which supports the necessary cell growth and luciferase induction, yet which does not mask the presence of toxic substances. To perform the assay, the test organisms are inoculated into a series of cuvettes containing growth medium and dilutions of the sample. After 18 hrs incubation at 27 C, control cuvettes show high light levels while sample dilutions containing toxic materials show decreasing light levels. Details of the test protocol and reproducibility are presented. Sensitivity data from this chronic toxicity test are summarized and compared with the Microtox{reg_sign} acute test and the Ceriodaphnia dubia chronic toxicity test method. This test method is about 20 times more sensitive than Microtox and exhibits sensitivity similar to C. dubia for tested metals and organic compounds.

  18. Turning on the Light: Lessons from Luminescence

    ERIC Educational Resources Information Center

    O'Hara, Patricia B.; Engelson, Carol; St. Peter, Wayne

    2005-01-01

    Some of the processes by which light is emitted without a simultaneous change in temperature are discussed and is classified as luminescence or cold light. Luminescent processes include triboluminescence, fluorescence, phosphorescence, chemiluminescence, and bioluminescence.

  19. Utilizing Nanofabrication to Construct Strong, Luminescent Materials

    SciTech Connect

    Chen, Wei; Huang, Gang; Lu, Hong B.; McCready, David E.; Joly, Alan G.; Bovin, Jan-Olov

    2006-05-28

    Luminescent materials have been utilized widely in applications from lighting to sensing. The new development of technologies based on luminescence properties requires the materials to have high luminescence efficiency and mechanical strength. In this article, we report the fabrication of luminescent materials possessing high mechanical strength by nanofabrication with polyvinyl alcohol used as a stabilizer or coupling agent. X-ray diffraction and high resolution transmission microscope observations reveal that the nanocomposite sample contains ZnS and ZnO nanoparticles as well as kozoite and sodium nitrate. The mechanical strength and hardness of these nanocomposite materials are higher than polycarbonate and some carbon nanotube reinforced nanocomposites. Strong luminescence is observed in the new nanocomposites and the luminescence intensity does not degrade following up to 30 minutes of X-ray irradiation. Our results indicate that nanofabrication may provide a good method to improve the mechanical strength of luminescent materials for some applications in which high strength luminescent materials are needed.

  20. Luminescent Magneto-Optical Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Khartsev, S. I.

    2012-03-01

    We compare luminescent properties of several Er-doped garnet films as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals: La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, Bi3Fe5O12, and Bi2.97Er0.03Fe4Al0.5Ga0.5O12. Er substituents on the dodecahedral lattice sites do not decrease giant Faraday rotation in Bi3Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching 6 ms in Gd2.9Er0.1Ga5O12. The first luminescent one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystal was composed from diamagnetic Sm3Ga5O12 and MO-active Bi2.97Er0.03Al0.5Ga0.5O12 garnet layers by rf-magnetron sputtering on Gd3Ga5O12(111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure Bi3Fe5O12. Photonic crystals owned a record high magneto-optical quality and a latching type (magnetic remnant) Faraday rotation (FR). At the resonance wavelength 775 nm, specific FR θF = - 14.1 deg/μm and MO-quality factor Q = 99.3 deg represent the highest MO performance achieved so far. Long-lived near-IR luminescence in Er substituted gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

  1. Luminescence study of homeopathic remedies

    NASA Astrophysics Data System (ADS)

    Lobyshev, Valentin I.; Tomkevitch, Marie

    2001-06-01

    It was shown in our recent papers that distilled water possesses intrinsic luminescence at wavelength of about 400 nm with excitation wavelength 300 nm, which is very sensitive to small amount of dissolved substances. This phenomena was chosen to study homeopathic remedies. Pronounced difference in the intensity of luminescence between several commercial preparations with the same potency and one preparation with various potencies was obtained. Long scale evolution of the spectra was registered and final result was dependent on preparation and its potency. Systematic study of homeopathic preparations of halit (natural sodium chloride) from 1 to 30 decimal dilution was done. A stepwise dilution with mechanical agitation between the dilution steps, the so-called potentisation, was produced specially by homeopathic company Weleda. Luminescence intensity against concentration (potency) of halit is non monotonous function with several maxima, the main maximum is located at 13-14-th dilution. Evolution of the spectra was registered during several months. The analogous potentisation treatment of water without additional substances results also in changes of the luminescence spectra, depending on the number of potentisation. The obtained differences of luminescence spectra at ultra high dilutions and potentisation show that the collective properties of water are really changed in homeopathic preparations.

  2. Method of measuring luminescence of a material

    SciTech Connect

    Miller, Steven D.

    2015-12-15

    A method of measuring luminescence of a material is disclosed. The method includes applying a light source to excite an exposed material. The method also includes amplifying an emission signal of the material. The method further includes measuring a luminescent emission at a fixed time window of about 10 picoseconds to about 10 nanoseconds. The luminescence may be radio photoluminescence (RPL) or optically stimulated luminescence (OSL).

  3. Nitric oxide in the control of luminescence from lantern shark (Etmopterus spinax) photophores.

    PubMed

    Claes, Julien M; Krönström, Jenny; Holmgren, Susanne; Mallefet, Jérôme

    2010-09-01

    Photophores (photogenic organs) of the lantern shark Etmopterus spinax are under hormonal control, with prolactin (PRL) and melatonin (MT) triggering the light emission. Differential sensitivity to these hormones in adult individuals suggests, however, that the luminescence of this shark is controlled by an additional mechanism. In this study, different techniques were used to investigate a potential modulator of E. spinax luminescence - nitric oxide (NO). NO synthase (NOS)-like immunoreactivity (IR) was found in the photocytes (photogenic cells) of the photophores. In addition, acetylated tubulin IR also supported the presence of nerves running through the photogenic tissue and innervating different structural elements of the photophores: photocytes, pigmented cells from the iris-like structure and lens cells. Pharmacological experiments confirmed a modulatory action of NO on the hormonally induced luminescence: NO donors sodium nitroprusside (SNP) and hydroxylamine decreased the time to reach the maximum amplitude (TL(max)) of MT-induced luminescence while these substances decreased the maximum amplitude of PRL-induced luminescence (and also the TL(max) in the case of SNP). The small impact of the NOS inhibitor l-NAME on hormonally induced luminescence suggests that NO is only produced on demand. The cGMP analogue 8BrcGMP mimicked the effects of NO donors suggesting that the effects of NO are mediated by cGMP.

  4. Specificity of aequorin luminescence to calcium

    NASA Technical Reports Server (NTRS)

    Shimomura, O.; Johnson, F. H.

    1975-01-01

    The presence of Pb(++), Co(++), Cu(++), and Cd(++), each of which possesses a certain luminescence-triggering activity of aequorin, potentially interferes with the specificity of the aequorin luminescence response to Ca(++). Interference by the above cations can be eliminated, without influencing the sensitivity of the luminescence of aequorin to Ca(++), by adding 1 mM of sodium diethyldithiocarbamate.

  5. A luminescent nanocrystal stress gauge

    SciTech Connect

    Choi, Charina; Koski, Kristie; Olson, Andrew; Alivisatos, Paul

    2010-10-25

    Microscale mechanical forces can determine important outcomes ranging from the site of material fracture to stem cell fate. However, local stresses in a vast majority of systems cannot be measured due to the limitations of current techniques. In this work, we present the design and implementation of the CdSe/CdS core/shell tetrapod nanocrystal, a local stress sensor with bright luminescence readout. We calibrate the tetrapod luminescence response to stress, and use the luminescence signal to report the spatial distribution of local stresses in single polyester fibers under uniaxial strain. The bright stress-dependent emission of the tetrapod, its nanoscale size, and its colloidal nature provide a unique tool that may be incorporated into a variety of micromechanical systems including materials and biological samples to quantify local stresses with high spatial resolution.

  6. Generation and Characterisation of a Pax8-CreERT2 Transgenic Line and a Slc22a6-CreERT2 Knock-In Line for Inducible and Specific Genetic Manipulation of Renal Tubular Epithelial Cells.

    PubMed

    Espana-Agusti, Judit; Zou, Xiangang; Wong, Kim; Fu, Beiyuan; Yang, Fengtang; Tuveson, David A; Adams, David J; Matakidou, Athena

    2016-01-01

    Genetically relevant mouse models need to recapitulate the hallmarks of human disease by permitting spatiotemporal gene targeting. This is especially important for replicating the biology of complex diseases like cancer, where genetic events occur in a sporadic fashion within developed somatic tissues. Though a number of renal tubule targeting mouse lines have been developed their utility for the study of renal disease is limited by lack of inducibility and specificity. In this study we describe the generation and characterisation of two novel mouse lines directing CreERT2 expression to renal tubular epithelia. The Pax8-CreERT2 transgenic line uses the mouse Pax8 promoter to direct expression of CreERT2 to all renal tubular compartments (proximal and distal tubules as well as collecting ducts) whilst the Slc22a6-CreERT2 knock-in line utilises the endogenous mouse Slc22a6 locus to specifically target the epithelium of proximal renal tubules. Both lines show high organ and tissue specificity with no extrarenal activity detected. To establish the utility of these lines for the study of renal cancer biology, Pax8-CreERT2 and Slc22a6-CreERT2 mice were crossed to conditional Vhl knockout mice to induce long-term renal tubule specific Vhl deletion. These models exhibited renal specific activation of the hypoxia inducible factor pathway (a VHL target). Our results establish Pax8-CreERT2 and Slc22a6-CreERT2 mice as valuable tools for the investigation and modelling of complex renal biology and disease. PMID:26866916

  7. Luminescence in the fluoride-containing phosphate-based glasses: a possible origin of their high resistance to nanosecond pulse laser-induced damage.

    PubMed

    Wang, Pengfei; Lu, Min; Gao, Fei; Guo, Haitao; Xu, Yantao; Hou, Chaoqi; Zhou, Zhiwei; Peng, Bo

    2015-01-01

    Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers. PMID:25716328

  8. Characterisation of neurotransmitter-induced electrolyte transport in cockroach salivary glands by intracellular Ca2+, Na+ and pH measurements in duct cells.

    PubMed

    Hille, Carsten; Walz, Bernd

    2008-02-01

    Ion-transporting acinar peripheral cells in cockroach salivary glands are innervated by dopaminergic and serotonergic fibres, but saliva-modifying duct cells are innervated only by dopaminergic fibres. We used microfluorometry to record intracellular Na+, Ca2+ and H+ concentrations ([Na+]i, [Ca2+]i and pHi) in duct cells of two types of preparation, viz ;lobes' consisting of acini with their duct system and ;isolated ducts' without acini, in order to obtain information about the transporters involved in saliva secretion and/or modification. Our results indicate that (1) stimulation of lobes by dopamine (DA) causes a strong drop of pHi and increases in [Na+]i and [Ca2+]i in duct cells; (2) in contrast, DA stimulation of isolated ducts produces only a small pHi drop and no changes in [Na+]i and [Ca2+]i; (3) pHi and [Ca2+]i changes are also induced in duct cells by serotonin (5-HT) stimulation of lobes, but not isolated ducts; (4) in the absence of CO2/HCO3(-), the DA-induced pH(i) drop is strongly reduced by removal of extracellular Cl(-) or inhibition of the Na+-K+-2Cl(-) cotransporter (NKCC); (5) in the presence of CO2/HCO3(-), the DA-induced pHi drop is not reduced by NKCC inhibition, but rather by inhibition of the Cl(-)/HCO3(-) exchanger (AE), Na+/H+ exchanger (NHE) or carbonic anhydrase. We suggest that DA and 5-HT act predominantly on acinar peripheral cells. Their activity (secretion of primary saliva) seems to cause changes in ion concentrations in duct cells. NKCC and/or AE/NHE activities are necessary for pHi changes in duct cells; we consider that these transporters are involved in the secretion of the NaCl-rich primary saliva.

  9. Influence of cations and anions on the induction of cell density-independent luminescence in Photorhabdus luminescens.

    PubMed

    Tabei, Yosuke; Ogawa, Akane; Era, Mariko; Ninomiya, Junko; Morita, Hiroshi

    2013-03-01

    Bioluminescence is emitted by various living organisms, including bacteria. While the induction mechanism in marine luminescent bacteria, such as Vibrio fischeri and V. harveyi, has been well characterized, this mechanism has not been studied in detail in the non-marine luminescent bacterium Photorhabdus luminescens. Therefore, we investigated the effect of cations and anions on the induction of luminescence by P. luminescens. Cultivation of cells in an inorganic salts solution (ISS) containing KCl, CaCl2 , MgCl2 , NaHCO3 , and MgSO4 resulted in a rapid increase in luminescence intensity. Moreover, the induction of luminescence in the ISS medium was not dependent on cell density, since cell densities remained unchanged during 48 h. Furthermore, we found that compounds containing K(+) , Mg(2+) , and HCO3(-) were necessary to induce cell density-independent luminescence. The intensity of luminescence per cell cultured in medium containing KCl, MgCl2 , and NaHCO3 was approximately 100-fold higher than that cultured in NB. In contrast, when cells actively grew in normal growth condition, the intensity of luminescence per cell was not increased even in the presence of K(+) , Mg(2+) , and HCO3(-) . Thus, these results suggest that the luminescence of P. luminescens is regulated by 2 independent cell density-dependent and -independent mechanisms. PMID:22733631

  10. pH luminescence switching, dihydrogen phosphate sensing, and cellular uptake of a heterobimetallic ruthenium(II)-rhenium(I) complex.

    PubMed

    Zheng, Ze-Bao; Wu, Yong-Quan; Wang, Ke-Zhi; Li, Fuyou

    2014-02-28

    A new heterobimetallic ruthenium(II)-rhenium(I) complex of [Ru(bpy)2(HL)Re(CO)3Cl](ClO4)2·6H2O (RuHLRe) {bpy = 2,2'-bipyridine and HL = 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} was synthesised and characterised by elemental analysis, proton nuclear magnetic resonance spectroscopy, and mass spectrometry. The ground- and excited-state acid-base properties of RuHLRe were studied using UV-Vis absorption spectrophotometric and spectrofluorimetric titrations in a 100 : 1 (v/v) Britton-Robinson buffer-CH3CN solution combined with luminescence lifetime measurements. The complex exhibited two-step separate protonation-deprotonation processes in both the ground and excited states. The complex acted as pH-induced "off-on-off" luminescence switches (I(on)/I(off) = 31.0 and 14.6), with one of the switching actions being driven by pH variations over the physiological pH range (5.3-8.0). Importantly, cellular imaging and cytotoxicity experiments demonstrated that RuHLRe rapidly and selectively illuminated the membrane of HeLa cells over fixed cells and exhibited reduced cytotoxicity at the imaging concentration compared to the Re(I)-free parent Ru(II) complex. In addition, RuHLRe acted as an efficient "turn on" emission sensor for H2PO4(-) and "turn off" emission sensor for F(-) and OAc(-).

  11. Characterisation of proteins extracted from the surface of Salmonella Typhimurium grown under SPI-2-inducing conditions by LC-ESI/MS/MS sequencing.

    PubMed

    Sherry, Aileen E; Inglis, Neil F; Stevenson, Andy; Fraser-Pitt, Douglas; Everest, Paul; Smith, David G E; Roberts, Mark

    2011-02-01

    Salmonella enterica has two pathogenicity islands encoding separate type three secretion systems (T3SS). Proteins secreted through these systems facilitate invasion and survival. After entry, Salmonella reside within a membrane bound vacuole, the Salmonella containing vacuole (SCV), where translocation of a second set of effectors by the Salmonella pathogenicity island 2 (SPI-2) T3SS is initiated. SPI-2 secretion in vitro can be induced by conditions that mimic the Salmonella containing vacuole. Utilising high-throughput mass spectrometry, we mapped the surface-attached proteome of S. Typhimurium SL1344 grown in vitro under SPI-2-inducing conditions and identified 108 proteins; using secretion signal prediction software, 43% of proteins identified contained a signal sequence. Of these proteins, 13 were known secreted effector proteins including SPI-2 effector proteins SseB, SseC, SseD, SseL, PipB2 and SteC, although surprisingly five were SPI-1 proteins, SipA, SipB, SipC, SipD and SopD, while 2 proteins SteA and SlrP are secreted by both T3SSs. This is the first in vitro study to demonstrate dual secretion of SPI-1 and SPI-2 proteins by S. Typhimurium and demonstrates the potential of high-throughput LC-ESI/MS/MS sequencing for the identification of novel proteins, providing a platform for subsequent comparative proteomic analysis, which should greatly assist understanding of the pathogenesis and inherent variation between serovars of Salmonella and ultimately help towards development of novel control strategies.

  12. In-situ luminescence monitoring of ion-induced damage evolution in SiO2 and Al2O3

    DOE PAGES

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; Weber, William J.

    2015-12-17

    Real-time, in-situ ionoluminescence measurements provide information of evolution of emission bands with ion fluence, and thereby establish a correlation between point defect kinetics and phase stability. Using fast light ions (2 MeV H and 3.5 He MeV) and medium mass-high energy ions (8 MeV O, E=0.5 MeV/amu), scintillation materials of a-SiO2, crystalline quartz, and Al2O3 are comparatively investigated at room temperature with the aim of obtaining a further insight on the structural defects induced by ion irradiation and understand the role of electronic energy loss on the damage processes. For more energetic heavy ions, the electronic energy deposition pattern offersmore » higher rates of excitation deeper into the material and allows to evaluate the competing mechanisms between the radiative and non-radiative de-excitation processes. Irradiations with 8 MeV O ions have been selected corresponding to the electronic stopping regime, where the electronic stopping power is dominant, and above the critical amorphization threshold for quartz. Lastly, the usefulness of IBIL and its specific capabilities as a sensitive tool to investigate the material characterization and evaluation of radiation effects are demonstrated.« less

  13. The effect of viscosity, applied frequency and driven pressure on the laser induced bubble luminescence in water-sulfuric acid mixtures

    NASA Astrophysics Data System (ADS)

    Sadighi-Bonabi, Rasoul; Alijan Farzad Lahiji, Faezeh; Razeghi, Fatemeh

    2016-06-01

    Production and oscillation of sonoluminescence bubbles by laser pulse in the presence of acoustic field in water and different concentrations of sulfuric acid are investigated. In the presence of acoustic field, the laser causes variable speed of sound, surface tension and density; and the host liquid acts as a compressible one and strongly affects the bubble's dynamics equations. The effect of various concentrations of sulfuric acid as a host liquid on the oscillation of bubble radius, bubble wall velocity and bubble interior temperature is studied. Furthermore, the effect of applied frequency on LI-SCBL in the presence of the acoustic field is investigated and an optimum sound wave frequency for the bubble oscillation and bubble interior temperature in pure water and SA is introduced. Based on the modification of RP equation, by applying the optimum frequency, the results indicate that the maximum bubble radius for LI-SCBL in the presence of the acoustic field is increased up to 7 ×10-4 m as this article presents, which is more than 40% improvement. This amount results in interior temperature of more than three times, from almost 5000 K in the previous works to almost 16 000 K in the present report. This is very similar to the experimental measurements for bubble radius induced by laser. Furthermore, the effects of driving pressure amplitudes on the bubble radius, the bubble interior temperature and the bubble wall velocity in different host liquids and in optimum frequency are investigated.

  14. Continuous irradiation induced luminescence from benzophenone, 4,4{prime}-dichlorobenzophenone, and 4-(dimethylamino)benzaldehyde in solid environments and its pressure dependence

    SciTech Connect

    Dreger, Z.A.; Drickamer, H.G.

    1997-02-20

    We report a strong emission change induced by continuous light irradiation in two ketones, benzophenone and 4,4{prime}-dichlorobenzophenone, and an aldehyde, 4-(dimethylamino)benzaldehyde, in their crystalline state as well as dissolved in solid polymers. With prolonged laser irradiation, a time evolution of the emission intensity shows complex features, but two clear competing trends can be distinguished: an increase and/or decrease of the emission intensity. It is shown that these trends may be a result of creation of either an emissive or a nonemissive species. The relative importance of these two pathways is significantly dependent on the type of medium and external pressure. The most characteristic feature of these dependencies is the fact that in crystalline environments, in contrast to polymers, the emission intensity at all pressures only decreases. A kinetic model is developed that assumes the lowest triplet state as the origin of the high photoreactivity of these molecules, causing their emission intensity change. This model embraces the observations either in crystalline or polymeric environments and is solved for two limiting cases: a predominance of the hydrogen abstraction reaction from the polymer or a predominance of the ionization due to biphotonic excitation of the triplet state. These processes are assumed responsible, respectively, for the creation of emissive and nonemissive photoproducts. 29 refs., 19 figs., 2 tabs.

  15. Luminescence lifetime determination for oxygen imaging in human tissue

    NASA Astrophysics Data System (ADS)

    Lochmann, C.; Häupl, T.; Beuthan, J.

    2008-02-01

    Imaging and monitoring of biochemical parameters in vitro and in vivo have become the goal of many investigations in medical physics. The main imaging technique used is laser-induced luminescence due to its cost effectiveness and diversity of applications [1]. One key parameter in medical investigations, for instance to control photodynamic therapy, is the molecular oxygen concentration. The use of optical methods provides possible means of measuring molecular oxygen. The basis of such a method is the measurement of the luminescence lifetime of a dye which is quenched by molecular oxygen. The molecular oxygen concentration can be monitored two-dimensionally by pixel-wise determination of the luminescence lifetime with a CCD-camera. An oxygen imaging system based on this principle was built and tested with a commercially available oxygen sensitive sol gel-layer. The embedded ruthenium complex is quenched by molecular oxygen and because of the oxygen permeability of the layer; it is suitable for oxygen measurements. The characteristics and dependence on the pH-value and temperature of the luminescence lifetime of the layer were examined in preparation for measurements on tissue to exclude cross-correlation of other quenching processes.

  16. Synergic effects of tryptamine and octopamine on ophiuroid luminescence (Echinodermata).

    PubMed

    Vanderlinden, C; Mallefet, J

    2004-10-01

    In ophiuroids, bioluminescence is under nervous control. Previous studies have shown that acetylcholine is the main neurotransmitter triggering light emission in Amphipholis squamata and Amphiura filiformis. By contrast, none of the neurotransmitters tested so far induced luminescence in two other ophiuroid species, Ophiopsila aranea and Ophiopsila californica. The aim of this work was thus to investigate the putative involvement of two biogenic amines, tryptamine and octopamine, in light emission of three ophiuroid species. A. filiformis responds to both tryptamine and octopamine, mainly on its arm segments, while O. californica only responds to tryptamine stimulation. By contrast, tryptamine and octopamine do not seem to be involved in O. aranea luminescence control since none of these substances induced light emission in this species. The synergic effects of several other drugs with tryptamine and octopamine were also tested.

  17. Electrical characterisation and predictive simulation of defects induced by keV Si{sup +} implantation in n-type Si

    SciTech Connect

    Nyamhere, C.; Cristiano, F.; Olivie, F.; Bedel-Pereira, E.; Essa, Z.; Bolze, D.; Yamamoto, Y.

    2013-05-14

    In this work, we focused on the analysis of implantation-induced defects, mainly small interstitial clusters (ICs) and {l_brace} 311{r_brace} defects introduced in n-type Si after ion implantation using deep level transient spectroscopy (DLTS). Silicon ions (at 160 keV or 190 keV) of fluences ranging from (0.1-8.0) Multiplication-Sign 10{sup 13} cm{sup -2} have been implanted into n-type Si and annealed at temperatures between 500 Degree-Sign C and 800 Degree-Sign C specifically to create small ICs or {l_brace} 311{r_brace} s rod-like defects. In samples dominated by small ICs, DLTS spectra show prominent deep levels at Ec - 0.24 eV and Ec - 0.54 eV. After increasing the fluence and temperature, i.e., reducing the number of small ICs and forming {l_brace} 311{r_brace} defects, the peak Ec - 0.54 eV is still dominant while other electron traps Ec - 0.26 eV and Ec - 0.46 eV are introduced. There were no observable deep levels in reference, non-implanted samples. The identity and origin of all these traps are interpreted in conjunction with recently developed predictive defect simulation models.

  18. Fourier transform infrared spectroscopic characterisation of heavy metal-induced metabolic changes in the plant-associated soil bacterium Azospirillum brasilense Sp7

    NASA Astrophysics Data System (ADS)

    Kamnev, A. A.; Antonyuk, L. P.; Tugarova, A. V.; Tarantilis, P. A.; Polissiou, M. G.; Gardiner, P. H. E.

    2002-06-01

    Structural and compositional features of whole cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp7 under standard and heavy metal-stressed conditions are analysed using Fourier transform infrared (FTIR) spectroscopy and compared with the FT-Raman spectroscopic data obtained previously [J. Mol. Struct. 563-564 (2001) 199]. The structural spectroscopic information is considered together with inductively coupled plasma-mass spectrometric (ICP-MS) analytical data on the content of the heavy metal cations (Co 2+, Cu 2+ and Zn 2+) in the bacterial cells. As a bacterial response to heavy metal stress, all the three metals, being taken up by bacterial cells from the culture medium (0.2 mM) in significant amounts (ca. 0.12, 0.48 and 4.2 mg per gram of dry biomass for Co, Cu and Zn, respectively), are shown to induce essential metabolic changes in the bacterium revealed in the spectra, including the accumulation of polyester compounds in bacterial cells and their enhanced hydration affecting certain IR vibrational modes of functional groups involved.

  19. Plasmon enhancement of luminescence upconversion.

    PubMed

    Park, Wounjhang; Lu, Dawei; Ahn, Sungmo

    2015-05-21

    Frequency conversion has always been an important topic in optics. Nonlinear optics has traditionally focused on frequency conversion based on nonlinear susceptibility but with the recent development of upconversion nanomaterials, luminescence upconversion has begun to receive renewed attention. While upconversion nanomaterials open doors to a wide range of new opportunities, they remain too inefficient for most applications. Incorporating plasmonic nanostructures provides a promising pathway to highly efficient upconversion. Naturally, a plethora of theoretical and experimental studies have been published in recent years, reporting enhancements up to several hundred. It is however difficult to make meaningful comparisons since the plasmonic fields are highly sensitive to the local geometry and excitation condition. Also, many luminescence upconversion processes involve multiple steps via different physical mechanisms and the overall output is often determined by a delicate interplay among them. This review is aimed at offering a comprehensive framework for plasmon enhanced luminescence upconversion. We first present quantum electrodynamics descriptions for all the processes involved in luminescence upconversion, which include absorption, emission, energy transfer and nonradiative transitions. We then present a bird's eye view of published works on plasmon enhanced upconversion, followed by more detailed discussion on comparable classes of nanostructures, the effects of spacer layers and local heating, and the dynamics of the plasmon enhanced upconversion process. Plasmon enhanced upconversion is a challenging and exciting field from the fundamental scientific perspective and also from technological standpoints. It offers an excellent system to study how optical processes are affected by the local photonic environment. This type of research is particularly timely as the plasmonics is placing heavier emphasis on nonlinearity. At the same time, efficient upconversion

  20. Luminescence and related properties of nanocrystalline porous silicon

    NASA Astrophysics Data System (ADS)

    Koshida, N.

    This document is part of subvolume C3 'Optical Properties' of volume 34 'Semiconductor quantum structures' of Landolt-Börnstein, Group III, Condensed Matter, on the optical properties of quantum structures based on group IV semiconductors. It discusses luminescence and related properties of nanocrystalline porous silicon. Topics include an overview of nanostructured silicon, its fabrication technology, and properties of nanocrystalline porous silicon such as confinement effects, photoluminescence, electroluminesce, carrier charging effects, ballistic transport and emission, and thermally induced acoustic emission.

  1. GABA inhibition of luminescence from lantern shark (Etmopterus spinax) photophores.

    PubMed

    Claes, Julien M; Krönström, Jenny; Holmgren, Susanne; Mallefet, Jérôme

    2011-03-01

    Photogenic organs (photophores) of the velvet belly lantern shark (Etmopterus spinax) are under hormonal control, since melatonin (MT) and prolactin (PRL) trigger luminescence while α-melanocyte-stimulating hormone (α-MSH) prevents this light to be emitted. A recent study supported, however, the presence of numerous nerve fibres in the photogenic tissue of this shark. Immunohistochemical and pharmacological results collected in this work support these nerve fibres to be inhibitory GABAergic nerves since (i) GABA immunoreactivity was detected inside the photogenic tissue, where previous labelling detected the nerve fibre structures and (ii) GABA was able to inhibit MT and PRL-induced luminescence, which was on the other hand increased by the GABA(A) antagonist bicuculline (BICU). In addition, we also demonstrated that BICU can induce light per se by provoking pigment retraction in the pigmented cells composing the iris-like structure of the photophore, attaining, however, only about 10% of hormonally induced luminescence intensity at 10(-3)mol L(-1). This strongly supports that a GABA inhibitory tonus controls photophore "aperture" in the photogenic tissue of E. spinax but also that MT and PRL have more than one target cell type in the photophores.

  2. Radiation Damage Mechanisms for Luminescence in Eu-doped GaN

    SciTech Connect

    Tringe, J W; Castelaz, J M; Felter, T E; Wetzel, C; Talley, C E; Morse, J D; Stevens, C G

    2005-11-01

    Thin films of Eu-doped GaN are irradiated with 500 keV He{sup +} ions to understand radiation damage mechanisms and to quantify luminescence efficiency. Ion beam induced luminescence was monitored spectroscopically as function of fluence. Behavior observed is consistent with simultaneous creation of non-radiative defects and destruction of luminescent centers associated with the 4f-4f core-level transition in Eu{sup 3+}. This model contrasts with a previous description which takes into account only non-radiative defect generation in GaN:Eu. Based on light from a BaF{sub 2} scintillator standard, the luminescent energy generation efficiency of GaN:Eu films doped to {approx}3 x 10{sup 18} cm{sup -3} Eu is estimated to be {approx}0.1%.

  3. Strong UV absorption and visible luminescence in ytterbium-doped aluminosilicate glass under UV excitation.

    PubMed

    Engholm, M; Norin, L; Aberg, D

    2007-11-15

    A broad visible luminescence band and characteristic IR luminescence of Yb(3+) ions are observed under UV excitation in ytterbium-doped aluminosilicate glass. Samples made under both oxidizing and reducing conditions are analyzed. A strong charge-transfer absorption band in the UV range is observed for glass samples containing ytterbium. Additional absorption bands are observed for the sample made under reducing conditions, which are associated with f-d transitions of divalent ytterbium. The visible luminescence band is attributed to 5d-4f emission from Yb(2+) ions, and the IR luminescence is concluded to originate from a relaxed charge-transfer transition. The findings are important to explain induced optical losses (photodarkening) in high-power fiber lasers. PMID:18026305

  4. 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.".

  5. Dating sediments using luminescence signals

    SciTech Connect

    Wintle, A. )

    1993-05-01

    Before siting a nuclear power station or a nuclear waste repository, it is necessary to establish that the area has been free of earthquake activity for a sufficient period of time. Evidence of past earthquake activity is often provided by faults in surface sediments. Age limits for fault formation can be set by obtaining the depositional ages of the sediment unit in which the fault was formed and the overlying sediment. A useful technique would be one that dating could be applied to the mineral grains that make up the sediments and that would give the time that has passed since the grains were blown or washed into position. Luminescence dating techniques, of which the most well known is thermo-luminescence (TL), provide such information. This approach has been successful in dating movement on the Wasatch Fault in Utah. A combination of TL and radiocarbon dates indicated that three faulting events had occurred within the past 5000 years. 2 refs., 1 fig.

  6. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-11-10

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  7. Apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  8. Material for a luminescent solar concentrator

    DOEpatents

    Andrews, L.J.

    1984-01-01

    A material for use in a luminescent solar concentrator, formed by ceramitizing the luminescent ion Cr/sup 3 +/ with a transparent ceramic glass containing mullite. The resultant material has tiny Cr/sup 3 +/-bearing crystallites dispersed uniformly through an amorphous glass. The invention combines the high luminescent efficiency of Cr/sup 3 +/ in the crystalline phase with the practical and economical advantages of glass technology.

  9. A portable luminescence dating instrument

    NASA Astrophysics Data System (ADS)

    Kook, M. H.; Murray, A. S.; Lapp, T.; Denby, P. H.; Ankjærgaard, C.; Thomsen, K.; Jain, M.; Choi, J. H.; Kim, G. H.

    2011-06-01

    We describe a portable luminescence reader suitable for use in remote localities in the field. The instrument weighs about 8 kg and is based around a 30 mm bialkali photomultiplier detecting signals through a glass filter centered on 340 nm. Stimulation is by 470 nm blue LEDs (24 W in total) operating in both continuous wave and pulsed mode; photon counting can be gated such that it is active only during the pulse off-period. There are also two bleaching light sources (470 nm, 5 W and 940 nm, 3 W), and the luminescence signals can be regenerated using a cold-cathode 30 kV X-ray tube, delivering ˜0.06 Gy.s -1. The three position sampling device has a heating element under each sampling position, able to heat the sample at 3 °C.s -1 up to at least 250 °C. The sampler can be inserted into unconsolidated sediments, and is designed to prevent exposure of the mineral grains to ambient light during sampling. The performance of the instrument in terms of sensitivity and reproducibility is comparable to that of the standard bench-top laboratory TL/OSL Risø reader. We show that the portable luminescence reader is able to measure accurately an ˜20 Gy quartz burial dose in a natural (unpretreated, no mineral separation) sandy sediment. We also show that, because of the configuration of the measurement head, the portable reader can be used to measure radioluminescence at elevated temperature in the presence of stimulation light; this facility is not available on conventional bench-top instruments. It is concluded that the portable luminescence reader can be used to accurately determine the quartz burial dose in loose sandy sediments in the field, without sample preparation or darkroom facilities.

  10. Solid-matrix luminescence analysis

    SciTech Connect

    Hurtubise, R.J.

    1993-01-15

    Several interactions with lumiphors adsorbed on filter paper were elucidated from experiments with moisture, modulus and heavy-atom salts. The data were interpreted using static and dynamic quenching models, heavy-atom theory, and a theory related to the modulus of paper. With cyclodextrin-salt matrices, it was shown that 10% [alpha]-cyclodextrin/NaCl was very effective for obtaining strong room-temperature fluorescence and moderate room-temperature phosphorescence from adsorbed stereoisomeric tetrols. Extensive photophysical information was obtained for the four tetrols on 10% [alpha]-cyclodextrin/NaCl. The photophysical information acquired was used to develop a method for characterizing two of the tetrols. Work with model compounds adsorbed on deuterated sodium acetate showed that C-H vibrations in the undeuterated sodium acetate were not responsible for the deactivation of the excited triplet state in the model phosphors investigated. A considerable amount of solution luminescence and solid-matrix luminescence data were compared. The most important finding was that in several cases the room-temperature solid-matrix luminescence quantum yields were greater than the solution low-temperature quantum yield values.

  11. Resonance-shifting luminescent solar concentrators

    DOEpatents

    Giebink, Noel Christopher; Wiederrecht, Gary P; Wasielewski, Michael R

    2014-09-23

    An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

  12. Luminescent detection of hydrazine and hydrazine derivatives

    DOEpatents

    Swager, Timothy M.; Thomas, III, Samuel W.

    2012-04-17

    The present invention generally relates to methods for modulating the optical properties of a luminescent polymer via interaction with a species (e.g., an analyte). In some cases, the present invention provides methods for determination of an analyte by monitoring a change in an optical signal of a luminescent polymer upon exposure to an analyte. Methods of the present invention may be useful for the vapor phase detection of analytes such as explosives and toxins. The present invention also provides methods for increasing the luminescence intensity of a polymer, such as a polymer that has been photobleached, by exposing the luminescent polymer to a species such as a reducing agent.

  13. Molecular decoding using luminescence from an entangled porous framework

    PubMed Central

    Takashima, Yohei; Martínez, Virginia Martínez; Furukawa, Shuhei; Kondo, Mio; Shimomura, Satoru; Uehara, Hiromitsu; Nakahama, Masashi; Sugimoto, Kunihisa; Kitagawa, Susumu

    2011-01-01

    Chemosensors detect a single target molecule from among several molecules, but cannot differentiate targets from one another. In this study, we report a molecular decoding strategy in which a single host domain accommodates a class of molecules and distinguishes between them with a corresponding readout. We synthesized the decoding host by embedding naphthalenediimide into the scaffold of an entangled porous framework that exhibited structural dynamics due to the dislocation of two chemically non-interconnected frameworks. An intense turn-on emission was observed on incorporation of a class of aromatic compounds, and the resulting luminescent colour was dependent on the chemical substituent of the aromatic guest. This unprecedented chemoresponsive, multicolour luminescence originates from an enhanced naphthalenediimide–aromatic guest interaction because of the induced-fit structural transformation of the entangled framework. We demonstrate that the cooperative structural transition in mesoscopic crystal domains results in a nonlinear sensor response to the guest concentration. PMID:21266971

  14. Molecular decoding using luminescence from an entangled porous framework.

    PubMed

    Takashima, Yohei; Martínez, Virginia Martínez; Furukawa, Shuhei; Kondo, Mio; Shimomura, Satoru; Uehara, Hiromitsu; Nakahama, Masashi; Sugimoto, Kunihisa; Kitagawa, Susumu

    2011-01-25

    Chemosensors detect a single target molecule from among several molecules, but cannot differentiate targets from one another. In this study, we report a molecular decoding strategy in which a single host domain accommodates a class of molecules and distinguishes between them with a corresponding readout. We synthesized the decoding host by embedding naphthalenediimide into the scaffold of an entangled porous framework that exhibited structural dynamics due to the dislocation of two chemically non-interconnected frameworks. An intense turn-on emission was observed on incorporation of a class of aromatic compounds, and the resulting luminescent colour was dependent on the chemical substituent of the aromatic guest. This unprecedented chemoresponsive, multicolour luminescence originates from an enhanced naphthalenediimide-aromatic guest interaction because of the induced-fit structural transformation of the entangled framework. We demonstrate that the cooperative structural transition in mesoscopic crystal domains results in a nonlinear sensor response to the guest concentration. PMID:21266971

  15. Hexagonal boron nitride luminescence dependent on vacuum level and surrounding gases

    SciTech Connect

    Korsaks, V.

    2015-10-15

    Highlights: • 400 nm Luminescence of hBN powder is sensitive to surrounding vacuum or oxygen gas. • Decrease of hBN powder grain size improves its oxygen sensing properties. • hBN powder is proposed as prospective material for oxygen gas sensors. - Abstract: Gas sensing properties of hBN powder bulk and nanosize were studied. It was demonstrated that for hBN powders with grain sizes of 70 nm, 1 μm and 5 μm the native defect-induced luminescence observed at 400 nm under 265 nm light excitation and room temperature is sensitive to oxygen gas reducing luminescence intensity. The highest value of luminescence intensity is reached when sample is in vacuum. Results obtained allow conclusion that the hBN powder is prospective for sensing of oxygen gas. Some material properties such as dependence of luminescence intensity on vacuum level and pumping time, ratio of luminescence intensity when sample is in vacuum and gas, its dependence on material grain size were studied.

  16. 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…

  17. Angular dependences of the luminescence and density of photon states in a chiral liquid crystal

    SciTech Connect

    Umanskii, B A; Blinov, L M; Palto, S P

    2013-11-30

    Luminescence spectra of a laser dye-doped chiral liquid crystal have been studied in a wide range of angles (up to 60°) to the axis of its helical structure using a semicylindrical quartz prism, which made it possible to observe the shift and evolution of the photonic band gap in response to changes in angle. Using measured spectra and numerical simulation, we calculated the spectral distributions of the density of photon states in such a cholesteric crystal for polarised and unpolarised light, which characterise its structure as that of a chiral one-dimensional photonic crystal. (optics of liquid crystals)

  18. Utilizing vertically aligned CdSe/CdS nanorods within a luminescent solar concentrator

    NASA Astrophysics Data System (ADS)

    Fisher, Martyn; Farrell, Daniel; Zanella, Marco; Lupi, Antonio; Stavrinou, Paul N.; Chatten, Amanda J.

    2015-01-01

    Optical characterisation methodologies are employed to validate a nanorod self-alignment technique for use in luminescent solar concentrators (LSCs). The nanorods utilised in this work were CdSe/CdS core/shell nanorods, and the self-alignment technique relied on the evaporation of a highly concentrated nanorod/xylene solution onto a glass substrate. Position and angular dependent light absorptivity measurements revealed evidence of vertical nanorod alignment over a limited region at the centre of the LSC sample. Vertical nanorod alignment is beneficial for absorbing diffuse/scattered sunlight and provides for a high light trapping efficiency in the LSC.

  19. Luminescent gold nanoparticles for bioimaging

    NASA Astrophysics Data System (ADS)

    Zhou, Chen

    Inorganic nanoparticles (NPs) with tunable and diverse material properties hold great potential as contrast agents for better disease management. Over the past decades, luminescent gold nanoparticles (AuNPs) with intrinsic emissions ranging from the visible to the near infrared have been synthesized and emerge as a new class of fluorophores for bioimaging. This dissertation aims to fundamentally understand the structure-property relationships in luminescent AuNPs and apply them as contrast agents to address some critical challenges in bioimaging at both the in vitro and in vivo level. In Chapter 2, we described the synthesized ~20 nm polycrystalline AuNPs (pAuNPs), which successfully integrated and enhanced plasmonic and fluorescence properties into a single AuNP through the grain size effect. The combination of these properties in one NP enabled AuNPs to serve as a multimodal contrast agent for in vitro optical microscopic imaging, making it possible to develop correlative microscopic imaging techniques. In Chapters 3-5, we proposed a feasible approach to optimize the in vivo kinetics and clearance profile of nanoprobes for multimodality in vivo bioimaging applications by using straightforward surface chemistry with luminescent AuNPs as a model. Luminescent glutathione-coated AuNPs of ~2 nm were synthesized. Investigation of the biodistribution showed that these glutathione-coated AuNPs (GS-AuNPs) exhibit stealthiness to the reticuloendothelial system (RES) organs and efficient renal clearance, with only 3.7+/-1.9% and 0.3+/-0.1% accumulating in the liver and spleen, and over 65% of the injection dose cleared out via the urine within the first 72 hours. In addition, ~2.5 nm NIR-emitting radioactive glutathione-coated [198Au]AuNPs (GS-[198Au]AuNPs) were synthesized for further evaluation of the pharmacokinetic profile of GS-AuNPs and potential multimodal imaging. The results showed that the GS-[198Au]AuNPs behave like small-molecule contrast agents in

  20. Luminescence and radiation resistance of undoped NaI crystals

    SciTech Connect

    Shiran, N. Boiaryntseva, I.; Gektin, A.; Gridin, S.; Shlyakhturov, V.; Vasuykov, S.

    2014-11-15

    Highlights: • The performance of NaI scintillators depends on luminescence properties. • A criterion of crystals’ purity level is radiation colorability at room temperature. • The traces of the most dangerous impurities were detected. • Crucial role in efficiency of pure NaI scintillator play the crystal perfection. - Abstract: Undoped NaI single crystal is an excellent scintillator at low temperature. However, scintillation parameters of different quality crystals vary in a wide range, significantly exceeding measurement error. Experimental data demonstrate the features of luminescence, radiation induced coloration, and afterglow dependence on the quality of nominally pure crystals. It is found that defects level that allows to elucidate artefacts introduced by traces of harmful impurities corresponds to 3 × 10{sup 15} cm{sup −3} that significantly overhead accuracy of chemical and absorption analysis. It is shown that special raw material treatment before and during the single crystal growth allows to reach NaI purity level that avoids impurities influence to the basic luminescence data.

  1. BRITICE-CHRONO: Constraining retreat of the last British-Irish Ice Sheet using luminescence geochronometry

    NASA Astrophysics Data System (ADS)

    Duller, Geoff; Smedley, Rachel; Bateman, Mark; Medialdea, Alicia; Chiverrell, Richard; Fabel, Derek; Clark, Chris; Consortium, Britice-Chrono

    2016-04-01

    The BRITICE-CHRONO project funded by NERC is a multi-million pound consortium designed to use multiple geochronometers to constrain the rate of retreat of the major outlets of the last British-Irish Ice Sheet (BIIS) at the end of the last glacial cycle. Cosmogenic isotopes, radiocarbon and luminescence dating methods are being applied to materials sampled along lines of ice retreat. Luminescence dating for this project has targeted glaciofluvial sediments associated with ice retreat and over 150 samples from around the British Isles have been analysed in two laboratories. All samples have been analysed using small aliquot or single grain measurements of quartz optically stimulated luminescence (OSL). The resulting dose distributions have been modelled to obtain the depositional age. The major challenges in the application of quartz OSL can be grouped into two categories: signal characteristics and statistical characterisation of dose distributions. Samples have been collected over the entire British Isles and have very variable characteristics. Some samples give bright OSL signals, whilst in other areas the quartz is dim. A pervasive problem is the occurrence of grains which appear to be quartz but which are sensitive to infrared stimulation. Effective screening of these grains is essential to avoid dose underestimation. The second challenge has been estimating appropriate numerical parameters for application of minimum age models. Extensive dose recovery experiments have been undertaken to form the basis for estimates of overdispersion, and in some areas these show highly variable luminescence characteristics. The reproducibility of the analyses undertaken has been assessed through an intercomparison between the two luminescence laboratories and the results of this exercise will be discussed.

  2. Solid-surface luminescence analysis

    SciTech Connect

    Hurtubise, R.J.

    1991-01-01

    We have characterized several interactions that are very important in solid-matrix luminescence. With silica gel chromatoplates and filter paper, simple equations were derived for calculating the individual contributions to the percent decrease in luminescence due to either moisture or to a quenching gas. For sodium acetate as a solid matrix and p-aminobenzoate as a model compound, it was concluded that p-aminobenzoate was incorporated into the crystal structure of sodium acetate, and the triplet energy was lost be skeletal vibrations in sodium acetate. Also, with the same system is was shown that p-aminobenzoate did not undergo rotational relaxation, and thus rotational processes did not contribute to the deactivation of the triplet state. Several results were obtained from model compounds adsorbed on filter paper under different temperature and humidity conditions and with a variety of heavy atoms present. Fundamental photophysical equations were used in calculating several basic parameters that revealed information on rate processes and how the absorbed energy was distributed in an adsorbed lumiphor. The most important advancement with filter paper was the development of equations that relate phosphorescence parameters of adsorbed phosphors to the Young's modulus of filter paper. These equations are based on a fundamental theory that relates the hydrogen-bonding network of paper to the modulus of paper.

  3. Functional silk: colored and luminescent.

    PubMed

    Tansil, Natalia C; Koh, Leng Duei; Han, Ming-Yong

    2012-03-15

    Silkworm silk is among the most widely used natural fibers for textile and biomedical applications due to its extraordinary mechanical properties and superior biocompatibility. A number of physical and chemical processes have also been developed to reconstruct silk into various forms or to artificially produce silk-like materials. In addition to the direct use and the delicate replication of silk's natural structure and properties, there is a growing interest to introduce more new functionalities into silk while maintaining its advantageous intrinsic properties. In this review we assess various methods and their merits to produce functional silk, specifically those with color and luminescence, through post-processing steps as well as biological approaches. There is a highlight on intrinsically colored and luminescent silk produced directly from silkworms for a wide range of applications, and a discussion on the suitable molecular properties for being incorporated effectively into silk while it is being produced in the silk gland. With these understanding, a new generation of silk containing various functional materials (e.g., drugs, antibiotics and stimuli-sensitive dyes) would be produced for novel applications such as cancer therapy with controlled release feature, wound dressing with monitoring/sensing feature, tissue engineering scaffolds with antibacterial, anticoagulant or anti-inflammatory feature, and many others.

  4. A comparative study of optical and radiative characteristics of X-ray-induced luminescent defects in Ag-doped glass and LiF thin films and their applications in 2-D imaging

    NASA Astrophysics Data System (ADS)

    Kurobori, T.; Miyamoto, Y.; Maruyama, Y.; Yamamoto, T.; Sasaki, T.

    2014-05-01

    We report novel disk-type X-ray two-dimensional (2-D) imaging detectors utilising Ag-doped phosphate glass and lithium fluoride (LiF) thin films based on the radiophotoluminescence (RPL) and photoluminescence (PL) phenomena, respectively. The accumulated X-ray doses written in the form of atomic-scale Ag-related luminescent centres in Ag-doped glass and F-aggregated centres in LiF thin films were rapidly reconstructed as a dose distribution using a homemade readout system. The 2-D images reconstructed from the RPL and PL detectors are compared with that from the optically stimulated luminescence (OSL) detector. In addition, the optical and dosimetric characteristics of LiF thin films are investigated and evaluated. The possibilities of dose distributions with a high spatial resolution on the order of microns over large areas, a wide dynamic range covering 11 orders of magnitude and a non-destructive readout are successfully demonstrated by combining the Ag-doped glass with LiF thin films.

  5. Upconversion luminescence in Yb 3+-doped yttrium aluminum garnets

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen; Bourdet, Gilbert; Christophe Chanteloup, Jean; Zou, Ji-Ping; Fulop, Annabelle

    2005-03-01

    In this paper, we present results on upconversion luminescence performed on Yb 3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb 3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb 3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  6. Characterisation of a track structure imaging detector.

    PubMed

    Casiraghi, M; Bashkirov, V A; Hurley, R F; Schulte, R W

    2015-09-01

    The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presented, which detects positive ions produced by radiation interacting with a gas-sensitive volume in order to obtain a high resolution image of the radiation track structure. The characterisation of the detector prototype was performed and different configurations of the device were tested by varying the detector cathode material and the working gas. Preliminary results show that the ionisation cluster size distribution can be obtained with this approach. Further work is planned to improve the detector efficiency in order to register the complete three-dimensional track structure of ionising radiation.

  7. THE RHIC HYDROGEN JET LUMINESCENCE MONITOR.

    SciTech Connect

    RUSSO,T.; BELLAVIA, S.; GASSNER, D.; THIEBERGER, P.; TRBOJEVIC, D.; TSANG, T.

    2007-06-25

    A hydrogen jet polarimeter was developed for the RHIC accelerator to improve the process of measuring polarization. Particle beams intersecting with gas molecules can produce light by the process known as luminescence. This light can then be focused, collected, and processed giving important information such as size, position, emittance, motion, and other parameters. The RHIC hydrogen jet polarimeter was modified in 2005 with specialized optics, vacuum windows, light transport, and a new camera system making it possible to monitor the luminescence produced by polarized protons intersecting the hydrogen beam. This paper describes the configuration and preliminary measurements taken using the RHIC hydrogen jet polarimeter as a luminescence monitor.

  8. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-01-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  9. Thermomechanical characterisation of cellular rubber

    NASA Astrophysics Data System (ADS)

    Seibert, H.; Scheffer, T.; Diebels, S.

    2016-09-01

    This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.

  10. Fluorescence quenching in luminescent porous silicon nanoparticles for the detection of intracellular Cu2+.

    PubMed

    Xia, Bing; Zhang, Wenyi; Shi, Jisen; Xiao, Shoujun

    2013-07-01

    After microwave-induced hydrosilylation reaction with 10-undecenoic acid, luminescent porous silicon nanoparticles (LPSiNPs) showed excellent fluorescence stability under physiological conditions. Fluorescence quenching in as-prepared LPSiNPs was highly sensitive with the concentration of Cu(2+) at μmol L(-1) level, which could be further applied to the detection of intracellular Cu(2+).

  11. Optical absorption and luminescence in neutron-irradiated, silica-based fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Clinard, F.W.

    1995-04-01

    The objectives of this work are to assess the effects of thermal annealing and photobleaching on the optical absorption of neutron-irradiated, silica fibers of the type proposed for use in ITER diagnostics, and to measure x-ray induced luminescence of unirradiated (virgin) and neutron-irradiated fibers.

  12. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles

    PubMed Central

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Kokenyesi, Sándor

    2016-01-01

    Summary Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  13. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles.

    PubMed

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Csarnovics, István; Kokenyesi, Sándor

    2016-01-01

    Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  14. Luminescence in quantum-confined cadmium selenide nanocrystals and nanorods in external electric fields

    SciTech Connect

    Gurinovich, L. I. Lutich, A. A.; Stupak, A. P.; Prislopsky, S. Ya.; Rusakov, E. K.; Artemyev, M. V.; Gaponenko, S. V.; Demir, H. V.

    2009-08-15

    It is found that the absorption and luminescence spectra of CdSe nanocrystals and nanorods depend on the external electric field. It is shown that the external electric field quenches the P-polarized photoluminescence of CdSe nanorods to a degree higher than the degree of field-induced quenching of the S-polarized photoluminescence. It is established that the nanocrystals are more sensitive to the external electric field than the nanorods. The effect of the external electric field on the luminescence properties of the semiconductor nanorods is discussed.

  15. Circularly Polarized Luminescence from Helically Chiral N,N,O,O-Boron-Chelated Dipyrromethenes.

    PubMed

    Alnoman, Rua B; Rihn, Sandra; O'Connor, Daniel C; Black, Fiona A; Costello, Bernard; Waddell, Paul G; Clegg, William; Peacock, Robert D; Herrebout, Wouter; Knight, Julian G; Hall, Michael J

    2016-01-01

    Helically chiral N,N,O,O-boron chelated dipyrromethenes showed solution-phase circularly polarized luminescence (CPL) in the red region of the visible spectrum (λem (max) from 621 to 663 nm). The parent dipyrromethene is desymmetrised through O chelation of boron by the 3,5-ortho-phenolic substituents, inducing a helical chirality in the fluorophore. The combination of high luminescence dissymmetry factors (|glum | up to 4.7 ×10(-3) ) and fluorescence quantum yields (ΦF up to 0.73) gave exceptionally efficient circularly polarized red emission from these simple small organic fluorophores, enabling future application in CPL-based bioimaging.

  16. Cell probing by delayed luminescence

    NASA Astrophysics Data System (ADS)

    Musumeci, Francesco; Ballerini, Monica; Baroni, Giuliana; Costato, Michele; Ferraro, Lorenzo; Milani, Marziale; Scordino, Agata; Triglia, Antonio

    1999-05-01

    Delayed luminescence (D.L.) is a measure that provides important information on biological systems fields, structures and activities, by counting impinging and emitted photons. Many recent experimental works have shown the existence of a close connection, sometimes analytically expressed between the biological state of the system and D.L. parameters. Our investigations aim to show that D.L. is a workable analytical technique covering a large number of disciplinary fields, from agriculture to pollution control and from medical diagnostics to food quality control. The authors have conducted systematic research about D.L. from unicellular alga Acetabularia acetabulum to Saccharomyces cerevisiae yeast cultures and about more complex systems such as Soya seed (Glycine max, L.) and its dependence on sample preparation, history, intracellular signaling, metabolism and pollutant presence. We will discuss the most relevant results together with theoretical considerations on the basic interaction at work between biological systems and electromagnetic fields.

  17. Endoscopic imaging of Cerenkov luminescence

    PubMed Central

    Kothapalli, Sri-Rajasekhar; Liu, Hongguang; Liao, Joseph C.; Cheng, Zhen; Gambhir, Sanjiv Sam

    2012-01-01

    We demonstrate feasibility of endoscopic imaging of Cerenkov light originated when charged nuclear particles, emitted from radionuclides, travel through a biological tissue of living subjects at superluminal velocity. The endoscopy imaging system consists of conventional optical fiber bundle/ clinical endoscopes, an optical imaging lens system, and a sensitive low-noise charge coupled device (CCD) camera. Our systematic studies using phantom samples show that Cerenkov light from as low as 1 µCi of radioactivity emitted from 18F-Fluorodeoxyglucose (FDG) can be coupled and transmitted through conventional optical fibers and endoscopes. In vivo imaging experiments with tumor bearing mice, intravenously administered with 18F-FDG, further demonstrated that Cerenkov luminescence endoscopy is a promising new tool in the field of endoscopic molecular imaging. PMID:22741069

  18. Wireless Luminescence Integrated Sensors (WLIS)

    SciTech Connect

    Simpson, M.L.; Sayler, G.S.

    2003-11-10

    The goal of this project was the development of a family of wireless, single-chip, luminescence-sensing devices to solve a number of difficult distributed measurement problems in areas ranging from environmental monitoring and assessment to high-throughput screening of combinatorial chemistry libraries. These wireless luminescence integrated sensors (WLIS) consist of a microluminometer, wireless data transmitter, and RF power input circuit all realized in a standard integrated circuit (IC) process with genetically engineered, whole-cell, bioluminescent bioreporters encapsulated and deposited on the IC. The end product is a family of compact, low-power, rugged, low-cost sensors. As part of this program they developed an integrated photodiode/signal-processing scheme with an rms noise level of 175 electrons/second for a 13-minute integration time, and a quantum efficiency of 66% at the 490-nm bioluminescent wavelength. this performance provided a detection limit of < 1000 photons/second. Although sol-gel has previously been used to encapsulate yeast cells, the reaction conditions necessary for polymerization (primarily low pH) have beforehand proven too harsh for bacterial cell immobilizations. Utilizing sonication methods, they have were able to initiate polymerization under pH conditions conductive to cell survival. both a toluene bioreporter (Pseudomonas putida TVA8) and a naphthalene bioreporter (Pseudomonas fluorescens HK44) were successfully encapsulated in sol-gel and shown to produce a fairly significant bioluminescent response. In addition to the previously developed naphthalene- and toluene-sensitive bioreporters, they developed a yeast-based xenoestrogen reporter. This technology has been licensed by Micro Systems Technologies, a startup company in Dayton, Ohio for applications in environmental containments monitoring, and for detecting weapons of mass destruction (i.e. homeland security).

  19. Luminescent iron clusters in solution

    NASA Astrophysics Data System (ADS)

    Goswami, Nirmal; Baksi, Ananya; Giri, Anupam; Xavier, Paulrajpillai Lourdu; Basu, Gautam; Pradeep, Thalappil; Pal, Samir Kumar

    2014-01-01

    Metal clusters, composed of a few atoms at the core, exhibit unique properties and have potential applications. Although atomically precise clusters of noble metals have been synthesized, analogous systems of reactive metals, such as iron, have not been realized in solution due to high reactivity. Here we report the synthesis and characterization of novel iron clusters in the hemoglobin matrix that are highly luminescent (quantum yield 10% at 565 nm). The super-paramagnetic iron clusters, after successful ligand exchange from protein and phase transfer from water to chloroform using tri-octylphosphineoxide (TOPO), were detected as [Fe10(TOPO)3(H2O)3]+, [Fe13(TOPO)2(H2O)]+ and [Fe8(TOPO)(H2O)2]+ by mass spectrometry. This study lays the groundwork for exploiting unique properties of soluble iron clusters.Metal clusters, composed of a few atoms at the core, exhibit unique properties and have potential applications. Although atomically precise clusters of noble metals have been synthesized, analogous systems of reactive metals, such as iron, have not been realized in solution due to high reactivity. Here we report the synthesis and characterization of novel iron clusters in the hemoglobin matrix that are highly luminescent (quantum yield 10% at 565 nm). The super-paramagnetic iron clusters, after successful ligand exchange from protein and phase transfer from water to chloroform using tri-octylphosphineoxide (TOPO), were detected as [Fe10(TOPO)3(H2O)3]+, [Fe13(TOPO)2(H2O)]+ and [Fe8(TOPO)(H2O)2]+ by mass spectrometry. This study lays the groundwork for exploiting unique properties of soluble iron clusters. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05784d

  20. 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.

  1. Calibration beads containing luminescent lanthanide ion complexes

    EPA Science Inventory

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including mi...

  2. Two-dimensional singlet oxygen imaging with its near-infrared luminescence during photosensitization

    PubMed Central

    Hu, Bolin; Zeng, Nan; Liu, Zhiyi; Ji, Yanhong; Xie, Weidong; Peng, Qing; Zhou, Yong; He, Yonghong; Ma, Hui

    2011-01-01

    Photodynamic therapy is a promising cancer treatment that involves activation of photosensitizer by visible light to create singlet oxygen. This highly reactive oxygen species is believed to induce cell death and tissue destruction in PDT. Our approach used a near-infrared area CCD with high quantum efficiency to detect singlet oxygen by its 1270-nm luminescence. Two-dimensional singlet oxygen images with its near-infrared luminescence during photosensitization could be obtained with a CCD integration time of 1 s, without scanning. Thus this system can produce singlet oxygen luminescence images faster and achieve more accurate measurements in comparison to raster-scanning methods. The experimental data show a linear relationship between the singlet oxygen luminescence intensity and sample concentration. This method provides a detection sensitivity of 0.0181 μg/ml (benzoporphyrin derivative monoacid ring A dissolved in ethanol) and a spatial resolution better than 50 μm. A pilot study was conducted on a total of six female Kunming mice. The results from this study demonstrate the system's potential for in vivo measurements. Further experiments were carried out on two tumor-bearing nude mice. Singlet oxygen luminescence images were acquired from the tumor-bearing nude mouse with intravenous injection of BPD-MA, and the experimental results showed real-time singlet oxygen signal depletion as a function of the light exposure. PMID:21280909

  3. Three-dimensional, multiwavelength Monte Carlo simulations of dermally implantable luminescent sensors.

    PubMed

    Long, Ruiqi; McShane, Mike

    2010-01-01

    Dermally implanted luminescent sensors have been proposed for monitoring of tissue biochemistry, which has the potential to improve treatments for conditions such as diabetes and kidney failure. Effective in vivo monitoring via noninvasive transdermal measurement of emission from injected microparticles requires a matched optoelectronic system for excitation and collection of luminescence. We applied Monte Carlo modeling to predict the characteristics of output luminescence from microparticles in skin to facilitate hardware design. Three-dimensional, multiwavelength Monte Carlo simulations were used to determine the spatial and spectral distribution of the escaping luminescence for different implantation depths, excitation light source properties, particle characteristics, and particle packing density. Results indicate that the ratio of output emission to input excitation power ranged 10(-3) to 10(-6) for sensors at the upper and lower dermal boundaries, respectively, and 95% of the escaping emission photons induced by a 10-mm-diam excitation beam were confined within an 18-mm circle. Tightly packed sensor configurations yielded higher output intensity with fewer particles, even after luminophore concentration effects were removed. Most importantly, for the visible wavelengths studied, the ability to measure spectral changes in emission due to glucose changes was not significantly affected by absorption and scattering of tissue, which supports the potential to accurately track changes in luminescence of sensor implants that respond to the biochemistry of the skin. PMID:20459285

  4. Three-dimensional, multiwavelength Monte Carlo simulations of dermally implantable luminescent sensors

    NASA Astrophysics Data System (ADS)

    Long, Ruiqi; McShane, Mike

    2010-03-01

    Dermally implanted luminescent sensors have been proposed for monitoring of tissue biochemistry, which has the potential to improve treatments for conditions such as diabetes and kidney failure. Effective in vivo monitoring via noninvasive transdermal measurement of emission from injected microparticles requires a matched optoelectronic system for excitation and collection of luminescence. We applied Monte Carlo modeling to predict the characteristics of output luminescence from microparticles in skin to facilitate hardware design. Three-dimensional, multiwavelength Monte Carlo simulations were used to determine the spatial and spectral distribution of the escaping luminescence for different implantation depths, excitation light source properties, particle characteristics, and particle packing density. Results indicate that the ratio of output emission to input excitation power ranged 10-3 to 10-6 for sensors at the upper and lower dermal boundaries, respectively, and 95% of the escaping emission photons induced by a 10-mm-diam excitation beam were confined within an 18-mm circle. Tightly packed sensor configurations yielded higher output intensity with fewer particles, even after luminophore concentration effects were removed. Most importantly, for the visible wavelengths studied, the ability to measure spectral changes in emission due to glucose changes was not significantly affected by absorption and scattering of tissue, which supports the potential to accurately track changes in luminescence of sensor implants that respond to the biochemistry of the skin.

  5. Luminescent photobioreactor design for improved algal growth and photosynthetic pigment production through spectral conversion of light.

    PubMed

    Mohsenpour, Seyedeh Fatemeh; Willoughby, Nik

    2013-08-01

    Growth characteristics of two strains of microalgae in bubble column photobioreactors were investigated under different cultivation conditions. Chlorella vulgaris and Gloeothece membranacea were cultivated in luminescent acrylic photobioreactors at different seed culture densities. Luminescent acrylic photobioreactors in blue, green, yellow, orange, and red colours capable of spectral conversion of light were used. The results indicated that the red luminescent photobioreactor enhanced biomass production in both strains of microalgae while pigmentation was induced under different light colours. Green light promoted chlorophyll production in C. vulgaris however chlorophyll production in G. membranacea cultures was less influenced by the light condition or culture density. Phycobiliproteins were the dominant pigments in G. membranacea and red light favoured synthesis of these pigments.

  6. Calibration beads containing luminescent lanthanide ion complexes

    NASA Astrophysics Data System (ADS)

    Leif, Robert C.; Jin, Dayong; Piper, James; Vallarino, Lidia M.; Williams, John W.; Yang, Sean; Zucker, Robert M.

    2008-02-01

    The reliability of lanthanide luminescence measurements, by both flow cytometry and digital microscopy, will be enhanced by the availability of narrow-band emitting lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments, including microscopes. Methods: 0.5, 3, and 5 micron (µm) beads containing a luminescent europium-complex were manufactured and the luminescence distribution of the 5 µm beads was measured with a time-delayed luminescence flow cytometer and a timedelayed digital microscope. The distribution of the luminescence intensity from the europium-complex in individual beads was determined on optical sections by confocal microscopy. The emission spectra of the beads under UV excitation were determined with a PARISS® spectrophotometer. The kinetics of the luminescence bleaching caused by UV irradiation were measured under LED excitation with a fluorescence microscope. Results: The kinetics of UV bleaching were very similar for the 0.5, 3, and 5 µm beads. Emission peaks were found at 592, 616, and 685 nanometers (nm). The width of the principal peak at half-maximum (616 nm) was 9.9 nm. The luminescence lifetimes in water and in air were 340 and 460 microseconds (µs), respectively. The distribution of the europium- complex in the beads was homogeneous. Conclusions: The 5 µm beads can be used for spectral calibration of microscopes equipped with a spectrograph, as test particles for time-delayed luminescence flow cytometers, and possibly as labels for macromolecules and cells.

  7. Luminescence conversion of blue light emitting diodes

    NASA Astrophysics Data System (ADS)

    Schlotter, P.; Schmidt, R.; Schneider, J.

    Using blue-emitting GaN/6HSiC chips as primary light sources, we have fabricated green, yellow, red and white emitting LEDs. The generation of mixed colors, as turquoise and magenta is also demonstrated. The underlying physical principle is that of luminescence down-conversion (Stokes shift), as typical for organic luminescent dye molecules. A white emitting LED, using an inorganic converter, Y3Al5O12:Ce3+( ), has also been realized.

  8. Luminescence dating of quaternary sediments: recent advances

    NASA Astrophysics Data System (ADS)

    Duller, G. A. T.

    2004-02-01

    Luminescence dating is unique amongst geochronological methods in dating the deposition of sediments based upon the properties of the constituent minerals. For Quaternary sediments the event being dated is the last exposure of the grains to daylight, and an implicit assumption is that this exposure was sufficient to remove any pre-existing signal. Until recently it has been difficult to test this assumption, other than by dating samples from a given depositional context with an age that is known from independent methods. There have been a series of technological and methodological developments in the past 5-10 yr that make it possible to undertake many replicate measurements of the luminescence from a single sample and hence to explicitly test whether for a specific sample all the grains had their luminescence signal reset at deposition. This allows the reliability of the luminescence age to be assessed. Where all the grains in a sample were not exposed to sufficient daylight to reset their luminescence signal, the apparent age will be an average value of the luminescence from all the grains measured at one time. Where many grains are measured simultaneously, this will overestimate the depositional age. The distribution of apparent age can be made clear by reducing the number of grains being measured in a given experiment, ultimately to the point of measuring individual sand-sized mineral grains. Copyright

  9. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    NASA Astrophysics Data System (ADS)

    Rybaltovsky, A. A.; Aleshkina, S. S.; Likhachev, M. E.; Bubnov, M. M.; Umnikov, A. A.; Yashkov, M. V.; Gur'yanov, Aleksei N.; Dianov, Evgenii M.

    2011-12-01

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al2O3 : SiO2, Al2O3 : Yb2O3 : SiO2, and P2O5 : Yb2O3 : SiO2. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb3+ ions to Yb2+. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb3+ ions.

  10. Synthesis and characterization of substituted Schiff-base ligands and their d(10) metal complexes: structure-induced luminescence tuning behaviors and applications in co-sensitized solar cells.

    PubMed

    Dong, Yu-Wei; Fan, Rui-Qing; Wang, Ping; Wei, Li-Guo; Wang, Xin-Ming; Zhang, Hui-Jie; Gao, Song; Yang, Yu-Lin; Wang, Yu-Lei

    2015-03-28

    Nine IIB group complexes, [ZnL1Cl2] (Zn1), [CdL1Cl2]2 (Cd1), [HgL1Cl2] (Hg1), [ZnL2Cl2] (Zn2), [CdL2Cl2] (Cd2), [HgL2Cl2] (Hg2), [ZnL3Cl2] (Zn3), [CdL3Cl2] (Cd3) and [HgL3Cl2] (Hg3), have been synthesized from the corresponding ortho-(6-methoxy-pyridyl)(CH[double bond, length as m-dash]NAr) (where Ar = 2,6-iPr2C6H3, L1; 4-MeC6H4, L2; 2-OMeC6H4, L3) Schiff base and structurally characterized by elemental analysis, FT-IR, (1)H NMR and X-ray single-crystal analysis. Crystallographic studies reveal that the center metal of the complexes adopts a distorted tetrahedron geometry (except for Cd1 and Cd3, which display square pyramidal geometry) and C-HCl hydrogen bonds and ππ stacking interactions contribute to three-dimensional supramolecular structures. The series of complexes exhibit tunable luminescence from blue, through green, to light yellow by varying the temperature (298 K and 77 K), both in solution and in the solid state. Moreover, the quantum yields range from 0.027 to 0.422, and decrease according to the order of the periodic table (Zn > Cd > Hg). These results indicate that the center atom of the complexes leads to the geometry differences and hence to the tunable luminescence properties. Because Zn1-Zn3 exhibited higher molar extinction coefficients and a distinct absorption region, they were employed as co-sensitizers in ruthenium dye N719-sensitized photoanodes to deliver light-electricity efficiency enhancement, being assembled with counter-electrodes and electrolyte to prepare ZnX/N719 (where ZnX = Zn1, Zn2, and Zn3) co-sensitized dye sensitized solar cell (DSSC) devices. The prepared co-absorbent could overcome the deficiency of N719 absorption in the low-wavelength region of the visible spectrum, and offset competitive visible-light absorption of I3(-). Application of these prepared complexes in N719-sensitized solar cells enhanced their performance by 10-36%, which indicated a potential application of these types of complexes in DSSCs. PMID:25597537

  11. Detecting Thermal Barrier Coating Delamination Using Visible and Near-Infrared Luminescence from Erbium-Doped Sublayers

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Bencic, T. J.; Martin, R. E.; Singh, J.; Wolfe, D. E.

    2007-01-01

    Nondestructive diagnostic tools are needed to monitor early stages of delamination progression in thermal barrier coatings (TBCs) because the risk of delamination induced coating failure will compromise engine performance and safety. Previous work has demonstrated that for TBCs composed of yttria-stabilized zirconia (YSZ), luminescence from a buried europium-doped sublayer can be utilized to identify the location of TBC delamination from the substantially higher luminescence intensity observed from the delaminated regions of the TBC. Luminescence measurements from buried europium-doped layers depend on sufficient transmittance of the 532 nm excitation and 606 nm emission wavelengths through the attenuating undoped YSZ overlayer to produce easily detected luminescence. In the present work, improved delamination indication is demonstrated using erbium-doped YSZ sublayers. For visible-wavelength luminescence, the erbium-doped sublayer offers the advantage of a very strong excitation peak at 517 nm that can be conveniently excited a 514 nm Ar ion laser. More importantly, the erbium-doped sublayer also produces near-infrared luminescence at 1550 nm that is effectively excited by a 980 nm laser diode. Both the 980 nm excitation and the 1550 nm emission are transmitted through the TBC with much less attenuation than visible wavelengths and therefore show great promise for delamination monitoring through thicker or more highly scattering TBCs. The application of this approach for both electron beam physical vapor deposited (EB-PVD) and plasma-sprayed TBCs is discussed.

  12. Luminescence and ESR studies of relationships between O(-)-centres and structural iron in natural and synthetically hydrated kaolinites.

    PubMed

    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.

  13. 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.

  14. Extraction Methods in Soil Phosphorus Characterisation

    NASA Astrophysics Data System (ADS)

    Soinne, Helena

    2010-05-01

    Extraction methods are widely used to assess the bioavailability of P and to characterise soil P reserves. Even though new and more sophisticated methods to characterise soil P are constantly developed the use of extraction methods is not likely to be replaced because of the relatively simple analytical equipment needed for the analysis. However, the large variety of extractants, pre-treatments and sample preparation procedures complicate the comparison of published results. In order to improve our understanding of the behaviour and cycling of P in soil, it is important to know the role of extracted P in the soil P cycle. The knowledge of the factors affecting the analytical outcome is a prerequisite for justified interpretation of the results. In this study, the effect of sample pre-treatment and properties of the used extractant on extractable molybdate-reactive phosphorus (MRP) and molybdate-unreactive phosphorus (MUP) was studied. Furthermore, the effect of sample preparation procedures prior the analysis on measured MRP and MUP was studied. Two widely used sequential extraction procedures were compared on their ability to show management induced differences on soil P. These results revealed that pre-treatments changed soil properties and air-drying was found to affect soil P, particularly extractable MUP, thought to represent organic P, by disrupting organic matter. This was evidenced by an increase in the water-extractable small-sized (<0.2 µm) P that, at least partly, took place at the expense of the large-sized (>0.2 µm) P. In addition to the effects of sample pre-treatment, the results showed that extractable organic P was sensitive to the chemical nature of the used extractant and to the sample preparation procedures employed prior to P analysis, including centrifugation and filtering of soil suspensions. Filtering may remove a major proportion of extractable MUP; therefore filtering cannot be recommended in the characterisation of solubilised MUP

  15. Characterisation of OSL and OSLN droplets for dosimetry.

    PubMed

    Nascimento, L F; D'Agostino, E; Vaniqui, A C S; Saldarriaga, C; Vanhavere, F; De Deene, Y

    2014-10-01

    In spite of considerable progress in neutron dosimetry, there is no dosemeter that is capable of measuring neutron doses independently of the neutron spectrum with good accuracy. Carbon-doped aluminium oxide (Al2O3:C) is a sensitive material for ionising radiation (beta-ray, X ray and electron) and has been used for applications in personal and medical dosimetry as an optically stimulated luminescence (OSL) dosemeter. Al2O3:C has a low sensitivity to neutron radiation; this prevents its application to neutron fields, representing a disadvantage of Al2O3:C-OSL when compared with LiF, which is used as a thermoluminescent detector. Recently an improvement for neutron dosimetry (Passmore and Kirr. Neutron response characterisation of an OSL neutron dosemeter. Radiat. Prot. Dosim. 2011; 144: 155-60) uses Al2O3:C coated with (6)Li2CO3 (OSLN),which gives the high-sensitive response as known for Al2O3:C with the advantage of being also sensitive to thermal neutrons. In this article, the authors compare small-size detectors (droplets) of Al2O3:C (OSL) and of Al2O3:C+(6)Li2CO3 (OSLN) and discuss the advantages and drawbacks of both materials, regarding size vs. response.

  16. Characterisation of OSL and OSLN droplets for dosimetry.

    PubMed

    Nascimento, L F; D'Agostino, E; Vaniqui, A C S; Saldarriaga, C; Vanhavere, F; De Deene, Y

    2014-10-01

    In spite of considerable progress in neutron dosimetry, there is no dosemeter that is capable of measuring neutron doses independently of the neutron spectrum with good accuracy. Carbon-doped aluminium oxide (Al2O3:C) is a sensitive material for ionising radiation (beta-ray, X ray and electron) and has been used for applications in personal and medical dosimetry as an optically stimulated luminescence (OSL) dosemeter. Al2O3:C has a low sensitivity to neutron radiation; this prevents its application to neutron fields, representing a disadvantage of Al2O3:C-OSL when compared with LiF, which is used as a thermoluminescent detector. Recently an improvement for neutron dosimetry (Passmore and Kirr. Neutron response characterisation of an OSL neutron dosemeter. Radiat. Prot. Dosim. 2011; 144: 155-60) uses Al2O3:C coated with (6)Li2CO3 (OSLN),which gives the high-sensitive response as known for Al2O3:C with the advantage of being also sensitive to thermal neutrons. In this article, the authors compare small-size detectors (droplets) of Al2O3:C (OSL) and of Al2O3:C+(6)Li2CO3 (OSLN) and discuss the advantages and drawbacks of both materials, regarding size vs. response. PMID:24381203

  17. Monitoring Temperatures of Tires Using Luminescent Materials

    NASA Technical Reports Server (NTRS)

    Bencic, Timothy J

    2006-01-01

    A method of noncontact, optical monitoring of the surface temperature of a tire has been devised to enable the use of local temperature rise as an indication of potential or impending failures. The method involves the use of temperature-sensitive paint (or filler): Temperature-sensitive luminescent dye molecules or other luminescent particles are incorporated into a thin, flexible material coating the tire surface of interest. (Alternatively, in principle, the luminescent material could be incorporated directly into the tire rubber, though this approach has not yet been tested.) The coated surface is illuminated with shorter-wavelength light to excite longer-wavelength luminescence, which is observed by use of a charge-coupled-device camera or a photodetector (see Figure 1). If temporally constant illumination is used, then the temperature can be deduced from the known temperature dependence of the intensity response of the luminescence. If pulsed illumination is used, then the temperature can be deduced from the known temperature dependence of the time or frequency response of the luminescence. If sinusoidally varying illumination is used, then the temperature can be deduced from the known temperature dependence of the phase response of the luminescence. Unlike a prior method of monitoring the temperature at a fixed spot on a tire by use of a thermocouple, this method is not restricted to one spot and can, therefore, yield information on the spatial distribution of temperature: in particular, it enables the discovery of newly forming hot spots where damage may be starting. Also unlike in the thermocouple method, the measurements in this method are not vulnerable to breakage of wires in repeated flexing of the tire. Moreover, unlike in another method in which infrared radiation is monitored as an indication of surface temperature, the luminescence measurements in this method are not significantly affected by changes in infrared emissivity. This method has been

  18. Anion-induced self-assembly of luminescent and magnetic homoleptic cyclic tetranuclear Ln4(salen)4 and Ln4(salen)2 complexes (Ln = Nd, Yb, Er, or Gd).

    PubMed

    Feng, Weixu; Zhang, Yao; Zhang, Zhao; Lü, Xingqiang; Liu, Han; Shi, Guoxiang; Zou, Dan; Song, Jirong; Fan, Daidi; Wong, Wai-Kwok; Jones, Richard A

    2012-11-01

    Unique homoleptic cyclic tetranuclear Ln(4)(Salen)(4) complexes [Ln(4)(L)(2)(HL)(2)(μ(3)-OH)(2)Cl(2)]·2Cl (Ln = Nd, 1; Ln = Yb, 2; Ln = Er, 3; Ln = Gd, 4) or Ln(4)(Salen)(2) complexes [Ln(4)(L)(2)(μ(3)-OH)(2)(OAc)(6)] (Ln = Nd, 5; Ln = Yb, 6; Ln = Er, 7; Ln = Gd, 8) have been self-assembled from the reaction of the hexadentate Salen-type Schiff-base ligand H(2)L with LnCl(3)·6H(2)O or Ln(OAc)(6)·6H(2)O (Ln = Nd, Yb, Er, or Gd), respectively (H(2)L: N,N'-bis(salicylidene)cyclohexane-1,2-diamine). The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 1-2 and 5-6 with emissive lifetimes in microsecond ranges are observed, and the sensitization arises from the excited state (both (1)LC and (3)LC) of the hexadentate Salen-type Schiff-base ligand with the flexible linker. Temperature dependence (1.8-300 K) magnetic susceptibility studies of the eight complexes suggest the presence of an antiferromagnetic interaction between the Ln(3+) ions.

  19. Luminescence spectroscopy of K3WO3F3 oxyfluoride crystals

    NASA Astrophysics Data System (ADS)

    Kozlov, A. V.; Pustovarov, V. A.

    2016-09-01

    Spectra of photoluminescence (PL) in region of 1.5-5.5 eV, PL excitation spectra (3-22 eV), PL decay kinetics, the temperature dependence of the PL were measured for single crystals and ceramics K3WO3F3 as well as irradiate ceramics K3WO3F3. Synchrotron radiation was used for low temperature PL experiments with time resolution. Single crystals are transparent in microwave, visible and near UV range, inter-band transition energy is Eg = 4.3 eV. The intrinsic luminescence of tungstates is usually ascribed to the radiative relaxation of exciton-like excitations localized on WO6 octahedra or WO4 tetrahedra. In K3WO3F3 the wide band luminescence in the region of 2.5 eV with the Stokes shift of 1.5 eV with the microsecond decay kinetics is connected with luminescence of triplet self-trapped excitons (STE). This luminescence is formed by electronic transitions in [WO3F3] octahedron. Different distortion of KWOF crystal lattice is manifested in the change of the Stokes shift of STE luminescence band. The 3.2 eV emission band in low-temperature PL spectrum with decay times of 1.8 ns and 11 ns corresponds to singlet STE luminescence. A new 2.9 eV emission band is discovered in low-temperature PL spectrum in the samples irradiated by fast electrons (E = 10 MeV, D = 160 kGy). This emission band is excited not intracenter mechanism, and through the creation of excitons bound on the defects. It is suggested that it is F-like centers of anionic sublattice induced by the mechanism of elastic collision.

  20. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  1. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  2. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  3. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  4. Characterisation of chocolate eating behaviour.

    PubMed

    Carvalho-da-Silva, A M; Van Damme, I; Wolf, B; Hort, J

    2011-10-24

    Knowledge concerning variation in chocolate eating behaviour amongst consumers, and the impact that differences in the physical properties of chocolate could have on such behaviour is limited. The eating behaviour of individuals, consuming two chocolate samples (A and B), of comparable melt viscosity but with different textural attributes, was investigated. Surface electromyography (sEMG) was used to evaluate masticator muscle activity and electroglottography (EGG) was used to record swallowing events. Results showed that observed differences in mouthcoating affected the in-mouth residence time: chocolate A, perceived as more mouthcoating, showed an increased total chewing time and time of last swallow. Key differences across subjects were: time and number of chews, time of last swallow and total number of swallows. Subjects were grouped into three clusters of eating behaviour characterised as, "fast chewers", "thorough chewers" and "suckers". The main differences between clusters were the time chocolate was kept in mouth, chew rate and muscle work.

  5. Characterising Complex Enzyme Reaction Data

    PubMed Central

    Rahman, Syed Asad; Thornton, Janet M.

    2016-01-01

    The relationship between enzyme-catalysed reactions and the Enzyme Commission (EC) number, the widely accepted classification scheme used to characterise enzyme activity, is complex and with the rapid increase in our knowledge of the reactions catalysed by enzymes needs revisiting. We present a manual and computational analysis to investigate this complexity and found that almost one-third of all known EC numbers are linked to more than one reaction in the secondary reaction databases (e.g., KEGG). Although this complexity is often resolved by defining generic, alternative and partial reactions, we have also found individual EC numbers with more than one reaction catalysing different types of bond changes. This analysis adds a new dimension to our understanding of enzyme function and might be useful for the accurate annotation of the function of enzymes and to study the changes in enzyme function during evolution. PMID:26840640

  6. Characterising Complex Enzyme Reaction Data.

    PubMed

    Dönertaş, Handan Melike; Martínez Cuesta, Sergio; Rahman, Syed Asad; Thornton, Janet M

    2016-01-01

    The relationship between enzyme-catalysed reactions and the Enzyme Commission (EC) number, the widely accepted classification scheme used to characterise enzyme activity, is complex and with the rapid increase in our knowledge of the reactions catalysed by enzymes needs revisiting. We present a manual and computational analysis to investigate this complexity and found that almost one-third of all known EC numbers are linked to more than one reaction in the secondary reaction databases (e.g., KEGG). Although this complexity is often resolved by defining generic, alternative and partial reactions, we have also found individual EC numbers with more than one reaction catalysing different types of bond changes. This analysis adds a new dimension to our understanding of enzyme function and might be useful for the accurate annotation of the function of enzymes and to study the changes in enzyme function during evolution.

  7. A convenient luminescence assay of ferroportin internalization to study its interaction with hepcidin.

    PubMed

    Song, Ge; Jiang, Qian; Xu, Ting; Liu, Ya-Li; Xu, Zeng-Guang; Guo, Zhan-Yun

    2013-04-01

    Hepcidin is a liver-secreted small disulfide-rich peptide that plays a key role in iron homeostasis by binding and mediating the internalization and degradation of the only iron efflux transporter so far known, ferroportin (Fpn). To study hepcidin-Fpn interactions, in the present study we established a convenient luminescence assay for the quantitative measurement of hepcidin-induced Fpn internalization by fusing a small nanoluciferase (NanoLuc, 171 amino acids) at the Fpn C-terminus. Once the NanoLuc-tagged Fpn was internalized, the measured luminescence was significantly decreased when assayed with the intact transiently transfected cells and an inducible expression system. Through the coexpression of a NanoLuc-tagged Fpn and an enhanced green fluorescent protein (EGFP)-tagged Fpn by the use of an inducible bidirectional promoter, we could measure the hepcidin-induced Fpn internalization qualitatively and quantitatively on the basis of the fluorescence of the tagged EGFP and the luminescence of the tagged NanoLuc. Thus, our present study provides a novel and convenient assay for measuring the hepcidin-Fpn interaction qualitatively and quantitatively. Through coexpression of a NanoLuc-tagged wild-type Fpn and an EGFP-tagged hepcidin-insensitive mutant [C326S]Fpn, we demonstrated that the mutant Fpn had no effect on hepcidin-induced internalization of wild-type Fpn, suggesting that wild-type Fpn and mutant Fpn are functionally independent.

  8. Luminescent Mycena: new and noteworthy species.

    PubMed

    Desjardin, Dennis E; Perry, Brian A; Lodge, D Jean; Stevani, Cassius V; Nagasawa, Eiji

    2010-01-01

    Seven species of Mycena are reported as luminescent, representing specimens collected in Belize, Brazil, Dominican Republic, Jamaica, Japan (Bonin Islands), Malaysia (Borneo) and Puerto Rico. Four of them represent new species (Mycena luxaeterna, M. luxarboricola, M. luxperpetua, M. silvaelucens) and three represent new reports of luminescence in previously described species (M. aff. abieticola, M. aspratilis, M. margarita). Mycena subepipterygia is synonymized with M. margarita, and M. chlorinosma is proposed as a possible synonym. Comprehensive descriptions, illustrations, photographs and comparisons with phenetically similar species are provided. A redescription of M. chlorophos, based on analyses of type specimens and recently collected topotypical material, is provided. The addition of these seven new or newly reported luminescent species of Mycena brings the total to 71 known bioluminescent species of fungi.

  9. Luminescence blinking of a reacting quantum dot.

    PubMed

    Routzahn, Aaron L; Jain, Prashant K

    2015-04-01

    Luminescence blinking is an inherent feature of optical emission from individual fluorescent molecules and quantum dots. There have been intense efforts, although not with complete resolution, toward the understanding of the mechanistic origin of blinking and also its mitigation in quantum dots. As an advance in our microscopic view of blinking, we show that the luminescence blinking of a quantum dot becomes unusually heavy in the temporal vicinity of a reactive transformation. This stage of heavy blinking is a result of defects/dopants formed within the quantum dot on its path to conversion. The evolution of blinking behavior along the reaction path allows us to measure the lifetime of the critical dopant-related intermediate in the reaction. This work establishes luminescence blinking as a single-nanocrystal level probe of catalytic, photocatalytic, and electrochemical events occurring in the solid-state or on semiconductor surfaces.

  10. Luminescence of europium (III) complexes for visualization

    NASA Astrophysics Data System (ADS)

    Kolontaeva, Olga A.; Pozharov, Mikhail V.; Korolovich, Vladimir F.; Khokhlova, Anastasia R.; Kirdyanova, Anna N.; Burmistrova, Natalia A.; Zakharova, Tamara V.; Goryacheva, Irina Y.

    2016-04-01

    With the purpose to develop bright non-toxic luminescent label for theranostic application we have studied complexation of lanthanide dipicolinates (2,6-pyridinedicarboxylates) by sodium alginate and effect of thermal exposure of synthesized micro-capsules on their luminescent properties. Synthesized micro-capsules are stable in acidic medium but dissolve at pH ~ 4 due to transformation of cationic europium dipicolinate complex to anionic. Luminescence studies have shown that emission spectra of europium(III)-alginate complexes (both chloride and dipicolinate) contain two intensive bands characteristic to Eu3+ ion (5D0 --> 7F1 (590 nm) and 5D0 --> 7F1 (612 nm)). We have also found that at 160ºC europium(III)- alginate micro-capsules decompose to black, soot-like substance, therefore, their thermal treatment must be performed in closed environment (i.e., sealed ampoules).

  11. 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.

  12. Modelling thermal transfer in optically stimulated luminescence of quartz

    NASA Astrophysics Data System (ADS)

    Pagonis, V.; Chen, R.; Wintle, A. G.

    2007-02-01

    A previously published kinetic model for the production of luminescence signals in quartz is used to investigate the production of thermally transferred optically stimulated luminescence (TT-OSL) signals. This paper provides a mathematical description of the thermal transfer mechanism for two different phenomena that have been observed in previously published experiments (Aitken and Smith 1988 Quat. Sci. Rev. 7 387-93). The starting point is the model proposed by Bailey (2001 Radiat. Meas. 33 17-45). The numerical values of some of the parameters are varied so that they match the experimental data. The effect caused by varying these values is investigated. The first of these phenomena takes place after storing optically bleached samples at room temperature; this involves the traps responsible for the 110 °C thermoluminescence (TL) peak of quartz acting as a refuge trap. The second phenomenon concerns OSL signals that are induced by heating the samples after the bleaching of the OSL signal and involves a putative TL peak at ~230 °C associated with the refuge trap; specifically, the paper presents a simulation of the temperature dependence of the OSL signal measured by successively heating the quartz samples to higher temperatures up to ~400 °C.

  13. Luminescence of apollo 11 lunar samples.

    PubMed

    Greenman, N N; Gross, H G

    1970-01-30

    Luminescence measurements were made of four lunar rocks, two terrestrial rocks (granite and gabbro), and one terrestrial mineral (willemite) by comparing the spectral curves with the curve of a barium sulfate standard. Efficiencies with 3000 angstrom excitation were < 6 x 10(-5) for the lunar samples, < 8 x 10(-5) for gabbro of very similar composition to the lunar samples, approximately 10(-4) for granite, and approximately 2 X 10(-2) for willemite. If these are typical values for other ultraviolet excitation wavelengths, the Apollo 11 site appears to contribute little to the observed lunar luminescence.

  14. Luminescence of apollo 11 lunar samples.

    PubMed

    Greenman, N N; Gross, H G

    1970-01-30

    Luminescence measurements were made of four lunar rocks, two terrestrial rocks (granite and gabbro), and one terrestrial mineral (willemite) by comparing the spectral curves with the curve of a barium sulfate standard. Efficiencies with 3000 angstrom excitation were < 6 x 10(-5) for the lunar samples, < 8 x 10(-5) for gabbro of very similar composition to the lunar samples, approximately 10(-4) for granite, and approximately 2 X 10(-2) for willemite. If these are typical values for other ultraviolet excitation wavelengths, the Apollo 11 site appears to contribute little to the observed lunar luminescence. PMID:17781561

  15. Simultaneous Luminescence Pressure and Temperature Mapping System

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (Inventor)

    1995-01-01

    A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (approximately 150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

  16. Simultaneous Luminescence Pressure and Temperature Mapping

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M. (Inventor)

    1998-01-01

    A simultaneous luminescence pressure and temperature mapping system is developed including improved dye application techniques for surface temperature and pressure measurements from 5 torr to 1000 torr with possible upgrade to from 0.5 torr to several atmospheres with improved camera resolution. Adsorbed perylene dye on slip-cast silica is pressure (oxygen) sensitive and reusable to relatively high temperatures (-150 C). Adsorbed luminescence has an approximately linear color shift with temperature, which can be used for independent temperature mapping and brightness pressure calibration with temperature.

  17. Characterisation of Erbium Doped Phosphate Glass

    NASA Astrophysics Data System (ADS)

    Rasid, A. A.; Rohani, M. S.; Sahar, M. R.; Kasim, A.

    2010-03-01

    A series of erbium doped phosphate glass has been successfully fabricated, and the determination of their density and luminescence properties has been carried out. It is particularly interesting to study the effect of modifying oxides to the properties of the glass. The glass density reduces with the increasing content of Na2O. The emission spectra from luminescence spectroscopy resolved six emission peaks from the excitation wavelength of 336.8 nm (3.69 eV). The emission of 4F7/2 gives two emission peaks, where the peak near 482 nm shows a higher intensity and the peak near 491 nm gives a weak emission spectra.

  18. Fabrication of luminescent porous silicon with stain etches and evidence that luminescence originates in amorphous layers

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; George, T.; Ksendzov, A.; Lin, T. L.; Pike, W. T.; Vasquez, R. P.; Wu, Z.-C.

    1992-01-01

    Simple immersion of Si in stain etches of HF:HNO3:H2O or NaNO2 in aqueous HF was used to produce films exhibiting luminescence in the visible similar to that of anodically-etched porous Si. All of the luminescent samples consist of amorphous porous Si in at least the near surface region. No evidence was found for small crystalline regions within these amorphous layers.

  19. Thermal and electron stimulated luminescence of natural bones, commercial hydroxyapatite and collagen.

    PubMed

    Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Rivera, T; Lozano, I B

    2014-01-01

    The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion [Formula: see text] or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered.

  20. Thermal and electron stimulated luminescence of natural bones, commercial hydroxyapatite and collagen.

    PubMed

    Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Rivera, T; Lozano, I B

    2014-01-01

    The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion [Formula: see text] or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered. PMID:24210921

  1. Acid synthesis of luminescent amine-functionalized or erbium-doped silica spheres for biological applications.

    PubMed

    Enrichi, Francesco; Trave, Enrico; Bersani, Marco

    2008-03-01

    In this work we discuss and investigate the morphological and optical properties of luminescent silica spheres which can have interesting applications in bioimaging and biosensing. The spheres are synthesized following an acid route by the hydrolysis and condensation of tetraethylortosilicate (TEOS) and can be functionalized by incorporation of aminopropyl-triethoxysilane (APTES) during the synthesis, inducing a significant luminescence that can be attributed to a recombination mechanism from localized organic defects related to -NH(2) groups. It is shown that the acid synthesis route produces very regular spherical particles, but their diameter vary in the range of 200-4,000 nm. The luminescence properties have been investigated and optimized by variation of the annealing temperature for the functionalized spheres, obtaining the most efficient PL emission after a thermal treatment of 1 h at 600 degrees C in air. Moreover, the possibility to introduce rare earths like erbium in the spheres was also studied and the corresponding Er(3) luminescence emission at 1.53 microm is reported in terms of intensity and lifetime, pointing out that erbium can be easily and efficiently incorporated during the acid synthesis giving high PL intensity with a good lifetime of 3.9 ms.

  2. Effects of hydrogen peroxide on light emission by various strains of marine luminescent bacteria.

    PubMed

    Katsev, Andrey M; Wegrzyn, Grzegorz; Szpilewska, Hanna

    2004-01-01

    Light-emitting bacteria are the most abundant and widespread luminescent organisms. Most species of such bacteria live in marine environments. However, until recently, biological role of bacterial luminescence remained unknown. Recent studies indicated that light produced in bacterial cells may stimulate DNA repair. Therefore, it is not surprising that agents that cause DNA damage induce expression of lux genes. Moreover, it was proposed previously that bacterial luciferases may be involved in detoxification of reactive oxygen species. Recently, this hypothesis was confirmed experimentally. Here we investigated effects of hydrogen peroxide on light emission by various strains of luminescent bacteria. We found that luminescence of strains with luciferase of fast kinetics of reaction decreased at considerably lower concentrations of H2O2 than that of strains with luciferase of the slow kinetics. The action (either direct or indirect) of luciferases as anti-oxidants seemed to be independent of activity of catalase, which was found to be different in various strains. Therefore, it seems that luciferases of the slow kinetics are more efficient in detoxification of reactive oxygen species than those of the fast kinetics.

  3. Enhancing and quenching luminescence with gold nanoparticle films: the influence of substrate on the luminescent properties.

    PubMed

    Guidelli, Eder José; Ramos, Ana Paula; Baffa, Oswaldo

    2016-01-01

    Gold nanoparticle (AuNP) films were sputtered over glass and aluminum substrates to enhance optically stimulated luminescence (OSL), a luminescent technique employed for radiation detection, from x-ray irradiated NaCl nanocrystals. The AuNP films deposited over glass led to enhanced-OSL emission, whereas the AuNP films deposited on aluminum substrates quenched the OSL emission. The enhanced-OSL intensity is proportional to the optical density of the film's plasmon resonance band at the stimulation wavelength. For the case of the AuNP/aluminum films, the luminescence quenching diminishes, and OSL intensity partially recovers upon increasing the distance between the AuNPs and the aluminum substrates, and between the luminescent nanocrystals and the AuNP films. These results suggest that plasmonic interactions between the emitter nanocrystals, the localized surface plasmons (LSP) of the AuNPs, and the substrate are responsible for the OSL enhancement and quenching. In this sense, the substrate dictates whether LSP relaxation occurs by radiative or non-radiative transisitions, leading to enhanced or quenched OSL, respectively. Therefore, besides showing that AuNP films can enhance and/or tune the sensitivity of luminescent radiation detectors, and demonstrating OSL as a new technique to investigate mechanisms of plasmon-enhanced luminescence, these results bring insights on how substrates strongly modify the optical properties of AuNP films. PMID:26606392

  4. Modeling Light Propagation in Luminescent Media

    NASA Astrophysics Data System (ADS)

    Sahin, Derya

    This study presents physical, computational and analytical modeling approaches for light propagation in luminescent random media. Two different approaches are used, namely (i) a statistical approach: Monte-Carlo simulations for photon transport and (ii) a deterministic approach: radiative transport theory. Both approaches account accurately for the multiple absorption and reemission of light at different wavelengths and for anisotropic luminescence. The deterministic approach is a generalization of radiative transport theory for solving inelastic scattering problems in random media. We use the radiative transport theory to study light propagation in luminescent media. Based on this theory, we also study the optically thick medium. Using perturbation methods, a corrected diffusion approximation with asymptotically accurate boundary conditions and a boundary layer solution are derived. The accuracy and the efficacy of this approach is verified for a plane-parallel slab problem. In particular, we apply these two approaches (MC and radiative transport theory) to model light propagation in semiconductor-based luminescent solar concentrators (LSCs). The computational results for both approaches are compared with each other and found to agree. The results of this dissertation present practical and reliable techniques to use for solving forward/inverse inelastic scattering problems arising in various research areas such as optics, biomedical engineering, nuclear engineering, solar science and material science.

  5. Exciton luminescence of 8-azasteroid microcrystals

    NASA Astrophysics Data System (ADS)

    Akhrem, A. A.; Borisevich, N. A.; Gulyakevich, O. V.; Knyukshto, V. N.; Mikhal'Chuk, A. L.; Tikhomirov, S. A.; Tolstorozhev, G. B.

    1999-05-01

    Luminescence of microcrystals of 2,3-methoxy-8-azagon-1,3,5(10),13-tetraene-12,17-dion of the class of molecules of biologically active steroids is detected at room temperature (293 K). It represents fast fluorescence of free and self-localized excitons and prolonged phosphorescence of triplet excitons.

  6. Simultaneous Luminescence Pressure and Temperature Measurement System for Hypersonic Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.

    1995-01-01

    Surface pressures and temperatures are determined from visible emission brightness and green-to-red color ratioing of induced luminescence from a ceramic surface with an organic dye coating. A ceramic-dye matrix of porous silica ceramic with an adsorbed dye is developed for high-temperature pressure sensitivity and stability (up to 150 C). Induced luminescence may be excited using a broad range of incident radiation from visible blue light (488-nm wavelength) to the near ultraviolet (365 nm). Ceramic research models and test samples are fabricated using net-form slip-casting and sintering techniques. Methods of preparation and effects of adsorption film thickness on measurement sensitivity are discussed. With the present 8-bit imaging system a 10% pressure measurement uncertainty from 50 to 760 torr is estimated, with an improvement to 5% from 3 to 1500 torr with a 12-bit imaging system.

  7. Quenching methods for background reduction in luminescence-based probe-target binding assays

    DOEpatents

    Cai, Hong; Goodwin, Peter M; Keller, Richard A.; Nolan, Rhiannon L.

    2007-04-10

    Background luminescence is reduced from a solution containing unbound luminescent probes, each having a first molecule that attaches to a target molecule and having an attached luminescent moiety, and luminescent probe/target adducts. Quenching capture reagent molecules are formed that are capable of forming an adduct with the unbound luminescent probes and having an attached quencher material effective to quench luminescence of the luminescent moiety. The quencher material of the capture reagent molecules is added to a solution of the luminescent probe/target adducts and binds in a proximity to the luminescent moiety of the unbound luminescent probes to quench luminescence from the luminescent moiety when the luminescent moiety is exposed to exciting illumination. The quencher capture reagent does not bind to probe molecules that are bound to target molecules and the probe/target adduct emission is not quenched.

  8. Paper-based biodetection using luminescent nanoparticles.

    PubMed

    Ju, Qiang; Noor, M Omair; Krull, Ulrich J

    2016-05-10

    Point-of-care and in-field technologies for rapid, sensitive and selective detection of molecular biomarkers have attracted much interest. Rugged bioassay technology capable of fast detection of markers for pathogens and genetic diseases would in particular impact the quality of health care in the developing world, but would also make possible more extensive screening in developed countries to tackle problems such as those associated with water and food quality, and tracking of infectious organisms in hospitals and clinics. Literature trends indicate an increasing interest in the use of nanomaterials, and in particular luminescent nanoparticles, for assay development. These materials may offer attributes for development of assays and sensors that could achieve improvements in analytical figures of merit, and provide practical advantages in sensitivity and stability. There is opportunity for cost-efficiency and technical simplicity by implementation of luminescent nanomaterials as the basis for transduction technology, when combined with the use of paper substrates, and the ubiquitous availability of cell phone cameras and associated infrastructure for optical detection and transmission of results. Luminescent nanoparticles have been described for a broad range of bioanalytical targets including small molecules, oligonucleotides, peptides, proteins, saccharides and whole cells (e.g., cancer diagnostics). The luminescent nanomaterials that are described herein for paper-based bioassays include metal nanoparticles, quantum dots and lanthanide-doped nanocrystals. These nanomaterials often have broad and strong absorption and narrow emission bands that improve opportunity for multiplexed analysis, and can be designed to provide emission at wavelengths that are efficiently processed by conventional digital cameras. Luminescent nanoparticles can be embedded in paper substrates that are designed to direct fluid flow, and the resulting combination of technologies can offer

  9. Paper-based biodetection using luminescent nanoparticles.

    PubMed

    Ju, Qiang; Noor, M Omair; Krull, Ulrich J

    2016-05-10

    Point-of-care and in-field technologies for rapid, sensitive and selective detection of molecular biomarkers have attracted much interest. Rugged bioassay technology capable of fast detection of markers for pathogens and genetic diseases would in particular impact the quality of health care in the developing world, but would also make possible more extensive screening in developed countries to tackle problems such as those associated with water and food quality, and tracking of infectious organisms in hospitals and clinics. Literature trends indicate an increasing interest in the use of nanomaterials, and in particular luminescent nanoparticles, for assay development. These materials may offer attributes for development of assays and sensors that could achieve improvements in analytical figures of merit, and provide practical advantages in sensitivity and stability. There is opportunity for cost-efficiency and technical simplicity by implementation of luminescent nanomaterials as the basis for transduction technology, when combined with the use of paper substrates, and the ubiquitous availability of cell phone cameras and associated infrastructure for optical detection and transmission of results. Luminescent nanoparticles have been described for a broad range of bioanalytical targets including small molecules, oligonucleotides, peptides, proteins, saccharides and whole cells (e.g., cancer diagnostics). The luminescent nanomaterials that are described herein for paper-based bioassays include metal nanoparticles, quantum dots and lanthanide-doped nanocrystals. These nanomaterials often have broad and strong absorption and narrow emission bands that improve opportunity for multiplexed analysis, and can be designed to provide emission at wavelengths that are efficiently processed by conventional digital cameras. Luminescent nanoparticles can be embedded in paper substrates that are designed to direct fluid flow, and the resulting combination of technologies can offer

  10. Tailoring luminescence color conversion via affinitive co-assembly of glutamates appended with pyrene and naphthalene dicarboximide units.

    PubMed

    Xing, Pengyao; Zhao, Zhuo; Hao, Aiyou; Zhao, Yanli

    2016-01-21

    Structural matching of two organic building blocks bearing glutamate units and different luminophores assembled into unilamellar nanovesicles in aqueous media through a co-assembly process. Aggregation-induced energy transfer took place in the co-assembled system, leading to controllable generation of multiple luminescence colors including white light.

  11. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-01-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1–40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1–40 peptide on the basis of their emission response. PMID:26419607

  12. Protein Nanocages for Delivery and Release of Luminescent Ruthenium(II) Polypyridyl Complexes.

    PubMed

    Li, Xiao; Zhang, Yajie; Chen, Hong; Sun, Jian; Feng, Fude

    2016-09-01

    In this report, noncovalent encapsulation of hydrophobic ruthenium(II) polyridyl complexes, Ru(bpy)2dppz(2+) and Ru(phen)2dppz(2+), into apoferritin cavity was achieved with high loading contents by effective prevention of Ru complex-induced protein aggregation, without disruption of protein native architecture. The Ru-loaded luminescent nanocomposites have demonstrated improved water solubility, easy manipulation, reduced cytotoxicity, and enhanced cellular uptake as compared to the nontreated Ru complexes. PMID:27547981

  13. EBIC and luminescence studies of defects in solar cells.

    PubMed

    Breitenstein, O; Bauer, J; Kittler, M; Arguirov, T; Seifert, W

    2008-01-01

    Electron beam-induced current (EBIC) can be used to detect electronic irregularities in solar cells, such as shunts and precipitates, and to perform physical characterization of defects by, e.g. measuring the temperature dependence of their recombination activity. Recently also luminescence methods such as electroluminescence (EL) and photoluminescence (PL) have been shown to provide useful information on crystal defects in solar cells. In this contribution it will be shown that the combined application of EBIC, EL and PL may deliver useful information on the presence and on the physical properties of crystal defects in silicon solar cells. Also pre-breakdown sites in multicrystalline cells can be investigated by reverse-bias EL and by microplasma-type EBIC, in comparison with lock-in thermography investigations.

  14. On surface Raman scattering and luminescence radiation in boron carbide.

    PubMed

    Werheit, H; Filipov, V; Schwarz, U; Armbrüster, M; Leithe-Jasper, A; Tanaka, T; Shalamberidze, S O

    2010-02-01

    The discrepancy between Raman spectra of boron carbide obtained by Fourier transform Raman and conventional Raman spectrometry is systematically investigated. While at photon energies below the exciton energy (1.560 eV), Raman scattering of bulk phonons of boron carbide occurs, photon energies exceeding the fundamental absorption edge (2.09 eV) evoke additional patterns, which may essentially be attributed to luminescence or to the excitation of Raman-active processes in the surface region. The reason for this is the very high fundamental absorption in boron carbide inducing a very small penetration depth of the exciting laser radiation. Raman excitations essentially restricted to the boron carbide surface region yield spectra which considerably differ from bulk phonon ones, thus indicating structural modifications.

  15. Luminescence and squeezing of a superconducting light-emitting diode

    NASA Astrophysics Data System (ADS)

    Hlobil, Patrik; Orth, Peter P.

    2015-05-01

    We investigate a semiconductor p -n junction in contact with superconducting leads that is operated under forward bias as a light-emitting diode. The presence of superconductivity results in a significant increase of the electroluminescence in a sharp frequency window. We demonstrate that the tunneling of Cooper pairs induces an additional luminescence peak on resonance. There is a transfer of superconducting to photonic coherence that results in the emission of entangled photon pairs and squeezing of the fluctuations in the quadrature amplitudes of the emitted light. We show that the squeezing angle can be electrically manipulated by changing the relative phase of the order parameters in the superconductors. We finally derive the conditions for lasing in the system and show that the laser threshold is reduced due to superconductivity. This reveals how the macroscopic coherence of a superconductor can be used to control the properties of light.

  16. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    SciTech Connect

    Grinblat, Gustavo; Comedi, David; Bern, Francis; Barzola-Quiquia, José; Esquinazi, Pablo; Tirado, Mónica

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1 V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  17. Characterisation of mycelial morphology using image analysis.

    PubMed

    Paul, G C; Thomas, C R

    1998-01-01

    Image analysis is now well established in quantifying and characterising microorganisms from fermentation samples. In filamentous fermentations it has become an invaluable tool for characterising complex mycelial morphologies, although it is not yet used extensively in industry. Recent method developments include characterisation of spore germination from the inoculum stage and of the subsequent dispersed and pellet forms. Further methods include characterising vacuolation and simple structural differentiation of mycelia, also from submerged cultures. Image analysis can provide better understanding of the development of mycelial morphology, of the physiological states of the microorganisms in the fermenter, and of their interactions with the fermentation conditions. This understanding should lead to improved design and operation of mycelial fermentations. PMID:9468800

  18. Luminescence and photoinduced absorption in ytterbium-doped optical fibres

    SciTech Connect

    Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E; Bubnov, M M; Umnikov, A A; Yashkov, M V; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-12-31

    Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role in photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.

  19. Semiconducting polymer encapsulated mesoporous silica particles with conjugated Europium complexes: toward enhanced luminescence under aqueous conditions.

    PubMed

    Zhang, Jixi; Prabhakar, Neeraj; Näreoja, Tuomas; Rosenholm, Jessica M

    2014-01-01

    Immobilization of lanthanide organic complexes in meso-organized hybrid materials for luminescence applications have attracted immense interest due to the possibility of controlled segregation at the nanoscopic level for novel optical properties. Aimed at enhancing the luminescence intensity and stability of the hybrid materials in aqueous media, we developed polyvinylpyrrolidone (PVP) stabilized, semiconducting polymer (poly(9-vinylcarbazole), PVK) encapsulated mesoporous silica hybrid particles grafted with Europium(III) complexes. Monosilylated β-diketonate ligands (1-(2-naphthoyl)-3,3,3-trifluoroacetonate, NTA) were first co-condensed in the mesoporous silica particles as pendent groups for bridging and anchoring the lanthanide complexes, resulting in particles with an mean diameter of ∼ 450 nm and a bimodal pore size distribution centered at 3.5 and 5.3 nm. PVK was encapsulated on the resulted particles by a solvent-induced surface precipitation process, in order to seal the mesopores and protect Europium ions from luminescence quenching by producing a hydrophobic environment. The obtained polymer encapsulated MSN-EuLC@PVK-PVP particles exhibit significantly higher intrinsic quantum yield (Φ(Ln) = 39%) and longer lifetime (τ(obs) = 0.51 ms), as compared with those without polymer encapsulation. Most importantly, a high luminescence stability was realized when MSN-EuLC@PVK-PVP particles were dispersed in various aqueous media, showing no noticeable quenching effect. The beneficial features and positive attributes of both mesoporous silica and semiconducting polymers as lanthanide-complex host were merged in a single hybrid carrier, opening up the possibility of using these hybrid luminescent materials under complex aqueous conditions such as biological/physiological environments.

  20. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions. PMID:26863291

  1. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions.

  2. Luminescent amino-functionalized or erbium-doped silica spheres for biological applications.

    PubMed

    Enrichi, Francesco

    2008-01-01

    This work presents the morphological and optical properties of luminescent silica spheres, discussing applications in bioimaging and biosensing. The spheres are obtained by the hydrolysis and condensation of tetraethylorthosilicate (TEOS) and can be synthesized by following either a basic or an acidic route. Luminescence emission is induced after incorporation of aminopropyltriethoxysilane (APTES) during synthesis or by introducing an optically active element, such as erbium, or other rare-earth elements. The luminescence properties of APTES-functionalized silica spheres have been investigated and optimized by varying the annealing temperature. On the other hand, erbium incorporation in silica spheres was also studied and the corresponding Er(3+) luminescence emission at 1.54 microm was evaluated for intensity and lifetime. The basic pH environment in the synthesis allows good control of the size of the spheres (approximately 200 nm in diameter), whereas the acidic route produces a wide dispersion in particle size (200-5000 nm). Both these approaches, however, can be followed to obtain an efficient photoluminescence (PL) emission for the APTES-functionalized silica spheres after 400-600 degrees C thermal treatment. If Er(NO(3))(3) is introduced in the basic solution, a rapid precipitation of Er(OH)(3) occurs, but erbium can be easily and efficiently incorporated in the acid-synthesized spheres, showing high PL intensity at 1.54 microm with lifetime of 3.9 ms. Finally, I discuss perspectives for the applications of these luminescent silica spheres, in particular as biological markers for bioimaging and biosensing.

  3. Optically Stimulated Luminescence (OSL) of Tooth Enamel and its Potential Use in Post-Radiation Exposure Triage

    PubMed Central

    DeWitt, R.; Klein, D. M.; Yukihara, E. G.; Simon, S. L.; McKeever, S. W. S.

    2009-01-01

    Optically stimulated luminescence (OSL) properties of dental enamel are discussed with a view to the development of an in-vivo dose assessment technique for medical triage following a radiological/nuclear accident or terrorist event. In the OSL technique, past radiation exposure is assessed by stimulating the sample with light of one wavelength and monitoring the luminescence at another wavelength under the assumption that the luminescence originates from the recombination of radiation-induced charges trapped at metastable defects in the enamel and that the intensity of the luminescence signal is in proportion to the absorbed radiation dose. Several primary findings emerged from this research: (a) sensitivities varied considerably between different teeth and also between fragments of the same tooth, (b) OSL signals were found to decay rapidly during the first 12 hours after irradiation and slower afterwards, (c) the fading rate of the luminescence signal varied between fragments, (d) blue light stimulation yields greater sensitivity than infra-red stimulation, while the OSL signal obtained with a high-intensity pulsed green-light laser was found to be not correlated with the radiation dose. Significant challenges remain to developing a practical in-vivo technique including the development of calibration procedures and lowering minimum detectable doses. PMID:20065717

  4. Materials for luminescent greenhouse solar collectors.

    PubMed

    Levitt, J A; Weber, W H

    1977-10-01

    Luminescent greenhouse solar collectors are potentially useful for concentrating sunlight onto photovoltaic power cells. Measurements of the performance of small-scale collectors made of two commercially available materials (Owens-Illinois ED2 neodymium-doped laser glass and rhodamine 6G-doped plastic) are presented. The results are encouraging, but they indicate a need for further spectral sensitization and for reduced matrix loss coefficient. The measurements with monochromatic illumination agree with the predictions of a mathematical model developed to take account of reemission following the absorption of luminescence. Under solar illumination, the model predicts photon flux concentrations of about 15 for optimized full-scale collectors made of the materials studied and concentrations of 110 for reasonably improved glass.

  5. Luminescent lanthanide chelates and methods of use

    DOEpatents

    Selvin, Paul R.; Hearst, John

    1997-01-01

    The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

  6. Tunable lifetime multiplexing using luminescent nanocrystals

    NASA Astrophysics Data System (ADS)

    Lu, Yiqing; Zhao, Jiangbo; Zhang, Run; Liu, Yujia; Liu, Deming; Goldys, Ewa M.; Yang, Xusan; Xi, Peng; Sunna, Anwar; Lu, Jie; Shi, Yu; Leif, Robert C.; Huo, Yujing; Shen, Jian; Piper, James A.; Robinson, J. Paul; Jin, Dayong

    2014-01-01

    Optical multiplexing plays an important role in applications such as optical data storage, document security, molecular probes and bead assays for personalized medicine. Conventional fluorescent colour coding is limited by spectral overlap and background interference, restricting the number of distinguishable identities. Here, we show that tunable luminescent lifetimes τ in the microsecond region can be exploited to code individual upconversion nanocrystals. In a single colour band, one can generate more than ten nanocrystal populations with distinct lifetimes ranging from 25.6 µs to 662.4 µs and decode their well-separated lifetime identities, which are independent of both colour and intensity. Such `τ-dots' potentially suit multichannel bioimaging, high-throughput cytometry quantification, high-density data storage, as well as security codes to combat counterfeiting. This demonstration extends the optical multiplexing capability by adding the temporal dimension of luminescent signals, opening new opportunities in the life sciences, medicine and data security.

  7. Luminescence of Pr 3+ in minerals

    NASA Astrophysics Data System (ADS)

    Gaft, Michael; Reisfeld, Renata; Panczer, Gerard; Uspensky, Eugene; Varrel, Bernard; Boulon, Georges

    1999-10-01

    Time-resolved luminescence spectroscopy coupled with selective excitation allows one to identify and assign the emission transitions of Pr 3+ in natural apatite, scheelite and anhydrite. Under steady state conditions they are hidden by the stronger bands and lines of Eu 2+, (WO 4) 2-, (MoO 4) 2-, Sm 3+ and Dy 3+. Of special interest are the transitions from the 1S 0 level emitting in the UV part of the spectrum. These transitions make Pr 3+ doped oxyapatite and anhydrite potential materials for UV laser. The long-lived luminescence of Pr 3+ in the visible range in apatite in the presence of uranyl and in scheelite may be ascribed to the participation of the 1S 0 level which serves as a trap of the excitation.

  8. Luminescence properties of silicon-cellulose nanocomposite

    NASA Astrophysics Data System (ADS)

    Pikulev, Vitaly; Loginova, Svetlana; Gurtov, Valery

    2012-07-01

    We have characterized the structure and luminescence properties for two-component material composed of nanocrystalline cellulose and nanocrystalline (less to 100 nm) silicon powder. An efficient and stable photoluminescence of nanocomposite, resistant to the influence of gas-phase oxidants, has been found. The obtained material has electret-like properties and demonstrates the possibility of multiple-recharging in an electric field near 5·103 V/cm at temperatures ranging from -70°C to 100°C. The presence of the electric field, as well as ozone or low-temperature plasma treatment, does not change the luminescence spectrum due to quantum size properties of silicon nanoparticles. We believe that these particles may appear in two states: both embedded in a cellulose matrix and in the form of mechanical mixture.

  9. SR-excited luminescence of corundum with native defects

    NASA Astrophysics Data System (ADS)

    Syurdo, A. I.; Kortov, V. S.; Pustovarov, V. A.; Sharafutdinov, F. F.; Zinin, E. I.

    1998-02-01

    Using synchrotron radiation (SR), radiation relaxation of electron excitations in nominally pure and anion-imperfect corundum crystals subject to irradiation with fast electrons and neutrons was studied. It was found that the luminescence decay time of F + centers depends on the surrounding defects. New data were obtained on the luminescence decay kinetics at 290, 380 and 400 nm, the luminescence being due to exciton-like bodies and complex F aggregate centers.

  10. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, Rhett L.; Ambrose, W. Patrick; Demas, James N.; Goodwin, Peter M.; Johnson, Mitchell E.; Keller, Richard A.; Petty, Jeffrey T.; Schecker, Jay A.; Wu, Ming

    1998-01-01

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

  11. Method and apparatus for reducing solvent luminescence background emissions

    DOEpatents

    Affleck, R.L.; Ambrose, W.P.; Demas, J.N.; Goodwin, P.M.; Johnson, M.E.; Keller, R.A.; Petty, J.T.; Schecker, J.A.; Wu, M.

    1998-10-27

    The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region. 6 figs.

  12. Luminescence of erbium ions in tellurite glasses

    SciTech Connect

    Savikin, Alexander P.; Grishin, Igor A.; Sharkov, Valery V.; Budruev, Andrei V.

    2013-11-15

    Optical characteristics of new generation of tellurite glasses having high stability against crystallization have been studied. As the initial reagents for the glasses synthesis on the base of tellurium oxide (TeO{sub 2}) there were used such oxides as WO{sub 3}, MoO{sub 3}, La{sub 2}O{sub 3}, Li{sub 2}CO{sub 3}, ZnO—Bi{sub 2}O{sub 2}CO{sub 3} and active components such as high purity Er{sub 2}O{sub 3}, Yb{sub 2}O{sub 3}, ErF{sub 3} and YbF{sub 3}. Intensities of luminescence at 1.53 µm of the erbium ions were determined after excitation at 975 nm. Experimental data obtained have shown the possibility to use the studied glasses doped by Er{sup 3+} and Yb{sup 3+} as active elements for fiber and integrated optics. - Graphical abstract: In contrast to the case of ZBLAN glass the TeO{sub 2}–WO{sub 3} (Er{sup 3+}) glass has bright intensity of luminescence at 1.53 µm for erbium ions that should be caused by excitation at 975 nm. Experimental data obtained have shown the possibility to use the studied glasses doped by Er{sup 3+} and Yb{sup 3+} as active elements for fiber and integrated optics. Display Omitted - Highlights: • We examined changes in growth of luminescence in doubly-doped tellurite glasses. • We found that luminescence grows in two orders by using Er{sup 3+} and Yb{sup 3+} at 1.53 μm. • We see possibility to use those glasses as active elements for integrated optics.

  13. Nonequivalent Substitution and Charge-Induced Emitter-Migration Design of Tuning Spectral and Duration Properties of NaCa2GeO4F:Mn(2+) Persistent Luminescent Phosphor.

    PubMed

    Wang, Zhenbin; Feng, Lin; Zhang, Jiachi; Ci, Zhipeng; Zhang, Zhiya; Wang, Yuhua

    2016-08-15

    We combine nonequivalent substitution and charge-induced emitter-migration approaches and design an efficient method to optionally tune the spectral and duration properties of NaCa2GeO4F:Mn(2+) phosphor. A series of representative codopants have been investigated in detail and classified into two categories: RA (RA = Li(+), Al(3+), N(3-), Ga(3+), B(3+)) and RB (RB = Mg(2+), F(-), Bi(3+), Zn(2+), Cd(2+), Sc(3+), Tm(3+)). Results reveal that the nonequivalent substitution of RA codopants would induce foreign negative defects and stabilize Mn(2+) emitters at octahedral Na/Ca sites for red emission. In constrast, the RB codopants would generate foreign positive defects and make Mn(2+) emitters migrate to tetrahedral Ge(4+) sites for green-yellow emission. At the same time, the RA codopants are in favor of the generation of intrinsic positive traps with shallow trap depth and thus efficiently improve the duration properties of phosphors. On the basis of the experimental results, a possible nonequivalent substitution and charge-induced emitter-migration model has been proposed, and we can optionally tune the spectral (568 ↔ 627 nm) and the duration (minutes to more than 6 h) properties according to this model. PMID:27482720

  14. Luminescent probes for optical in vivo imaging

    NASA Astrophysics Data System (ADS)

    Texier, Isabelle; Josserand, Veronique; Garanger, Elisabeth; Razkin, Jesus; Jin, Zhaohui; Dumy, Pascal; Favrot, Marie; Boturyn, Didier; Coll, Jean-Luc

    2005-04-01

    Going along with instrumental development for small animal fluorescence in vivo imaging, we are developing molecular fluorescent probes, especially for tumor targeting. Several criteria have to be taken into account for the optimization of the luminescent label. It should be adapted to the in vivo imaging optical conditions : red-shifted absorption and emission, limited overlap between absorption and emission for a good signal filtering, optimized luminescence quantum yield, limited photo-bleaching. Moreover, the whole probe should fulfill the biological requirements for in vivo labeling : adapted blood-time circulation, biological conditions compatibility, low toxicity. We here demonstrate the ability of the imaging fluorescence set-up developed in LETI to image the bio-distribution of molecular probes on short times after injection. Targeting with Cy5 labeled holo-transferrin of subcutaneous TS/Apc (angiogenic murine breast carcinoma model) or IGROV1 (human ovarian cancer) tumors was achieved. Differences in the kinetics of the protein uptake by the tumors were evidenced. IGROV1 internal metastatic nodes implanted in the peritoneal cavity could be detected in nude mice. However, targeted metastatic nodes in lung cancer could only be imaged after dissection of the mouse. These results validate our fluorescence imaging set-up and the use of Cy5 as a luminescent label. New fluorescent probes based on this dye and a molecular delivery template (the RAFT molecule) can thus be envisioned.

  15. Tuning luminescence and reducing reabsorption of CdSe quantum disks for luminescent solar concentrators

    NASA Astrophysics Data System (ADS)

    Lin, Huichuan; Xie, Peng; Liu, Yong; Zhou, Xiang; Li, Baojun

    2015-08-01

    Cadmium selenide (CdSe) quantum disks (QDs) have been synthesized for application in luminescent solar concentrators (LSCs). Luminescence tuning and reabsorption reduction of the QDs were achieved by controlling their size using a hot injection method. The overlap of the absorption and photoluminescence spectra of the as-prepared CdSe QDs was negligible. The as-prepared CdSe QDs were incorporated into polymethylmethacrylate without aggregation and luminescence quenching. The obtained highly transparent composites with non-affecting light-emitting properties were used as LSCs. The placement of a CdSe QDs doped LSC prototype (10 × 1 × 0.1 cm) on a Si-cell resulted in a 201% increase in the electrical power output of the Si-cell compared with that of the bare Si-cell.

  16. Dislocation luminescence in GaN single crystals under nanoindentation.

    PubMed

    Huang, Jun; Xu, Ke; Fan, Ying Min; Wang, Jian Feng; Zhang, Ji Cai; Ren, Guo Qiang

    2014-01-01

    This work presents an experimental study on the dislocation luminescence in GaN by nanoindentation, cathodoluminescence, and Raman. The dislocation luminescence peaking at 3.12 eV exhibits a series of special properties in the cathodoluminescence measurements, and it completely disappears after annealing at 500°C. Raman spectroscopy shows evidence for existence of vacancies in the indented region. A comprehensive investigation encompassing cathodoluminescence, Raman, and annealing experiments allow the assignment of dislocation luminescence to conduction-band-acceptor transition involving Ga vacancies. The nanoscale plasticity of GaN can be better understood by considering the dislocation luminescence mechanism.

  17. Luminescence color as a characteristic for selection in poultry eggs

    NASA Astrophysics Data System (ADS)

    Rybalova, Natalya B.; Vasiljeva, Ludmilia T.; Zamorskaja, Tatjana; Bychajev, Al.

    1996-12-01

    This work concerns luminescence of egg shell and chick down and livability and egg production of hens. It was established that the best layers showed orange color of egg shell luminescence at the beginning of the laying period. Yellow color of chick down luminescence indicates on the chicken's good development especially concerning its digestive and circulatory systems, and connects with its future high livability and egg production. So the use of the color of luminescence is advisable as an additional characteristic providing good possibility to forecast the development of a chicken, its resistance for stressors, its livability and egg production afterwards.

  18. A new luminescence beam profile monitor for intense proton and heavy ion beams

    SciTech Connect

    Tsang,T.; Bellavia, S.; Connolly, R.; Gassner, D.; Makdisi, Y.; Russo, T.; Thieberger, P.; Trbojevic, D.; Zelenski, A.

    2008-10-01

    A new luminescence beam profile monitor is realized in the polarized hydrogen gas jet target at the Relativistic Heavy Ion Collider (RHIC) facility. In addition to the spin polarization of the proton beam being routinely measured by the hydrogen gas jet, the luminescence produced by beam-hydrogen excitation leads to a strong Balmer series lines emission. A selected hydrogen Balmer line is spectrally filtered and imaged to produce the transverse RHIC proton beam shape with unprecedented details on the RHIC beam profile. Alternatively, when the passage of the high energy RHIC gold ion beam excited only the residual gas molecules in the beam path, sufficient ion beam induced luminescence is produced and the transverse gold ion beam profile is obtained. The measured transverse beam sizes and the calculated emittances provide an independent confirmation of the RHIC beam characteristics and to verify the emittance conservation along the RHIC accelerator. This optical beam diagnostic technique by making use of the beam induced fluorescence from injected or residual gas offers a truly noninvasive particle beam characterization, and provides a visual observation of proton and heavy ion beams. Combined with a longitudinal bunch measurement system, a 3-dimensional spatial particle beam profile can be reconstructed tomographically.

  19. Optically Stimulated Luminescence (OSL) of dental enamel for retrospective assessment of radiation exposure

    PubMed Central

    Yukihara, E.G.; Mittani, J.; McKeever, S.W.S.; Simon, S.L.

    2009-01-01

    This paper briefly reviews the optically stimulated luminescence (OSL) properties of dental enamel and discusses the potential and challenges of OSL for filling the technology gap in biodosimetry required for medical triage following a radiological/nuclear accident or terrorist event. The OSL technique uses light to stimulate a radiation-induced luminescence signal from materials previously exposed to ionizing radiation. This luminescence originates from radiation-induced defects in insulating crystals and is proportional to the absorbed dose of ionizing radiation. In our research conducted to date, we focused on fundamental investigations of the OSL properties of dental enamel using extracted teeth and tabletop OSL readers. The objective was to obtain information to support the development of the necessary instrumentation for retrospective dosimetry using dental enamel in laboratory, or for in situ and non-invasive accident dosimetry using dental enamel in emergency triage. An OSL signal from human dental enamel was detected using blue, green, or IR stimulation. Blue/green stimulation associated with UV emission detection seems to be the most appropriate combination in the sense that there is no signal from un-irradiated samples and the shape of the OSL decay is clear. Improvements in the minimum detection level were achieved by incorporating an ellipsoidal mirror in the OSL system to maximize light collection. Other possibilities to improve the sensitivity and research steps necessary to establish the feasibility of the technique for retrospective assessment of radiation exposure are also discussed. PMID:19623269

  20. Plasmonic luminescent core-shell nanocomposites-enhanced chemiluminescence arising from the decomposition of peroxomonosulfite

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Xue, Wei; Lu, Chao; Li, Hai-fang; Zheng, Yongzan; Lin, Jin-Ming

    2013-12-01

    A core-shell structure of plasmonic luminescent nanocomposite, Ni@SiO2@FITC@SiO2 (NSFS) combining the stable luminescence of fluorophore with the excellent plasmonic property of metal nanomaterials, has been synthesized through layer-by-layer assembly. The effect of NSFS on the ultraweak chemiluminescence (CL) reaction of hydrogen peroxide (H2O2) and sodium bisulfite (NaHSO3) was explored for the first time. It was found that the CL intensity from the decomposition of peroxomonosulfite was significantly enhanced by NSFS. The mechanism of the nanocomposite-enhanced CL was revealed as the coupling of chemically induced excited states of fluorescein isothiocyanate (FITC) with surface plasmons of Ni nanoparticles based on studies of CL emission spectra, electron spin resonance spectra, extinction spectra and fluorescence spectra. The work sheds new light on the characteristics of the versatile materials and gives us new insight into the optical properties of fluorophores.

  1. Plasmonic luminescent core-shell nanocomposites-enhanced chemiluminescence arising from the decomposition of peroxomonosulfite.

    PubMed

    Chen, Hui; Xue, Wei; Lu, Chao; Li, Hai-fang; Zheng, Yongzan; Lin, Jin-Ming

    2013-12-01

    A core-shell structure of plasmonic luminescent nanocomposite, Ni@SiO2@FITC@SiO2 (NSFS) combining the stable luminescence of fluorophore with the excellent plasmonic property of metal nanomaterials, has been synthesized through layer-by-layer assembly. The effect of NSFS on the ultraweak chemiluminescence (CL) reaction of hydrogen peroxide (H2O2) and sodium bisulfite (NaHSO3) was explored for the first time. It was found that the CL intensity from the decomposition of peroxomonosulfite was significantly enhanced by NSFS. The mechanism of the nanocomposite-enhanced CL was revealed as the coupling of chemically induced excited states of fluorescein isothiocyanate (FITC) with surface plasmons of Ni nanoparticles based on studies of CL emission spectra, electron spin resonance spectra, extinction spectra and fluorescence spectra. The work sheds new light on the characteristics of the versatile materials and gives us new insight into the optical properties of fluorophores.

  2. Water dispersible, non-cytotoxic, cross-linked luminescent AIE dots: Facile preparation and bioimaging applications

    NASA Astrophysics Data System (ADS)

    Liu, Meiying; Zhang, Xiqi; Yang, Bin; Deng, Fengjie; Li, Zhen; Wei, Junchao; Zhang, Xiaoyong; Wei, Yen

    2014-12-01

    Fluorescent organic nanoparticles have attracted great current research interest due to their superior properties as compared with small organic dyes and fluorescent inorganic nanoparticles. However, fluorescent organic nanoparticles based on conventional organic dyes often result in significant fluorescence decrease due to the notorious aggregation-caused quenching effect. On the other hand, these fluorescent organic nanoparticles obtained from self-assembly are normally not stable in diluted solution. Therefore, the development of novel fluorescent organic nanoparticles which could overcome these limitations is highly desirable for their practical biomedical applications. In this work, water dispersible, non-cytotoxic and cross-linked luminescent polymeric nanoparticles based on aggregation induced emission dyes were prepared via one pot emulsion polymerization. These cross-linked luminescent polymeric nanoparticles emitted strong red fluorescence and were highly stable in diluted aqueous solution, making them highly potential for various biomedical applications.

  3. Characterising an aluminium oxide dosimetry system.

    PubMed

    Conheady, Clement F; Gagliardi, Frank M; Ackerly, Trevor

    2015-09-01

    In vivo dosimetry is recommended as a defence-in-depth strategy in radiotherapy treatments and is currently employed by clinics around the world. The characteristics of a new optically stimulated luminescence dosimetry system were investigated for the purpose of replacing an aging thermoluminescence dosimetry system for in vivo dosimetry. The stability of the system was not sufficient to satisfy commissioning requirements and therefore it has not been released into clinical service at this time. PMID:26224358

  4. Characterisation of diamond coatings with different morphologies by Raman spectroscopy using various laser wavelengths.

    PubMed

    Rudigier, Moritz; Haubner, Roland

    2012-05-01

    Since the beginning of low-pressure diamond synthesis, Raman spectroscopy has been widely used to identify and characterise the quality of diamonds. The diamond crystal is characterised by a Raman peak at about 1,332 cm(-1). Other peaks are associated with miscellaneous carbon structures, e.g. graphite and amorphous phases. In recent years, both well-faceted crystalline diamonds and nanocrystalline and ultrananocrystalline diamonds have been investigated. For these fine-grained materials, the diamond peak at 1,332 cm(-1) disappears and the intensities of peaks at other wavelengths increase. To study the influence of the Raman laser wavelength, three lasers were used (472.681 nm, blue; 532.1 nm, green; 632.81 nm, red). For well-faceted diamonds, the Raman spectra with blue and green laser light were similar. A shift of the peak maxima and different intensities were observed. With use of the red laser, a strong luminescence peak and low peak intensities for the various carbon-related peaks occurred. When the diamond morphology changes from well-faceted to fine-grained ballas diamond, the spectra are similar for all three lasers.

  5. Synthesis and characterisation of chromium carbides

    NASA Astrophysics Data System (ADS)

    Detroye, M.; Reniers, F.; Buess-Herman, C.; Vereecken, J.

    1997-11-01

    This paper presents the synthesis and the characterisation of various chromium carbide compounds. Thin Cr 23C 6 films were deposited by reactive sputtering while Cr 7C 3 films were formed by the carburisation of chromium films in a CH 4/H 2 atmosphere. Cr xC y powders were synthesised from various precursors (Cr, CrN, Cr 2O 3) by reaction with CH 4/H 2 at high temperature. The samples were characterised by AES, XRD and electron diffraction. The effects of the experimental parameters (gas composition, temperature, reaction time) on the purity, the phase formed and the composition of the product of reaction are examined and discussed.

  6. Two color blinking of single strain-induced GaAs quantum dots

    SciTech Connect

    Bertram, D.; Hanna, M.C.; Nozik, A.J.

    1999-05-01

    In this letter we report on a temporal instability in the ground and excited state luminescence of a single strain-induced quantum dot. Using a microscopic photoluminescence technique, we record spectra from a single strain-induced quantum dot in the GaAs/(AlGa)As material system. On a time scale of seconds the luminescence shows an increase and decrease in intensity with an increase of the ground state luminescence correlating with a decrease in the excited state luminescence intensity and vice versa. We term the observed effect two color blinking. {copyright} {ital 1999 American Institute of Physics.}

  7. Experimental observation of the luminescence flash at the collapse phase of a bubble produced by pulsed discharge in water

    SciTech Connect

    Huang, Yifan; Zhang, Liancheng; Zhu, Xinlei; Liu, Zhen Yan, Keping; Chen, Jim

    2015-11-02

    This letter presents an experimental observation of luminescence flash at the collapse phase of an oscillating bubble produced by a pulsed discharge in water. According to the high speed records, the flash lasts around tens of microseconds, which is much longer than the lifetime of laser and ultrasound induced luminescence flashes in nanoseconds and picoseconds, respectively. The pulse width of temperature waveform and minimum radius calculated at the collapse phase also show that the thermodynamic and dynamic signatures of the bubbles in this work are much larger than those of ultrasound and laser induced bubbles both in time and space scales. However, the peak temperature at the point of collapse is close to the results of ultrasound and laser induced bubbles. This result provides another possibility for accurate emission spectrum measurement other than amplification of the emitted light, such as increasing laser energy or sound energy or substituting water with sulphuric acid.

  8. Experimental observation of the luminescence flash at the collapse phase of a bubble produced by pulsed discharge in water

    NASA Astrophysics Data System (ADS)

    Huang, Yifan; Zhang, Liancheng; Chen, Jim; Zhu, Xinlei; Liu, Zhen; Yan, Keping

    2015-11-01

    This letter presents an experimental observation of luminescence flash at the collapse phase of an oscillating bubble produced by a pulsed discharge in water. According to the high speed records, the flash lasts around tens of microseconds, which is much longer than the lifetime of laser and ultrasound induced luminescence flashes in nanoseconds and picoseconds, respectively. The pulse width of temperature waveform and minimum radius calculated at the collapse phase also show that the thermodynamic and dynamic signatures of the bubbles in this work are much larger than those of ultrasound and laser induced bubbles both in time and space scales. However, the peak temperature at the point of collapse is close to the results of ultrasound and laser induced bubbles. This result provides another possibility for accurate emission spectrum measurement other than amplification of the emitted light, such as increasing laser energy or sound energy or substituting water with sulphuric acid.

  9. Doped luminescent materials and particle discrimination using same

    SciTech Connect

    Doty, F. Patrick; Allendorf, Mark D; Feng, Patrick L

    2014-10-07

    Doped luminescent materials are provided for converting excited triplet states to radiative hybrid states. The doped materials may be used to conduct pulse shape discrimination (PSD) using luminescence generated by harvested excited triplet states. The doped materials may also be used to detect particles using spectral shape discrimination (SSD).

  10. Ultrashort pulse laser microsurgery system with plasma luminescence feedback control

    SciTech Connect

    Kim, B.M.; Feit, M.D.; Rubenchik, A.M.; Gold, D.M.; Darrow, C.B.; Da Silva, L.B.

    1997-11-10

    Plasma luminescence spectroscopy was used for precise ablation of bone tissue during ultrashort pulse laser (USPL) micro-spinal surgery. Strong contrast of the luminescence spectra between bone marrow and spinal cord provided the real time feedback control so that only bone tissue can be selectively ablated while preserving the spinal cord.

  11. Luminescent Processes Elucidated by Simple Experiments on ZnS.

    ERIC Educational Resources Information Center

    Schwankner, R.; And Others

    1981-01-01

    Describes some impurity-related optical properties of semiconductors, with special emphasis on the luminescence of zinc sulfide (ZnS). Presents and interprets five experiments using a ZnS screen, ultraviolet lamp, transparent Dewar liquid nitrogen, and a helium/neon gas base. Includes application of luminescence measurements to archaeology. (SK)

  12. Electroluminescent apparatus having a structured luminescence conversion layer

    DOEpatents

    Krummacher, Benjamin Claus

    2008-09-02

    An apparatus such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer disposed on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains color-changing and non-color-changing regions arranged in a particular pattern.

  13. Method for altering the luminescence of a semiconductor

    DOEpatents

    Barbour, J. Charles; Dimos, Duane B.

    1999-01-01

    A method is described for altering the luminescence of a light emitting semiconductor (LES) device. In particular, a method is described whereby a silicon LES device can be selectively irradiated with a radiation source effective for altering the intensity of luminescence of the irradiated region.

  14. Measuring Carrier Lifetime in GaAs by Luminescence

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1986-01-01

    Luminescence proposed as nondestructive technique for measuring Shockley-Read-Hall (SRH) recombination lifetime GaAs. Sample irradiated, and luminescence escapes through surface. Measurement requires no mechanical or electrical contact with sample. No ohmic contacts or p/n junctions needed. Sample not scrapped after tested.

  15. Method for altering the luminescence of a semiconductor

    DOEpatents

    Barbour, J.C.; Dimos, D.B.

    1999-01-12

    A method is described for altering the luminescence of a light emitting semiconductor (LES) device. In particular, a method is described whereby a silicon LES device can be selectively irradiated with a radiation source effective for altering the intensity of luminescence of the irradiated region. 4 figs.

  16. 'Attached cell' antigen 28.3.7 mapping to human chromosome 15 characterises TPA-induced differentiation of the promyelocytic HL-60 cell line to give macrophage/monocyte populations.

    PubMed Central

    Blaineau, C; Avner, P; Tunnacliffe, A; Goodfellow, P

    1983-01-01

    Human cells growing in vitro attached to the substratum express a cell antigen called 28.3.7 identified by a species-specific monoclonal antibody. This antigen is not expressed on human cells growing in suspension. The antigen has a mol. wt. in reduced SDS-polyacrylamide gel electrophoresis gels of 95 000 and in human-mouse somatic cell hybrids, expression of the antigen is controlled by a gene, MIC7, mapping to human chromosome 15. The antigen functions as a marker for macrophage differentiation. In vitro differentiation of the 28.3.7 antigen-negative human promyelocytic leukaemia line HL-60 induced by phorbol ester, results in the formation of a macrophage/monocyte population and the concomitant expression of the 28.3.7 antigen on this adherent cell population. Images Fig. 1. PMID:6641710

  17. A real-time, high-resolution optical fibre dosemeter based on optically stimulated luminescence (OSL) of KBr:Eu, for potential use during the radiotherapy of cancer.

    PubMed

    Gaza, R; McKeever, S W S

    2006-01-01

    A real-time optically stimulated luminescence (OSL) dosimetry system for potential in vivo use during radiotherapy treatments is proposed. Single-crystal europium-doped KBr samples were grown in a Bridgman furnace, and characterised using optical absorption techniques. An algorithm for the processing of the OSL signal was defined for use in real-time measurements, and its performance was studied on data obtained with a home-built reader, using optical-fibre-coupled dosemeters. OSL dose-response, fading properties and temperature dependence of the signal were investigated in correlation with the concentration of Eu(2+) dopant in the sample. PMID:16644971

  18. In-situ luminescence monitoring of ion-induced damage evolution in SiO2 and Al2O3

    SciTech Connect

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; Weber, William J.

    2015-12-17

    Real-time, in-situ ionoluminescence measurements provide information of evolution of emission bands with ion fluence, and thereby establish a correlation between point defect kinetics and phase stability. Using fast light ions (2 MeV H and 3.5 He MeV) and medium mass-high energy ions (8 MeV O, E=0.5 MeV/amu), scintillation materials of a-SiO2, crystalline quartz, and Al2O3 are comparatively investigated at room temperature with the aim of obtaining a further insight on the structural defects induced by ion irradiation and understand the role of electronic energy loss on the damage processes. For more energetic heavy ions, the electronic energy deposition pattern offers higher rates of excitation deeper into the material and allows to evaluate the competing mechanisms between the radiative and non-radiative de-excitation processes. Irradiations with 8 MeV O ions have been selected corresponding to the electronic stopping regime, where the electronic stopping power is dominant, and above the critical amorphization threshold for quartz. Lastly, the usefulness of IBIL and its specific capabilities as a sensitive tool to investigate the material characterization and evaluation of radiation effects are demonstrated.

  19. Mitochondrial respiratory complex I probed by delayed luminescence spectroscopy.

    PubMed

    Baran, Irina; Ionescu, Diana; Privitera, Simona; Scordino, Agata; Mocanu, Maria Magdalena; Musumeci, Francesco; Grasso, Rosaria; Gulino, Marisa; Iftime, Adrian; Tofolean, Ioana Teodora; Garaiman, Alexandru; Goicea, Alexandru; Irimia, Ruxandra; Dimancea, Alexandru; Ganea, Constanta

    2013-12-01

    The role of mitochondrial complex I in ultraweak photon-induced delayed photon emission [delayed luminescence (DL)] of human leukemia Jurkat T cells was probed by using complex I targeting agents like rotenone, menadione, and quercetin. Rotenone, a complex I-specific inhibitor, dose-dependently increased the mitochondrial level of reduced nicotinamide adenine dinucleotide (NADH), decreased clonogenic survival, and induced apoptosis. A strong correlation was found between the mitochondrial levels of NADH and oxidized flavin mononucleotide (FMNox) in rotenone-, menadione- and quercetin-treated cells. Rotenone enhanced DL dose-dependently, whereas quercetin and menadione inhibited DL as well as NADH or FMNox. Collectively, the data suggest that DL of Jurkat cells originates mainly from mitochondrial complex I, which functions predominantly as a dimer and less frequently as a tetramer. In individual monomers, both pairs of pyridine nucleotide (NADH/reduced nicotinamide adenine dinucleotide phosphate) sites and flavin (FMN-a/FMN-b) sites appear to bind cooperatively their specific ligands. Enhancement of delayed red-light emission by rotenone suggests that the mean time for one-electron reduction of ubiquinone or FMN-a by the terminal Fe/S center (N2) is 20 or 284 μs, respectively. All these findings suggest that DL spectroscopy could be used as a reliable, sensitive, and robust technique to probe electron flow within complex I in situ.

  20. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    PubMed

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence.

  1. Magnetic-luminescent spherical particles synthesized by ultrasonic spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Michel, Norma L.; Flores, Dora L.; Hirata, Gustavo A.

    2015-07-01

    The combination of magnetic and luminescent properties in a single particle system, opens-up a wide range of potential applications in biotechnology and biomedicine. In this work, we performed the synthesis of magnetic-luminescent Gd2O3:Eu3+@Fe2O3 particles by ultrasonic spray pyrolysis performed in a tubular furnace. In order to achieve the composite formation, commercial superparamagnetic Fe3O4 nanoparticles were coated with a luminescent Eu3+-doped Gd2O3 shell in a low-cost one-step process. The spray pyrolysis method yields deagglomerated spherical shape magneto/luminescent particles. The photoluminescence spectra under UV excitation (λExc = 265 nm) of the magnetic Gd2O3:Eu3+@Fe2O3 compound showed the characteristic red emission of Eu3+ (λEm = 612 nm). This magneto/luminescent system will find applications in biomedicine and biotechnology.

  2. Luminescence of erbium-doped bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Oprea, Isabella-Ioana; Hesse, Hartmut; Betzler, Klaus

    2006-07-01

    Absorption and luminescence properties of erbium ions in the binary glass system bismuth oxide (Bi 2O 3)-boric oxide (B 2O 3) are measured for the composition range 25-65 mol% Bi 2O 3. A Judd-Ofelt analysis of the typical erbium bands in the absorption spectra reveals comparably high Judd-Ofelt coefficients. This indicates a substantial mixing of other electronic configuration into the 4f N configuration by the random crystal fields in the glasses. All coefficients are decreasing with increasing Bi 2O 3 content, this effect being most pronounced with Ω2. Luminescence decay times and radiative efficiencies show an expressed dependence on the glass composition. Radiative efficiencies of all luminescence bands increase with increasing Bi 2O 3 content—accompanied, however, by a slight narrowing of the bands. Except the common luminescence bands of erbium, upconversion luminescence at a wavelength of 0.54 μm could be detected.

  3. Optical Receiver Based On Luminescent Light Trapping

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Cole, Terry; Zewail, Ahmed H.

    1991-01-01

    Experiment demonstrates feasibility of optical-communication receiver based on luminescent light trapping. Light-gathering element plate of transparent material impregnated with laser dye. Light from distant laser transmitter falls on plate and absorbed by dye molecules, which become excited and reradiate. Reradiated light confined within plate by total internal reflection as it propagates toward edge of plate. Light arriving at edge escapes from plate and detected by small, high-speed, high-gain photomultiplier tubes or other photosensitive devices. Simple, inexpensive, and accepts light from almost any angle. Receiver of this configuration supports reception of data at rate of 13 MHz and higher.

  4. Circularly Polarized Luminescence from Simple Organic Molecules.

    PubMed

    Sánchez-Carnerero, Esther M; Agarrabeitia, Antonia R; Moreno, Florencio; Maroto, Beatriz L; Muller, Gilles; Ortiz, María J; de la Moya, Santiago

    2015-09-21

    This article aims to show the identity of "circularly polarized luminescent active simple organic molecules" as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented.

  5. Synchronous luminescence spectroscopy of human breast tissues

    NASA Astrophysics Data System (ADS)

    Majumdar, S. K.; Gupta, P. K.

    1998-06-01

    We report, to our knowledge, the first use of synchronous luminescence (SL) spectroscopy for autofluorescence diagnosis of cancer. The spectral narrowing effect of the SL spectroscopy led to an easier identification of the different fluorophores present in human breast tissues and provided relative estimate of their concentration in qualitative agreement with the estimates obtained from conventional excitation and emission spectroscopy. Further, the SL spectra from human breast tissues could discriminate cancerous tissues from benign tumors and normal tissues with a sensitivity and specificity of 100% in a study involving 34 patients with breast tumor (19 ductal carcinomas and 15 fibroadenomas).

  6. Research Update: Luminescence in lead halide perovskites

    NASA Astrophysics Data System (ADS)

    Srimath Kandada, Ajay Ram; Petrozza, Annamaria

    2016-09-01

    Efficiency and dynamics of radiative recombination of carriers are crucial figures of merit for optoelectronic materials. Following the recent success of lead halide perovskites in efficient photovoltaic and light emitting technologies, here we review some of the noted literature on the luminescence of this emerging class of materials. After outlining the theoretical formalism that is currently used to explain the carrier recombination dynamics, we review a few significant works which use photoluminescence as a tool to understand and optimize the operation of perovskite based optoelectronic devices.

  7. Development of novel edible luminescent nanoparticle sensors

    NASA Astrophysics Data System (ADS)

    Jalalian, Sanaz

    This project has developed a novel class of edible hydrocolloid food nanosensors which are doped with luminescent chromophores and investigated whether they can be used to provide information about the local food matrix - temperature, oxygen concentration, and the presence of food-borne pathogens. The luminescence properties of the probes such as phosphorescence and fluorescence provide the sensor sensitivity to the food properties. Hydrocolloid nanoparticles were made from gelatin and starch with diameters ranging from 50 to ˜200 nm and labeled with food grade luminescent probes. The chromophore was covalently and non-covalently attached to the nanoparticle and the photophysical properties of the probe in the food system were studied. Temperature sensors were developed by using the phosphorescence sensitivity of a chromophore to temperature. Experiments with two different probes, namely erythrosine B labeled gelatin nanoparticles and phloxine B labeled gelatin nanoparticles have demonstrated that both probes can be effectively used as temperature sensors in liquid and solid food. The Van't Hoff plots of ln(IDF/IP) versus 1/T vary monotonically over a relatively wide temperature range and thus provide a basis for estimating temperature from measurements of phosphorescence and delayed fluorescence. The tests indicated that the presence of some ingredients such as tannin and anthocyanins in the composition of the food may prohibit the use of gelatin nanoparticle probes due to precipitation of gelatin nanoparticles. The luminescence quenching of the probe by oxygen was used to develop a nanoparticle sensor for oxygen. The results of experiments on liquid and solid food samples indicate that erythrosine B labeled gelatin nanoparticles can be used as a probe to detect the presence or absence of oxygen in some liquid foods. Precise control of oxygen concentration in solutions will pose a challenge as has been observed in this study. The probe did not work as an

  8. Near-Field Enhanced Negative Luminescent Refrigeration

    NASA Astrophysics Data System (ADS)

    Chen, Kaifeng; Santhanam, Parthiban; Fan, Shanhui

    2016-08-01

    We consider a near-field enhanced negative luminescent refrigeration system made of a polar material supporting surface-phonon polariton resonances and a narrow-band-gap semiconductor under a reverse bias. We show that in the near-field regime, such a device yields significant cooling power density and a high efficiency close to the Carnot limit. In addition, the performance of our system still persists even in the presence of strong nonidealities such as Auger recombination and sub-band-gap thermal radiation from free carriers.

  9. High pressure luminescence probes in polymers

    SciTech Connect

    Drickamer, H.G.

    1980-01-01

    High pressure luminescence has proved to be a very powerful tool for characterizing crystalline solids and liquids. Two problems involving glassy polymers are analyzed. In the first problem the excited states of azulene and its derivatives are used to probe intermolecular interactions in PMMA and PS. In the second problem the change in emission intensity with pressure from two excimer states of polyvinylcarbazole as a pure polymer and in dilute solution in polystyrene (PS), polymethylmethacrylate (PMMA) and polyisoliutylene (PIB) is studied. The relative emission from the two states depends strongly on the possibility for motion of polymer segments. The observations are related to the proximity to the glass transition.

  10. Luminescent solar concentrators with fiber geometry.

    PubMed

    Edelenbosch, Oreane Y; Fisher, Martyn; Patrignani, Luca; van Sark, Wilfried G J H M; Chatten, Amanda J

    2013-05-01

    The potential of a fibre luminescent solar concentrator has been explored by means of both analytical and ray-tracing techniques. Coated fibres have been found to be more efficient than homogeneously doped fibres, at low absorption. For practical fibres concentration is predicted to be linear with fibre length. A 1 m long, radius 1 mm, fibre LSC doped with Lumogen Red 305 is predicted to concentrate the AM1.5 g spectrum up to 1100 nm at normal incidence by ~35 x. The collection efficiency under diffuse and direct irradiance in London has been analysed showing that, even under clear sky conditions, in winter the diffuse contribution equals the direct.

  11. Single layer multi-color luminescent display

    NASA Technical Reports Server (NTRS)

    Robertson, James B. (Inventor)

    1991-01-01

    The invention is a multi-color luminescent display comprising an insulator substrate and a single layer of host material which may be a phosphor deposited thereon that hosts one or more differential impurities, therein forming a pattern of selected and distinctly colored phosphors such as blue, green, and red phosphors in a single layer of host material. Transparent electrical conductor means may be provided for subjecting selected portions of the pattern of colored phosphors to an electric field thereby forming a multi-color, single layer electroluminescent display.

  12. Luminescence and color center distributions in K3YB6O12:Ce3+ phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Li; Wan, Yingpeng; Weng, Honggen; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

    2016-08-01

    Polycrystalline Ce3+-doped K3YB6O12 (1–14 mol%) phosphors were prepared by facile chemical sol–gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4f –5d transitions of Ce3+ ions. The absolute quantum efficiency (QE) of K3YB6O12:Ce3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole–dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host.

  13. Luminescence and color center distributions in K3YB6O12:Ce3+ phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Li; Wan, Yingpeng; Weng, Honggen; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

    2016-08-01

    Polycrystalline Ce3+-doped K3YB6O12 (1-14 mol%) phosphors were prepared by facile chemical sol-gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4f -5d transitions of Ce3+ ions. The absolute quantum efficiency (QE) of K3YB6O12:Ce3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole-dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host.

  14. Charged defects during alpha-irradiation of actinide oxides as revealed by Raman and luminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Mohun, R.; Desgranges, L.; Léchelle, J.; Simon, P.; Guimbretière, G.; Canizarès, A.; Duval, F.; Jegou, C.; Magnin, M.; Clavier, N.; Dacheux, N.; Valot, C.; Vauchy, R.

    2016-05-01

    We have recently evidenced an original Raman signature of alpha irradiation-induced defects in UO2. In this study, we aim to determine whether the same signature also exists in different actinide oxides, namely ThO2 and PuO2. Sintered UO2 and ThO2 were initially irradiated with 21 MeV He2+ ions using a cyclotron device and were subjected to an in situ luminescence experiment followed by Raman analysis. In addition, a PuO2 sample which had accumulated self-irradiation damage due to alpha particles was investigated only by Raman measurement. Results obtained for the initially white ThO2 showed that a blue color appeared in the irradiated areas as well as luminescence signals during irradiation. However, Raman spectroscopic analysis showed the absence of Raman signature in ThO2. In contrast, the irradiated UO2 and PuO2 confirmed the presence of the Raman signature but no luminescence peaks were observed. The proposed mechanism involves electronic defects in ThO2, while a coupling between electronic defects and phonons is required to explain the Raman spectra for UO2 and PuO2.

  15. Reverse lyotropic liquid crystals from europium nitrate and P123 with enhanced luminescence efficiency.

    PubMed

    Yi, Sijing; Li, Qintang; Liu, Hongguo; Chen, Xiao

    2014-10-01

    Fabrication of lyotropic aggregates containing the lanthanide ions is becoming a preferable way to prepare novel functional materials. Here, the lyotropic liquid crystals (LLCs) of reverse hexagonal, reverse bicontinuous cubic, and lamellar phases have been constructed in sequence directly from the mixtures of Eu(NO3)3·6H2O and Pluronic P123 amphiphilc block copolymer with increasing the salt proportion. Their phase types and structural characteristics were analyzed using polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements. The driving forces of reverse LLC phase formation were investigated using Fourier-transformed infrared spectroscopy (FTIR) and rheological measurements. The hydrated europium salt was found to act not only as a solvent here, but also as the bridge to form hydrogen bonding between coordinated water molecules and PEO blocks, which played a key role in the reverse LLCs formation. Compared to those in aqueous solutions and solid state, the enhanced luminescence quantum yields and prolonged excited state lifetimes were observed in two europium containing reverse mesophases. The luminescence quenching effect of lanthanide ions was efficiently suppressed, probably due to the substitution of coordinated water molecules by oxyethyl groups of P123 and ordered phase structures of LLCs, where the coordinated europium ions were confined and isolated by PEO blocks. The optimum luminescence performance was then found to exist in the reverse hexagonal phase. The obtained results on such lanthanide-induced reverse LLCs should be referable for designing new luminescent soft materials construction to expand their application fields.

  16. Luminescent DNA- and agar-based membranes.

    PubMed

    Leones, R; Fernandes, M; Ferreira, R A S; Cesarino, I; Lima, J F; Carlos, L D; Bermudez, V de Zea; Magon, C J; Donoso, J P; Silva, M M; Pawlicka, A

    2014-09-01

    Luminescent materials containing europium ions are investigated for different optical applications. They can be obtained using bio-macromolecules, which are promising alternatives to synthetic polymers based on the decreasing oil resources. This paper describes studies of the DNA- and Agar-europium triflate luminescent membranes and its potential technological applications are expanded to electroluminescent devices. Polarized optical microscopy demonstrated that the samples are birefringent with submicrometer anisotropy. The X-ray diffraction analysis revealed predominantly amorphous nature of the samples and the atomic force microscopy images showed a roughness of the membranes of 409.0 and 136.1 nm for the samples of DNA10Eu and Agar1.11Eu, respectively. The electron paramagnetic resonance spectra of the DNA(n)Eu membranes with the principal lines at g ≈ 2.0 and g ≈ 4.8 confirmed uniform distribution of rare earth ions in a disordered matrix. Moreover, these strong and narrow resonance lines for the samples of DNA(n)Eu when compared to the Agar(n)Eu suggested a presence of paramagnetic radicals arising from the DNA matrix. The emission spectra suggested that the Eu3+ ions occupy a single local environment in both matrices and the excitation spectra monitored around the Eu emission lines pointed out that the Eu3+ ions in the Agar host were mainly excited via the broad band component rather than by direct intra-4f(6) excitation, whereas the opposite case occurred for the DNA-based sample.

  17. Luminescent Quantum Dots as Ultrasensitive Biological Labels

    NASA Astrophysics Data System (ADS)

    Nie, Shuming

    2000-03-01

    Highly luminescent semiconductor quantum dots have been covalently coupled to biological molecules for use in ultrasensitive biological detection. This new class of luminescent labels is considerably brighter and more resistant againt photobleaching in comparison with organic dyes. Quantum dots labeled with the protein transferrin undergo receptor-mediated endocytosis (RME) in cultured HeLa cells, and those dots that were conjugated to immunomolecules recognize specific antibodies or antigens. In addition, we show that DNA functionalized quantum dots can be used to target specific genes by hybridization. We expect that quantum dot bioconjugates will have a broad range of biological applications, such as ligand-receptor interactions, real-time monitoring of molecular trafficking inside living cells, multicolor fluorescence in-situ hybridization (FISH), high-sensitivity detection in miniaturized devices (e.g., DNA chips), and fluorescent tagging of combinatorial chemical libraries. A potential clinical application is the use of quantum dots for ultrasensitive viral RNA detection, in which as low as 100 copies of hepatitis C and HIV viruses per ml blood should be detected.

  18. Quantitative Characterization of Cerenkov Luminescence Imaging

    NASA Astrophysics Data System (ADS)

    Gill, Ruby

    An optical imaging modality for small animal cancer studies using Cerenkov radiation is currently being developed in the Cherry lab at the University of California, Davis. Cerenkov radiation is a well-known phenomenon, in which optical photons are emitted when a charged particle moves faster than the speed of light in a medium. This emerging modality is referred to as Cerenkov Luminescence Imaging. The significance of this work is that it enables imaging on widely available small animal optical imaging systems of radionuclides being developed for therapeutic applications and positron emitting radiotracers developed for diagnostic purposes. A Monte Carlo based simulation was performed to predict the number of photons expected for a given radionuclide decay. The simulations calculated Cerenkov light intensity produced by radionuclides of interest for nuclear imaging and radionuclide therapy treatments. A quantitative understanding of Cerenkov light levels using parameters that are representative of situations encountered in vivo will help guide future applications and possible clinical implementation of Cerenkov luminescence imaging.

  19. Luminescent films for chemo- and biosensing.

    PubMed

    Guan, Weijiang; Zhou, Wenjuan; Lu, Jun; Lu, Chao

    2015-10-01

    Luminescent films have received great interest for chemo-/bio-sensing applications due to their distinct advantages over solution-based probes, such as good stability and portability, tunable shape and size, non-invasion, real-time detection, extensive suitability in gas/vapor sensing, and recycling. On the other hand, they can achieve selective and sensitive detection of chemical/biological species using special luminophores with a recognition moiety or the assembly of common luminophores and functional materials. Nowadays, the extensively used assembly techniques include drop-casting/spin-coating, Langmuir-Blodgett (LB), self-assembled monolayers (SAMs), layer-by-layer (LBL), and electrospinning. Therefore, this review summarizes the recent advances in luminescent films with these assembly techniques and their applications in chemo-/bio-sensing. We mainly focused on the discussion of the relationship between the sensing properties of the films and their architecture. Furthermore, we discussed some critical challenges existing in this field and possible solutions that have been or are being developed to overcome these challenges.

  20. Application of in vivo micro-computed tomography in the temporal characterisation of subchondral bone architecture in a rat model of low-dose monosodium iodoacetate-induced osteoarthritis

    PubMed Central

    2011-01-01

    Introduction Osteoarthritis (OA) is a complex, multifactorial joint disease affecting both the cartilage and the subchondral bone. Animal models of OA aid in the understanding of the pathogenesis of OA and testing suitable drugs for OA treatment. In this study we characterized the temporal changes in the tibial subchondral bone architecture in a rat model of low-dose monosodium iodoacetate (MIA)-induced OA using in vivo micro-computed tomography (CT). Methods Male Wistar rats received a single intra-articular injection of low-dose MIA (0.2 mg) in the right knee joint and sterile saline in the left knee joint. The animals were scanned in vivo by micro-CT at two, six, and ten weeks post-injection, analogous to early, intermediate, and advanced stages of OA, to assess architectural changes in the tibial subchondral bone. The articular cartilage changes in the tibiae were assessed macroscopically and histologically at ten weeks post-injection. Results Interestingly, tibiae of the MIA-injected knees showed significant bone loss at two weeks, followed by increased trabecular thickness and separation at six and ten weeks. The trabecular number was decreased at all time points compared to control tibiae. The tibial subchondral plate thickness of the MIA-injected knee was increased at two and six weeks and the plate porosity was increased at all time points compared to control. At ten weeks, histology revealed loss of proteoglycans, chondrocyte necrosis, chondrocyte clusters, cartilage fibrillation, and delamination in the MIA-injected tibiae, whereas the control tibiae showed no changes. Micro-CT images and histology showed the presence of subchondral bone sclerosis, cysts, and osteophytes. Conclusions These findings demonstrate that the low-dose MIA rat model closely mimics the pathological features of progressive human OA. The low-dose MIA rat model is therefore suitable to study the effect of therapeutic drugs on cartilage and bone in a non-trauma model of OA. In vivo

  1. Luminescent chiral lanthanide(III) complexes as potential molecular probes

    PubMed Central

    Muller, Gilles

    2009-01-01

    This perspective gives an introduction into the design of luminescent lanthanide(III)-containing complexes possessing chiral properties and used to probe biological materials. The first part briefly describes general principles, focusing on the optical aspect (i.e. lanthanide luminescence, sensitization processes) of the most emissive trivalent lanthanide ions, europium and terbium, incorporated into molecular luminescent edifices. This is followed by a short discussion on the importance of chirality in the biological and pharmaceutical fields. The second part is devoted to the assessment of the chiroptical spectroscopic tools available (typically circular dichroism and circularly polarized luminescence) and the strategies used to introduce a chiral feature into luminescent lanthanide(III) complexes (chiral structure resulting from a chiral arrangement of the ligand molecules surrounding the luminescent center or presence of chiral centers in the ligand molecules). Finally, the last part illustrates these fundamental principles with recent selected examples of such chiral luminescent lanthanide-based compounds used as potential probes of biomolecular substrates. PMID:19885510

  2. Luminescence imaging of water during alpha particle irradiation

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Komori, Masataka; Koyama, Shuji; Toshito, Toshiyuki

    2016-05-01

    The luminescence imaging of water using the alpha particle irradiation of several MeV energy range is thought to be impossible because this alpha particle energy is far below the Cerenkov-light threshold and the secondary electrons produced in this energy range do not emit Cerenkov-light. Contrary to this consensus, we found that the luminescence imaging of water was possible with 5.5 MeV alpha particle irradiation. We placed a 2 MBq of 241Am alpha source in water, and luminescence images of the source were conducted with a high-sensitivity, cooled charge-coupled device (CCD) camera. We also carried out such imaging of the alpha source in three different conditions to compare the photon productions with that of water, in air, with a plastic scintillator, and an acrylic plate. The luminescence imaging of water was observed from 10 to 20 s acquisition, and the intensity was linearly increased with time. The intensity of the luminescence with the alpha irradiation of water was 0.05% of that with the plastic scintillator, 4% with air, and 15% with the acrylic plate. The resolution of the luminescence image of water was better than 0.25 mm FWHM. Alpha particles of 5.5 MeV energy emit luminescence in water. Although the intensity of the luminescence was smaller than that in air, it was clearly observable. The luminescence of water with alpha particles would be a new method for alpha particle detection and distribution measurements in water.

  3. An Artificial Experimenter for Enzymatic Response Characterisation

    NASA Astrophysics Data System (ADS)

    Lovell, Chris; Jones, Gareth; Gunn, Steve R.; Zauner, Klaus-Peter

    Identifying the characteristics of biological systems through physical experimentation, is restricted by the resources available, which are limited in comparison to the size of the parameter spaces being investigated. New tools are required to assist scientists in the effective characterisation of such behaviours. By combining artificial intelligence techniques for active experiment selection, with a microfluidic experimentation platform that reduces the volumes of reactants required per experiment, a fully autonomous experimentation machine is in development to assist biological response characterisation. Part of this machine, an artificial experimenter, has been designed that automatically proposes hypotheses, then determines experiments to test those hypotheses and explore the parameter space. Using a multiple hypotheses approach that allows for representative models of response behaviours to be produced with few observations, the artificial experimenter has been employed in a laboratory setting, where it selected experiments for a human scientist to perform, to investigate the optical absorbance properties of NADH.

  4. Characterisation of neutron fields at Cernavoda NPP.

    PubMed

    Cauwels, Vanessa; Vanhavere, Filip; Dumitrescu, Dorin; Chirosca, Alecsandru; Hager, Luke; Million, Marc; Bartz, James

    2013-04-01

    Near a nuclear reactor or a fuel container, mixed neutron/gamma fields are very common, necessitating routine neutron dosimetry. Accurate neutron dosimetry is complicated by the fact that the neutron effective dose is strongly dependent on the neutron energy and the direction distribution of the neutron fluence. Neutron field characterisation is indispensable if one wants to obtain a reliable estimate for the neutron dose. A measurement campaign at CANDU nuclear power plant located in Cernavoda, Romania, was set up to characterise the neutron fields in four different locations and to investigate the behaviour of different neutron personal dosemeters. This investigation intends to assist in choosing a suitable neutron dosimetry system at this nuclear power plant.

  5. Preparation and Characterisation of Nevirapine Oral Nanosuspensions

    PubMed Central

    Raju, Anju; Reddy, A. Jagdeesh; Satheesh, J.; Jithan, A. V.

    2014-01-01

    The objective of this study was to prepare and characterise nevirapine nanosuspensions so as to improve the dissolution rate of nevirapine. Nevirapine is a nonnucleoside reverse transcriptase inhibitor of immunodeficiency virus type-1 and it is poorly water-soluble antiretroviral drug. The low solubility of nevirapine can lead to decreased and variable oral bioavailability. Nanosuspension can overcome the oral bioavailability problem of nevirapine. Nevirapine nanosuspensions were prepared using nanoedge method. The suspensions were stabilised using surfactants Lutrol F 127 or Poloxamer 407 and hydroxypropyl methyl cellulose. The nanosuspension was characterised for particle size, polydispersibility index, crystalline state, particle morphology, in vitro drug release and pharmacokinetics in rats after oral administration. The results support the claim for the preparation of nanosuspensions with enhanced solubility and bioavailability. PMID:24799740

  6. Surface pressure measurement by oxygen quenching of luminescence

    NASA Technical Reports Server (NTRS)

    Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

    1994-01-01

    Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

  7. Surface pressure measurement by oxygen quenching of luminescence

    NASA Technical Reports Server (NTRS)

    Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

    1993-01-01

    Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

  8. Control of luminescence from lantern shark (Etmopterus spinax) photophores.

    PubMed

    Claes, Julien M; Mallefet, Jérôme

    2011-05-01

    The velvet belly lantern shark (Etmopterus spinax) is a common deep-sea shark that has been used, in the recent years, as a model for experimental studies on physiological control of shark luminescence. These studies demonstrated that, unlike any other luminous organism, the luminescence of this shark was under a dual control of hormones and neurotransmitters (or neuromodulators). This paper, by making a short review of histological and pharmacological results from these studies, aims to propose a first model of luminescence control in E. spinax.

  9. Luminescent Solar Concentrators--a review of recent results.

    PubMed

    van Sark, Wilfried G J H M; Barnham, Keith W J; Slooff, Lenneke H; Chatten, Amanda J; Büchtemann, Andreas; Meyer, Andreas; McCormack, Sarah J; Koole, Rolf; Farrell, Daniel J; Bose, Rahul; Bende, Evert E; Burgers, Antonius R; Budel, Tristram; Quilitz, Jana; Kennedy, Manus; Meyer, Toby; Donegá, C De Mello; Meijerink, Andries; Vanmaekelbergh, Daniel

    2008-12-22

    Luminescent solar concentrators (LSCs) generally consist of transparent polymer sheets doped with luminescent species. Incident sunlight is absorbed by the luminescent species and emitted with high quantum efficiency, such that emitted light is trapped in the sheet and travels to the edges where it can be collected by solar cells. LSCs offer potentially lower cost per Wp. This paper reviews results mainly obtained within the framework of the Full-spectrum project. Two modeling approaches are presented, i.e., a thermodynamic and a ray-trace one, as well as experimental results, with a focus on LSC stability.

  10. PEG functionalized luminescent lipid particles for cellular imaging

    NASA Astrophysics Data System (ADS)

    Rana, Suman; Barick, K. C.; Shetake, Neena G.; Verma, Gunjan; Aswal, V. K.; Panicker, Lata; Pandey, B. N.; Hassan, P. A.

    2016-08-01

    We report here the synthesis, characterization and cellular uptake of luminescent micelle-like particles with phospholipid core and non-ionic PEG based surfactant polysorbate 80 shell. The adsorption of polysorbate 80 at the interface of lipid containing microemulsion droplets and its solidification upon removal of solvent leads to anchoring of PEG chain to the lipid particles. Hydrophobic partitioning of luminescent molecules, sodium 3-hydroxynaphthalene-2-carboxylic acid to the phospholipid core offers additional functionality to these particles. Thus, the cooperative assembly of lipid, non-ionic amphiphile and organic luminescent probe leads to the formation of multifunctional biocompatible particles which are useful for simultaneous imaging and therapy.

  11. Quantification of the luminescence intensity of natural materials

    NASA Technical Reports Server (NTRS)

    Watson, R. D.; Hessin, T. D.; Hemphill, W. R.

    1973-01-01

    Review of some of the results of an evaluation of the use of an airborne Fraunhofer line discriminator (FLD) for the detection of sun-stimulated luminescence emitted by rhodamine WT dye and some other materials. Rhodamine dye is reported to have been detected by airborne FDL in sea water in concentrations of less than 2 ppb. Experiments with a fluorescence spectrometer in the laboratory indicate that luminescence of some samples of crude and refined petroleum exceeds the luminescence intensity of rhodamine dye in concentrations of 10 ppm.

  12. Luminescence dating of the Wabar meteorite craters, Saudi Arabia

    USGS Publications Warehouse

    Prescott, J.R.; Robertson, G.B.; Shoemaker, C.; Shoemaker, E.M.; Wynn, J.

    2004-01-01

    Luminescence dating has been used to find the age of meteorite impact craters at Wabar (Al Hadida) in Saudi Arabia. The luminescence characteristics of the shocked material were determined. Using a variety of luminescence dating techniques applied to impactite formed by the meteorite, and to the underlying sand, the age is found to be 290 ± 38 years. A comparison is made with two possible historically recorded ages. An impact as young as this has implications for the assessment of hazards from the impact on Earth of small meteorites.

  13. Characterisation of plasma synthetic jet actuators in quiescent flow

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2016-08-01

    An experimental characterisation study of a large-volume three-electrode plasma synthetic jet actuator (PSJA) is presented. A sequential discharge power supply system is used to activate the PSJA. Phase-locked planar particle image velocimetry (PIV) and time-resolved Schlieren imaging are used to characterise the evolution of the induced flow field in quiescent flow conditions. The effect of orifice diameter is investigated. Results indicate three distinct features of the actuator-induced flow field. These are the initial shock waves, the high speed jet and vortex rings. Two types of shock waves with varied intensities, namely a strong shock wave and a weak shock wave, are issued from the orifice shortly after the ignition of the discharge. Subsequently, the emission of a high speed jet is observed, reaching velocities up to 130 m s‑1. Pronounced oscillation of the exit velocity is caused by the periodical behaviour of capacitive discharge, which also led to the formation of vortex ring trains. Orifice diameter has no influence on the jet acceleration stage and the peak exit velocity. However, a large orifice diameter results in a rapid decline of the exit velocity and thus a short jet duration time. Vortex ring propagation velocities are measured at peak values ranging from 55 m s‑1–70 m s‑1. In the case of 3 mm orifice diameter, trajectory of the vortex ring severely deviates from the actuator axis of symmetry. The development of this asymmetry in the flow field is attributed to asymmetry in the electrode configuration.

  14. Characterisation of plasma synthetic jet actuators in quiescent flow

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2016-08-01

    An experimental characterisation study of a large-volume three-electrode plasma synthetic jet actuator (PSJA) is presented. A sequential discharge power supply system is used to activate the PSJA. Phase-locked planar particle image velocimetry (PIV) and time-resolved Schlieren imaging are used to characterise the evolution of the induced flow field in quiescent flow conditions. The effect of orifice diameter is investigated. Results indicate three distinct features of the actuator-induced flow field. These are the initial shock waves, the high speed jet and vortex rings. Two types of shock waves with varied intensities, namely a strong shock wave and a weak shock wave, are issued from the orifice shortly after the ignition of the discharge. Subsequently, the emission of a high speed jet is observed, reaching velocities up to 130 m s-1. Pronounced oscillation of the exit velocity is caused by the periodical behaviour of capacitive discharge, which also led to the formation of vortex ring trains. Orifice diameter has no influence on the jet acceleration stage and the peak exit velocity. However, a large orifice diameter results in a rapid decline of the exit velocity and thus a short jet duration time. Vortex ring propagation velocities are measured at peak values ranging from 55 m s-1-70 m s-1. In the case of 3 mm orifice diameter, trajectory of the vortex ring severely deviates from the actuator axis of symmetry. The development of this asymmetry in the flow field is attributed to asymmetry in the electrode configuration.

  15. Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: A new luminescent uranyl benzoate specie

    NASA Astrophysics Data System (ADS)

    Kumar, Satendra; Maji, S.; Joseph, M.; Sankaran, K.

    2015-03-01

    Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3]- which is highly luminescent. In particular, three sharp bands at 431, 443, 461 nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68 μs which is much more compared to the lifetime of uncomplexed uranyl (20 μs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3]- specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed.

  16. Characterization of Fundamental Luminescence Properties of the Mars Soil Simulant JSC Mars-1 and Their Relevance to Absolute Dating of Martian Eolian Sediments

    NASA Astrophysics Data System (ADS)

    Lepper, Kenneth; McKeever, Stephen W. S.

    2000-04-01

    This report explores the potential for luminescence dating techniques to provide absolute age determinations of eolian sediments on the surface of Mars, including those incorporated in the martian polar ice caps. Fundamental thermally and optically stimulated luminescence properties of bulk samples of JSC Mars-1 soil simulant are reported and their relevance to the development of dating procedures is discussed. The radiation-induced luminescence signals (both thermoluminescence, TL, and optically stimulated luminescence, OSL) from JSC Mars-1 are found to have a wide dynamic dose-response range, with the luminescence increasing linearly to the highest doses used (936 Gy), following irradiation with 90Sr/ 90Y beta particles. The signals are also susceptible to solar resetting, with the OSL signals decreasing to <10% of their original levels within the first 20 min of exposure to sunlight. The TL signal also decays rapidly, being reduced to ˜15% within the first 20 min, but reaches a stable, nonzero level at long bleaching times. Neither the TL nor the OSL signals exhibit fading (i.e., loss of signal after irradiation before TL or OSL readout), nor do they exhibit significant sensitivity changes upon repeated irradiation and readout. These three properties (wide dynamic range, solar bleaching, and signal stability) form a stable base for future investigation of the material for luminescence dating and form a preliminary step toward development of dating protocols for terrestrial analogs of Mars surface materials. We conclude that luminescence dating, properly developed, holds the potential to be a valuable tool for absolute dating of martian eolian sediments

  17. Non-wettable, oxidation-stable, brightly luminescent, perfluorodecyl-capped silicon nanocrystal film.

    PubMed

    Qian, Chenxi; Sun, Wei; Wang, Liwei; Chen, Changlong; Liao, Kristine; Wang, Wendong; Jia, Jia; Hatton, Benjamin D; Casillas, Gilberto; Kurylowicz, Marty; Yip, Christopher M; Mastronardi, Melanie L; Ozin, Geoffrey A

    2014-11-12

    Here we describe for the first time the synthesis of colloidally stable, brightly luminescent perfluorodecyl-capped silicon nanocrystals and compare the properties of solutions and films made from them with those of their perhydrodecyl-capped relatives. The perfluorodecyl capping group compared to the perhydrodecyl capping group yields superior hydrophobicity and much greater resistance to air oxidation, the enhanced electron-withdrawing character induces blue shifts in the wavelength of photoluminescence, and the lower-frequency carbon-fluorine stretching modes disfavor non-radiative relaxation pathways and boost the absolute photoluminescence quantum yield. Together these attributes bode well for advanced materials and biomedical applications founded upon perfluorodecyl-protected silicon nanocrystals.

  18. Carrier decay and luminescence characteristics in hadron irradiated MOCVD GaN

    NASA Astrophysics Data System (ADS)

    Gaubas, E.; Ceponis, T.; Pavlov, J.; Jasiunas, A.; Jonkus, V.; Meskauskaite, D.; Tekorius, A.

    2014-12-01

    Crystalline GaN is a promising material for producing of the radiation hard particle detectors of different types capable to operate in harsh areas of particle accelerators. Moreover, GaN crystals show rather efficient luminescence properties in several spectral bands under excitation by high energy radiation. Thereby, GaN material can be employed for fabrication of a combined device which is able to operate both as scintillating and charge collecting detector. However, the efficiency of such detectors and their functionality has insufficiently been investigated. This work is addressed to study the evolution of the efficiency of photon and hadron induced luminescence. To evaluate the density of excess carriers induced by the high energy protons, a correlation between the microwave probed photoconductivity transients and the proton induced luminescence intensity has been examined using 1.6 MeV protons to produce a nearly homogeneous and rather strong excitation in 2.6 μm thick MOCVD grown GaN epi-layers. To estimate the radiation hardness of such material, the evolution of the photoconductivity transients and of the proton induced photoluminescence characteristics has been studied by in situ measurements of the changes of luminescence intensity and photoconductivity decay rate during the exposure to a proton beam reaching fluences up to 1015 cm-2. The production rate of radiation defects, determined from in situ and post-irradiation examination of the changes of radiative and non-radiative recombination have been examined by combining penetrative hadron (nuclear reactor neutrons and 24 GeV/c protons) irradiations with those of the 1.6 MeV protons. The parameters of the efficiency κP of carrier pair generation by a single proton of κP = nP/NP cong 1.3 × 107 cm-3 per proton and κPApr = 40 carrier pairs per a micrometer of layer depth per proton have been estimated. The production rate of radiation defects is estimated to be KP cong 0.6 cm-1 for both penetrative

  19. Optical absorption and luminescence studies of fast neutron-irradiated complex oxides for jewellery applications

    NASA Astrophysics Data System (ADS)

    Mironova-Ulmane, N.; Skvortsova, V.; Popov, A. I.

    2016-07-01

    We studied the optical absorption and luminescence of agate (SiO2), topaz (Al2[SiO4](F,OH)2), beryl (Be3Al2Si6O18), and prehnite (Ca2Al(AlSi3O10)(OH)2) doped with different concentrations of transition metal ions and exposed to fast neutron irradiation. The exchange interaction between the impurity ions and the defects arising under neutron irradiation causes additional absorption as well as bands' broadening in the crystals. These experimental results allow us to suggest the method for obtaining new radiation-defect induced jewellery colors of minerals due to neutron irradiation.

  20. Ti:Sapphire micro-structures by femtosecond laser inscription: Guiding and luminescence properties

    NASA Astrophysics Data System (ADS)

    Ren, Yingying; Jiao, Yang; Vázquez de Aldana, Javier R.; Chen, Feng

    2016-08-01

    We report on the fabrication of buried cladding waveguides with different diameters in a Ti:Sapphire crystal by femtosecond laser inscription. The propagation properties are studied, showing that the cladding waveguides could support near- to mid-infrared waveguiding at both TE and TM polarizations. Confocal micro-photoluminescence experiments reveal that the original fluorescence properties in the waveguide region are very well preserved, while it suffers from a strong quenching at the centers of laser induced filaments. Broadband waveguide fluorescence emissions with high efficiency are realized, indicating the application of the cladding waveguides in Ti:Sapphire as compact broadband luminescence sources in biomedical fields.

  1. Effect of low energy ion irradiation on CdTe crystals: Luminescence enhancement

    SciTech Connect

    Olvera, J.; Plaza, J. L.; Dios, S. de; Dieguez, E.; Martinez, O.; Avella, M.

    2010-12-15

    In this work we show that low energy ion sputtering is a very efficient technique as a cleaning process for CdTe substrates. We demonstrate, by using several techniques like grazing-angle x-ray diffraction, cathodoluminescence, microluminescence, and micro-Raman spectroscopy that the luminescent properties of CdTe substrates can be very much increased when CdTe surfaces are irradiated with low energy Argon ions. We postulate that this enhancement is mainly due to the removal of surface damage induced by the cutting and polishing processes. The formation of a low density of nonluminescent aggregates after the sputtering process has also been observed.

  2. Characterisation of fan-beam collimators.

    PubMed

    Pareto, D; Pavía, J; Falcón, C; Juvells, I; Cot, A; Ros, D

    2001-02-01

    Fan-beam collimators offer a good balance between resolution and noise. The collimator response may be included in iterative reconstruction algorithms in order to improve single-photon emission tomography (SPET) resolution. To this end, accurate determination of the focal region and characterisation of the collimator response as a function of the source co-ordinates must be performed. In this paper, a method to characterise fanbeam collimators is evaluated. First, we calculated the real focal region and the accuracy of the collimator convergence. Then, we confirmed the hypothesis that Gaussian distributions adequately fit the collimator responses, although no individualised treatment was performed for the tails of detector response which are associated with scattering and septal penetration. Finally, analytical functions were used to model the resolution and sensitivity. The parameter values in these functions were obtained from experimental measures by non-linear regression fitting. Our findings show differences of 1.43% between nominal and real focal length and standard deviations of 2.5 mm in the x-direction and 7.1 mm in the y-direction for the focal convergence. The correlation coefficients between experimental and predicted values were 0.994 for resolution and 0.991 for sensitivity. As a consequence, the proposed method can be used to characterise the collimator response.

  3. Container Verification Using Optically Stimulated Luminescence

    SciTech Connect

    Tanner, Jennifer E.; Miller, Steven D.; Conrady, Matthew M.; Simmons, Kevin L.; Tinker, Michael R.

    2008-10-01

    Containment verification is a high priority for safeguards containment and surveillance. Nuclear material containers, safeguards equipment cabinets, camera housings, and detector cable conduit are all vulnerable to tampering. Even with a high security seal on a lid or door, custom-built hinges and interfaces, and special colors and types of finishes, the surfaces of enclosures can be tampered with and any penetrations repaired and covered over. With today’s technology, these repairs would not be detected during a simple visual inspection. Several suggested solutions have been to develop complicated networks of wires, fiber-optic cables, lasers or other sensors that line the inside of a container and alarm when the network is disturbed. This results in an active system with real time evidence of tampering but is probably not practical for most safeguards applications. A more practical solution would be to use a passive approach where an additional security feature was added to surfaces which would consist of a special coating or paint applied to the container or enclosure. One type of coating would incorporate optically stimulated luminescent (OSL) material. OSL materials are phosphors that luminesce in proportion to the ionizing radiation dose when stimulated with the appropriate optical wavelengths. The OSL fluoresces at a very specific wavelength when illuminated at another, very specific wavelength. The presence of the pre-irradiated OSL material in the coating is confirmed using a device that interrogates the surface of the enclosure using the appropriate optical wavelength and then reads the resulting luminescence. The presence of the OSL indicates that the integrity of the surface is intact. The coating itself could be transparent which would allow the appearance of the container to remain unchanged or the OSL material could be incorporated into certain paints or epoxies used on various types of containers. The coating could be applied during manufacturing

  4. Super-luminescent jet light generated by femtosecond laser pulses

    PubMed Central

    Xu, Zhijun; Zhu, Xiaonong; Yu, Yang; Zhang, Nan; Zhao, Jiefeng

    2014-01-01

    Phenomena of nonlinear light-matter interaction that occur during the propagation of intense ultrashort laser pulses in continuous media have been extensively studied in ultrafast optical science. In this vibrant research field, conversion of the input laser beam into optical filament(s) is commonly encountered. Here, we demonstrate generation of distinctive single or double super-luminescent optical jet beams as a result of strong spatial-temporal nonlinear interaction between focused 50 fs millijoule laser pulses and their induced micro air plasma. Such jet-like optical beams, being slightly divergent and coexisting with severely distorted conical emission of colored speckles, are largely different from optical filaments, and obtainable when the focal lens of proper f-number is slightly tilted or shifted. Once being collimated, the jet beams can propagate over a long distance in air. These beams not only reveal a potentially useful approach to coherent optical wave generation, but also may find applications in remote sensing. PMID:24463611

  5. Excitonic luminescence upconversion in a two-dimensional semiconductor

    NASA Astrophysics Data System (ADS)

    Jones, Aaron M.; Yu, Hongyi; Schaibley, John R.; Yan, Jiaqiang; Mandrus, David G.; Taniguchi, Takashi; Watanabe, Kenji; Dery, Hanan; Yao, Wang; Xu, Xiaodong

    2016-04-01

    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. This phenomenon lies at the heart of optical refrigeration in solids, where upconversion relies on anti-Stokes processes enabled either by rare-earth impurities or exciton-phonon coupling. Here, 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. Since the charged exciton binding energy closely matches the 31 meV A1' optical phonon, 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. In addition, 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.

  6. On the luminescence properties of CaSO4:Ce.

    PubMed

    Lapraz, D; Prevost, H; Iacconi, P; Guigues, C; Benabdesselam, M; Briand, D

    2002-01-01

    The luminescent properties of cerium doped calcium sulphate are studied: fluorescence and excitation spectra, optical absorption and thermoluminescence (TSL). It is known that, in rare earth doped CaSO4, only cerium induces a strong 400 degrees C TSL peak. In CaSO4:0.2%Ce samples synthesised under oxidising conditions, the recovery step of Ce3+ fluorescence is correlated with the 400 degrees C TSL peak readout, as mentioned by Nair er al. Our results indicate that an oxidation of Ce3+ ion does occur under X-irradiation (Ce3+ --> Ce4+), followed by a complete return to the trivalent state after thermal annealing at about 500 degrees C; our results confirm the hypothesis of Nair et al that Ce3+ ions are oxidised by ionising irradiation. So, a pure redox reaction seems the most probable for the 400 degrees C TSL peak of CaSO4:Ce. Moreover, the use of the 400 degrees C TSL peak for high temperature dosimetry applications is discussed.

  7. The delayed luminescence spectroscopy as tool to investigate the cytotoxic effect on human cancer cells of drug-loaded nanostructured lipid carrier

    NASA Astrophysics Data System (ADS)

    Grasso, R.; Gulino, M.; Scordino, A.; Musumeci, F.; Campisi, A.; Bonfanti, R.; Carbone, C.; Puglisi, G.

    2016-05-01

    The first results concerning the possibility to use Delayed Luminescence spectroscopy to evaluate the in vitro induction of cytotoxic effects on human glioblastoma cells of nanostructured lipid carrier and drug-loaded nanostructured lipid carrier are showed in this contribution. We tested the effects of nanostructured lipid carrier, ferulic acid and ferulic acidloaded nanostructured lipid carrier on U-87MG cell line. The study seems to confirm the ability of Delayed Luminescence to be sensible indicator of alterations induced on functionality of the mitochondrial respiratory chain complex I in U-87MG cancer cells when treated with nanostructured lipid carriers.

  8. Luminescence, absorption and morphology studies of laser-damage sites in silica glasses and coatings

    NASA Astrophysics Data System (ADS)

    Gallais, Laurent; Capoulade, Jeremie; Wagner, Frank; Krol, Helene; Natoli, Jean-Yves; Commandre, Mireille; Kurbanov, Saidislam

    2005-12-01

    The analysis of modifications induced by laser damage in optical materials is important for understanding the damage process. In this work, we study the morphological and structural modifications induced by a nano-second pulsed laser (355 and 1064nm) on fused silica samples (Suprasil, Herasil) and silica thin films (deposited by IP, IAD, EBD, IAD). The morphological changes are analyzed using optical microscopy, optical 3D surface profiler. The absorption modifications are measured by photothermal microscopy with a micronic resolution. Luminescence (excited at 244nm) mappings are also performed on damage sites and the luminescence spectra analyzed. Based on these measurements, we study the different laser damage step that we have identified: initiation by absorbing nanoscale defects, heating of the defect and the surrounding matrix, modification of the surrounding material that becomes absorbing, and macroscopic damage at final. We identify and spatially resolve several kinds of defects induced by catastrophic breakdown and we also discuss the observed structural changes on damage sites, taking into account the physical processes involved.

  9. Luminescent solar concentrator improvement by stimulated emission

    NASA Astrophysics Data System (ADS)

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W.; Schmidt, Timothy W.; Argyros, Alexander

    2015-12-01

    Luminescent solar concentrators (LSCs) offer the prospect of reducing the cost of solar energy, and are a promising candidate for building integrated photovoltaic (PV) structures. However, the realization of commercially viable efficiency of LSCs is currently hindered by reabsorption losses. In this work, a method is introduced for reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire length of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption, and directed by the seed laser towards a small target PV cell. A mathematical model of such a system is presented which identifies different physical parameters responsible for the power conversion efficiency and gives the net effective output power.

  10. Thermal luminescence spectroscopy chemical imaging sensor.

    PubMed

    Carrieri, Arthur H; Buican, Tudor N; Roese, Erik S; Sutter, James; Samuels, Alan C

    2012-10-01

    The authors present a pseudo-active chemical imaging sensor model embodying irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. We elaborate on various optimizations, simulations, and animations of the integrated sensor design and apply it to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor must measure and process a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully. PMID:23033092

  11. Photostimulated luminescence properties of neutron image plates

    NASA Astrophysics Data System (ADS)

    Popov, A. I.; Zimmermann, J.; McIntyre, G. J.; Wilkinson, C.

    2016-09-01

    The luminescence properties of two commercial neutron-sensitive image-plates based on Gd2O3-doped BaFBr:Eu2+ storage phosphors are examined. These are white Fuji plates and blue Fuji plates (BAS-ND) with Gd2O3 content by weight of 34% and 50%, respectively. Both plates show two maxima in the photostimulation spectrum near 500 nm and 600 nm, with the ratio of the peak responses (I600 nm/I500 nm) 1.39 and 0.53 for the white and blue plates respectively. The optimum wavelengths for photostimulation for the two phosphors are therefore different. The response of the blue plate is only 25% that of the white plate, if each is stimulated at its optimum wavelength.

  12. Irradiated Shellfish: Identification by Photostimulated Luminescence

    PubMed Central

    Di Schiavi, Maria Teresa; Falconi, Grazia; Verità, Francesca Della; Cavallina, Roberta

    2014-01-01

    The irradiation of food is a technology used in the industry to prevent the deterioration of foodstuff in some countries. The European Community legislation states that each Member State must carry out annual checks on the products during commercialisation. The Istituto Zooprofilattico Sperimentale delle regioni Lazio e Toscana (Rome, Italy) has developed and validated the screening method of photostimulated luminescence UNI EN 13751:2009 to identify irradiated shellfish. A total of 30 tests of shellfish samples, consisting of 22 certified as irradiated and 8 not-irradiated samples, were performed. The validation procedure was based on sensitivity and specificity; the compatibility between the screening method and the reference standard EN 13751:2009 was evaluated. Data were processed: 100% sensitivity and 100% specificity were obtained. Results obtained in our laboratory were perfectly compatible with the reference standard. For this reason, the method has been validated and proved to be suitable for its intended use. PMID:27800335

  13. Luminescent solar concentrators utilizing stimulated emission.

    PubMed

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

    2016-03-21

    Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power. PMID:27136870

  14. Luminescent solar concentrators utilizing stimulated emission.

    PubMed

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

    2016-03-21

    Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power.

  15. EXAFS characterisation of metal bonding in highly luminescent, UV stable, water-soluble and biocompatible lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Kalyakina, A.; Utochnikova, V.; Trigub, A.; Zubavichus, Y.; Kuzmina, N.; Bräse, S.

    2016-05-01

    The combination of X-ray diffraction with EXAFS was employed to assess the coordination environment of lanthanide complexes in solutions. This method is based on the assumption that the local structure of lanthanide complexes in solution combines elements of the crystal structure of the complex in the solid state (single- or polycrystalline) and the elements of the local structure of a lanthanide salt, completely dissociated in the solvent (usually chlorides). The success of this approach is demonstrated with the lanthanide (III) 2,3,4,5,6-pentafluorobenzoate complexes, where the local structure in aqueous and methanol solutions were estimated. Moreover, the dissociation degree of the complexes in aqueous and methanol solutions was evaluated.

  16. Luminescence in crosslinked polyethylene at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Bamji, S. S.; Bulinski, A. T.; Suzuki, H.; Matsuki, M.; Iwata, Z.

    1993-10-01

    Electrical treeing is often responsible for the breakdown of insulating materials used in power apparatus such as high-voltage transformers, cables, and capacitors. Insulation, such as crosslinked polyethylene (XLPE), used in underground high-voltage cables usually operates at temperatures above ambient. This paper describes the characteristics of luminescence, emitted prior to electrical tree inception, at a crosslinked polyethylene-semiconducting material (XLPE-semicon) interface held above room temperature. Use of a sensitive light detection system showed that XLPE subjected to elevated temperatures emits luminescence even without voltage application. This light was attributed to thermoluminescence which decreased with the decrease in the concentration of the crosslinking by-products present in the polymer. The spectra of thermoluminescence were only in the visible range. On the other hand, electroluminescence occurred when the XLPE-semicon interface was held above room temperature and subjected to high electric stress. This light did not depend on the concentration of the crosslinking by-products and the spectra of electroluminescence were in the visible and the ultraviolet ranges. It is proposed that XLPE-semicon interface held at elevated temperature and subjected to long-term voltage application initially emits both thermoluminescence and electroluminescence. As the crosslinking by-products exude out of the polymer, thermoluminescence decreases with time and ultimately ceases, but electroluminescence occurs as long as the voltage is applied to the polymer. Although the intensity of electroluminescence emitted at high temperature was lower than that emitted at ambient, sufficient ultraviolet radiation was emitted. The ultraviolet radiation could photodegrade the polymer and lead to electrical tree inception.

  17. Topaz and Kyanite Luminescence Under High Pressure

    NASA Astrophysics Data System (ADS)

    O'Bannon, E. F., III; Williams, Q. C.

    2014-12-01

    The luminescence spectra of Cr3+ in heat-treated topaz Al2SiO4(OH,F)2 and natural kyanite Al2SiO5 were measured from 650 - 800 nm in a hydrostatic environment up to pressures of 15 GPa. The R1 and R2 peaks of topaz shift at average rates of 0.30 nm/GPa and 0.22 nm/GPa, respectively, implying that the deformation of the Cr3+ octahedra increases with pressure. Three peaks are fit under each R line of topaz at both room and high pressure, and these peaks are associated with different Al sites into which the Cr substitutes. The shift of the R lines in topaz under pressure is remarkably linear, which appears to be a general feature of many Cr3+-bearing oxides: the underlying cause of this linearity may lie in anharmonic coupling with lattice vibrations. In this context, we also characterize the frequency shifts of two vibronic peaks within topaz. The R1 and R2 peaks of kyanite shift at 0.37 nm/GPa and 0.88 nm/GPa respectively. Two peaks are fit under R1 and three peaks are fit under R2 of kyanite at both room and high pressure; this result is also consistent with three different Cr3+ sites in this material. The R lines in kyanite are notably optically anisotropic, depending strongly on crystallographic orientation: this is most strongly manifested in the R2 peak. The Cr3+ luminescence in these materials provides a sensitive probe of pressure-dependent shifts in the local geometry of the Al-sites in these materials, which are analyzed in the context of previous single-crystal x-ray diffraction measurements.

  18. Luminescent DNA- and agar-based membranes.

    PubMed

    Leones, R; Fernandes, M; Ferreira, R A S; Cesarino, I; Lima, J F; Carlos, L D; Bermudez, V de Zea; Magon, C J; Donoso, J P; Silva, M M; Pawlicka, A

    2014-09-01

    Luminescent materials containing europium ions are investigated for different optical applications. They can be obtained using bio-macromolecules, which are promising alternatives to synthetic polymers based on the decreasing oil resources. This paper describes studies of the DNA- and Agar-europium triflate luminescent membranes and its potential technological applications are expanded to electroluminescent devices. Polarized optical microscopy demonstrated that the samples are birefringent with submicrometer anisotropy. The X-ray diffraction analysis revealed predominantly amorphous nature of the samples and the atomic force microscopy images showed a roughness of the membranes of 409.0 and 136.1 nm for the samples of DNA10Eu and Agar1.11Eu, respectively. The electron paramagnetic resonance spectra of the DNA(n)Eu membranes with the principal lines at g ≈ 2.0 and g ≈ 4.8 confirmed uniform distribution of rare earth ions in a disordered matrix. Moreover, these strong and narrow resonance lines for the samples of DNA(n)Eu when compared to the Agar(n)Eu suggested a presence of paramagnetic radicals arising from the DNA matrix. The emission spectra suggested that the Eu3+ ions occupy a single local environment in both matrices and the excitation spectra monitored around the Eu emission lines pointed out that the Eu3+ ions in the Agar host were mainly excited via the broad band component rather than by direct intra-4f(6) excitation, whereas the opposite case occurred for the DNA-based sample. PMID:25924317

  19. Renewable energy: Better luminescent solar panels in prospect

    NASA Astrophysics Data System (ADS)

    Debije, Michael

    2015-03-01

    Devices known as luminescent solar concentrators could find use as renewable-energy generators, but have so far been plagued by a major light-reabsorption effect. A new study offers a promising route to tackling this problem.

  20. Luminescent Metal-Containing Polymers for White Light Emission.

    PubMed

    Ho, Cheuk-Lam; Wong, Wai-Yeung

    2016-10-01

    This chapter focuses on the recent developments in luminescent metallopolymers. Synthetic routes to these polymers are briefly described and their applications in polymer white light-emitting diodes are discussed.

  1. Luminescent Metal-Containing Polymers for White Light Emission.

    PubMed

    Ho, Cheuk-Lam; Wong, Wai-Yeung

    2016-10-01

    This chapter focuses on the recent developments in luminescent metallopolymers. Synthetic routes to these polymers are briefly described and their applications in polymer white light-emitting diodes are discussed. PMID:27573506

  2. Optically stimulated luminescence in Cu+ doped lithium orthophosphate

    NASA Astrophysics Data System (ADS)

    Barve, R. A.; Patil, R. R.; Moharil, S. V.; Bhatt, B. C.; Kulkarni, M. S.

    2015-02-01

    Optically stimulated luminescence (OSL) in Cu+ doped Li3PO4 synthesized by co-precipitation technique using different phosphorus precursors was studied. Changes in the luminescent properties were observed with change in the phosphorus precursors. All the synthesized phosphors showed intense fading but the OSL sensitivity was comparable to that of the commercially available Al2O3:C (Landauer Inc.). In general, BSL (blue stimulated luminescence) decay was very fast but the GSL (green stimulated luminescence) decay was comparable to that of Al2O3:C phosphor. Phosphors with fast decay, good sensitivity and intense fading are suitable for real-time dosimetry. Therefore, Cu-doped Li3PO4 could be developed for real-time dosimetry using a fiber optic based OSL reader system.

  3. Enhancing the efficiency of luminescent solar concentrators (LSCs)

    NASA Astrophysics Data System (ADS)

    Assadi, M. Khalaji; Hanaei, H.; Mohamed, Norani Muti; Saidur, R.; Bakhoda, Shokoufeh; Bashiri, Robabeh; Moayedfar, M.

    2016-09-01

    Recent developments in the endeavor to enhance the efficiency of luminescent solar concentrators (LSCs) are presented in this paper along with an analysis of LSC devices. In recent years, several experimental and numerical research works have been carried out to improve the performance of LSCs in different ways. LSCs date back to the 1970s and comprise an extremely interesting notion of solar cells for various reasons. First, LSCs are cost-competitive and function in diffuse light, and as such, it is not necessary to use expensive solar tracking devices. Second, luminescence facilitates the cells to gather only cold light, which results in higher PV efficiency. LSCs generally consist of transparent polymer sheets doped with luminescent species. The luminescent species absorb incident sunlight and emit it with high quantum efficiency, such that the emitted light is trapped in the sheet and travels to the edges where the solar cells can collect it.

  4. Near-Infrared Quantum Cutting Long Persistent Luminescence.

    PubMed

    Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

    2016-01-01

    By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called "near-infrared quantum cutting long persistent luminescence (NQPL)", which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr(3+),Yb(3+). It reveals that both the two-step energy transfer of model (I) and the one-step energy transfer of model (IV) occur in (3)P0 levels of Pr(3+). Although the actual efficiency is not sufficient for the practical application at this primitive stage, this discovery and the associated materials are still expected to have important implications for several fields such as crystalline Si solar cells and bio-medical imaging. PMID:27143282

  5. Near-Infrared Quantum Cutting Long Persistent Luminescence

    PubMed Central

    Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

    2016-01-01

    By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called “near-infrared quantum cutting long persistent luminescence (NQPL)”, which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr3+,Yb3+. It reveals that both the two-step energy transfer of model (I) and the one-step energy transfer of model (IV) occur in 3P0 levels of Pr3+. Although the actual efficiency is not sufficient for the practical application at this primitive stage, this discovery and the associated materials are still expected to have important implications for several fields such as crystalline Si solar cells and bio-medical imaging. PMID:27143282

  6. Luminescent coupling in planar opto-electronic devices

    SciTech Connect

    Wilkins, Matthew Valdivia, Christopher E.; Gabr, Ahmed M.; Hinzer, Karin; Masson, Denis; Fafard, Simon

    2015-10-14

    Effects of luminescent coupling are observed in monolithic 5 V, five-junction GaAs phototransducers. Power conversion efficiency was measured at 61.6% ± 3% under the continuous, monochromatic illumination for which they were designed. Modeling shows that photon recycling can account for up to 350 mV of photovoltage in these devices. Drift-diffusion based simulations including a luminescent coupling term in the continuity equation show a broadening of the internal quantum efficiency curve which agrees well with experimental measurements. Luminescent coupling is shown to expand the spectral bandwidth of the phototransducer by a factor of at least 3.5 for devices with three or more junctions, even in cases where multiple absorption/emission events are required to transfer excess carriers into the limiting junction. We present a detailed description of the novel luminescent coupling modeling technique used to predict these performance enhancements.

  7. Biocompatible luminescent silicon quantum dots for imaging of cancer cells.

    PubMed

    Erogbogbo, Folarin; Yong, Ken-Tye; Roy, Indrajit; Xu, Gaixia; Prasad, Paras N; Swihart, Mark T

    2008-05-01

    Luminescent silicon quantum dots (Si QDs) have great potential for use in biological imaging and diagnostic applications. To exploit this potential, they must remain luminescent and stably dispersed in water and biological fluids over a wide range of pH and salt concentration. There have been many challenges in creating such stable water-dispersible Si QDs, including instability of photoluminescence due their fast oxidation in aqueous environments and the difficulty of attaching hydrophilic molecules to Si QD surfaces. In this paper, we report the preparation of highly stable aqueous suspensions of Si QDs using phospholipid micelles, in which the optical properties of Si nanocrystals are retained. These luminescent micelle-encapsulated Si QDs were used as luminescent labels for pancreatic cancer cells. This paves the way for silicon quantum dots to be a valuable optical probe in biomedical diagnostics.

  8. Luminescence in Li2BaP2O7.

    PubMed

    Hatwar, L R; Wankhede, S P; Moharil, S V; Muthal, P L; Dhopte, S M

    2015-09-01

    The photo-, thermo- and optically stimulated luminescence in Li2BaP2O7 activated with Eu(2+) /Cu(+) are reported. Strong thermoluminescence, which is about two times greater than LiF-TLD 100 was observed in the Eu(2+) -activated sample. It also exhibited optically stimulated luminescence sensitivity of ~20% that of commercial Al2O3:C phosphor. PMID:25351563

  9. Luminescence-based optical sensor systems for monitoring water parameters

    NASA Astrophysics Data System (ADS)

    Lobnik, Aleksandra; Turel, Matejka; Korent, Špela Mojca

    2007-06-01

    Lanthanide-sensitized luminescence is very attractive because the intramolecular energy transfers between the absorbing ligand and the luminescent ion results in strong narrow-band fluorescence with a large Stokes' shift and long decay times. We will report about several sensor systems based either on sol-gel materials or lanthanide chelates for monitoring and controlling water parameters, such as heavy metals, amines, phosphates.

  10. Radiation damage and luminescence properties of gamma aluminum oxynitride transparent ceramic

    NASA Astrophysics Data System (ADS)

    Du, Xinhua; Yao, Shiyue; Jin, Xihai; Chen, Haohong; Li, Weifeng; Liang, Bo

    2015-09-01

    This paper reports on the radiation damage of gamma aluminum oxynitride (γ-AlON) transparent ceramic, which remarkably degrades UV-vis transparency and hence limits its applications in optoelectronic devices. The radiation-induced optical absorption of the as-sintered γ-AlON consists of at least two subbands: one is in the UV region with a peak at 270 nm and the other optical absorption band centers at 550 nm, covering the whole visible light spectrum, which makes the sample colored. Interestingly, all the radiation-induced color centers can be completely ‘bleached’ by low temperature annealing. In the thermoluminescence curve, we observed a broad luminescence in the range of 25-300 °C with the peak at 120 °C. Furthermore, the x-ray excited luminescence spectra revealed that there exist multiple emission centers in the γ-AlON. Based on this experimental fact, the radiation damage and luminescent mechanisms were studied. These optical properties of the γ-AlON are considered to be related to defect states. In the as-sintered γ-AlON, charge balancing is realized by the co-existence of \\text{V}\\text{Al}\\prime\\prime \\prime and \\text{O}\\text{N}\\bullet , and the predominant defect form is ≤ft[\\text{V}\\text{Al}\\prime\\prime \\prime-\\text{3O}\\text{N}\\bullet\\right] , which is optically inactive and no optical absorption occurs. However, isolated \\text{V}\\text{Al}\\prime\\prime \\prime and \\text{O}\\text{N}\\bullet can be formed by irradiation and it is these that are responsible for the radiation damage of γ-AlON transparent ceramic. In the end, the UV absorption and visible-light absorption in the irradiated sample were ascribed to VAl-related and ON-related intrinsic defects, respectively.

  11. Synthesis of cytocompatible luminescent titania/fluorescein hybrid nanoparticles.

    PubMed

    Shiba, Kota; Tagaya, Motohiro; Hanagata, Nobutaka

    2014-05-14

    Luminescent titania-fluorescein (FS) hybrid nanoparticles (NPs) were successfully synthesized by a sol-gel reaction of titanium alkoxide in the presence of octadecylamine using a fluidic reactor with a Y-type channel. The molar ratio of FS/Ti ratio was varied in the range from 1/1000 to 1/100 in order to obtain the hybrid NPs with the different luminescent behavior. The shape of the NPs is spherical and their sizes are 400 nm which is almost the same irrespective of the FS content, suggesting the different FS molecular states in one NP. We also demonstrated that the hybrid NPs exhibited a characteristic luminescence; the NPs with the higher and lower FS contents exhibited an enhanced luminescence in PBS and air, respectively, indicating that the FS states responded to the molecular environment. Through cytocompatible experiments using the NPs, it turned out that they had a high compatibility for fibroblasts. Therefore, the preparation of a series of the luminescent NPs with a tunable luminescence property was achieved. The results will lead to a guideline to determine a proper combination between material composition and an environment where they are used, being useful for biomedical applications.

  12. Flight testing of a luminescent surface pressure sensor

    NASA Technical Reports Server (NTRS)

    Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

    1992-01-01

    NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

  13. Luminescent molecular rods - transition-metal alkynyl complexes.

    PubMed

    Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

    2005-01-01

    A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes. PMID:22179333

  14. Luminescent molecular rods - transition-metal alkynyl complexes.

    PubMed

    Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

    2005-01-01

    A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes.

  15. Isolation and characterisation of plant defensins from seeds of Asteraceae, Fabaceae, Hippocastanaceae and Saxifragaceae.

    PubMed

    Osborn, R W; De Samblanx, G W; Thevissen, K; Goderis, I; Torrekens, S; Van Leuven, F; Attenborough, S; Rees, S B; Broekaert, W F

    1995-07-17

    From seeds of Aesculus hippocastanum, Clitoria ternatea, Dahlia merckii and Heuchera sanguinea five antifungal proteins were isolated and shown to be homologous to plant defensins previously characterised from radish seeds and gamma-thionins from Poaceae seeds. Based on the spectrum of their antimicrobial activity and the morphological distortions they induce on fungi the peptides can be divided into two classes. The peptides did not inhibit any of three different alpha-amylases. PMID:7628617

  16. Platinum(iv) N-heterocyclic carbene complexes: their synthesis, characterisation and cytotoxic activity.

    PubMed

    Bouché, M; Dahm, G; Wantz, M; Fournel, S; Achard, T; Bellemin-Laponnaz, S

    2016-07-28

    Platinum(ii) N-heterocyclic carbene complexes have been oxidized by bromine or iodobenzene dichloride to provide the fully characterised corresponding platinum(iv) NHC complexes. Antiproliferative activities of Pt(iv) NHC complexes were assayed against several cancer cell lines and the results were correlated with respect to their stability. Mechanistic investigations revealed that mitochondrial dysfunction and ROS production were associated with the cytotoxic process induced by these compounds. PMID:27331604

  17. Instantaneous frequency based newborn EEG seizure characterisation

    NASA Astrophysics Data System (ADS)

    Mesbah, Mostefa; O'Toole, John M.; Colditz, Paul B.; Boashash, Boualem

    2012-12-01

    The electroencephalogram (EEG), used to noninvasively monitor brain activity, remains the most reliable tool in the diagnosis of neonatal seizures. Due to their nonstationary and multi-component nature, newborn EEG seizures are better represented in the joint time-frequency domain than in either the time domain or the frequency domain. Characterising newborn EEG seizure nonstationarities helps to better understand their time-varying nature and, therefore, allow developing efficient signal processing methods for both modelling and seizure detection and classification. In this article, we used the instantaneous frequency (IF) extracted from a time-frequency distribution to characterise newborn EEG seizures. We fitted four frequency modulated (FM) models to the extracted IFs, namely a linear FM, a piecewise-linear FM, a sinusoidal FM, and a hyperbolic FM. Using a database of 30-s EEG seizure epochs acquired from 35 newborns, we were able to show that, depending on EEG channel, the sinusoidal and piecewise-linear FM models best fitted 80-98% of seizure epochs. To further characterise the EEG seizures, we calculated the mean frequency and frequency span of the extracted IFs. We showed that in the majority of the cases (>95%), the mean frequency resides in the 0.6-3 Hz band with a frequency span of 0.2-1 Hz. In terms of the frequency of occurrence of the four seizure models, the statistical analysis showed that there is no significant difference( p = 0.332) between the two hemispheres. The results also indicate that there is no significant differences between the two hemispheres in terms of the mean frequency ( p = 0.186) and the frequency span ( p = 0.302).

  18. Synthesis and study of the luminescent properties of europium-doped yttrium niobate

    NASA Astrophysics Data System (ADS)

    Mester, A. Yu.; Mozharov, A. M.; Trofimov, A. N.; Zamoryanskaya, M. V.

    2016-05-01

    A method of synthesis of single-phase europium-doped yttrium niobate powders without using additional fluxes is developed. Using this method, a series of samples with different europium concentrations are synthesized. The phase composition, grain size, and luminescent properties of the synthesized powders are studied. The optimal dopant concentration corresponding to the maximum luminescence intensity is determined. It is shown that the decay time of the most intense luminescence line of europium decreases with increasing europium concentration. Comparative analysis of the luminescent properties of calcium tungstate and the luminescent properties of a synthesized sample with the highest luminescence intensity is performed.

  19. Luminescence of phosphorus containing oxide materials: Crystalline SiO2-P and 3P2O5ṡ7SiO2; CaOṡP2O5; SrOṡP2O5 glasses

    NASA Astrophysics Data System (ADS)

    Trukhin, A. N.; Smits, K.; Jansons, J.; Berzins, D.; Chikvaidze, G.; Griscom, D. L.

    2014-10-01

    Luminescence of phosphate glasses such as CaOṡP2O5 and SrOṡP2O5 is compared with that of phosphorus doped crystalline α-quartz and phosphosilicate glass with content 3P2O5ṡ7SiO2. Water & OH groups are found by IR spectra in these materials. The spectrum of luminescence contains many bands in the range 1.5 - 5.5 eV. The luminescence bands in UV range at 4.5-5 eV are similar in those materials. Decay duration in exponential approximation manifests a time constant about 37 ns. Also a component in μs range was detected. PL band of μs component is shifted to low energy with respect to that of ˜37 ns component. This shift is about 0.6 eV. It is explained as singlet-triplet splitting of excited state. Below 14 K increase of luminescence kinetics duration in μs range was observed and it was ascribed to zero magnetic field splitting of triplet excited state of the center. Yellow-red luminescence was induced by irradiation in phosphorus doped crystalline α-quartz, phosphosilicate glasses. The yellowl uminescence contains two bands at 600 and 740 nm. Their decay is similar under 193 nm laser and may be fitted with the first order fractal kinetics or stretched exponent. Thermally stimulated luminescence contains only band at 600 nm. The 248 nm laser excites luminescence at 740 nm according to intra center process with decay time constant about 4 ms at 9 K. Both type of luminescence UV and yellow were ascribed to different defects containing phosphorus. P-doped α-quartz sample heated to 550 co become opalescent. Ir spectra related to water & OH groups are changed. Photoluminescence intensity of all three bands, UV (250 nm), yellow (600 nm) and red (740 nm) strongly diminished and disappeared after heating to 660 C°. Radiation induced red luminescence of non-bridging oxygen luminescence center (NBO) appeared in crystal after heat treatment. We had observed a crystalline version of this center (l. Skuja et al, Nuclear Instruments and Methods in Physics Research B

  20. Characterisation of fine particles by flow cytometry in estuarine and coastal Arctic waters

    NASA Astrophysics Data System (ADS)

    Moreira-Turcq, Patricia F.; Martin, Jean Marie

    1998-06-01

    The chemical and biological nature of suspended pico- (<2 μm) and nano- (2-10 μm) particles was studied by flow cytometry in the Lena River delta and Laptev Sea, Russia, during September 1991. Forward and wide-angle light scatter, natural fluorescence of phytoplankton, and induced fluorescence of organic molecules were used to characterise natural suspended particles. Organic and inorganic particles were identified by staining with specific fluorochromes: FITC for proteins, Con A-FITC for glucose/mannose, and PNA for galactose. Living and nonliving organic particles were distinguished by analysing simultaneously natural red fluorescence (chlorophyll) and organic staining. The upper Lena River and its delta were characterised by a high concentration of total particles (18.5±4.9×10 5 per cm 3), mostly inorganic (13.6±5.4×10 5 per cm 3). In the coastal and open waters of the Laptev Sea, organic particles dominated. Generally, the most important fraction of small organic particles were nonliving (organic detritus, TEP, and organic coatings) characterised by the presence of proteins and polysaccharides. The phytoplanktonic cells were characterised by a high fraction of picoplankton (1000-50 000 cells per cm 3) dominated by Synechococcus sp. and small picoeukaryotes.

  1. Comprehensive soil surface characterisation by RADAR

    NASA Astrophysics Data System (ADS)

    Seeger, Manuel; Gronz, Oliver; Beiske, Joshua

    2015-04-01

    The characteristics of the soil's surface have been revealed to be extremely relevant for soil surface processes. Texture, aggregates and roughness are interdependent across scales and have a strong influence on infiltration, runoff generation, water flow velocity as well as on particle detachment and transport. They also have shown to be relevant for splash detachment and initialisation of concentrated flow. But these soil surface characteristics are also highly variable during erosive events, and thus, their impact on the processes mentioned above may change. Therefore it is necessary to develop methods for a comprehensive and quantitative characterisation of the soils' surface across scales. Here, we present a first approach using a frequency modulated polarimetric radar to characterise different surfaces (from flat to rough in a scale of cm to dm size of the roughness elements) and of different materials (steel plates as strong reflector, sand [0.5-1 mm], fine [2-4 mm] and coarse [15-30 mm] rock fragments. The radar is a prototype built by IMST GmbH (Kamp-Lintfort, Germany), emitting on the 24 GHz band, allowing for a frequency modulation between 500 and 2500 MHz with variable ramp times. The emission is on a circular clockwise polarisation, whilst it is able to receive both, clockwise and counter-clockwise polarisations. We tested also the dependency of the reflected signals on imaging position and angle, as well as on the different emission parameters, such as amplitude modulation and ramp time. The results show that the angle of acquisition influences clearly the received signal intensity (in both polarisation directions). This implies the need to develop topographical corrections for further applications. In addition we could observe a significant influence of the device position on the results, which implies, on one hand, a high sensitivity relating to the soil's surface, but on the other hand it leads to a high level of uncertainty. The reflection

  2. High-Rate Characterisation of Hexanitrostilbene

    NASA Astrophysics Data System (ADS)

    Claridge, Robert; Parker, Adam; Proud, William

    2007-06-01

    Hexanitrostilbene (HNS) is a nitro-aromatic insensitive secondary explosive currently used in a number of insensitive munitions (IM) applications and under consideration for several others. The physical behavior of HNS is therefore important for the development of safe and reliable weapons systems. As part of a comprehensive suite of shock characterisation experiments, one-dimensional plate impact experiments have been performed on HNS IV at two different densities. The unreacted Hugoniot curve was established at each density and the results compared to those reported in the literature. The data obtained from these experiments will assist in the modelling of ignition and growth within HNS based explosives systems.

  3. Characterisation and biological treatment of greywater.

    PubMed

    Hernández Leal, L; Zeeman, G; Temmink, H; Buisman, C

    2007-01-01

    Characterisation of greywater was conducted in two different greywater streams in the Netherlands (Groningen and Sneek). The concentrations of macropollutants and nutrients measured were very different in both streams; in particular the COD was 425 mg/L in Groningen's water whereas in Sneek it was 1,583 mg/L. The aerobic treatment of greywater in a fed-batch reactor led to a 90% removal of COD at different organic loading rates. Anaerobically, the removal reached 40% COD removal on average, the possible reason being the high amount of surfactants present in the influent.

  4. Characterization of phenotype variations of luminescent and non-luminescent variants of Vibrio harveyi wild type and quorum sensing mutants.

    PubMed

    Hong, N T X; Baruah, K; Vanrompay, D; Bossier, P

    2016-03-01

    Vibrio harveyi, a luminescent Gram-negative motile marine bacterium, is an important pathogen responsible for causing severe diseases in shrimp, finfish and molluscs leading to severe economic losses. Non-luminescent V. harveyi obtained by culturing luminescent strains under static and dark condition were reported to alter the levels of virulence factors and metalloprotease gene and luxR expression when compared to their luminescent variants. Presently, we conducted an in vitro study aiming at the characterization of virulence-related phenotypic traits of the wild-type V. harveyi BB120 strain and its isogenic quorum sensing mutants before and after switching to the non-luminescent status. We measured the production of caseinase, haemolysin and elastase and examined swimming motility and biofilm formation. Our results showed that switching from the bioluminescent to the non-luminescent state changed the phenotypic physiology or behaviour of V. harveyi resulting in alterations in caseinase and haemolytic activities, swimming motility and biofilm formation. The switching capacity was to a large extent independent from the quorum sensing status, in that quorum sensing mutants were equally capable of making the phenotypic switch.

  5. Carboxyl-Functionalized Ionic Liquid Assisted Preparation of Flexible, Transparent, and Luminescent Chitosan Films as Vapor Luminescent Sensor.

    PubMed

    Yang, Daqing; Wang, Yige; He, Liang; Li, Huanrong

    2016-08-01

    Herein we present a novel method to synthesize flexible self-standing films consisting of europium(III) complexes in nanoclay and chitosan, which are transparent and luminescent. Preparation takes place under aqueous conditions assisted by a carboxyl-functionalized ionic liquid (IL). The latter is used not only as a replacement for acetic acid to dissolve chitosan but, surprisingly, also to enhance the luminescence efficiency of the final films. A brighter luminescence is observed for the films prepared assisted with the ionic liquids compared to those by using acetic acid. The reason is that the ionic liquid used to dissolve chitosan can decrease proton strength on embedded platelets primarily through ion-exchange process and thus can increase the coordination number of europium(III) complexes. Exposure of the films to Et3N vapors can cause a further remarkable luminescence enhancement, while significant luminescence quenching occurred upon exposure to HCl vapors. The films are promising for applications in areas such as optoelectronics and vapor-sensitive luminescent sensors. PMID:27424528

  6. Measurement of solid-state optical refrigeration by two-band differential luminescence thermometry

    SciTech Connect

    Hehlen, Markus P; Epstein, Richard I; Patterson, Wendy M; Sheik - Bahae, Mansoor; Seletskiy, D V

    2009-01-01

    We present a non-contact spectroscopic teclmique for the measurement of laser-induced temperature changes in solids. Two-band differential luminescence thermometry (TBDLT) achieves a sensitivity of {approx}7 mK and enables precise measurement of the net quantum efficiency of optical refrigerator materials. TBDLT detects internal temperature changes by decoupling surface and bulk heating effects via time-resolved luminescence spectroscopy. Several Yb{sup 3+}-doped fluorozirconate (ZBLANI) glasses fabricated from precursors of varying purity and by different processes are analyzed in detail. A net quantum efficiency of 97.39% at 238 K (at a pump wavelength of 1020.5 nm) is found for a ZBLANI:1%Yb{sup 3+} laser-cooling sample produced from metal fluoride precursors that were purified by chelate-assisted solvent extraction and dried in hydrofluoric gas. In comparison, a ZBLANI:1%Yb{sup 3+} sample produced from commercial-grade metal fluoride precursors showed pronounced laser-induced heating that is indicative of a substantially higher impurity concentration. TBDLT enables rapid and sensitive benchmarking of laser-cooling materials and provides critical feedback to the development and optimization of high-performance optical cryocooler materials.

  7. Luminescence dating of ancient Darhad basin, Mongolia

    NASA Astrophysics Data System (ADS)

    Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

    2016-04-01

    . Thus, age control on existing 14C ages from this site is limited, chronological interpretation based on the 14C ages is still incomplete in Hodon outcrop sediments. OSL (Optically Stimulated Luminescence) is an alternative method for dating to overcome the problems associated with 14C methods. OSL has been extensively used for dating arctic sediments (Thomas et al., 2006; more). Previous optical ages on Darhad paleolake sediments obtained using IRSL (Infrared-stimulated luminescence) on feldspars (Gillespie et al., 2008; Batbaatar et al., 2009). Feldspar has much brighter luminescence than quartz, while the OSL signal of feldspars bleaches at least one order of magnitude slower than the OSL signal of quartz (Godfrey-Smith et al., 1988; Huntly and Lamothe, 2001; Mauz and Bungenstock, 2007; Kim et al., 2012). In glaciofluvial, glaciolacustrine environments, inadequate bleaching of the OSL signal is known to be a potential problem of burial ages (Thomas et al., 2006). OSL dating of permafrost deposits may also involve uncertainty about the inhomogeneous radiation field surrounding the dosimeter and the absorption of ionizing energy alternately by water and ice in a not-constant pore volume (Haeberli et al., 2003). In this study, we test the applicability of quartz OSL dating for the uppermost paleolake sediments in the Hodon outcrop of the Darhad basin. The OSL results were systematically compared with additional radiocarbon ages from wood fragments to conclude the reliability of the OSL dates and to construct intensive chronology for Late-Pleistocene Darhad paleolake. To evaluate the time of recent expansion of the paleolake, the northern piedmont (Talyn outcrop) of the basin was dated by OSL.

  8. Self-aligned optical couplings by self-organized waveguides toward luminescent targets in organic/inorganic hybrid materials.

    PubMed

    Yoshimura, Tetsuzo; Iida, Makoto; Nawata, Hideyuki

    2014-06-15

    Self-organization of optical waveguides is observed between two opposed optical fibers placed in a photosensitive organic/inorganic hybrid material, Sunconnect. A luminescent target containing coumarin 481 was deposited onto the edge of one of the two fibers at the core. When a 448-nm write beam was introduced from the other fiber, the write beam and the luminescence from the photoexcited target increased the refractive index of Sunconnect to induce self-focusing. Traces of waveguides were seen to grow from the cores of both fibers and merged into a single self-aligned optical coupling between the fibers. This optical solder functionality enabled increases in both coupling efficiency and tolerance to lateral misalignment of the fibers.

  9. Self-aligned optical couplings by self-organized waveguides toward luminescent targets in organic/inorganic hybrid materials.

    PubMed

    Yoshimura, Tetsuzo; Iida, Makoto; Nawata, Hideyuki

    2014-06-15

    Self-organization of optical waveguides is observed between two opposed optical fibers placed in a photosensitive organic/inorganic hybrid material, Sunconnect. A luminescent target containing coumarin 481 was deposited onto the edge of one of the two fibers at the core. When a 448-nm write beam was introduced from the other fiber, the write beam and the luminescence from the photoexcited target increased the refractive index of Sunconnect to induce self-focusing. Traces of waveguides were seen to grow from the cores of both fibers and merged into a single self-aligned optical coupling between the fibers. This optical solder functionality enabled increases in both coupling efficiency and tolerance to lateral misalignment of the fibers. PMID:24978520

  10. Turn-on phosphorescence by metal coordination to a multivalent terpyridine ligand: a new paradigm for luminescent sensors.

    PubMed

    Fermi, Andrea; Bergamini, Giacomo; Roy, Myriam; Gingras, Marc; Ceroni, Paola

    2014-04-30

    A hexathiobenzene molecule carrying six terpyridine (tpy) units at the periphery has been designed to couple the aggregation induced phosphorescence, displayed by the core in the solid state, to the metal binding properties of the tpy units. Upon Mg(2+) complexation in THF solution, phosphorescence of the hexathiobenzene core is turned on. Metal ion coordination yields the formation of a supramolecular polymer which hinders intramolecular rotations and motions of the core chromophore, thus favoring radiative deactivation of the luminescent excited state. Upon excitation of the [Mg(tpy)2](2+) units of the polymeric structure, sensitization of the core phosphorescence takes place with >90% efficiency. The light-harvesting polymeric antenna can be disassembled upon fluoride ion addition, thereby switching off luminescence and offering a new tool for fluoride ion sensing. This unique system can, thus, serve as cation or anion sensor. PMID:24725096

  11. The Luminescence and ESR of a Synthetic Emerald and the Natural Ones Mined from Santa Terezinha in Brazil

    NASA Astrophysics Data System (ADS)

    Ohkura, Hiroshi; Hashimoto, Hisashi; Mori, Yuzo; Chiba, Yoshinori; Isotani, Sadao

    1987-09-01

    Both the luminescence and ESR of a synthetic (KC-) emerald and a natural (ST-) type, mined from Santa Terezinha in Brazil, have been studied. The luminescence spectra of the impurity Cr3+ ions in both emeralds consist of two zerophonon lines followed by satellite bands. The satellite band of the ST-emerald shows huge intensity and broad width compared with that of the KC-emerald. The ESR of the Cr3+ ions in the ST-emerald is specific in the anisotropy of the g-factor and has a wider peak-to-peak value than the KC-emerald. We propose that these differences are caused by an interaction induced by the presence of a large number of impurity Fe3+ ions contained in the ST-emerald. The existence of Fe3+ and their concentrations were estimated by ESR.

  12. Luminescence of rutile structured crystalline silicon dioxide (stishovite)

    NASA Astrophysics Data System (ADS)

    Trukhin, A. N.; Smits, K.; Chikvaidze, G.; Dyuzheva, T. I.; Lityagina, L. M.

    2014-07-01

    Luminescence spectrum of synthetic mono-crystalline stishovite comprises a slow blue band at ~400 nm (~3.1 eV) and a fast UV band at ~260 nm (~4.7 eV), as well as some bands in near-infrared range of spectra. The NIR luminescence of stishovite crystal, excited with lasers 532 nm, 248 nm and 193 nm as well as x-ray, possesses several sharp lines. A zero phonon line is situated at 787 nm (1.57 eV) and grows with cooling. An anti-Stokes line is located at 771 nm (1.68 eV). This line disappears with cooling. In a powder sample of stishovite created by shock waves generated by the impact of a 50-m-diameter meteorite in Arizona 50,000 years ago, the PL broad blue band is situated at 425 nm (2.9 eV), the UV band at ~260 nm (~4.7 eV), and the sharp lines, seen only under 193 nm laser, at 689 nm (1.789 eV), 694 nm (1.785 eV) and 706 nm (1.754 eV). We ascribe the fast UV luminescence to singlet-singlet transitions and the slow blue band to triplet-singlet transitions of the same intrinsic defect of stishovite in both types of samples. The blue band in stishovite crystal exhibits delayed luminescence of recombination nature, whereas the blue band of Arizona's powder sample does not exhibit such effect. This difference is explained by different surroundings of luminescence center in those samples. NIR luminescence of mono-crystalline stishovite is ascribed to carbon impurity penetrated in the sample from graphite heater. NIR luminescence of powder from Arizona has not yet found an explanation.

  13. Ferrous ion induced photon emission as a method to quantify oxidative stress in stored boar spermatozoa.

    PubMed

    Gogol, Piotr; Pieszka, Marek

    2008-01-01

    The aim of the study was to evaluate the effect of semen storage on ferrous ion induced luminescence of boar spermatozoa and to determine the relationship between parameters of this luminescence and lipid peroxidation as measured by malondialdehyde (MDA) contents. Boar semen samples were diluted in Biosolwens extender and stored for 12 days at 15 degrees C. Luminescence and MDA were measured directly after dilution (day 0) and at 6 and 12 days of semen storage. Luminescence was measured at 20 degrees C using a luminometer equipped with a cooled photomultiplier with a spectral response range from 370 to 620 nm. Emission was induced by adding FeSO4 solution (final concentration 0.05 mM). MDA content was measured by the HPLC method. The day of storage had a significant effect on some luminescence parameters and MDA content in spermatozoa. A significant correlation was observed between luminescence parameters and MDA concentration. The results of the study confirm that induced luminescence is strictly related to lipid peroxidation in spermatozoa that occur during boar semen storage. Parameters of luminescence treated as a holistic response of cells to oxidative stress can be useful for monitoring spermatozoa quality during semen preservation. PMID:19055043

  14. X-ray spectroscopy studies of nonradiative energy transfer processes in luminescent lanthanide materials

    NASA Astrophysics Data System (ADS)

    Pacold, Joseph I.

    having a strong charge-transfer character. A second primary result comes from an an x-ray excited optical luminescence (XEOL) study that demonstrates, for the first time, that the high flux of modern synchrotron light sources can induce high fractional populations of excited states in trivalent lanthanide phosphors. In this work we have identified the leading-order nonlinear-response mechanism by drawing on strong similarities between XEOL and cathodoluminescence. These results establish the groundwork for studies that would allow deeper inquiry into energy-transfer mechanisms through time-resolved x-ray pump/optical-probe spectroscopies, through time-resolved x-ray emission spectroscopy, or through quantifying of higher-order nonlinear effects at further-enhanced fractional excitation levels. The above scientific results are augmented by a supporting effort in instrumental methodology. This includes the development of high-efficiency x-ray emission spectrometers and their use in collaborations to study pressure-induced changes in f-electron physics and to characterize the intermediate states that occur after photoexcitation of the photosystem-II protein.

  15. Gated Luminescence Imaging of Silicon Nanoparticles.

    PubMed

    Joo, Jinmyoung; Liu, Xiangyou; Kotamraju, Venkata Ramana; Ruoslahti, Erkki; Nam, Yoonkey; Sailor, Michael J

    2015-06-23

    The luminescence lifetime of nanocrystalline silicon is typically on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally present in cells and tissues. Time-gated imaging, where the image is acquired at a time after termination of an excitation pulse, allows discrimination of a silicon nanoparticle probe from these endogenous signals. Because of the microsecond time scale for silicon emission, time-gated imaging is relatively simple to implement for this biocompatible and nontoxic probe. Here a time-gated system with ∼10 ns resolution is described, using an intensified CCD camera and pulsed LED or laser excitation sources. The method is demonstrated by tracking the fate of mesoporous silicon nanoparticles containing the tumor-targeting peptide iRGD, administered by retro-orbital injection into live mice. Imaging of such systemically administered nanoparticles in vivo is particularly challenging because of the low concentration of probe in the targeted tissues and relatively high background signals from tissue autofluorescence. Contrast improvements of >100-fold (relative to steady-state imaging) is demonstrated in the targeted tissues.

  16. Grassy Silica Nanoribbons and Strong Blue Luminescence

    NASA Astrophysics Data System (ADS)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  17. Grassy Silica Nanoribbons and Strong Blue Luminescence

    PubMed Central

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-01-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications. PMID:27666663

  18. Luminescent Solar Concentrators in the Algal Industry

    NASA Astrophysics Data System (ADS)

    Hellier, Katie; Corrado, Carley; Carter, Sue; Detweiler, Angela; Bebout, Leslie

    2013-03-01

    Today's industry for renewable energy sources and highly efficient energy management systems is rapidly increasing. Development of increased efficiency Luminescent Solar Concentrators (LSCs) has brought about new applications for commercial interests, including greenhouses for agricultural crops. This project is taking first steps to explore the potential of LSCs to enhance production and reduce costs for algae and cyanobacteria used in biofuels and nutraceuticals. This pilot phase uses LSC filtered light for algal growth trials in greenhouses and laboratory experiments, creating specific wavelength combinations to determine effects of discrete solar light regimes on algal growth and the reduction of heating and water loss in the system. Enhancing the optimal spectra for specific algae will not only increase production, but has the potential to lessen contamination of large scale production due to competition from other algae and bacteria. Providing LSC filtered light will reduce evaporation and heating in regions with limited water supply, while the increased energy output from photovoltaic cells will reduce costs of heating and mixing cultures, thus creating a more efficient and cost effective production system.

  19. Luminescent Silica Nanoparticles for cancer diagnosis

    PubMed Central

    Montalti, Marco; Petrizza, Luca; Rampazzo, Enrico; Zaccheroni, Nelsi; Marchiò, Serena

    2015-01-01

    Fluorescence imaging techniques are becoming essential in preclinical investigations, and the research of suitable tools for in vivo measurements is gaining more and more importance and attention. Nanotechnology entered the field to try to find solutions for many limitation at the state of the art, and luminescent nanoparticles (NPs) are one of the most promising materials proposed for future diagnostic implementation. NPs constitute also a versatile platform that can allow facile multi-functionalization to perform multimodal imaging or theranostic (simultaneous diagnosis and therapy). In this contribution we have focussed our attention only on dye doped silica or silica-based NPs conjugated with targeting moieties to enable specific cancer cells imaging and differentiation, even if also a few non targeted systems have been cited and discussed for completeness. We have summarized common synthetic approaches to these materials and then surveyed the most recent imaging applications of silica-based nanoparticles in cancer. The field of theranostic is so important and stimulating that, even if it is not the central topic of this paper, we have included some significant examples. We have then concluded with short hints on systems already in clinical trials and examples of specific applications in children tumours. This review tries to describe and discuss, through focussed examples, the great potentialities of these materials in the medical field, with the aim to encourage further research to implement applications that are still rare. PMID:23458621

  20. Gated Luminescence Imaging of Silicon Nanoparticles

    PubMed Central

    Joo, Jinmyoung; Liu, Xiangyou; Kotamraju, Venkata Ramana; Ruoslahti, Erkki; Nam, Yoonkey; Sailor, Michael J.

    2016-01-01

    The luminescence lifetime of nanocrystalline silicon is typically on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally present in cells and tissues. Time-gated imaging, where the image is acquired at a time after termination of an excitation pulse, allows discrimination of a silicon nanoparticle probe from these endogenous signals. Because of the microsecond time scale for silicon emission, time-gated imaging is relatively simple to implement for this biocompatible and nontoxic probe. Here a time-gated system with ~10 ns resolution is described, using an intensified CCD camera and pulsed LED or laser excitation sources. The method is demonstrated by tracking the fate of mesoporous silicon nanoparticles containing the tumor-targeting peptide iRGD, administered by retro-orbital injection into live mice. Imaging of such systemically administered nanoparticles in vivo is particularly challenging because of the low concentration of probe in the targeted tissues and relatively high background signals from tissue autofluorescence. Contrast improvements of >100-fold (relative to steady-state imaging) is demonstrated in the targeted tissues. PMID:26034817

  1. Luminescence of some airborne plant materials

    NASA Astrophysics Data System (ADS)

    Satterwhite, Melvin B.

    1997-07-01

    The objective of this study was to describe the excitation- emission spectra of seed pubescence, pollen and spores, and senesced plant materials that could be carried in the air column. Reference samples were a mature green-colored corn leaf, green-, yellow- and brown-colored soybean leaves, cellulose, commercial grade cotton batting and a soil. Spectral luminescence signatures were collected over the 300 to 800 nanometer region using a scanning spectrofluorometer. The excitation-emission spectra were broadband emission centroids in the 400-nm to 600-nm spectrum. Emission maxima were associated with the 440-nm, 470-nm and 370-nm excitation bands and the 455-nm to 590-nm emission bands. The coma of milkweed, silkvine, cotton (raw), cottonwood seeds and yellow- colored pollen and spores were highly fluorescent. The pappus of thistles, dandelion and goat's beard seeds and newly senesced grass leaves and glumes had moderate to high fluorescence. Dark brown-colored mushroom spores and weathered, senesced plant materials had low fluorescence. The emission spectra resembled that of regent, microcrystalline cellulose although impurities incorporated within the plant materials altered their emission intensities from that of cellulose. Moderate to low emissions were from tan- to dark brown-colored materials, whereas the white-colored or light, tan-colored materials had high emissions.

  2. Dynamics of polydots: Soft luminescent polymeric nanoparticles

    DOE PAGES

    Maskey, Sabina; Osti, Naresh C.; Grest, Gary S.; Perahia, Dvora

    2016-03-04

    The conformation and dynamics of luminescent polymers collapsed into nanoparticles or polydots were studied using fully atomistic molecular dynamics (MD) simulations, providing a first insight into their internal dynamics. Controlling the conformation and dynamics of confined polymers is essential for realization of the full potential of polydots in nanomedicine and biotechnology. Specifically, the shape and internal dynamics of polydots that consist of highly rigid dialkyl p-phenylene ethynylene (PPE) are probed as a function of temperature. At room temperature, the polydots are spherical without any correlations between the aromatic rings on the PPE backbone. With increasing temperature, they expand and becomemore » slightly aspherical; however, the polymers remain confined. The coherent dynamic structure factor reveals that the internal motion of the polymer backbone is arrested, and the side chains dominate the internal dynamics of the polydots. Lastly, these new soft nanoparticles retain their overall shape and dynamics over an extended temperature range, and their conformation is tunable via their degree of expansion.« less

  3. Nonimaging optics in luminescent solar concentration.

    PubMed

    Markman, B D; Ranade, R R; Giebink, N C

    2012-09-10

    Light trapped within luminescent solar concentrators (LSCs) is naturally limited in angular extent by the total internal reflection critical angle, θcrit, and hence the principles of nonimaging optics can be leveraged to increase LSC concentration ratio by appropriately reshaping the edges. Here, we use rigorous ray-tracing simulations to explore the potential of this concept for realistic LSCs with compound parabolic concentrator (CPC)-tapered edges and show that, when applied to a single edge, the concentration ratio is increased by 23% while maintaining >90% of the original LSC optical efficiency. Importantly, we find that CPC-tapering all of the edges enables a significantly greater intensity enhancement up to 35% at >90% of the original optical efficiency, effectively enabling two-dimensional concentration through a cooperative, ray-recycling effect in which rays rejected by one CPC are accepted by another. These results open up a significant opportunity to improve LSC performance at virtually no added manufacturing cost by incorporating nonimaging optics into their design. PMID:23037529

  4. Luminescence characteristics of caffeine and theophylline1

    NASA Astrophysics Data System (ADS)

    Andino, M. M.; De Lima, C. G.; Winefordner, J. D.

    The luminescence properties of solutions of caffeine and theophylline in methanol are observed. The effects of the solvent pH, the presence of a heavy atom and the matrix or substrate on the fluorescence and phosphorescence properties of the compounds are evaluated. Caffeine and theophylline fluorescence can be observed at room temperature from dilute methanolic solutions and strong phosphorescence is observed at low temperature when the matrix is in a polycrystalline state. Acidic and basic media cause spectral changes and reduce the intensity of the low temperature phosphorescence. Iodide is a good heavy-atom enhancer of both the low temperature and room temperature phosphorescence of caffeine and theophylline. The intensity of the phosphorescence at room temperature and when spotted on filter paper depends on the type of filter paper and the pH of the spotting solution and/or the pH of the wet surface at the moment of spotting. Theophylline is more sensitive than caffeine to the microenvironment. Under the appropriate experimental conditions, both low temperature and room temperature phosphorescence could be used as analytical tools for the determination of caffeine and theophylline.

  5. 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...

  6. A REVIEW OF APPLICATIONS OF LUMINESCENCE TO MONITORING OF CHEMICAL CONTAMINANTS IN THE ENVIRONMENT

    EPA Science Inventory

    The recent analytical literature on the application of luminescence techniques to the measurement of various classes of environmentally significant chemicals has been reviewed. Luminescent spectroscopy based methods are compared to other current techniques. Also, examples of rece...

  7. Patterning, integration and characterisation of polymer optical oxygen sensors for microfluidic devices.

    PubMed

    Nock, Volker; Blaikie, Richard J; David, Tim

    2008-08-01

    This paper describes a process for the layer-by-layer fabrication and integration of luminescent dye-based optical oxygen sensors into microfluidic devices. Application of oxygen-sensitive platinum(ii) octaethylporphyrin ketone fluorescent dye dissolved in polystyrene onto glass substrates by spin-coating was studied. Soft lithography with polydimethylsiloxane (PDMS) stamps and reactive ion etching in oxygen plasma were used to produce sensor patterns with a minimum feature size of 25 microm. Sensors patterns were integrated into a PDMS microfluidic device by plasma bonding. No degradation of the sensor response as a result of the lithography and pattern-transfer processes was detected. Gaseous and dissolved oxygen (DO) detection was characterised using fluorescence microscopy. The intensity signal ratio of the sensor films was found to increase almost two-fold from 3.6 to 6.8 by reducing film thickness from 1.3 microm to 0.6 microm. Calibration of DO measurement showed linear Stern-Volmer behaviour that was constant for flow rates from 0.5 to 2 mL min(-1). The calibrated sensors were subsequently used to demonstrate laterally resolved detection of oxygen inside a microfluidic channel. The fabrication process provides a novel, easy to use method for the repeatable integration of optical oxygen sensors into cell-culture and lab-on-a-chip devices.

  8. Luminescent instabilities and nonradiative processes in rare earth systems

    NASA Astrophysics Data System (ADS)

    Redmond, Shawn Michael

    This research is an outgrowth of earlier experiments that demonstrated bistable luminescence in heavy metal halide crystals doped with trivalent ytterbium ions. This type of instability has importance as a fundamentally new physical phenomenon with a potential application for fast all-optical switching as well as a limitation on compact solid state laser performance. In this thesis, the investigation of luminescent instabilities is extended to bistable energy transfer processes in crystals and to the observation of "bistable" blackbody emission in rare earth nanopowders. High resolution laser spectroscopy was used to study bistable luminescence and energy transfer in Yb,Er:CsCdBr3 crystals at cryogenic temperatures. For the first time, it was found that bistable behavior associated with Yb 3+ ions was transferred to Er3+ through resonant energy transfer. Bistability of the resulting sensitized luminescence caused sufficiently dramatic changes in the crystal dynamics so as to change the color of emission from yellow to green. This color changing phenomenon is fully explained in the present work and is referred to as "chromatic switching." Temperature is a critical variable that is known to govern luminescent instabilities in all current theories. Therefore, in a search for new systems with luminescent instabilities at high temperatures, materials with extreme thermal properties were investigated as part of this research. Yb,Er:Y 2O3 nanopowders were selected for this purpose. Nanopowders exhibit greatly reduced thermal conductivity and were verified during the course of this work to cause enhanced absorption as the result of multiple scattering. Significant spectral differences between Yb,Er:Y2O 3 nanopowders and single crystals also emerged. Measurements of erbium upconversion luminescence versus pump intensity in resonance with the ytterbium absorption transition revealed striking new optical phenomena: strong luminescent quenching, intense "bistable" blackbody

  9. User guide for luminescence sampling in archaeological and geological contexts

    USGS Publications Warehouse

    Nelson, Michelle S.; Gray, Harrison J.; Johnson, Jack A.; Rittenour, Tammy M.; Feathers, James K.; Mahan, Shannon

    2015-01-01

    Luminescence dating provides a direct age estimate of the time of last exposure of quartz or feldspar minerals to light or heat and has been successfully applied to deposits, rock surfaces, and fired materials in a number of archaeological and geological settings. Sampling strategies are diverse and can be customized depending on local circumstances, although all sediment samples need to include a light-safe sample and material for dose-rate determination. The accuracy and precision of luminescence dating results are directly related to the type and quality of the material sampled and sample collection methods in the field. Selection of target material for dating should include considerations of adequacy of resetting of the luminescence signal (optical and thermal bleaching), the ability to characterize the radioactive environment surrounding the sample (dose rate), and the lack of evidence for post-depositional mixing (bioturbation in soils and sediment). Sample strategies for collection of samples from sedimentary settings and fired materials are discussed. This paper should be used as a guide for luminescence sampling and is meant to provide essential background information on how to properly collect samples and on the types of materials suitable for luminescence dating.

  10. Study of Luminescence Characteristics of Trivalent Terbium in Silicate Glass

    NASA Technical Reports Server (NTRS)

    West, Mike S.; Armagan, Guzin; Winfree, William P.

    1995-01-01

    An important use of silicate glasses doped with terbium oxide (Tb2O3) is their use as fiber optic sensors for high-resolution imaging applications requiring the detection of x-rays (e.g. tomography and radiography). The x-ray radiation is absorbed by the glass, producing electron-hole pairs (excitons). The excitons migrate through the glass matrix and then recombine, emitting characteristic Tb(3+) luminescence in the optical wavelength region. This emission is due to forbidden transitions of 4f electrons and therefore has a long decay time. Long decay time is undesirable when imaging transient events since it results in blurring in time of the images. It has been reported elsewhere that in crystals Tb(3+) ions can act both as luminescence centers and as fluorescence traps. These traps can capture excitons and delay their recombination. This delayed fluorescence is seen as a long lived, secondary component to the luminescence decay curve, or afterglow. Such a secondary decay component to the luminescence decay of Tb(3+) has been observed before in soda glass following pulsed optical excitation. In order to determine the conditions under which afterglow occurs, an understanding of the material's luminescent properties is required.

  11. Recent Advances on Luminescent Enhancement-Based Porous Silicon Biosensors.

    PubMed

    Jenie, S N Aisyiyah; Plush, Sally E; Voelcker, Nicolas H

    2016-10-01

    Luminescence-based detection paradigms have key advantages over other optical platforms such as absorbance, reflectance or interferometric based detection. However, autofluorescence, low quantum yield and lack of photostability of the fluorophore or emitting molecule are still performance-limiting factors. Recent research has shown the need for enhanced luminescence-based detection to overcome these drawbacks while at the same time improving the sensitivity, selectivity and reducing the detection limits of optical sensors and biosensors. Nanostructures have been reported to significantly improve the spectral properties of the emitting molecules. These structures offer unique electrical, optic and magnetic properties which may be used to tailor the surrounding electrical field of the emitter. Here, the main principles behind luminescence and luminescence enhancement-based detections are reviewed, with an emphasis on europium complexes as the emitting molecule. An overview of the optical porous silicon microcavity (pSiMC) as a biosensing platform and recent proof-of-concept examples on enhanced luminescence-based detection using pSiMCs are provided and discussed.

  12. Occurrence and Expression of Luminescence in Vibrio cholerae▿

    PubMed Central

    Grim, Christopher J.; Taviani, Elisa; Alam, Munirul; Huq, Anwar; Sack, R. Bradley; Colwell, Rita R.

    2008-01-01

    Several species of the genus Vibrio, including Vibrio cholerae, are bioluminescent or contain bioluminescent strains. Previous studies have reported that only 10% of V. cholerae strains are luminescent. Analysis of 224 isolates of non-O1/non-O139 V. cholerae collected from Chesapeake Bay, MD, revealed that 52% (116/224) were luminescent when an improved assay method was employed and 58% (130/224) of isolates harbored the luxA gene. In contrast, 334 non-O1/non-O139 V. cholerae strains isolated from two rural provinces in Bangladesh yielded only 21 (6.3%) luminescent and 35 (10.5%) luxA+ isolates. An additional 270 clinical and environmental isolates of V. cholerae serogroups O1 and O139 were tested, and none were luminescent or harbored luxA. These results indicate that bioluminescence may be a trait specific for non-O1/non-O139 V. cholerae strains that frequently occur in certain environments. Luminescence expression patterns of V. cholerae were also investigated, and isolates could be grouped based on expression level. Several strains with defective expression of the lux operon, including natural K variants, were identified. PMID:18065611

  13. Luminescent Colloidal Semiconductor Nanocrystals Containing Copper: Synthesis, Photophysics, and Applications.

    PubMed

    Knowles, Kathryn E; Hartstein, Kimberly H; Kilburn, Troy B; Marchioro, Arianna; Nelson, Heidi D; Whitham, Patrick J; Gamelin, Daniel R

    2016-09-28

    Copper-doped semiconductors are classic phosphor materials that have been used in a variety of applications for many decades. Colloidal copper-doped semiconductor nanocrystals have recently attracted a great deal of interest because they combine the solution processability and spectral tunability of colloidal nanocrystals with the unique photoluminescence properties of copper-doped semiconductor phosphors. Although ternary and quaternary semiconductors containing copper, such as CuInS2 and Cu2ZnSnS4, have been studied primarily in the context of their photovoltaic applications, when synthesized as colloidal nanocrystals, these materials have photoluminescence properties that are remarkably similar to those of copper-doped semiconductor nanocrystals. This review focuses on the luminescent properties of colloidal copper-doped, copper-based, and related copper-containing semiconductor nanocrystals. Fundamental investigations into the luminescence of copper-containing colloidal nanocrystals are reviewed in the context of the well-established luminescence mechanisms of bulk copper-doped semiconductors and copper(I) molecular coordination complexes. The use of colloidal copper-containing nanocrystals in applications that take advantage of their luminescent properties, such as bioimaging, solid-state lighting, and luminescent solar concentrators, is also discussed.

  14. Water-triggered luminescent "nano-bombs" based on supra-(carbon nanodots).

    PubMed

    Lou, Qing; Qu, Songnan; Jing, Pengtao; Ji, Wenyu; Li, Di; Cao, Junsheng; Zhang, Hong; Liu, Lei; Zhao, Jialong; Shen, Dezhen

    2015-02-25

    Novel luminescent "nano-bombs" based on a self-assembled system of carbon-nanodots, termed supra-CDs, are developed. The luminescence of these luminescent "nano-bombs" depends strongly on water contact; they show weak emission in toluene and decompose in contact with water, resulting in strong photoluminescence. Paper coated with these "nano-bombs" is successfully applied for water-jet printing of luminescence patterns and the mapping of human sweat-pore patterns.

  15. Crystal structures and optical properties of new quaternary strontium europium aluminate luminescent nanoribbons

    DOE PAGES

    Li, Xufan; Budai, John D.; Liu, Feng; Chen, Yu-Sheng; Howe, Jane Y.; Sun, Chengjun; Tischler, Jonathan Zachary; Meltzer, Richard; Pan, Zhengwei

    2014-11-12

    We report the synthesis and characterizations of three series of quaternary strontium europium aluminate (Sr-Eu-Al-O; SEAO) luminescent nanoribbons that show blue, green, and yellow luminescence from localized Eu2+ luminescent centers. These three series of SEAO nanoribbons are: blue luminescent, tetragonal Sr1-xEuxAl6O10 (01-xEuxAl2O4 (01-xEuxAl2O4 (0

  16. Luminescence emission of natural fluorite and synthetic CaF2:Mn (TLD-400)

    NASA Astrophysics Data System (ADS)

    Topaksu, Mustafa; Correcher, Virgilio; Garcia-Guinea, Javier

    2016-02-01

    The luminescence properties of natural white fluorite indicate that it could be employed as radiation dosimeter similarly to synthetic CaF2:Mn (TLD-400). The cathodoluminescence emission of the natural sample (two maxima) meanwhile TLD-400 (one peak) exhibits a different behaviour associated with the chemical composition. The mineral sample displays (i) a significant UV-blue emission associated with different structural defects (negligible in the synthetic sample) and (ii) a shift of the green emission to higher wavelengths respect to the TLD-400. The green induced TL emission also shows significant differences in intensity (higher in TLD-400) and sensitivity. Both samples display a complex induced green TL glow curve that could not be analysed assuming the model based on the discrete trap distribution. The Tm-Tstop method indicates the presence of close overlapping groups of components linked probably to a continuum in the trap distribution rather than a single trapping level.

  17. Neutron flux characterisation of the Pavia TRIGA Mark II research reactor for radiobiological and microdosimetric applications.

    PubMed

    Alloni, D; Prata, M; Salvini, A; Ottolenghi, A

    2015-09-01

    Nowadays the Pavia TRIGA reactor is available for national and international collaboration in various research fields. The TRIGA Mark II nuclear research reactor of the Pavia University offers different in- and out-core neutron irradiation channels, each characterised by different neutron spectra. In the last two years a campaign of measurements and simulations has been performed in order to guarantee a better characterisation of these different fluxes and to meet the demands of irradiations that require precise information on these spectra in particular for radiobiological and microdosimetric studies. Experimental data on neutron fluxes have been collected analysing and measuring the gamma activity induced in thin target foils of different materials irradiated in different TRIGA experimental channels. The data on the induced gamma activities have been processed with the SAND II deconvolution code and finally compared with the spectra obtained with Monte Carlo simulations. The comparison between simulated and measured spectra showed a good agreement allowing a more precise characterisation of the neutron spectra and a validation of the adopted method. PMID:25958412

  18. Analytical characterisation of homoeopathic mother tinctures.

    PubMed

    Biber, A; Franck-Karl, G; Waimer, F; Riegert, U; Wiget, R

    2009-03-01

    Quality of homoeopathic mother tinctures is assured by the definition of the starting material, the manufacturing process and the analytical characteristics described in the monograph. Traditionally analytical characterisation of the mother tincture comprises appearance, odour, identity, density and dry residue. According to annex I of directive 2001/83/EC an assay is only performed in case of a health hazard due to toxic compounds. The concept of marker substances as usually used in phytotherapy cannot be transferred to mother tinctures without research effort. For example the marker substances echinacoside, apigenin-7-glucoside and rosmarinic acid found in dried underground parts of Echinacea pallida Nutt., dried flower heads of Matricaria recutita L. and dried herb of Pulmonaria officinalis L. cannot be found in homoeopathic mother tinctures prepared from fresh material thereof. PMID:19275866

  19. Ytterbium (III) Luminescence in m-Methylbenzoic Acid-Containing Compounds.

    PubMed

    Kalinovskaya, I V; Zadorozhnaya, A N

    2015-05-01

    Complex compounds of ytterbium(III) with m-methylbenzoic acid and nitrogen-containing ligands luminescent in near infrared range have been synthesized. Spectral luminescence characteristics of heteroligand compounds of ytterbium(III) have been investigated. It has been established that ytterbium (III) m-methylbenzoate with 1,10-phenanthroline is characterized by the highest luminescence intensity.

  20. Preparation and characterisation of hexamidine salts.

    PubMed

    Parisi, Nicola; Matts, Paul J; Lever, Rebecca; Hadgraft, Jonathan; Lane, Majella E

    2015-09-30

    Hexamidine diisethionate (HEX D) has been used in the personal care industry and in a number of over-the-counter (OTC) drug products as an antimicrobial agent since the 1950's. Recently, the compound has also been investigated for its beneficial effects on skin health. Surprisingly, there is only limited information describing the physicochemical properties of this compound in the literature. The objective of this work was therefore to conduct a comprehensive programme of characterisation of HEX D as well as its dihydrochloride salt (HEX H). HEX H was prepared from HEX D by a simple acid addition reaction. Both salts were characterised using Nuclear Magnetic Resonance (NMR), Differential scanning calorimetry (DSC), and Thermogravimetric analysis (TGA). A new high performance liquid chromatographic method was developed and validated for both compounds. The pH in aqueous solution as well as respective distribution coefficients between octanol and pH 7.4 buffer were also determined. Finally, solubility and short term stability studies were conducted in a range of solvents. NMR analysis confirmed the preparation of HEX H from HEX D. Thermal analysis indicated the melting points of HEX D and HEX H were 225°C and 266°C respectively. HPLC analysis confirmed the purity of both salts. LogD values at pH 7.4 were -0.74 for HEX D and -0.70 for HEX H respectively. The physicochemical properties of two HEX salts have been established using a range of analytical approaches. Detailed solubility and stability data have also been collated. This information will be useful in the design of novel formulations for targeted delivery of these compounds to the skin.

  1. Cryogels: morphological, structural and adsorption characterisation.

    PubMed

    Gun'ko, Vladimir M; Savina, Irina N; Mikhalovsky, Sergey V

    2013-01-01

    Experimental results on polymer, protein, and composite cryogels and data treatment methods used for morphological, textural, structural, adsorption and diffusion characterisation of the materials are analysed and compared. Treatment of microscopic images with specific software gives quantitative structural information on both native cryogels and freeze-dried materials that is useful to analyse the drying effects on their structure. A combination of cryoporometry, relaxometry, thermoporometry, small angle X-ray scattering (SAXS), equilibrium and kinetic adsorption of low and high-molecular weight compounds, diffusion breakthrough of macromolecules within macroporous cryogel membranes, studying interactions of cells with cryogels provides a consistent and comprehensive picture of textural, structural and adsorption properties of a variety of cryogels. This analysis allows us to establish certain regularities in the cryogel properties related to narrow (diameter 0.4100 μm) with boundary sizes within modified life science pore classification. Particular attention is paid to water bound in cryogels in native superhydrated or freeze-dried states. At least, five states of water - free unbound, weakly bound (changes in the Gibbs free energy-ΔG<0.5-0.8 kJ/mol) and strongly bound (-ΔG>0.8 kJ/mol), and weakly associated (chemical shift of the proton resonance δ(H)=1-2 ppm) and strongly associated (δ(H)=3-6 ppm) waters can be distinguished in hydrated cryogels using (1)H NMR, DSC, TSDC, TG and other methods. Different software for image treatment or developed to analyse the data obtained with the adsorption, diffusion, SAXS, cryoporometry and thermoporometry methods and based on regularisation algorithms is analysed and used for the quantitative morphological, structural and adsorption characterisation of individual and composite cryogels, including polymers

  2. GNSS station characterisation for ionospheric scintillation applications

    NASA Astrophysics Data System (ADS)

    Romano, Vincenzo; Spogli, Luca; Aquino, Marcio; Dodson, Alan; Hancock, Craig; Forte, Biagio

    2013-10-01

    Ionospheric scintillations are fluctuations in the phase and amplitude of the signals from GNSS (Global Navigation Satellite Systems) occurring when they cross regions of electron density irregularities in the ionosphere. Such disturbances can cause serious degradation of several aspects of GNSS system performance, including integrity, accuracy and availability. The two indices adopted worldwide to characterise ionospheric scintillations are: the amplitude scintillation index, S4, which is the standard deviation of the received power normalised by its mean value, and the phase scintillation index, σΦ, which is the standard deviation of the de-trended carrier phase. Collaborative work between NGI and INGV supports a permanent network of GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers that covers a wide range of latitudes in the northern European sector. Data from this network has contributed significantly to several papers during the past few years (see e.g. De Franceschi et al., 2008; Aquino et al., 2009; Spogli et al., 2009, 2010; Alfonsi et al., 2011). In these investigations multipath effects and noise that contaminate the scintillation measurements are largely filtered by applying an elevation angle threshold. A deeper analysis of the data quality and the development of a more complex filtering technique can improve the results obtained so far. The structures in the environment of each receiver in the network which contaminate scintillation measurements should be identified in order to improve the quality of the scintillation and TEC data by removing error sources due to the local environment. The analysis in this paper considers a data set characterised by quiet ionospheric conditions of the mid-latitude station located in Nottingham (UK), followed by a case study of the severe geomagnetic storm, which occurred in late 2003, known generally as the "Halloween Storm".

  3. Exoplanetary Characterisation Observatory (EChO)

    NASA Astrophysics Data System (ADS)

    Waldmann, Ingo; Tinetti, Giovanna

    2013-04-01

    The science of extrasolar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 800-plus planets being detected, and over 2000 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are? The Exoplanet Characterisation Observatory (EChO) is a space mission dedicated to undertaking spectroscopy of transiting exoplanets over the widest range possible and is currently being studied by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The mission is based around a highly stable space platform with a 1.2 m class telescope at L2, hosting a suit of spectrographs providing continuous spectral coverage from 0.5 to 16 microns. Such a broad and simultaneous wavelength coverage allows the unique insight into the atmospheric make up of these foreign worlds and allows us to study their planetary and atmospheric compositions and evolutions.

  4. Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media

    NASA Astrophysics Data System (ADS)

    Crane, R. A.; Cuthbert, M. O.; Timms, W.

    2015-09-01

    We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge-induced flow, no flow and centrifuge-induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite-clay-dominated core samples. All core samples exhibited a non-Fickian tracer breakthrough (early tracer arrival), combined with a decrease in tracer concentration immediately after each period of interrupted flow. This is indicative of dual (or multi-)porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s) and the low hydraulic conductivity domain) during interrupted flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash-Sutcliffe model efficiency coefficient was > 0.97 for all samples). In combination, interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.

  5. Luminescence efficiency of silica during ion beam excitation

    NASA Astrophysics Data System (ADS)

    Abu-Hassan, L. H.; Townsend, P. D.

    1988-05-01

    During ion beam implantation of silica light is produced by electronic excitation of the glass network. In order to vary the mechanisms of excitation and decay data were taken with a wide range of ions and ion energies (e.g. H +, H +2, He +, Ne +, N +, N +2 and A + from 5 keV to 2.8 MeV). The results suggest that the light is generated with different luminescence efficiency in regions of electronic damage, collision damage and, in the case of nitrogen, of impurities. Additionally, exciton or electron diffusion from the implanted region generates luminescence several microns beneath the implant. The relative efficiencies in these processes are discussed. One consequence of these differences is that in measurements of the luminescence efficiency as a function of energy one observes an apparent peak in efficiency if the sequence commences at high energy. The "peak" is a function of the initial energy.

  6. Luminescence centers in anhydrite, barite, celestite and their synthesized analogs

    NASA Astrophysics Data System (ADS)

    Gaft, M. L.; Bershov, L. V.; Krasnaya, A. R.; Yaskolko, V. Ya.

    1985-01-01

    The intrinsic luminescence center (LC) of SO{4/2-}appears at 360 nm in all types of sulfates, but is absent in sulfates with large quantities of impurities. Three nonequivalent Gd3+ LC have been observed in luminescence spectra of anhydrite. Gd3+, Ce3+ O{2/-}LC were established in celestite. Photoluminescence (PL) bands in the sulfates were assigned as follows: the band at 460 nm is related to Eu2+ (a connection with Al3+ or donor-acceptor pair is possible also) in sulfates of Ca and Ba; bands at 520 nm and 590 nm are related to VO4, MoO4 and TiO4 substituting SO4; the band at 660 nm is assigned to Ti3+ X-ray luminescence (XL) band at 620 nm is assigned to Ag+.

  7. Luminescent complexes of terbium ion for molecular recognition of ibuprofen.

    PubMed

    Selivanova, Natalia; Vasilieva, Kristina; Galyametdinov, Yury

    2014-05-01

    The complexation behavior and luminescent properties of terbium (Tb(3+) ) complexes containing bi-dental ligands were studied: nitrogen - 1,10-phenanthroline, and oxygen - trifluoroacetylacetone as well as acetylacetone ligands with ibuprofen (Ibu; a non-steroidal anti-inflammatory drug). Aqueous and aqueous alcohol microheterogeneous solutions were used as media. The effects of solubilization by various micellar solutions, pH and ligand type on luminescent properties of Tb(3+) complexes were investigated. Sensitized luminescence of mixed ligand complex Tb(1,10-phenanthroline)-Ibu and dynamic quenching effect in complex Tb(trifluoroacetylacetone)3 -Ibu allow Ibu determination with the limit of detection 5.3 × 10(-8)  mol/L and 1.26 × 10(-6)  mol/L, respectively.

  8. Synthesis, characterization, and green luminescence in ZnO nanocages.

    PubMed

    Snure, Michael; Tiwari, Ashutosh

    2007-02-01

    In this paper, we report the synthesis, characterization and observation of green luminescence in ZnO nanocages. A novel low temperature solution-based technique has been developed for growing highly porous ZnO nano-cages from coarse ZnO precursor powders. Various samples, prepared in this study, were characterized using several different characterization tools such as X-ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Raman, Photoluminescence and Optical Transmission Spectroscopy. It has been shown that ZnO nanocages exhibit green luminescence, with PL data showing a broad green peak at 510 nm. The shift and broadening in the luminescence peaks are understood to arise because of the onset of deep level defects in the system.

  9. Spectral and luminescent properties of ammonia cyclopalladated complexes

    NASA Astrophysics Data System (ADS)

    Nikolaeva, M. V.; Puzyk, M. V.

    2013-12-01

    The synthesis of ammonia cyclometalated palladium(II) complexes [Pd(NH3)2C^N]ClO4 (C^N is the deprotonated form of 2-phenylpyridine, 2-(para-tolyl)pyridine, 7,8-benzo(h)quinoline, 2,6-diphenylpyridine, and 4-phenylpyrimidine) is developed. The IR and electronic absorption and emission spectra of these complexes are studied. It is found that the ammine and analogous ethylenediamine cyclometalated Pd(II) complexes have similar spectral and luminescent properties and the same nature of the electronically excited 3(π-π*)-type state responsible for the long-lived luminescence, the π and π* orbitals being localized on the corresponding cyclometalating ligand. The efficient temperature quenching of the luminescence of Pd(II) complexes at room temperature is assigned to the thermally activated population of metal-centered electronically excited states with subsequent nonradiative deactivation.

  10. Luminescence dating of Middle Stone Age deposits at Die Kelders.

    PubMed

    Feathers, J K; Bush, D A

    2000-01-01

    Luminescence dating of sediments has not been used extensively for dating Middle Stone Age deposits in South Africa, despite its potential for contributing to a poorly dated record. Such deposits at Die Kelders cave, on the southern South African coast, consist of narrow bands of occupation debris separated by thicker layers of aeolian sands containing much less evidence of occupation. Homogeneous, aeolian sediments are usually considered ideal for luminescence dating. Here we report luminescence analyses of five samples from these sands that demonstrate sufficient bleaching prior to burial to validate dating and that yield ages of about 60-70 ka, in agreement with other evidence from sedimentology, archaeology and electron spin resonance. Lack of significant differences in the ages suggests the deposits accumulated fairly rapidly during the early part of the Last Glaciation. PMID:10627398

  11. Infrared luminescence for real time ionizing radiation detection

    SciTech Connect

    Veronese, Ivan Mattia, Cristina De; Cantone, Marie Claire; Fasoli, Mauro; Chiodini, Norberto; Vedda, Anna; Mones, Eleonora

    2014-08-11

    Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the “stem effect,” is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb{sup 3+}, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required.

  12. Luminescent Probes for Ultrasensitive Detection of Nucleic Acids

    PubMed Central

    Krasnoperov, Lev N.; Marras, Salvatore A.E.; Kozlov, Maxim; Wirpsza, Laura; Mustaev, Arkady

    2010-01-01

    Novel amino-reactive derivatives of lanthanide-based luminescent labels of enhanced brightness and metal retention were synthesized and used for the detection of complementary DNA oligonucleotides by molecular beacons. Time-resolved acquisition of the luminescent signal that occurs upon hybridization of the probe to the target enabled the avoidance of short-lived background fluorescence, markedly enhancing the sensitivity of detection, which was less than 1 pM. This value is about 50 to 100 times more sensitive than the level achieved with conventional fluorescence-based molecular beacons, and is 10 to 60 times more sensitive than previously reported for other lanthanide-based hybridization probes. These novel luminescent labels should significantly enhance the sensitivity of all type of nucleic acid hybridization probes, and could dramatically improve the detection limit of other biopolymers and small compounds that are used in a variety of biological applications. PMID:20085336

  13. Luminescent microbanding in speleothems: High-resolution chronology and paleoclimate

    NASA Astrophysics Data System (ADS)

    Shopov, Y. Y.; Ford, D. C.; Schwarcz, H. P.

    1994-05-01

    When illuminated by ultraviolet light, many calcite speleothems (stalagmites, stalactites, flowstones) display luminescence caused by the presence of organic (humic) substances occluded in the calcite. The amplitude of luminescence varies in a banded pattern parallel to growth layering. Through 14C and thermal ionization mass spectrometry uranium-series dating, we show that cyclical oscillations in the luminescence have periodicities ranging from a few days to ≥105 yr. A well-defined annual cycle is present in many vadose-zone speleothems and can be used to define the chronology of short-term events. This cycle is probably a response to hydrological events in the recharge to the cave. Longer term oscillations are inferred to be controlled by climate, through its effect on organic activity in the overlying soil.

  14. Spodumene and garnet luminescence excited by subnanosecond electron beams

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh.; Burachenko, A. G.; Solomonov, V. I.; Tarasenko, V. F.

    2011-11-01

    Pulsed cathodoluminescence of spodumene and yttrium-aluminum garnet crystals activated by Mn2+ and Nd3+ ions, respectively, is investigated. The luminescence was excited upon crystal irradiation by electron beams with current densities of 35 and 100 A/cm2 and average electron energy of ˜ 50 keV for 0.1, 0.25, and 0.65 ns. It is demonstrated that the electron beam duration decreased to several tenth of a nanosecond does not lead to essential changes of the mechanisms of pulsed cathodoluminescence excitation and character of its spectrum, but in this case, the intensity of luminescence of the hole centers increases compared with the intracenter luminescence.

  15. New developments in luminescence for solar energy utilization

    NASA Astrophysics Data System (ADS)

    Reisfeld, Renata

    2010-07-01

    As our fossil sources of energy diminish constantly search for alternative energy solutions becomes vital. The interest in exploiting solar energy for photovoltaic electricity has grown exponentially in recent decade, however, its high cost is still a limiting factor for massive uses. Static luminescent concentrator could provide a partial solution if properly designed. The paper summarizes the requirements for efficient and photostable luminescent concentrators, provides the latest results and ideas and shows how they can be materialized. It is demonstrated how the plate efficiency can be improved by applying a thin film with optical contact to transparent plate, silver plasmons that increase the transition probability of the colorants, photonic systems preventing the escape of the luminescence from the plate when traveling to the cell, creating fluorescence in the UV and visible part of the spectrum, using materials in which the absorption and emission from different electronic levels prevent self-absorption.

  16. Reproducibility and utility of dune luminescence chronologies

    NASA Astrophysics Data System (ADS)

    Leighton, Carly L.; Thomas, David S. G.; Bailey, Richard M.

    2014-02-01

    Optically stimulated luminescence (OSL) dating of dune deposits has increasingly been used as a tool to investigate the response of aeolian systems to environmental change. Amalgamation of individual dune accumulation chronologies has been employed in order to distinguish regional from local geomorphic responses to change. However, advances in dating have produced chronologies of increasing complexity. In particular, questions regarding the interpretation of dune ages have been raised, including over the most appropriate method to evaluate the significance of suites of OSL ages when local 'noisy' and discontinuous records are combined. In this paper, these issues are reviewed and the reproducibility of dune chronologies is assessed. OSL ages from two cores sampled from the same dune in the northeast Rub' al Khali, United Arab Emirates, are presented and compared, alongside an analysis of previously published dune ages dated to within the last 30 ka. Distinct periods of aeolian activity and preservation are identified, which can be tied to regional climatic and environmental changes. This case study is used to address fundamental questions that are persistently asked of dune dating studies, including the appropriate spatial scale over which to infer environmental and climatic change based on dune chronologies, whether chronological hiatuses can be interpreted, how to most appropriately combine and display datasets, and the relationship between geomorphic and palaeoclimatic signals. Chronological profiles reflect localised responses to environmental variability and climatic forcing, and amalgamation of datasets, with consideration of sampling resolution, is required; otherwise local factors are always likely to dominate. Using net accumulation rates to display ages may provide an informative approach of analysing and presenting dune OSL chronologies less susceptible to biases resulting from insufficient sampling resolution.

  17. Sedimentological processes in lahars: Insights from optically stimulated luminescence analysis

    NASA Astrophysics Data System (ADS)

    Muñoz-Salinas, Esperanza; Bishop, Paul; Zamorano, Jose-Juan; Sanderson, David

    2012-01-01

    A lahar is a sediment-laden flow capable of major destructive impacts on infrastructure and human life. How lahars transport sediment is thus a key issue for understanding lahar sedimentology and behavior, especially in terms of the lahar's hydraulic and rheological properties, which can be substantially altered as the lahar gains or loses material during its travel. In this research, we analyze lahar entrainment processes by evaluating luminescence signals (total photon counts) from lahar sediments using blue luminescence signals (BLSL). A portable OSL reader that analyzes several grams of polymineral and polygrain-size samples was applied. We use data from three lahars in the Tenenepanco and Huiloac gorges on Popocatépetl volcano (Mexico) to elucidate the ways in which lahars may gain, lose and transport sediment during flow. Sediment samples for luminescence analysis were taken through the full thickness of the lahar deposits at eight different sites for two lahars (1997 and 2001) and at one site for a lahar that occurred > 500 yrs ago. Mean luminescence values obtained for the 1997 lahar help to evaluate the relationship between the lahar entrainment processes and the drainage at the different sites. For the 2001 lahar this relationship was also established taking into account the channel slope. The main conclusion is that luminescence signals (total photon counts) can be used to detect entrained material in the flow because the bulked materials modify the final OSL signals. The application of this type of luminescence analysis thus has the potential to provide a better understanding of sediment entrainment in these sediment-laden flows.

  18. Nanosecond and ultrafast optical power limiting in luminescent Fe2O3 hexagonal nanomorphotype

    NASA Astrophysics Data System (ADS)

    Thomas, Paulose; Sreekanth, P.; Abraham, K. E.

    2015-02-01

    Nonlinear optical absorption and optical power limiting properties of Fe2O3 hexagonal nanomorphotype are investigated using open aperture Z-scan technique with the 5 ns and 100 fs laser pulses, at 532 nm and 800 nm excitation domains. At relatively low pulse energies (below 5 μJ), sample shows saturable absorption (SA), but on going to the higher energies an interesting switchover from saturable absorption to effective two photon absorption is observed in both excitation domains. The magnitude of effective two photon absorption coefficients is calculated to be in the range of 10-10 m/W for nanosecond and 10-15 m/W for femtosecond laser pulse energies, respectively. XRD and TEM study reveals the polycrystalline nature, hexagonal morphology, and size of the nanostructure. The luminescence emission property is examined by photoluminescence spectroscopy (PL). It is found that some strange features exist in the luminescence spectra that are consistent with the nanoparticles size distribution. The PL emission lines are explained as originated from various optical band edges due to the size induced quantum confinement and band gap resonant PL absorption/emission behavior of semiconductor nanostructures.

  19. A solid-state dedicated circularly polarized luminescence spectrophotometer: Development and application

    NASA Astrophysics Data System (ADS)

    Harada, Takunori; Hayakawa, Hiroshi; Watanabe, Masayuki; Takamoto, Makoto

    2016-07-01

    A new solid-state dedicated circularly polarized luminescence (CPL) instrument (CPL-200CD) was successfully developed for measuring true CPL spectra for optically anisotropic samples on the basis of the Stokes-Mueller matrix approach. Electric components newly installed in the CPL-200CD include a pulse motor-driven sample rotation holder and a 100 kHz lock-in amplifier to achieve the linearly polarized luminescence measurement, which is essential for obtaining the true CPL signal for optically anisotropic samples. An acquisition approach devised for solid-state CPL analysis reduces the measurement times for a data set by ca. 98% compared with the time required in our previous method. As a result, the developed approach is very effective for samples susceptible to light-induced degradation. The theory and implementation of the method are described, and examples of its application to a CPL sample with macroscopic anisotropies are provided. An important advantage of the developed instrument is its ability to obtain molecular information for both excited and ground states because circular dichroism measurements can be performed by switching the monochromatic light to white light without rearrangement of the sample.

  20. Structural and luminescence properties of GaN nanowires grown using cobalt phthalocyanine as catalyst

    NASA Astrophysics Data System (ADS)

    Yadav, Shivesh; Rodríguez-Fernández, Carlos; de Lima, Mauricio M.; Cantarero, Andres; Dhar, Subhabrata

    2015-12-01

    Catalyst free methods have usually been employed to avoid any catalyst induced contamination for the synthesis of GaN nanowires with better transport and optical properties. Here, we have used a catalytic route to grow GaN nanowires, which show good optical quality. Structural and luminescence properties of GaN nanowires grown by vapor-liquid-solid technique using cobalt phthalocyanine as catalyst are systematically investigated as a function of various growth parameters such as the growth temperature and III/V ratio. The study reveals that most of the nanowires, which are several tens of microns long, grow along [ 10 1 ¯ 0 ] direction. Interestingly, the average wire diameter has been found to decrease with the increase in III/V ratio. It has also been observed that in these samples, defect related broad luminescence features, which are often present in GaN, are completely suppressed. At all temperatures, photoluminescence spectrum is found to be dominated only by a band edge feature, which comprises of free and bound excitonic transitions. Our study furthermore reveals that the bound excitonic feature is associated with excitons trapped in certain deep level defects, which result from the deficiency of nitrogen during growth. This transition has a strong coupling with the localized vibrational modes of the defects.

  1. Bright luminescence from pure DNA-curcumin-based phosphors for bio hybrid light-emitting diodes.

    PubMed

    Reddy, M Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s(-1). Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  2. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-08-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s‑1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

  3. Preparation and luminescence properties of ZnO:Ga - polystyrene composite scintillator.

    PubMed

    Burešová, Hana; Procházková, Lenka; Turtos, Rosana Martinez; Jarý, Vítězslav; Mihóková, Eva; Beitlerová, Alena; Pjatkan, Radek; Gundacker, Stefan; Auffray, Etiennette; Lecoq, Paul; Nikl, Martin; Čuba, Václav

    2016-07-11

    Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-exponential decay with the decay time around 500 ps.

  4. Bright luminescence from pure DNA-curcumin-based phosphors for bio hybrid light-emitting diodes.

    PubMed

    Reddy, M Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s(-1). Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

  5. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    PubMed Central

    Reddy, M. Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s−1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  6. Calcium involvement in the luminescence control of three ophiuroid species (Echinodermata).

    PubMed

    Dewael, Y; Mallefet, J

    2002-02-01

    Although it has been shown that calcium is involved in the control of the luminous reaction of many invertebrate phyla, its role in Echinoderms is poorly documented. The aim of this work was to carry out a comparative study of calcium requirement of KCl-induced light emission by arm segments and dissociated luminous cells from three ophiuroid species, Ophiopsila californica, O. aranea and Amphiura filiformis. Results show a gradual inhibition of the luminescence when preparations are incubated in artificial sea water with lowered calcium concentration. The calcium substitutes Ba(2+) and Sr(2+) could act either as blockers or as substitutes, depending on the ophiuroid species; while calcium blockers Co(2+), Ni(2+) and Cd(2+) inhibit light emission in A. filiformis and in O. californica, but not in O. aranea. The nature of putative calcium voltage-gated channel has been studied pharmacologically using 1,4-dihydropyridine, benzodiazepine, phenylalkylamine and trifluoroperazine. From our results, it is proposed that calcium could act via an L-type voltage-gated calcium channel in O. californica and A. filiformis but not in O. aranea. The precise role of calcium in luminescence control still remains unknown; it could act as a second messenger or as a co-factor of the luminous reaction.

  7. Preparation and luminescence properties of ZnO:Ga - polystyrene composite scintillator.

    PubMed

    Burešová, Hana; Procházková, Lenka; Turtos, Rosana Martinez; Jarý, Vítězslav; Mihóková, Eva; Beitlerová, Alena; Pjatkan, Radek; Gundacker, Stefan; Auffray, Etiennette; Lecoq, Paul; Nikl, Martin; Čuba, Václav

    2016-07-11

    Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-exponential decay with the decay time around 500 ps. PMID:27410805

  8. On the discovery of an unusual luminescent pigment in Van Gogh's painting "Les bretonnes et le pardon de pont Aven"

    NASA Astrophysics Data System (ADS)

    Comelli, D.; Nevin, A.; Brambilla, A.; Osticioli, I.; Valentini, G.; Toniolo, L.; Fratelli, M.; Cubeddu, R.

    2012-01-01

    Spectrally and lifetime-resolved UV-induced luminescence imaging have been applied to the in situ analysis of Vincent Van Gogh's painting on paper "Les bretonnes et le pardon de pont Aven". The in situ investigation revealed the presence of an unusual microsecond green emission from the white painted areas of the watercolour, and this long-lived emission has not been reported in modern paintings by other authors. In order to attribute and suggest an identification of the luminescent pigment, our analysis was integrated with further measurements on commercially available modern white pigments (zinc white, Lithopone white, Blanc Fixe, zinc sulphide, and copper-doped zinc sulphide) and with an in-depth study of the synthesis processes of zinc-based pigments available at the end of the 19th century. Analysis suggested an attribution of the unusual emission from the Van Gogh painting to a particular variety of zinc sulphide pigment, characterized by the presence of copper impurities which were unintentionally introduced in the crystal matrix during its production. The present study is the first application of lifetime imaging for the mapping of long-lived luminescence from the semi-conductor pigment.

  9. Dental depth profilometry using simultaneous frequency-domain infrared photothermal radiometry and laser luminescence for the diagnosis of dental caries

    NASA Astrophysics Data System (ADS)

    Nicolaides, Lena; Garcia, Jose A.; Mandelis, Andreas; Abrams, Stephen H.

    2001-04-01

    Frequency-domain IR photothermal radiometry is introduced as a dynamic dental diagnostic tool and its main features are compared with modulated laser luminescence for quantifying sound and carious enamel or dentin. Dental caries found in the fissures or grooves of teeth is very difficult to diagnose or quantify with the present clinical techniques. Visual examination and dental radiographs do not detect the presence of decay until there has been significant carious destruction of the tooth. A high-spatial-resolution dynamic experimental imaging set-up, which can provide simultaneous measurements of laser-induced frequency-domain IR photothermal radiometric and luminescence signals form defects in teeth, was developed. Following optical absorption of laser photons, the new set-up can monitor simultaneously and independently the non-radiative conversion, and the radiative de-excitation in turbid media such as hard dental tissue. This work is intended to show the complementarity between modulated luminescence and photothermal frequency scans in detecting carious lesions in teeth. A sound extracted molar with a dentin-enamel interface was introduced to examine the depth profilometric abilities of the method. Occlusal surfaces of teeth with potential areas of demineralization or carious destruction in the fissures were examined and compared to the signals produced by the sound enamel establishing the depth profilometric abilities of the method. The significance to clinical dentistry lies in the potential of this technique to detect and monitor early carious lesions in the pits and fissures of teeth.

  10. Enhanced luminescence excitation via efficient optical energy transfer (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Aad, Roy; Nomenyo, Komla D.; Bercu, Bogdan; Couteau, Christophe; Sallet, Vincent; Rogers, David J.; Molinari, Michael; Lérondel, Gilles

    2015-10-01

    Luminescent nanoscale materials (LNMs) have received widespread interest in sensing and lighting applications due to their enhanced emissive properties. For sensing applications, LNMs offer improved sensitivity and fast response time which allow for lower limits of detection. Meanwhile, for lighting applications, LNMs, such as quantum dots, offer an improved internal quantum efficiency and controlled color rendering which allow for better lighting performances. Nevertheless, due to their nanometric dimensions, nanoscale materials suffer from extremely weak luminescence excitation (i.e. optical absorption) limiting their luminescence intensity, which in turn results in a downgrade in the limits of detection and external quantum efficiencies. Therefore, enhancing the luminescence excitation is a major issue for sensing and lighting applications. In this work, we report on a novel photonic approach to increase the luminescence excitation of nanoscale materials. Efficient luminescence excitation increase is achieved via a gain-assisted waveguided energy transfer (G-WET). The G-WET concept consists on placing nanoscale materials atop of a waveguiding active (i.e. luminescent) layer with optical gain. Efficient energy transfer is thus achieved by exciting the nanoscale material via the tail of the waveguided mode of the active layer emission. The G-WET concept is demonstrated on both a nanothin layer of fluorescent sensitive polymer and on CdSe/ZnS quantum dots coated on ZnO thin film, experimentally proving up to an 8-fold increase in the fluorescence of the polymer and a 3-fold increase in the luminescence of the CdSe/ZnS depending of the active layer emission regime (stimulated vs spontaneous emission). Furthermore, we will discuss on the extended G-WET concept which consists on coating nanoscale materials on a nanostructured active layer. The nanostructured active layer offers the necessary photonic modulation and a high specific surface which can presumably lead to

  11. Reversibly tunable upconversion luminescence by host-guest chemistry.

    PubMed

    Taniguchi, Takaaki; Murakami, Tomoaki; Funatsu, Asami; Hatakeyama, Kazuto; Koinuma, Michio; Matsumoto, Yasumichi

    2014-09-01

    Tuning upconversion (UPC) luminescence using external stimuli and fields, as well as chemical reactions, is expected to lead to novel and efficient optical sensors. Herein, highly tunable UPC luminescence was achieved through a host-guest chemistry approach. Specifically, interlayer ion exchange reactions reversibly tuned the emission intensity and green-red color of Er/Yb-codoped A2La2Ti3O10 layered perovskite, where A corresponds to proton and alkali metal ions, enabling the visualization of host-guest interactions and reactions. PMID:25122035

  12. [Synthesis, characterization and NIR luminescence properties of erbium organic complexes].

    PubMed

    Wang, Huai-shan; Qian, Guo-dong; Wang, Min-quan; Luo, Yong-shi; Lin, Jiu-ling

    2005-03-01

    Several erbium organic complexes, hydrated erbium binary complexes with acetylacetone (AcAc) or dibenzoylmethane (DBM), erbium ternary complexes derived from 1,10-phenanthroline (Phen) with acetylacetone (AcAc), dibenzoylmethane (DBM) or trifluoroacetylacetone (TFA), were synthesized and identified by elemental analysis. The UV-Vis absorption and FTIR spectra measurements have been employed for all the erbium complexes. Near infrared (NIR) photoluminescence properties, such as luminescence intensity and effective bandwidth, of the erbium complexes were also studied. As a result, the erbium ternary complex with AcAc and Phen exhibits the most excellent luminescence properties among those investigated complexes.

  13. Luminescence of Apollo 14 and Apollo 15 lunar samples.

    NASA Technical Reports Server (NTRS)

    Greenman, N. N.; Gross, H. G.

    1972-01-01

    Luminescence measurements have been made of Apollo 14 lunar samples with far UV, X-ray, and proton irradiation and of Apollo 15 lunar samples with X-ray irradiation. Preliminary efficiencies with the far UV are in the range .01 to .001; efficiencies with X-rays and protons are in the range .000001 to .00000001. The crystalline igneous rocks show higher efficiencies, in general, than the breccias and glasses, and the ratio of intensity of the green to the blue luminescence peak tends to be higher for the crystalline igneous rocks than for the breccias and glasses.

  14. Expression and characterisation of recombinant molecules in transgenic soybean.

    PubMed

    da Cunha, Nicolau B; Murad, Andre M; Vianna, Giovanni R; Coelho, Cintia; Rech, Elibio L

    2013-01-01

    Seeds are organs specialised in accumulating proteins, and they may provide a potential economically viable platform for the large-scale production and storage of many molecules for pharmaceutical and other productive sectors. Soybean [Glycine max (L.) Merrill] has a high seed protein content and represents an excellent source of abundant and cheap biomass. Under greenhouse conditions and a daily photoperiod of 23 h of light, the soybean plant's vegetative growth can be significantly extended by inducing more than a tenfold increase in seed production when compared with plants cultivated under field conditions. Some factors involved in the production of different recombinant proteins in soybean seeds are discussed in this review. These include transgenic system, regulatory sequences and the use of Mass Spectrometry as a new tool for molecular characterisation of seed produced recombinant proteins. The important intrinsic characteristics and possibility of genetically engineering soybean seeds, using current advances in recombinant DNA technology including metabolic engineering and synthetic biology, should form the foundation for large-scale and more precise genome modification, making this crop an important candidate as bioreactor for production of recombinant molecules.

  15. Characterising two-pathogen competition in spatially structured environments.

    PubMed

    Poletto, Chiara; Meloni, Sandro; Van Metre, Ashleigh; Colizza, Vittoria; Moreno, Yamir; Vespignani, Alessandro

    2015-01-01

    Different pathogens spreading in the same host population often generate complex co-circulation dynamics because of the many possible interactions between the pathogens and the host immune system, the host life cycle, and the space structure of the population. Here we focus on the competition between two acute infections and we address the role of host mobility and cross-immunity in shaping possible dominance/co-dominance regimes. Host mobility is modelled as a network of traveling flows connecting nodes of a metapopulation, and the two-pathogen dynamics is simulated with a stochastic mechanistic approach. Results depict a complex scenario where, according to the relation among the epidemiological parameters of the two pathogens, mobility can either be non-influential for the competition dynamics or play a critical role in selecting the dominant pathogen. The characterisation of the parameter space can be explained in terms of the trade-off between pathogen's spreading velocity and its ability to diffuse in a sparse environment. Variations in the cross-immunity level induce a transition between presence and absence of competition. The present study disentangles the role of the relevant biological and ecological factors in the competition dynamics, and provides relevant insights into the spatial ecology of infectious diseases. PMID:25600088

  16. Characterising two-pathogen competition in spatially structured environments

    NASA Astrophysics Data System (ADS)

    Poletto, Chiara; Meloni, Sandro; van Metre, Ashleigh; Colizza, Vittoria; Moreno, Yamir; Vespignani, Alessandro

    2015-01-01

    Different pathogens spreading in the same host population often generate complex co-circulation dynamics because of the many possible interactions between the pathogens and the host immune system, the host life cycle, and the space structure of the population. Here we focus on the competition between two acute infections and we address the role of host mobility and cross-immunity in shaping possible dominance/co-dominance regimes. Host mobility is modelled as a network of traveling flows connecting nodes of a metapopulation, and the two-pathogen dynamics is simulated with a stochastic mechanistic approach. Results depict a complex scenario where, according to the relation among the epidemiological parameters of the two pathogens, mobility can either be non-influential for the competition dynamics or play a critical role in selecting the dominant pathogen. The characterisation of the parameter space can be explained in terms of the trade-off between pathogen's spreading velocity and its ability to diffuse in a sparse environment. Variations in the cross-immunity level induce a transition between presence and absence of competition. The present study disentangles the role of the relevant biological and ecological factors in the competition dynamics, and provides relevant insights into the spatial ecology of infectious diseases.

  17. Characterising two-pathogen competition in spatially structured environments.

    PubMed

    Poletto, Chiara; Meloni, Sandro; Van Metre, Ashleigh; Colizza, Vittoria; Moreno, Yamir; Vespignani, Alessandro

    2015-01-20

    Different pathogens spreading in the same host population often generate complex co-circulation dynamics because of the many possible interactions between the pathogens and the host immune system, the host life cycle, and the space structure of the population. Here we focus on the competition between two acute infections and we address the role of host mobility and cross-immunity in shaping possible dominance/co-dominance regimes. Host mobility is modelled as a network of traveling flows connecting nodes of a metapopulation, and the two-pathogen dynamics is simulated with a stochastic mechanistic approach. Results depict a complex scenario where, according to the relation among the epidemiological parameters of the two pathogens, mobility can either be non-influential for the competition dynamics or play a critical role in selecting the dominant pathogen. The characterisation of the parameter space can be explained in terms of the trade-off between pathogen's spreading velocity and its ability to diffuse in a sparse environment. Variations in the cross-immunity level induce a transition between presence and absence of competition. The present study disentangles the role of the relevant biological and ecological factors in the competition dynamics, and provides relevant insights into the spatial ecology of infectious diseases.

  18. Microfluidic approaches for epithelial cell layer culture and characterisation

    PubMed Central

    Thuenauer, Roland; Rodriguez-Boulan, Enrique; Römer, Winfried

    2014-01-01

    In higher eukaryotes, epithelial cell layers line most body cavities and form selective barriers that regulate the exchange of solutes between compartments. In order to fulfil these functions, the cells assume a polarised architecture and maintain two distinct plasma membrane domains, the apical domain facing the lumen and the basolateral domain facing other cells and the extracellular matrix. Microfluidic biochips offer the unique opportunity to establish novel in vitro models of epithelia in which the in vivo microenvironment of epithelial cells is precisely reconstituted. In addition, analytical tools to monitor biologically relevant parameters can be directly integrated on-chip. In this review we summarise recently developed biochip designs for culturing epithelial cell layers. Since endothelial cell layers, which line blood vessels, have similar barrier functions and polar organisation as epithelial cell layers, we also discuss biochips for culturing endothelial cell layers. Furthermore, we review approaches to integrate tools to analyse and manipulate epithelia and endothelia in microfluidic biochips, including methods to perform electrical impedance spectroscopy, methods to detect substances undergoing trans-epithelial transport via fluorescence, spectrophotometry, and mass spectrometry, techniques to mechanically stimulate cells via stretching and fluid flow-induced shear stress, and methods to carry out high-resolution imaging of vesicular trafficking with light microscopy. Taken together, this versatile microfluidic toolbox enables novel experimental approaches to characterise epithelial monolayers. PMID:24668405

  19. A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution

    NASA Astrophysics Data System (ADS)

    Hao, Ji-Na; Yan, Bing

    2016-06-01

    A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection. Electronic supplementary information (ESI) available: Experimental procedure, N2 adsorption-desorption isotherms, IR spectra, EDX mappings, ICP data, luminescence data, PXRD patterns, UV-Vis spectra, and XPS spectra. See DOI: 10.1039/c6nr02446g

  20. 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.