A novel combined approach of diffuse reflectance UV-Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application.

PubMed

Kumar, Raj; Sharma, Vishal

2017-03-15

The present research is focused on the analysis of writing inks using destructive UV-Vis spectroscopy (dissolution of ink by the solvent) and non-destructive diffuse reflectance UV-Vis-NIR spectroscopy along with Chemometrics. Fifty seven samples of blue ballpoint pen inks were analyzed under optimum conditions to determine the differences in spectral features of inks among same and different manufacturers. Normalization was performed on the spectroscopic data before chemometric analysis. Principal Component Analysis (PCA) and K-mean cluster analysis were used on the data to ascertain whether the blue ballpoint pen inks could be differentiated by their UV-Vis/UV-Vis NIR spectra. The discriminating power is calculated by qualitative analysis by the visual comparison of the spectra (absorbance peaks), produced by the destructive and non-destructive methods. In the latter two methods, the pairwise comparison is made by incorporating the clustering method. It is found that chemometric method provides better discriminating power (98.72% and 99.46%, in destructive and non-destructive, respectively) in comparison to the qualitative analysis (69.67%). Copyright © 2016 Elsevier B.V. All rights reserved.

Ultraviolet-Visible (UV-Vis) Microspectroscopic System Designed for the In Situ Characterization of the Dehydrogenation Reaction Over Platinum Supported Catalytic Microchannel Reactor.

PubMed

Suarnaba, Emee Grace Tabares; Lee, Yi Fuan; Yamada, Hiroshi; Tagawa, Tomohiko

2016-11-01

An ultraviolet visible (UV-Vis) microspectroscopic system was designed for the in situ characterization of the activity of the silica supported platinum (Pt) catalyst toward the dehydrogenation of 1-methyl-1,4-cyclohexadiene carried out in a custom-designed catalytic microreactor cell. The in situ catalytic microreactor cell (ICMC) with inlet/outlet ports was prepared using quartz cover as the optical window to facilitate UV-Vis observation. A fabricated thermometric stage was adapted to the UV-Vis microspectrophotometer to control the reaction temperature inside the ICMC. The spectra were collected by focusing the UV-Vis beam on a 30 × 30 µm area at the center of ICMC. At 393 K, the sequential measurement of the spectra recorded during the reaction exhibited a broad absorption peak with maximum absorbance at 260 nm that is characteristic for gaseous toluene. This result indicates that the silica supported Pt catalyst is active towards the dehydrogenation of 1-methyl-1,4-cyclohexadiene at the given experimental conditions. The onset of coke formation was also detected based on the appearance of absorption bands at 300 nm. The UV-Vis microspectroscopic system developed can be used further in studying the mechanism of the dehydrogenation reaction. © The Author(s) 2016.

Newer views of the Moon: Comparing spectra from Clementine and the Moon Mineralogy Mapper

USGS Publications Warehouse

Kramer, G.Y.; Besse, S.; Nettles, J.; Combe, J.-P.; Clark, R.N.; Pieters, C.M.; Staid, M.; Malaret, E.; Boardman, J.; Green, R.O.; Head, J.W.; McCord, T.B.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 m absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 m band depths than M 3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions. Copyright 2011 by the American Geophysical Union.

Newer views of the Moon: Comparing spectra from Clementineand the Moon Mineralogy Mapper

USGS Publications Warehouse

Georgiana Y. Kramer,; Sebastian Besse,; Nettles, Jeff; Jean-Philippe Combe,; Clark, Roger N.; Pieters, Carle M.; Matthew Staid,; Joseph Boardman,; Robert Green,; McCord, Thomas B.; Malaret, Erik; Head, James W.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 μm absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 μm band depths than M3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions.

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter.

PubMed

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-05

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C 10 mimBF 4 , C 12 mimBF 4 , C 16 mimBF 4 ) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C 16 mimBF 4 >CTAB>C 12 mimBF 4 >C 10 mimBF 4 . Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1 H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes. Copyright © 2018 Elsevier B.V. All rights reserved.

Study of interaction between ionic liquids and orange G in aqueous solution with UV-vis spectroscopy and conductivity meter

NASA Astrophysics Data System (ADS)

Zha, Jin-Ping; Zhu, Meng-Ting; Qin, Li; Wang, Xin-Hong

2018-05-01

The interactions between Orange G (OG) with three kinds of ionic liquid surfactants (C10mimBF4, C12mimBF4, C16mimBF4) and CTAB were studied with UV-Vis spectra and conductivity measurements. The systematic changes in UV-Vis spectra with an increase of carbon-chain length may be observed in presence of OG. They correspond to CMC of every system, respectively, and the CMCs of four systems have exhibit the decrease of CMCs compared to pure surfactant. The binding constants are calculated from the results of conductivity measurements in the order of C16mimBF4 > CTAB > C12mimBF4 > C10mimBF4. Furthermore, system behaviors presented significant association of complex formation and micelles formation, i.e. the change in UV-Vis spectra before and after the formation of micelles in mixed systems. In addition, Fourier-transform infrared (FT-IR) spectroscopy and 1H NMR analysis further confirmed that the complexes are formed by hydrogen bond and van der Waal force. These findings could provide scientific guidance for extraction and separation of dyes.

Theoretical and Experimental Spectroscopic Analysis of Cyano-Substituted Styrylpyridine Compounds

PubMed Central

Castro, Maria Eugenia; Percino, Maria Judith; Chapela, Victor M.; Ceron, Margarita; Soriano-Moro, Guillermo; Lopez-Cruz, Jorge; Melendez, Francisco J.

2013-01-01

A combined theoretical and experimental study on the structure, infrared, UV-Vis and 1H NMR data of trans-2-(m-cyanostyryl)pyridine, trans-2-[3-methyl-(m-cyanostyryl)] pyridine and trans-4-(m-cyanostyryl)pyridine is presented. The synthesis was carried out with an efficient Knoevenagel condensation using green chemistry conditions. Theoretical geometry optimizations and their IR spectra were carried out using the Density Functional Theory (DFT) in both gas and solution phases. For theoretical UV-Vis and 1H NMR spectra, the Time-Dependent DFT (TD-DFT) and the Gauge-Including Atomic Orbital (GIAO) methods were used, respectively. The theoretical characterization matched the experimental measurements, showing a good correlation. The effect of cyano- and methyl-substituents, as well as of the N-atom position in the pyridine ring on the UV-Vis, IR and NMR spectra, was evaluated. The UV-Vis results showed no significant effect due to electron-withdrawing cyano- and electron-donating methyl-substituents. The N-atom position, however, caused a slight change in the maximum absorption wavelengths. The IR normal modes were assigned for the cyano- and methyl-groups. 1H NMR spectra showed the typical doublet signals due to protons in the trans position of a double bond. The theoretical characterization was visibly useful to assign accurately the signals in IR and 1H NMR spectra, as well as to identify the most probable conformation that could be present in the formation of the styrylpyridine-like compounds. PMID:23429190

Measurement of phenols dearomatization via electrolysis: the UV-Vis solid phase extraction method.

PubMed

Vargas, Ronald; Borrás, Carlos; Mostany, Jorge; Scharifker, Benjamin R

2010-02-01

Dearomatization levels during electrochemical oxidation of p-methoxyphenol (PMP) and p-nitrophenol (PNP) have been determined through UV-Vis spectroscopy using solid phase extraction (UV-Vis/SPE). The results show that the method is satisfactory to determine the ratio between aromatic compounds and aliphatic acids and reaction kinetics parameters during treatment of wastewater, in agreement with results obtained from numerical deconvolution of UV-Vis spectra. Analysis of solutions obtained from electrolysis of substituted phenols on antimony-doped tin oxide (SnO(2)--Sb) showed that an electron acceptor substituting group favored the aromatic ring opening reaction, preventing formation of intermediate quinone during oxidation. (c) 2009 Elsevier Ltd. All rights reserved.

[Preparation of a kind of SERS-active substrates for spot fast analysis].

PubMed

Ji, Nan; Li, Zhi-Shi; Zhao, Bing; Zou, Bo

2013-02-01

A kind of SERS-active substrates was prepared using chemical self-assembly method, aiming at spot fast analysis using portable Raman spectrometer. PDDA was first absorbed on the inner wall of vials, and then Ag colloids were assembled on the inner wall. UV-Vis spectra and Raman spectra of two kinds of blank vials were investigated and the transparent vials were thought to be better for SERS-vials. UV-Vis spectra were used to monitor the assembly process of Ag colloids. SERS activity of our substrates was characterized using p-ATP as probing molecules.

Oxidation of municipal wastewater by free radicals mechanism. A UV/Vis spectroscopy study.

PubMed

Giannakopoulos, E; Isari, E; Bourikas, K; Karapanagioti, H K; Psarras, G; Oron, G; Kalavrouziotis, I K

2017-06-15

This study investigates the oxidation of municipal wastewater (WW) by complexation with natural polyphenols having radical scavenging activity, such as (3,4,5 tri-hydroxy-benzoic acid) gallic acid (GA) in alkaline pH (>7), under ambient O 2 and temperature. Physicochemical and structural characteristics of GA-WW complex-forming are evaluated by UV/Vis spectroscopy. The comparative analysis among UV/Vis spectra of GA monomer, GA-GA polymer, WW compounds, and GA-WW complex reveals significant differences within 350-450 and 500-900 nm. According to attenuated total reflectance (ATR) spectroscopy and thermogravimetric analysis (TGA), these spectra differences correspond to distinct complexes formed. This study suggests a novel role of natural polyphenols on the degradation and humification of wastes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative analysis by UV-Vis absorption spectroscopy of amino groups attached to the surface of carbon-based nanoparticles

NASA Astrophysics Data System (ADS)

Saraswati, T. E.; Astuti, A. R.; Rismana, N.

2018-03-01

Carbon-based nanoparticles must be modified due to their wide array of applications, especially when they are used as biomaterials. After modifying, quantitative analysis of the functional group is essential to evaluate a number of the available functional groups applied for further functionalization. In this study, we modified the carbon-based nanoparticles by amino group using submerged arc discharge in different liquids. The attached amino groups were then characterised and quantified by UV-Vis spectroscopy. This amino group functionalization was also confirmed by Fourier transform infrared (FTIR) spectra. The FTIR spectra of amine-modified nanoparticles show the definitive absorption peaks of N—H amine, C—H, C=O, C—N and Fe—O at 3418.97; 3000–2850 1700–1600 1400–1100 and 480-550 cm-1, respectively. The amine groups have different performance signals between the amine-modified and unmodified nanoparticles. The FTIR spectra results were correlated with the UV-Vis absorption spectroscopy method using acidic methyl orange. The UV-Vis absorption spectroscopy shows that the absorbance of methyl orange represented to amino groups number was 1.3 times higher when the pH of the solution was increased. The absorbance intensity was then used to estimate the quantity of amine groups attached.

The color of complexes and UV-vis spectroscopy as an analytical tool of Alfred Werner's group at the University of Zurich.

PubMed

Fox, Thomas; Berke, Heinz

2014-01-01

Two PhD theses (Alexander Gordienko, 1912; Johannes Angerstein, 1914) and a dissertation in partial fulfillment of a PhD thesis (H. S. French, Zurich, 1914) are reviewed that deal with hitherto unpublished UV-vis spectroscopy work of coordination compounds in the group of Alfred Werner. The method of measurement of UV-vis spectra at Alfred Werner's time is described in detail. Examples of spectra of complexes are given, which were partly interpreted in terms of structure (cis ↔ trans configuration, counting number of bands for structural relationships, and shift of general spectral features by consecutive replacement of ligands). A more complete interpretation of spectra was hampered at Alfred Werner's time by the lack of a light absorption theory and a correct theory of electron excitation, and the lack of a ligand field theory for coordination compounds. The experimentally difficult data acquisitions and the difficult spectral interpretations might have been reasons why this method did not experience a breakthrough in Alfred Werner's group to play a more prominent role as an important analytical method. Nevertheless the application of UV-vis spectroscopy on coordination compounds was unique and novel, and witnesses Alfred Werner's great aptitude and keenness to always try and go beyond conventional practice.

Size determination of gold nanoparticles in silicate glasses by UV-Vis spectroscopy

NASA Astrophysics Data System (ADS)

Ali, Shahid; Khan, Younas; Iqbal, Yaseen; Hayat, Khizar; Ali, Muhammad

2017-01-01

A relatively easier and more accurate method for the determination of average size of metal nanoparticles/aggregates in silicate glasses based on ultraviolet visible (UV-Vis) spectra fitted with the Mie and Mie-Gans models was reported. Gold ions were diffused into sodalime silicate and borosilicate glasses by field-assisted solid-state ion-exchange technique using the same experimental parameters for both glasses. Transmission electron microscopy was performed to directly investigate the morphology and distribution of the dopant nanoparticles. UV-Vis spectra of the doped glasses showed broad surface plasmon resonance peaks in their fingerprint regions, i.e., at 525 and 500 nm for sodalime silicate and borosilicate glass matrices, respectively. These spectra were fitted with the Mie model for spherical nanoparticles and the Mie-Gans model for spheroidal nanoparticles. Although both the models were developed for colloidal nanoparticles, the size of the nanoparticles/aggregates calculated was accurate to within ˜10% in both the glass matrices in comparison to the size measured directly from the transmission electron microscope images.

Mechanisms of Photo Degradation for Layered Silicate-Polycarbonate Nanocomposites

DTIC Science & Technology

2005-09-01

crystal was used as the sampling accessory. The UV/VIS spectra were recorded using a Cary 5G UV/VIS/ near - infrared (NIR) spectrometer set to scan in...transform infrared spectroscopy. The results reveal that the carbonate linkages undergo a scission reaction upon UV exposure, thereby compromising the...were wiped clean before spectroscopic analysis. 3.3 Spectroscopic Measurements Infrared measurements were recorded on a Nicolet model 560 Magna

Spectroscopic and first-principles calculation studies of the chemical forms of palladium ion in nitric acid solution for development of disposal of high-level radioactive nuclear wastes

NASA Astrophysics Data System (ADS)

Watanabe, Shinta; Sato, Toshikazu; Yoshida, Tomoko; Nakaya, Masato; Yoshino, Masahito; Nagasaki, Takanori; Inaba, Yusuke; Takeshita, Kenji; Onoe, Jun

2018-04-01

We have investigated the chemical forms of palladium (Pd) ion in nitric acid solution, using XAFS/UV-vis spectroscopic and first-principles methods in order to develop the disposal of high-level radioactive nuclear liquid wastes (HLLW: radioactive metal ions in 2 M nitric acid solution). The results of theoretical calculations and XAFS/UV-vis spectroscopy indicate that Pd is a divalent ion and forms a square-planar complex structure coordinated with four nitrate ions, [Pd(NO3)4]2-, in nitric acid solution. This complex structure is also thermodynamically predicted to be most stable among complexes [Pd(H2O)x(NO3)4-x]x-2 (x = 0-4). Since the overall feature of UV-vis spectra of the Pd complex was independent of nitric acid concentration in the range 1-6 M, the structure of the Pd complex remains unchanged in this range. Furthermore, we examined the influence of γ-ray radiation on the [Pd(NO3)4]2- complex, using UV-vis spectroscopy, and found that UV-vis spectra seemed not to be changed even after 1.0 MGy irradiation. This implies that the Pd complex structure will be still stable in actual HLLW. These findings obtained above are useful information to develop the vitrification processes for disposal of HLLW.

DFT modeling, UV-Vis and IR spectroscopic study of acetylacetone-modified zirconia sol-gel materials.

PubMed

Georgieva, Ivelina; Danchova, Nina; Gutzov, Stoyan; Trendafilova, Natasha

2012-06-01

Theoretical and spectroscopic studies of a series of monomeric and dimeric complexes formed through the modification of a zirconium butoxide precursor with acetylacetone and subsequent hydrolysis and/or condensation have been performed by applying DFT/B3LYP/6-31++G(d) and highly accurate RI-ADC(2) methods as well as IR and UV-Vis transmittance and diffuse reflectance spectroscopies. Based on DFT model calculations and simulated and experimental UV-Vis and IR spectra of all the studied structures, the most probable building units of the Zr(IV)-AcAc gel were predicted: the dimeric double hydroxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)(OH)(2br) 9 and the monooxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)O(br)·2H(2)O 12. In both structures, the two AcAc ligands are coordinated to one Zr atom. It was shown that building units 9 and 12 determine the photophysical and vibrational properties of the gel material. The observed UV-Vis and IR spectra of Zr(IV)-AcAc gel were interpreted and a relation between the spectroscopic and structural data was derived. The observed UV-Vis bands at 315 nm and 298/288 nm were assigned to partial ligand-metal transitions and to intra-/inter-AcAc ligand transitions, respectively.

Multiconfigurational and DFT analyses of the electromeric formulation and UV-vis absorption spectra of the superoxide adduct of ferrous superoxide reductase.

PubMed

Attia, Amr A A; Cioloboc, Daniela; Lupan, Alexandru; Silaghi-Dumitrescu, Radu

2016-12-01

The putative initial adduct of ferrous superoxide reductase (SOR) with superoxide has been alternatively formulated as ferric-peroxo or ferrous-superoxo. The ~600-nm UV-vis absorption band proposed to be assigned to this adduct (either as sole intermediate in the SOR catalytic cycle, or as one of the two intermediates) has recently been interpreted as due to a ligand-to-metal charge transfer, involving thiolate and superoxide in a ferrous complex, contrary to an alternative assignment as a predominantly cysteine thiolate-to-ferric charge transfer in a ferric-peroxo electromer. In an attempt to clarify the electromeric formulation of this adduct, we report a computational study using a multiconfigurational complete active space self-consistent field (MC-CASSCF) wave function approach as well as modelling the UV-vis absorption spectra with time-dependent density functional theory (TD-DFT). The MC-CASSCF calculations disclose a weak interaction between iron and the dioxygenic ligand and a dominant configuration with an essentially ferrous-superoxo character. The computed UV-vis absorption spectra reveal a marked dependence on the choice of density functional - both in terms of location of bands and in terms of orbital contributors. For the main band in the visible region, besides the recently reported thiolate-to-superoxide charge transfer, a more salient, and less functional-dependent, feature is a thiolate-to-ferric iron charge transfer, consistent with a ferric-peroxo electromer. By contrast, the computed UV-vis spectra of a ferric-hydroperoxo SOR model match distinctly better (and with no qualitative dependence on the DFT methodology) the 600-nm band as due to a mainly thiolate-to-ferric character - supporting the assignment of the SOR "600-nm intermediate" as a S=5/2 ferric-hydroperoxo species. Copyright © 2016 Elsevier Inc. All rights reserved.

The structural and spectroscopic investigation of 2-chloro-3-methylquinoline by DFT method and UV-Vis, NMR and vibrational spectral techniques combined with molecular docking analysis

NASA Astrophysics Data System (ADS)

Kose, Etem; Atac, Ahmet; Bardak, Fehmi

2018-07-01

This study comprises the structural and spectroscopic evaluation of a quinoline derivative, 2-chloro-3-methylquinoline (2Cl3MQ), via UV-Vis, 1H and 13C NMR, FT-IR and FT-Raman techniques experimentally, theoretically with DFT and TD-DFT quantum chemical calculations at B3LYP/6-311++G (d, p) level of theory, and investigation of the in silico pharmaceutical potent of 2Cl3MQ in comparison to 2ClnMQ (n = 3,4,7,8,9,10) substituted quinolines. The experimental measurements were recorded as follows; UV-vis spectra were obtained in the range of 200-400 nm in the water and ethanol solvents. 1H and 13C NMR spectra were recorded in CDCl3. Vibrational spectra were obtained in the region of 4000-400 cm-1 and 3500-10 cm-1 for FT-IR and FT-Raman spectra, respectively. Structural and spectroscopic features obtained through theoretical evaluations include: electrostatic features, atomic charges and molecular electrostatic potential surface, the frontier molecular orbital characteristics, the density of states and their overlapping nature, the electronic transition properties, thermodynamical and nonlinear optical characteristics, and predicted UV-Vis, 1H and 13C NMR, FT-IR and FT-Raman spectra. Ligand-enzyme interactions of 2ClnMQ (n = 3,4,7,8,9,10) substituted quinolines with Malate Synthase from Mycobacterium Tuberculosis (MtbMS) were investigated via molecular docking. The role of position of methyl substitution on the inhibitor character of the ligands was discussed on the basis of noncovalent interaction profiles.

Characterizing the weathering induced changes in optical performance and properties of poly(ethylene-terephthalate) via MaPd:RTS spectroscopy

NASA Astrophysics Data System (ADS)

Gordon, Devin A.; DeNoyer, Lin; Meyer, Corey W.; Sweet, Noah W.; Burns, David M.; Bruckman, Laura S.; French, Roger H.

2017-08-01

Poly(ethylene-terephthalate) (PET) film is widely used in photovoltaic module backsheets for its dielectric break- down strength, and in applications requiring high optical clarity for its high transmission in the visible region. However, PET degrades and loses optical clarity under exposure to ultraviolet (UV) irradiance, heat, and moisture. Stabilizers are often included in PET formulation to increase its longevity; however, even these are subject to degradation and further reduce optical clarity. To study the weathering induced changes in the optical properties in PET films, samples of a UV-stabilized grade of PET were exposed to heat, moisture, and UV irradiance as prescribed by ASTM-G154 Cycle 4 for 168 hour time intervals. UV-Vis reflection and transmission spectra were collected via Multi-Angle, Polarization-Dependent, Reflection, Transmission, and Scattering (MaPd:RTS) spectroscopy after each exposure interval. The resulting spectra were used to calculate the complex index of refraction throughout the UV-Vis spectral region via an iterative optimization process based upon the Fresnel equations. The index of refraction and extinction coefficient were found to vary throughout the UV-Vis region with time under exposure. The spectra were also used to investigate changes in light scattering behavior with increasing exposure time. The intensity of scattered light was found to increase at higher angles with time under exposure.

Spectroscopic (vibrational, NMR and UV-vis.) and quantum chemical investigations on 4-hexyloxy-3-methoxybenzaldehyde.

PubMed

Abbas, Ashgar; Gökce, Halil; Bahçeli, Semiha

2016-01-05

In this study, the 4-hexyloxy-3-methoxybenzaldehyde compound as one of the derivatives of vanillin which is a well known flavoring agent, C14H20O3, has been investigated by experimentally and extensively utilizing density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. In this context, the optimized geometry, vibrational frequencies, (1)H and (13)C NMR chemical shifts, UV-vis. (in gas phase and in methanol solvent) spectra, HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic parameters and atomic charges of 4-hexyloxy-3-methoxybenzaldehyde have been calculated. In addition, theoretically predicted IR, Raman and UV-vis. (in gas phase and in methanol solvent) spectra of the mentioned molecule have been constructed. The results calculated were compared with the experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis, structural characterization and tautomeric properties of some novel bis-azo dyes derived from 5-arylidene-2,4-thiazolidinone

NASA Astrophysics Data System (ADS)

Mohammadi, Asadollah; Safarnejad, Mastaneh

Nine new bis-azo dyes derived from 5-arylidene-2,4-thiazolidinone have been synthesized in two steps using Knoevenagel condensation and diazotization-coupling reaction. The structures of the compounds were confirmed by UV-vis, IR, 1H NMR and 13C NMR spectroscopic techniques. The spectral characterizations demonstrate that there is an equilibrium between the azo (T1) and hydrazine (T2 and T3) tautomers for all prepared dyes in solutions. In addition, the solvatochromic behavior of the prepared dyes was evaluated using polarity/polarizability parameter (π*) in various solvents. The UV-vis absorption spectra of dyes show a bathochromic shift with increasing polarity and base strength of the solvents. Finally, the effects of acid and base on the UV-vis absorption spectra of the dyes with different substituent in diazo component are reported.

Computing UV/vis spectra using a combined molecular dynamics and quantum chemistry approach: bis-triazin-pyridine (BTP) ligands studied in solution.

PubMed

Höfener, Sebastian; Trumm, Michael; Koke, Carsten; Heuser, Johannes; Ekström, Ulf; Skerencak-Frech, Andrej; Schimmelpfennig, Bernd; Panak, Petra J

2016-03-21

We report a combined computational and experimental study to investigate the UV/vis spectra of 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine (BTP) ligands in solution. In order to study molecules in solution using theoretical methods, force-field parameters for the ligand-water interaction are adjusted to ab initio quantum chemical calculations. Based on these parameters, molecular dynamics (MD) simulations are carried out from which snapshots are extracted as input to quantum chemical excitation-energy calculations to obtain UV/vis spectra of BTP ligands in solution using time-dependent density functional theory (TDDFT) employing the Tamm-Dancoff approximation (TDA). The range-separated CAM-B3LYP functional is used to avoid large errors for charge-transfer states occurring in the electronic spectra. In order to study environment effects with theoretical methods, the frozen-density embedding scheme is applied. This computational procedure allows to obtain electronic spectra calculated at the (range-separated) DFT level of theory in solution, revealing solvatochromic shifts upon solvation of up to about 0.6 eV. Comparison to experimental data shows a significantly improved agreement compared to vacuum calculations and enables the analysis of relevant excitations for the line shape in solution.

Development and validation of a FIA/UV-vis method for pK(a) determination of oxime based acetylcholinesterase reactivators.

PubMed

Musil, Karel; Florianova, Veronika; Bucek, Pavel; Dohnal, Vlastimil; Kuca, Kamil; Musilek, Kamil

2016-01-05

Acetylcholinesterase reactivators (oximes) are compounds used for antidotal treatment in case of organophosphorus poisoning. The dissociation constants (pK(a1)) of ten standard or promising acetylcholinesterase reactivators were determined by ultraviolet absorption spectrometry. Two methods of spectra measurement (UV-vis spectrometry, FIA/UV-vis) were applied and compared. The soft and hard models for calculation of pK(a1) values were performed. The pK(a1) values were recommended in the range 7.00-8.35, where at least 10% of oximate anion is available for organophosphate reactivation. All tested oximes were found to have pK(a1) in this range. The FIA/UV-vis method provided rapid sample throughput, low sample consumption, high sensitivity and precision compared to standard UV-vis method. The hard calculation model was proposed as more accurate for pK(a1) calculation. Copyright © 2015 Elsevier B.V. All rights reserved.

Improved analysis of Monascus pigments based on their pH-sensitive UV-Vis absorption and reactivity properties.

PubMed

Shi, Kan; Chen, Gong; Pistolozzi, Marco; Xia, Fenggeng; Wu, Zhenqiang

2016-09-01

Monascus pigments, a mixture of azaphilones mainly composed of red, orange and yellow pigments, are usually prepared in aqueous ethanol and analysed by ultraviolet-visible (UV-Vis) spectroscopy. The pH of aqueous ethanol used during sample preparation and analysis has never been considered a key parameter to control; however, this study shows that the UV-Vis spectra and colour characteristics of the six major pigments are strongly influenced by the pH of the solvent employed. In addition, the increase of solvent pH results in a remarkable increase of the amination reaction of orange pigments with amino compounds, and at higher pH (≥ 6.0) a significant amount of orange pigment derivatives rapidly form. The consequent impact of these pH-sensitive properties on pigment analysis is further discussed. Based on the presented results, we propose that the sample preparation and analysis of Monascus pigments should be uniformly performed at low pH (≤ 2.5) to avoid variations of UV-Vis spectra and the creation of artefacts due to the occurrence of amination reactions, and ensure an accurate analysis that truly reflects pigment characteristics in the samples.

Synthesis and characterization of Y2O3 nano-material: An experimental and theoretical study

NASA Astrophysics Data System (ADS)

Ahmad, Sheeraz; Faizan, Mohd; Ahmad, Shabbir; Ikram, Mohd

2018-04-01

We made an attempt to synthesize pure Y2O3 nanomaterial by using the sol-gel method followed by annealing at 600°C and 900°C. The synthesized Y2O3 nanoparticle was characterized by using XRD, FTIR, and UV-Vis spectroscopy. The structural refinement was performed using FULLPROF software by the Rietveld method. The refinement parameters such as lattice constant, atomic position, occupancy, R-factor and goodness of fit (χ2) were calculated. The nanoparticle has a single phase cubic structure with Ia -3 space group. The main absorption band in FTIR spectra centered at 560 cm-1 is attributed to Y-O vibration while the broadband at 3450 cm-1 arises due to O-H vibration. The band gap was obtained from the reflectance spectra using the K-M function F(R∞). The optimized structural parameters and UV-Vis spectrum were calculated using DFT and TD-DFT/B3LYP methods in bulk phase of Y2O3 and compared with experimental UV-Vis spectra in nanophase.

TDDFT calculations and photoacoustic spectroscopy experiments used to identify phenolic acid functional biomolecules in Brazilian tropical fruits in natura

NASA Astrophysics Data System (ADS)

Lourenço Neto, M.; Agra, K. L.; Suassuna Filho, J.; Jorge, F. E.

2018-03-01

Time-dependent density functional theory (TDDFT) calculations of electronic transitions have been widely used to determine molecular structures. The excitation wavelengths and oscillator strengths obtained with the hybrid exchange-correlation functional B3LYP in conjunction with the ADZP basis set are employed to simulate the UV-Vis spectra of eight phenolic acids. Experimental and theoretical UV-Vis spectra reported previously in the literature are compared with our results. The fast, sensitive and non-destructive technique of photoacoustic spectroscopy (PAS) is used to determine the UV-Vis spectra of four Brazilian tropical fresh fruits in natura. Then, the PAS along with the TDDFT results are for the first time used to investigate and identify the presence of phenolic acids in the fruits studied in this work. This theoretical method with this experimental technique show to be a powerful and cheap tool to detect the existence of phenolic acids in fruits, vegetables, cereals, and grains. Comparison with high performance liquid chromatography results, when available, is also carried out.

[Using UV-Vis Absorbance for Characterization of Maturity in Composting Process with Different Materials].

PubMed

Zhao, Yue; Wei, Yu-quan; Li, Yang; Xi, Bei-dou; Wei, Zi-min; Wang, Xing-lei; Zhao, Zhi-nan; Ding, Jei

2015-04-01

The present study was conducted to assess the degree of humification in DOM during composting using different raw materials, and their effect on maturity of compost based on UV-Vis spectra measurements and chemometrics method. The raw materials of composting studied included chicken manure, pig manure, kitchen waste, lawn waste, fruits and vegetables waste, straw waste, green waste, sludge, and municipal solid waste. During composting, the parameters of UV-Vis spectra of DOM, including SUVA254 , SUVA280 , E250/E365, E4/E6, E2/E4, E2/E6, E253/E203, E253/E220, A226-400, S275-295 and S350-400 were calculated, Statistical analysis indicated that all the parameter were significantly changed during composting. SUVA254 and SUVA280 of DOM were continuously increased, E250/E365 and E4/E6 were continuously decreased in DOM, while A226-400, S275-295 and S350-400 of DOM at the final stage were significantly different with those at other stages of composting. Correlation analysis indicated that the parameters were significantly correlated with each other except for E2/E4 and E235/E203. Furthermore, principal component analysis suggested that A226-400, SUVA254, S350-400, SUVA280 and S275~295 were reasonable parameters for assessing the compost maturity. To distinguish maturity degree among different composts, hierarchical cluster analysis, an integrated tool utilizing multiple UV-Vis parameters, was performed based on the data (A226-400, SUVA254, S350-400, SUVA280 and S275-295) of DOM derived from the final stage of composting. Composts from different sources were clustered into 2 groups. The first group included chicken manure, pig manure, lawn waste, fruits and vegetables waste, green waste, sludge, and municipal solid waste characterized by a lower maturity degree, and the second group contained straw waste and kitchen waste associated with a higher maturity degree. The above results suggest that a multi-index of UV-Vis spectra could accurately evaluate the compost maturity, and A226-400, SUVA254, S350-400, SUVA280 and S275-295 of DOM could serve as primary parameters when the compost maturity was assessed using UV-Vis spectra.

Preparation and spectral properties of europium hydrogen squarate microcrystals

NASA Astrophysics Data System (ADS)

Kolev, T.; Danchova, N.; Shandurkov, D.; Gutzov, S.

2018-04-01

A simple scheme for preparation of europium hydrogen squarate octahydrate microcrystals, Eu(HSq)3·8H2O is demonstrated. The microcrystalline powders obtained have a potential application as non-centrosymmetric and UV radiation - protective hybrid optical material. The site-symmetry of the Eu - ion is C2V or lower, obtained from diffuse reflectance spectra. The formation of europium hydrogen squarate is supported by IR - spectroscopy, UV-vis spectroscopy, chemical analysis and X-ray diffraction. A detailed analysis of the UV-vis and IR spectra of the micropowders prepared is presented. The reaction between europium oxide and squaric acid leads to formation of microcrystalline plate-like crystals of europium hydrogen squarate Eu(HSq)3·8H2O, a non-centrosymmetric hybrid optical material with a potential application as UV radiation - protective coatings.

The Predictive Power of the Annellation Theory: The Case of the C26H16 Cata-Condensed Benzenoid Polycyclic Aromatic Hydrocarbons.

PubMed

Oña-Ruales, Jorge O; Ruiz-Morales, Yosadara

2015-10-22

The Annellation Theory was applied to establish the locations of maximum absorbance for the p and β bands in the UV-vis spectra of eight benzenoid cata-condensed polycyclic aromatic hydrocarbons (PAHs) with molecular formula C26H16 and no available syntheses procedures. In this group of eight isomers, there are seven compounds with potential carcinogenic properties due to geometrical constraints. In addition, crude oil and asphaltene absorption spectra exhibit similar properties, and the PAHs in heavier crude oils and asphaltenes are known to be the source of the color of heavy oils. Therefore, understanding the electronic bands of PAHs is becoming increasingly important. The methodology was validated using information for the remaining 29 isomers with available UV-vis spectra. The results satisfactorily agree with the results from semiempirical calculations made using the ZINDO/S approach. The locations of maximum absorbance for the p and β bands in the UV-vis spectra of the eight C26H16 cata-condensed isomers dibenzo[c,m]tetraphene, naphtho[1,2-c]chrysene, dibenzo[c,f]tetraphene, benzo[f]picene, naphtho[2,1-a]tetraphene, naphtho[2,1-c]tetraphene, dibenzo[c,l]chrysene, and naphtho[1,2-a]tetraphene were established for the first time.

Effects of Regolith Properties on UV/VIS Spectra and Implications for Lunar Remote Sensing

NASA Astrophysics Data System (ADS)

Coman, Ecaterina Oana

Lunar regolith chemistry, mineralogy, various maturation factors, and grain size dominate the reflectance of the lunar surface at ultraviolet (UV) to visible (VIS) wavelengths. These regolith properties leave unique fingerprints on reflectance spectra in the form of varied spectral shapes, reflectance intensity values, and absorption bands. With the addition of returned lunar soils from the Apollo and Luna missions as ground truth, these spectral fingerprints can be used to derive maps of global lunar chemistry or mineralogy to analyze the range of basalt types on the Moon, their spatial distribution, and source regions for clues to lunar formation history and evolution. The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) is the first lunar imager to detect bands at UV wavelengths (321 and 360 nm) in addition to visible bands (415, 566, 604, 643, and 689 nm). This dissertation uses a combination of laboratory and remote sensing studies to examine the relation between TiO2 concentration and WAC UV/VIS spectral ratios and to test the effects of variations in lunar chemistry, mineralogy, and soil maturity on ultraviolet and visible wavelength reflectance. Chapter 1 presents an introduction to the dissertation that includes some background in lunar mineralogy and remote sensing. Chapter 2 covers coordinated analyses of returned lunar soils using UV-VIS spectroscopy, X-ray diffraction, and micro X-ray fluorescence. Chapter 3 contains comparisons of local and global remote sensing observations of the Moon using LROC WAC and Clementine UVVIS TiO2 detection algorithms and Lunar Prospector (LP) Gamma Ray Spectrometer (GRS)-derived FeO and TiO2 concentrations. While the data shows effects from maturity and FeO on the UV/VIS detection algorithm, a UV/VIS relationship remains a simple yet accurate method for TiO2 detection on the Moon.

Self-assembly of nitrogen-doped carbon nanoparticles: a new ratiometric UV-vis optical sensor for the highly sensitive and selective detection of Hg(2+) in aqueous solution.

PubMed

Ruan, Yudi; Wu, Lie; Jiang, Xiue

2016-05-23

Water-soluble nitrogen-doped carbon nanoparticles (N-CNPs) prepared by the one-step hydrothermal treatment of uric acid were found to show ratiometric changes in their UV-vis spectra due to Hg(2+)-mediated self-assembly. For the first time, such a property was developed into a UV-vis optical sensor for detecting Hg(2+) in aqueous solutions with high sensitively and selectively (detection limit = 1.4 nM). More importantly, this novel sensor exhibits a higher linear sensitivity over a wider concentration range compared with the fluorescence sensor based on the same N-CNPs. This work opens an exciting new avenue to explore the use of carbon nanoparticles in constructing UV-vis optical sensors for the detection of metal ions and the use of carbon nanoparticles as a new building block to self-assemble into superlattices.

Molecular dynamics simulation and TDDFT study of the structures and UV-vis absorption spectra of MCT-β-CD and its inclusion complexes.

PubMed

Lu, Huijuan; Wang, Yujiao; Xie, Xiaomei; Chen, Feifei; Li, Wei

2015-01-01

In this research, the inclusion ratios and inclusion constants of MCT-β-CD/PERM and MCT-β-CD/CYPERM inclusion complexes were measured by UV-vis and fluorescence spectroscopy. The inclusion ratios are both 1:1, and the inclusion constants are 60 and 342.5 for MCT-β-CD/PERM and MCT-β-CD/CYPERM, respectively. The stabilities of inclusion complexes were investigated by MD simulation. MD shows that VDW energy plays a vital role in the stability of inclusion complex, and the destruction of inclusion complex is due to the increasing temperature. The UV-vis absorption spectra of MCT-β-CD and its inclusion complexes were studied by time-dependent density functional theory (TDDFT) method employing BLYP-D3, B3LYP-D3 and M06-2X-D3 functionals. BLYP-D3 well reproduces the UV-vis absorption spectrum and reveals that the absorption bands of MCT-β-CD mainly arise from n→π(∗) and n→σ(∗) transition, and those of inclusion complexes mainly arise from intramolecular charge transfer (ICT). ICT results in the shift of main absorption bands of MCT-β-CD. Copyright © 2015 Elsevier B.V. All rights reserved.

Growth of block copolymer stabilized metal nanoparticles probed simultaneously by in situ XAS and UV-Vis spectroscopy.

PubMed

Nayak, C; Bhattacharyya, D; Jha, S N; Sahoo, N K

2016-01-01

The growth of Au and Pt nanoparticles from their respective chloride precursors using block copolymer-based reducers has been studied by simultaneous in situ measurement of XAS and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at INDUS-2 SRS at RRCAT, Indore, India. While the XANES spectra of the precursor give real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed at the intermediate stages of growth. The growth kinetics of both types of nanoparticles are found to be almost similar and are found to follow three stages, though the first stage of nucleation takes place earlier in the case of Au than in the case of Pt nanoparticles due to the difference in the reduction potential of the respective precursors. The first two stages of the growth of Au and Pt nanoparticles as obtained by in situ XAS measurements could be corroborated by simultaneous in situ measurement of UV-Vis spectroscopy also.

Keto-enol tautomerism of (E)-2-[(3,4-dimethylphenylimino)methyl]-4-nitrophenol: Synthesis, X-ray, FT-IR, UV-Vis, NMR and quantum chemical characterizations

NASA Astrophysics Data System (ADS)

Özek Yıldırım, Arzu; Yıldırım, M. Hakkı; Albayrak Kaştaş, Çiǧdem

2017-01-01

(E)-2-((3,4-dimethylphenylimino)methyl)-4-nitrophenol, which is a new Schiff base compound, was synthesized and characterized by experimental and computational methods. Molecular geometry, harmonic oscillator model of aromaticity (HOMA) indices, intra- and inter-molecular interactions in the crystal structure were determined by using single crystal X-ray diffraction technique. The optimized structures, which are obtained by Gaussian and Slater type orbitals, were compared to experimental structures to determine how much correlation is found between the experimental and the calculated properties. Intramolecular and hyperconjugative interactions of bonds have been found by Natural Bond Orbital analysis. The experimental infrared spectrum of the compound has been analyzed in detail by the calculated infrared spectra and Potential Energy Distribution analysis. To find out about the correlation between the solvent polarity and the enol-keto equilibrium, experimental UV-Visible spectra of the compound were obtained in benzene, CHCl3, EtOH and DMSO solvents. In these solvents, the UV-Vis spectra and relaxed potential energy surface scan (PES) calculations have been performed to get more insight into the equilibrium dynamics. Solvent effects in UV-Vis and PES calculations have been taken into account by using Polarizable Continuum Modelling method. 1H and 13C NMR spectra of the compound (in DMSO) were analyzed. The computational study of nonlinear optical properties shows that the compound can be used for the development of nonlinear optical materials.

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

Janeoo, Shashi; Sharma, Mamta, E-mail: mamta.phy85@gmail.com; Goswamy, J.

Polyaniline-indium oxide (In{sub 2}O{sub 3}/PANI) nanocomposite have been prepared by in-situ polymerization of aniline and as-synthesized In{sub 2}O{sub 3} nanoparticles. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transformation infrared (FTIR) and UV/Vis spectroscopy techniques are used to investigate the structural and optical properties of In{sub 2}O{sub 3}/PANI nanocomposite. TEM analysis shows In{sub 2}O{sub 3} nanoparticles are embedded in PANI nanofibers. FTIR spectra show the good interactions between PANI nanofibers and In{sub 2}O{sub 3} nanoparticles. The band gap and electronic transitions in In{sub 2}O{sub 3}/PANI nanocomposite is determined by using UV/Vis spectra.

Effect of solution concentration on the structured order and optical properties of short-chain polyene biomolecules

NASA Astrophysics Data System (ADS)

Ouyang, Shunli; Sun, Chenglin; Zhou, Mi; Li, Dongfei; Wang, Weiwei; Qu, Guannan; Li, Zuowei; Gao, Shuqin; Yang, Jiange

2010-09-01

We have measured the Raman spectra and UV-Vis absorption spectra of linear polyene biomolecules (β-carotene and lycopene) in CS2 at low concentrations (10-6-10-10 mol/L). With decreasing concentration, all the carbon-carbon vibrations form a coherent mode in ordered β-carotene and lycopene due to extended π-conjugation that gives strong electron-phonon coupling, which leads to an anomalous experimental phenomenon. We observed an extremely high Raman scattering cross section( RSCS) and the Raman activities in β-carotene and lycopene are characterized by intensive overtones and combinations. Further, the UV-Vis absorption bands become narrower.

Chemical composition and surfactant characteristics of marine foams investigated by means of UV-vis, FTIR and FTNIR spectroscopy.

PubMed

Mecozzi, Mauro; Pietroletti, Marco

2016-11-01

In this study, we collected the ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) and Fourier transform near-infrared (FTNIR) spectra of marine foams from different sites and foams produced by marine living organisms (i.e. algae and molluscs) to retrieve information about their molecular and structural composition. UV-vis spectra gave information concerning the lipid and pigment contents of foams. FTIR spectroscopy gave a more detailed qualitative information regarding carbohydrates, lipids and proteins in addition with information about the mineral contents of foams. FTNIR spectra confirmed the presence of carbohydrates, lipids and proteins in foams. Then, due to the higher content of structural information of FTIR spectroscopy with respect to FTNIR and UV-vis, we join the FTIR spectra of marine foams to those of humic substance from marine sediments and to the spectra of foams obtained by living organisms. We submitted this resulting FTIR spectral dataset to statistical multivariate methods to investigate specific aspects of foams such as structural similarity among foams and in addition, contributions from the organic matter of living organisms. Cluster analysis (CA) evidenced several cases (i.e. clusters) of marine foams having high structural similarity with foams from vegetal and animal samples and with humic substance extracted from sediments. These results suggested that all the living organisms of the marine environment can give contributions to the chemical composition of foams. Moreover, as CA also evidenced cases of structural differences within foam samples, we applied two-dimensional correlation analysis (2DCORR) to the FTIR spectra of marine foams to investigate the molecular characteristics which caused these structural differences. Asynchronous spectra of two-dimensional correlation analysis showed that the structural heterogeneity among foam samples depended reasonably on the presence and on the qualitative difference of electrostatic (hydrogen bonds) and nonpolar (van der Waals and π-π) interactions involving carbohydrate proteins and lipids present. The presence and relevance of these interactions agree with the supramolecular and surfactant characteristics of marine organic matter described in the scientific literature.

Effects of gamma radiation on commercial food packaging films—study of changes in UV/VIS spectra

NASA Astrophysics Data System (ADS)

Moura, E. A. B.; Ortiz, A. V.; Wiebeck, H.; Paula, A. B. A.; Silva, A. L. A.; Silva, L. G. A.

2004-09-01

The effects of gamma irradiation doses up to 100 kGy on the optical properties of different commercial packaging films were studied in this paper. The packaging films analyzed were: polyethylene "LDPE", amide 6-amide 6.6 copolymer "PA6-PA6.6" and poly(ethylene terephthalate) "PET". An investigation on film samples before and after irradiation was performed by UV/VIS spectroscopy. The results showed that, in the absorption spectra of irradiated LDPE and PA6-PA6.6 films, a red-shift in the wavelength of the UV cutoff and a marked reduction in % transmittance (at low wavelengths) occur with increasing radiation dose. With respect to PET samples, no significant changes were observed in either light absorption or transmittance.

Optical properties of ZnO/BaCO3 nanocomposites in UV and visible regions.

PubMed

Zak, Ali Khorsand; Hashim, Abdul Manaf; Darroudi, Majid

2014-01-01

Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol-gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO3 nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV-Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV-Vis spectra. 81.05.Dz; 78.40.Tv; 42.70.-a.

Identification of intermediates in zeolite-catalyzed reactions by in situ UV/Vis microspectroscopy and a complementary set of molecular simulations.

PubMed

Hemelsoet, Karen; Qian, Qingyun; De Meyer, Thierry; De Wispelaere, Kristof; De Sterck, Bart; Weckhuysen, Bert M; Waroquier, Michel; Van Speybroeck, Veronique

2013-12-02

The optical absorption properties of (poly)aromatic hydrocarbons occluded in a nanoporous environment were investigated by theoretical and experimental methods. The carbonaceous species are an essential part of a working catalyst for the methanol-to-olefins (MTO) process. In situ UV/Vis microscopy measurements on methanol conversion over the acidic solid catalysts H-SAPO-34 and H-SSZ-13 revealed the growth of various broad absorption bands around 400, 480, and 580 nm. The cationic nature of the involved species was determined by interaction of ammonia with the methanol-treated samples. To determine which organic species contribute to the various bands, a systematic series of aromatics was analyzed by means of time-dependent density functional theory (TDDFT) calculations. Static gas-phase simulations revealed the influence of structurally different hydrocarbons on the absorption spectra, whereas the influence of the zeolitic framework was examined by using supramolecular models within a quantum mechanics/molecular mechanics framework. To fully understand the origin of the main absorption peaks, a molecular dynamics (MD) study on the organic species trapped in the inorganic host was essential. During such simulation the flexibility is fully taken into account and the effect on the UV/Vis spectra is determined by performing TDDFT calculations on various snapshots of the MD run. This procedure allows an energy absorption scale to be provided and the various absorption bands determined from in situ UV/Vis spectra to be assigned to structurally different species. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values

NASA Astrophysics Data System (ADS)

Razuc, Mariela; Garrido, Mariano; Caro, Yamile S.; Teglia, Carla M.; Goicoechea, Héctor C.; Fernández Band, Beatriz S.

2013-04-01

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

Spectral information (gas, liquid and solid phase from EUV-VUV-UV-Vis-NIR) and related data (e.g. information concerning publications on quantum yield studies or photolysis studies) from published papers

NASA Astrophysics Data System (ADS)

Noelle, A.; Hartmann, G. K.; Martin-Torres, F. J.

2010-05-01

The science-softCon "UV/Vis+ Spectra Data Base" is a non-profit project established in August 2000 and is operated in accordance to the "Open Access" definitions and regulations of the CSPR Assessment Panel on Scientific Data and Information (International Council for Science, 2004, HYPERLINK "http://www.science-softcon.de/spectra/cspr.pdf" ICSU Report of the CSPR Assessment Panel on Data and Information; ISBN 0-930357-60-4). The on-line database contains currently about 5600 spectra (from low to very high resolution, at different temperatures and pressures) and datasheets (metadata) of about 850 substances. Additional spectra/datasheets will be added continuously. In addition more than 250 links to on-line free available original publications are provided. The interdisciplinary of this photochemistry database provides a good interaction between different research areas. So, this database is an excellent tool for scientists who investigate on different fields such as atmospheric chemistry, astrophysics, agriculture, analytical chemistry, environmental chemistry, medicine, remote sensing, etc. To ensure the high quality standard of the fast growing UV/Vis+ Spectra Data Base an international "Scientific Advisory Group" (SAG) has been established in 2004. Because of the importance of maintenance of the database the support of the scientific community is crucial. Therefore we would like to encourage all scientists to support this data compilation project thru the provision of new or missing spectral data and information.

The Lowest Triplet of Tetracyanoquinodimethane via UV-vis Absorption Spectroscopy with Br-Containing Solvents.

PubMed

Khvostenko, Olga G; Kinzyabulatov, Renat R; Khatymova, Laysan Z; Tseplin, Evgeniy E

2017-10-05

This study was undertaken to find the previously unknown lowest triplet of the isolated molecule of tetracyanoquinodimethane (TCNQ), which is a widely used organic semiconductor. The problem is topical because the triplet excitation of this compound is involved in some processes which occur in electronic devices incorporating TCNQ and its derivatives, and information on the TCNQ triplet is needed for better understanding of these processes. The lowest triplet of TCNQ was obtained at 1.96 eV using UV-vis absorption spectroscopy with Br-containing solvents. Production of the triplet band with sufficient intensity in the spectra was provided by the capacity of the Br atom to augment the triplet excitation and through using a 100 mm cuvette. The assignment of the corresponding spectral band to the triplet transition was made by observation that this band appeared only in the spectra recorded in Br-containing solvents but not in spectra recorded in other solvents. Additional support for the triplet assignment came from the overall UV-vis absorption spectra of TCNQ recorded in various solvents, using a 10 mm cuvette, in the 1.38-6.5 eV energy range. Singlet transitions of the neutral TCNQ o molecule and doublet transitions of the TCNQ ¯ negative ion were identified in these overall spectra and were assigned with TD B3LYP/6-31G calculations. Determination of the lowest triplet of TCNQ attained in this work may be useful for theoretical studies and practical applications of this important compound.

Characterisation of PDO olive oil Chianti Classico by non-selective (UV-visible, NIR and MIR spectroscopy) and selective (fatty acid composition) analytical techniques.

PubMed

Casale, M; Oliveri, P; Casolino, C; Sinelli, N; Zunin, P; Armanino, C; Forina, M; Lanteri, S

2012-01-27

An authentication study of the Italian PDO (protected designation of origin) extra virgin olive oil Chianti Classico was performed; UV-visible (UV-vis), Near-Infrared (NIR) and Mid-Infrared (MIR) spectroscopies were applied to a set of samples representative of the whole Chianti Classico production area. The non-selective signals (fingerprints) provided by the three spectroscopic techniques were utilised both individually and jointly, after fusion of the respective profile vectors, in order to build a model for the Chianti Classico PDO olive oil. Moreover, these results were compared with those obtained by the gas chromatographic determination of the fatty acids composition. In order to characterise the olive oils produced in the Chianti Classico PDO area, UNEQ (unequal class models) and SIMCA (soft independent modelling of class analogy) were employed both on the MIR, NIR and UV-vis spectra, individually and jointly, and on the fatty acid composition. Finally, PLS (partial least square) regression was applied on the UV-vis, NIR and MIR spectra, in order to predict the content of oleic and linoleic acids in the extra virgin olive oils. UNEQ, SIMCA and PLS were performed after selection of the relevant predictors, in order to increase the efficiency of both classification and regression models. The non-selective information obtained from UV-vis, NIR and MIR spectroscopy allowed to build reliable models for checking the authenticity of the Italian PDO extra virgin olive oil Chianti Classico. Copyright © 2011 Elsevier B.V. All rights reserved.

Spectroscopic properties for identifying sapphire samples from Ban Bo Kaew, Phrae Province, Thailand

NASA Astrophysics Data System (ADS)

Mogmued, J.; Monarumit, N.; Won-in, K.; Satitkune, S.

2017-09-01

Gemstone commercial is a high revenue for Thailand especially ruby and sapphire. Moreover, Phrae is a potential gem field located in the northern part of Thailand. The studies of spectroscopic properties are mainly to identify gemstone using advanced techniques (e.g. UV-Vis-NIR spectrophotometry, FTIR spectrometry and Raman spectroscopy). Typically, UV-Vis-NIR spectrophotometry is a technique to study the cause of color in gemstones. FTIR spectrometry is a technique to study the functional groups in gem-materials. Raman pattern can be applied to identify the mineral inclusions in gemstones. In this study, the natural sapphires from Ban Bo Kaew were divided into two groups based on colors including blue and green. The samples were analyzed by UV-Vis-NIR spectrophotometer, FTIR spectrometer and Raman spectroscope for studying spectroscopic properties. According to UV-Vis-NIR spectra, the blue sapphires show higher Fe3+/Ti4+ and Fe2+/Fe3+ absorption peaks than those of green sapphires. Otherwise, green sapphires display higher Fe3+/Fe3+ absorption peaks than blue sapphires. The FTIR spectra of both blue and green sapphire samples show the absorption peaks of -OH,-CH and CO2. The mineral inclusions such as ferrocolumbite and rutile in sapphires from this area were observed by Raman spectroscope. The spectroscopic properties of sapphire samples from Ban Bo Kaew, Phrae Province, Thailand are applied to be the specific evidence for gemstone identification.

Reduction of the 3,4,9,10-perylenediimides and the formation of eletrodeposited films based on their radical anions

NASA Astrophysics Data System (ADS)

Zhu, Yuan-Yuan; Gu, Shuang-Xi

2014-09-01

The reduction of the two 3,4,9,10-perylene diimide (PDI) derivatives in the mixture of hydrazine hydrate and N,N-dimethylformamide was investigated by the UV-vis absorption spectra, fluorescence spectra (FL) and electron spin resonance spectroscopy (ESR). The time dependence of the PDI content, as well as the structure of PDI aggregates were also investigated and discussed. Combining the electro-migration behavior of PDI-· with the molecular self-assembly properties, the films of two PDI derivatives (PDI-32 and PDI-123) were successfully fabricated via anode electro-deposition (AED). The difference of aggregation state between the two PDI films was studied by UV-vis absorption spectra, XRD and SEM. Based on these, the formation mechanism of PDI films was also deduced.

Spectral Analysis of 3-(Adamantan-1-yl)-4-Ethyl-1-[(4-Phenylpiperazin-1-yl) Methyl]-1 H-1,2,4-Triazole-5(4 H)-Thione

NASA Astrophysics Data System (ADS)

Mindarava, Y. L.; Shundalau, M. B.; Al-Wahaibi, L. H.; El-Emam, A. A.; Matsukovich, A. S.; Gaponenko, S. V.

2018-05-01

Vibrational IR (3200-650 cm-1) and Raman spectra (3200-150 cm-1) of adamantane-containing 3-(adamantan-1-yl)-4-ethyl-1-[(4-phenylpiperazin-1-yl)methyl]-1H-1,2,4-triazole-5(4H)-thione, which is promising for drug design, were examined. The UV/Vis spectrum (450-200 nm) of the compound in EtOH was measured. Full geometry optimization using density functional theory (DFT) in the B3LYP/cc-pVDZ approximation allowed the equilibrium configuration of the molecule to be determined and IR and Raman spectra to be calculated. Based on these, the experimental vibrational IR and Raman spectra were interpreted and the biological activity indices were predicted. The UV/Vis spectrum of the title compound was simulated at the time-dependent DFT/CAM-B3LYP/cc-pVDZ level with and without solvent effects and at the ab initio multi-reference perturbation theory XMCQDPT2 level. The UV/Vis spectrum that was simulated using the multi-reference XMCQDPT2 approximation agreed very successfully with the experimental data, in contrast to the single-reference DFT method. This was probably a consequence of intramolecular charge transfer.

Prediction of the Ultraviolet-Visible Absorption Spectra of Polycyclic Aromatic Hydrocarbons (Dibenzo and Naphtho) Derivatives of Fluoranthene.

PubMed

Oña-Ruales, Jorge O; Ruiz-Morales, Yosadara

2017-06-01

The annellation theory method has been used to predict the locations of maximum absorbance (LMA) of the ultraviolet-visible (UV-Vis) spectral bands in the group of polycyclic aromatic hydrocarbons (PAHs) C 24 H 14 (dibenzo and naphtho) derivatives of fluoranthene (DBNFl). In this group of 21 PAHs, ten PAHs present a sextet migration pattern with four or more benzenoid rings that is potentially related to a high molecular reactivity and high mutagenic conduct. This is the first time that the locations of maximum absorbance in the UV-Vis spectra of naphth[1,2- a]aceanthrylene, dibenz[ a,l]aceanthrylene, indeno[1,2,3- de]naphthacene, naphtho[1,2- j]fluoranthene, naphth[2,1- e]acephenanthrylene, naphth[2,1- a]aceanthrylene, dibenz[ a,j]aceanthrylene, naphth[1,2- e]acephenanthrylene, and naphtho[2,1- j]fluoranthene have been predicted. Also, this represents the first report about the application of the annellation theory for the calculation of the locations of maximum absorbance in the UV-Vis spectra of PAHs with five-membered rings. Furthermore, this study constitutes the premier investigation beyond the pure benzenoid classical approach toward the establishment of a generalized annellation theory that will encompass not only homocyclic benzenoid and non-benzenoid PAHs, but also heterocyclic compounds.

Standardized UV-vis spectra as the foundation for a threshold-based, integrated photosafety evaluation.

PubMed

Bauer, Daniel; Averett, Lacey A; De Smedt, Ann; Kleinman, Mark H; Muster, Wolfgang; Pettersen, Betty A; Robles, Catherine

2014-02-01

Phototoxicity is a relatively common phenomenon and is an adverse effect of some systemic drugs. The fundamental initial step of photochemical reactivity is absorption of a photon; however, little guidance has been provided thus far regarding how ultraviolet-visible (UV-vis) light absorption spectra may be used to inform testing strategies for investigational drugs. Here we report the results of an inter-laboratory study comparing the data from harmonized UV-vis light absorption spectra obtained in methanol with data from the in vitro 3T3 Neutral Red Uptake Phototoxicity Test. Six pharmaceutical companies submitted data according to predefined quality criteria for 76 compounds covering a wide range of chemical classes showing a diverse but "positive"-enhanced distribution of photo irritation factors (22%: PIF<2, 12%: PIF 2-5, 66%: PIF>5). For compounds being formally positive (PIF value above 5) the lowest reported molar extinction coefficient (MEC) was 1700 L mol⁻¹ cm⁻¹ in methanol. However, the majority of these formally positive compounds showed MEC values being significantly higher (up to almost 40,000 L mol⁻¹ cm⁻¹). In conclusion, an MEC value of 1000 L mol⁻¹ cm⁻¹ may represent a reasonable and pragmatic threshold warranting further experimental photosafety evaluation. Copyright © 2013 Elsevier Inc. All rights reserved.

Spectral Analysis of 3-(Adamantan-1-yl)-4-Ethyl-1-[(4-Phenylpiperazin-1-yl) Methyl]-1H-1,2,4-Triazole-5(4H)-Thione

NASA Astrophysics Data System (ADS)

Mindarava, Y. L.; Shundalau, M. B.; Al-Wahaibi, L. H.; El-Emam, A. A.; Matsukovich, A. S.; Gaponenko, S. V.

2018-05-01

Vibrational IR (3200-650 cm-1) and Raman spectra (3200-150 cm-1) of adamantane-containing 3-(adamantan-1-yl)-4-ethyl-1-[(4-phenylpiperazin-1-yl)methyl]-1H-1,2,4-triazole-5(4H)-thione, which is promising for drug design, were examined. The UV/Vis spectrum (450-200 nm) of the compound in EtOH was measured. Full geometry optimization using density functional theory (DFT) in the B3LYP/cc-pVDZ approximation allowed the equilibrium configuration of the molecule to be determined and IR and Raman spectra to be calculated. Based on these, the experimental vibrational IR and Raman spectra were interpreted and the biological activity indices were predicted. The UV/Vis spectrum of the title compound was simulated at the time-dependent DFT/CAM-B3LYP/cc-pVDZ level with and without solvent effects and at the ab initio multi-reference perturbation theory XMCQDPT2 level. The UV/Vis spectrum that was simulated using the multi-reference XMCQDPT2 approximation agreed very successfully with the experimental data, in contrast to the single-reference DFT method. This was probably a consequence of intramolecular charge transfer.

Experimental and theoretical studies on IR, Raman, and UV-Vis spectra of quinoline-7-carboxaldehyde.

PubMed

Kumru, M; Küçük, V; Kocademir, M; Alfanda, H M; Altun, A; Sarı, L

2015-01-05

Spectroscopic properties of quinoline-7-carboxaldehyde (Q7C) have been studied in detail both experimentally and theoretically. The FT-IR (4000-50 cm(-1)), FT-Raman (4000-50 cm(-1)), dispersive-Raman (3500-50 cm(-1)), and UV-Vis (200-400 nm) spectra of Q7C were recorded at room temperature (25 °C). Geometry parameters, potential energy surface about CCH(O) bond, harmonic vibrational frequencies, IR and Raman intensities, UV-Vis spectrum, and thermodynamic characteristics (at 298.15K) of Q7C were computed at Hartree-Fock (HF) and density functional B3LYP levels employing the 6-311++G(d,p) basis set. Frontier molecular orbitals, molecular electrostatic potential, and Mulliken charge analyses of Q7C have also been performed. Q7C has two stable conformers that are energetically very close to each other with slight preference to the conformer that has oxygen atom of the aldehyde away from the nitrogen atom of the quinoline. Copyright © 2014 Elsevier B.V. All rights reserved.

Theoretical study on the spectroscopic properties of CO3(*-).nH2O clusters: extrapolation to bulk.

PubMed

Pathak, Arup K; Mukherjee, Tulsi; Maity, Dilip K

2008-10-24

Vertical detachment energies (VDE) and UV/Vis absorption spectra of hydrated carbonate radical anion clusters, CO(3)(*-).nH(2)O (n=1-8), are determined by means of ab initio electronic structure theory. The VDE values of the hydrated clusters are calculated with second-order Moller-Plesset perturbation (MP2) and coupled cluster theory using the 6-311++G(d,p) set of basis functions. The bulk VDE value of an aqueous carbonate radical anion solution is predicted to be 10.6 eV from the calculated weighted average VDE values of the CO(3)(*-).nH(2)O clusters. UV/Vis absorption spectra of the hydrated clusters are calculated by means of time-dependent density functional theory using the Becke three-parameter nonlocal exchange and the Lee-Yang-Parr nonlocal correlation functional (B3LYP). The simulated UV/Vis spectrum of the CO(3)(*-).8H(2)O cluster is in excellent agreement with the reported experimental spectrum for CO(3)(*-) (aq), obtained based on pulse radiolysis experiments.

Solvent effect in implicit/explicit model on FT-IR, 1H, 13C and 19F NMR, UV-vis and fluorescence spectra, linear, second- and third-nonlinear optical parameters of 2-(trifluoromethyl)benzoic acid: Experimental and computational study

NASA Astrophysics Data System (ADS)

Avcı, Davut; Altürk, Sümeyye; Tamer, Ömer; Kuşbazoğlu, Mustafa; Atalay, Yusuf

2017-09-01

FT-IR, 1H, 13C and 19F NMR, UV-vis and fluorescence spectra for 2-(trifluoromethyl)benzoic acid (2-TFMBA) were recorded. DFT//B3LYP/6-31++G(d,p) calculations were used to determine the optimized molecular geometry, vibrational frequencies, 1H, 13C and 19F GIAO-NMR chemical shifts of 2-TFMBA. The detailed assignments of vibrational frequencies were carried out on the basis of potential energy distribution (PED) by using VEDA program. TD-DFT/B3LYP/6-31++G(d,p) calculations with the PCM (polarizable continuum model) in ethanol and DMSO solvents based on implicit/explicit model and gas phase in the excited state were employed to investigate UV-vis absorption and fluorescence emission wavelengths. The UV-vis and emission spectra were given in ethanol and DMSO solvents, and the major contributions to the electronic transitions were obtained. In addition, the NLO parameters (β, γ and χ(3)) and frontier molecular orbital energies of 2-TFMBA were calculated by using B3LYP/6-31++G(d,p) level. The NLO parameters of 2-TFMBA were compared with that of para-Nitroaniline (pNA) and urea which are the typical NLO materials. The refractive index (n) is calculated by using the Lorentz-Lorenz equation to observe polarization behavior of 2-TFMBA in DMSO and ethanol solvents. In order to investigate intramolecular and hydrogen bonding interactions, NBO calculations were also performed by the same level. To sum up, considering the well-known biological role, photochemical properties of 2-TFMBA were discussed.

A Raman and UV-Vis study of catecholamines oxidized with Mn(III)

NASA Astrophysics Data System (ADS)

Barreto, W. J.; Ponzoni, S.; Sassi, P.

1998-12-01

A UV-Vis and Raman spectroscopy study of three aminochromes generated through Mn 3+ oxidation of the dopamine, L-dopa and adrenaline molecules at physiological pH was performed. The UV-Vis spectra of the catecholamines oxidized using Mn 3+ in buffer solution at pH 7.2 show a band at ca. 300 nm, formed by two transitions at 280 nm and 300 nm assigned to an La and Lb transition respectively, and other at ca. 470 nm assigned to an n- π* transition localized in the carbonyl group. This assignment is suggested by the UV-Vis and Raman spectra of ortho-aminoquinone generated by MnO 2 oxidation of a dopamine aqueous acidic solution. The resonance Raman spectra of the three chromes at buffer pH 7.2 show a very similar feature and the most intense bands are observed in the spectral range 1100-1800 cm -1. The band around 1680 cm -1 for the three compounds is assigned to a ν(CO) stretching vibration, 1630 cm -1 to the ν(CC) ring mode, two bands at 1423, 1439 cm -1; 1427, 1438 cm -1 and 1456, 1475 cm -1 are assigned to a ν(CN +) vibration, for aminochrome, dopachrome and adrenochrome, respectively. The excitation profiles for the most intense bands for aminochrome and adrenochrome were obtained. The band assigned to the ν(CN +) present a red shift with respect to the visible band peak, however the band in adrenochrome at 1475 cm -1 shows a profile similar to ν(CO) and ν(CC) modes that reflects the methyl group effect on mixing this mode more effectively with the ν(CC) ring mode.

A rapid approach for measuring silver nanoparticle concentration and dissolution in seawater by UV-Vis.

PubMed

Sikder, Mithun; Lead, Jamie R; Chandler, G Thomas; Baalousha, Mohammed

2018-03-15

Detection and quantification of engineered nanoparticles (NPs) in environmental systems is challenging and requires sophisticated analytical equipment. Furthermore, dissolution is an important environmental transformation process for silver nanoparticles (AgNPs) which affects the size, speciation and concentration of AgNPs in natural water systems. Herein, we present a simple approach for the detection, quantification and measurement of dissolution of PVP-coated AgNPs (PVP-AgNPs) based on monitoring their optical properties (extinction spectra) using UV-vis spectroscopy. The dependence of PVP-AgNPs extinction coefficient (ɛ) and maximum absorbance wavelength (λ max ) on NP size was experimentally determined. The concentration, size, and extinction spectra of PVP-AgNPs were characterized during dissolution in 30ppt synthetic seawater. AgNPs concentration was determined as the difference between the total and dissolved Ag concentrations measured by inductively coupled plasma-mass spectroscopy (ICP-MS); extinction spectra of PVP-AgNPs were monitored by UV-vis; and size evolution was monitored by atomic force microscopy (AFM) over a period of 96h. Empirical equations for the dependence of maximum absorbance wavelength (λ max ) and extinction coefficient (ɛ) on NP size were derived. These empirical formulas were then used to calculate the size and concentration of PVP-AgNPs, and dissolved Ag concentration released from PVP-AgNPs in synthetic seawater at variable particle concentrations (i.e. 25-1500μgL -1 ) and in natural seawater at particle concentration of 100μgL -1 . These results suggest that UV-vis can be used as an easy and quick approach for detection and quantification (size and concentration) of sterically stabilized PVP-AgNPs from their extinction spectra. This approach can also be used to monitor the release of Ag from PVP-AgNPs and the concurrent NP size change. Finally, in seawater, AgNPs dissolve faster and to a higher extent with the decrease in NP concentration toward environmentally relevant concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectral analysis of lunar analogue samples

NASA Astrophysics Data System (ADS)

Offringa, Marloes; Foing, Bernard

2016-04-01

Analyses of samples derived from terrestrial analogue sites are used to study lunar processes in their geological context (Foing, Stoker, Ehrenfreund, 2011). For this study samples from the volcanic region of the Eifel, Germany collected during field campaigns (Foing et al., 2010), are analyzed with a variety of spectrometers. The aim is to obtain a database of analyzed samples that could be used as a reference for future in situ measurements. Equipment used in the laboratory consists of a Fourier Transform Infrared (FTIR) spectrometer, an X-Ray Fluorescence (XRF) spectrometer, a Raman laser spectrometer, as well as UV-VIS and NIR reflectance spectrometers. The Raman, UV-VIS and NIR are also used in combination with the EXoGeoLab mock-up lander during field campaigns (Foing, Stoker, Ehrenfreund, 2011). Calibration of the UV-VIS and NIR reflectance spectrometers is the main focus of this research in order to obtain the clearest spectra. The calibration of the UV-VIS and NIR reflectance spectrometers requires the use of a good light source as well as suitable optical fibers to create a signal that covers the widest range in wavelengths available. To eliminate noise towards the edges of this range, multiple measurements are averaged and data is processed by dividing the signal by reference spectra. Calibration of the devices by creating a new dark and reference spectra has to take place after every sample measurement. In this way we take into account changes that occur in the signal due to the eating of the devices during the measurements. Moreover, the integration time is adjusted to obtain a clear signal without leading to oversaturation in the reflectance spectrum. The typical integration times for the UV-VIS reflectance spectrometer vary between 1 - 18 s, depending on the amount of daylight during experiments. For the NIR reflectance spectrometer the integration time resulting in the best signals is approximately 150 ms in combination with a broad spectrum light source. Together with taking an average over ±600 measurements per sample this leads to the best spectral signals that can be acquired with this set-up. Obtained spectra can be tested for accuracy by comparing them with stationary laboratory spectrometers such as the FTIR spectrometer. Future campaigns involving the employment of the spectrometers on the ExoGeoLab lander would prove the applicability of the equipment in the field.

Benchmark studies of UV-vis spectra simulation for cinnamates with UV filter profile.

PubMed

Garcia, Ricardo D'A; Maltarollo, Vinícius G; Honório, Káthia M; Trossini, Gustavo H G

2015-06-01

Skin cancer is a serious public health problem worldwide, being incident over all five continents and affecting an increasing number of people. As sunscreens are considered an important preventive measure, studies to develop better and safer sunscreens are crucial. Cinnamates are UVB filters with good efficiency and cost-benefit, therefore, their study could lead to the development of new UV filters. A benchmark to define the most suitable density functional theory (DFT) functional to predict UV-vis spectra for ethylhexyl methoxycinnamate was performed. Time-dependent DFT (TD-DFT) calculations were then carried out [B3LYP/6-311 + G(d,p) and B3P86/6-311 + G(d,p) in methanol environment] for seven cinammete derivatives implemented in the Gaussian 03 package. All DFT/TD-DFT simulations were performed after a conformational search with the Monte-Carlo method and MMFF94 force field. B3LYP and B3P86 functionals were better at reproducing closely the experimental spectra of ethylhexyl methoxycinnamate. Calculations of seven cinnamates showed a λmax of around 310 nm, corroborating literature reports. It was observed that the energy for the main electronic transition was around 3.95 eV and could be explained by electron delocalization on the aromatic ring and ester group, which is important to UV absorption. The methodology employed proved to be suitable for determination of the UV spectra of cinnamates and could be used as a tool for the development of novel UV filters.

Biosynthesis of ZnO nanoparticles using rambutan (Nephelium lappaceumL.) peel extract and their photocatalytic activity on methyl orange dye

NASA Astrophysics Data System (ADS)

Karnan, Thenmozhi; Selvakumar, Stanly Arul Samuel

2016-12-01

In the present study, describes the synthesis of ZnO nanoparticles from rambutan (Nephelium lappaceumL.) peel extract via bio synthesis method and developed a new low cost technology to prepare ZnO nanoparticles. During the synthesis, fruit peel extract act as a natural ligation agent. The successfully prepared product was analyzed with some standard characterization studies like X-Ray Diffraction (XRD), UV-VIS Diffuse reflectance spectra (UV-Vis DRS), Field Emission Scanning Electron Microscope (FESEM), High resolution transmittance electron microscope (HR-TEM), N2 adsorption-desorption isotherm and UV-Vis absorption Spectroscopy. The photocatalytic activity of ZnO nanoparticles was evaluated by photodegradation of methyl orange (MO) dye under UV light and the result depicts around 83.99% decolorisation efficiency at 120 min of illumination. In addition with photodecolorisation, mineralization was also achieved. The mineralization has been confirmed by measuring Chemical Oxygen Demand (COD) values.

Molecular Engineering of UV/Vis Light-Emitting Diode (LED)-Sensitive Donor-π-Acceptor-Type Sulfonium Salt Photoacid Generators: Design, Synthesis, and Study of Photochemical and Photophysical Properties.

PubMed

Wu, Xingyu; Jin, Ming; Xie, Jianchao; Malval, Jean-Pierre; Wan, Decheng

2017-11-07

A series of donor-π-acceptor-type sulfonium salt photoacid generators (PAGs) were designed and synthesized by systematically changing electron-donating groups, π-conjugated systems, electron-withdrawing groups, and the number of branches through molecular engineering. These PAGs can effectively decompose under UV/Vis irradiation from a light-emitting diode (LED) light source because of the matching absorption and emitting spectra of the LEDs. The absorption and acid-generation properties of these sulfonium salts were elucidated by UV/Vis spectroscopy and so forth. Results indicated that the PAG performance benefited from the introduction of strong electron-donating groups, specific π-conjugated structures, certain electron-withdrawing groups, or two-branched structures. Most sulfonium salts showed potential as photoinitiators under irradiation by a wide variety of UV and visible LEDs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis Characterization and DNA Interaction Studies of a New Zn(II) Complex Containing Different Dinitrogen Aromatic Ligands

PubMed Central

Shahabadi, Nahid; Mohammadi, Somaye

2012-01-01

A mononuclear complex of Zn(II), [Zn(DIP)2 (DMP)] (NO3)2 ·2H2O in which DIP is 4,7-diphenyl-1,10-phenanthroline and DMP is 4,4′-dimethyl-2,2′-bipyridine has been prepared and characterized by 1HNMR spectroscopy, FT-IR, UV-Vis and elemental analysis techniques. DNA-binding properties of the complex were studied using UV-vis spectra, circular dichroism (CD) spectra, fluorescence, cyclic voltammetry (CV), and viscosity measurements. The results indicate that this zinc(II) complex can intercalate into the stacked base pairs of DNA and compete with the strong intercalator ethidium bromide for the intercalative binding sites. PMID:22956919

Synthesis, structural characterization, antimicrobial activities and theoretical investigations of some 4-(4-aminophenylsulfonyl) phenylimino) methyl)-4-(aryldiazenyl) phenol

NASA Astrophysics Data System (ADS)

Ghasemian, Motaleb; Kakanejadifard, Ali; Karami, Tahereh

2016-11-01

The azo-azomethine dyes with a different substitution have been designed from the reaction of 4,4‧-diaminodiphenyl sulfone with 2-hydroxy-5-(aryldiazenyl)benzaldehyde. The compounds have been characterized by elemental analysis, Mass, IR, UV-Vis, TGA-DTA and NMR spectroscopy. The solvatochromism behaviors, effects of substitution and pH on the electronic absorption spectra of dyes were evaluated. The in vitro antimicrobial activities were also screened for their potential for antibiotic activities by broth micro dilution method. Also, the optimum molecular geometries, molecular electrostatic potential (MEP), nucleus-independent chemical shift (NICS) and frontier molecular orbitals (FMO), vibrational spectra (IR) and electronic absorption (UV-Vis) spectra of the title compounds have been investigated with the help of DFT and TDDFT methods with 6-311 ++G(d,p) basis sets and PCM calculations. The results of the calculations show excellent agreement with the experimental value.

Synthesis, spectral and quantum chemical studies on NO-chelating sulfamonomethoxine-cyclophosph(V)azane and its Er(III) complex.

PubMed

Alaghaz, Abdel-Nasser M A; Ammar, Reda A A; Koehler, Gottfried; Wolschann, Karl Peter; El-Gogary, Tarek M

2014-07-15

Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of novel ethane-1,2-diol-dichlorocyclophosph(V)azane of sulfamonomethoxine (L), and its binuclear Er(III) complex. Different tautomers of the ligand were optimized at the ab initio DFT level. Keto-form structure is about 15.8 kcal/mol more stable than the enol form (taking zpe correction into account). Simulated IR frequencies were scaled and compared with that experimentally measured. TD-DFT method was used to compute the UV-VIS spectra which show good agreement with measured electronic spectra. The structures of the novel isolated products are proposed based on elemental analyses, IR, UV-VIS, (1)H NMR, (31)P NMR, SEM, XRD spectra, effective magnetic susceptibility measurements and thermogravimetric analysis (TGA). Copyright © 2014 Elsevier B.V. All rights reserved.

A Comparison of Analytical and Data Preprocessing Methods for Spectral Fingerprinting

PubMed Central

LUTHRIA, DEVANAND L.; MUKHOPADHYAY, SUDARSAN; LIN, LONG-ZE; HARNLY, JAMES M.

2013-01-01

Spectral fingerprinting, as a method of discriminating between plant cultivars and growing treatments for a common set of broccoli samples, was compared for six analytical instruments. Spectra were acquired for finely powdered solid samples using Fourier transform infrared (FT-IR) and Fourier transform near-infrared (NIR) spectrometry. Spectra were also acquired for unfractionated aqueous methanol extracts of the powders using molecular absorption in the ultraviolet (UV) and visible (VIS) regions and mass spectrometry with negative (MS−) and positive (MS+) ionization. The spectra were analyzed using nested one-way analysis of variance (ANOVA) and principal component analysis (PCA) to statistically evaluate the quality of discrimination. All six methods showed statistically significant differences between the cultivars and treatments. The significance of the statistical tests was improved by the judicious selection of spectral regions (IR and NIR), masses (MS+ and MS−), and derivatives (IR, NIR, UV, and VIS). PMID:21352644

Online spectral fit tool (OSFT) for analyzing reflectance spectra

NASA Astrophysics Data System (ADS)

Penttilä, A.; Kohout, T.; Muinonen, K.

2015-10-01

We present an algorithm and its implementation for fitting continuum and absorption bands to UV/VIS/NIR reflectance spectra. The implementation is done completely in JavaScript and HTML, and will run in any modern web browser without requiring external libraries to be installed.

Synthesis, spectroscopic investigation and theoretical studies of 2-((E)-(2-(2-cyanoacetyl)hydrazono)methyl)-4-((E)-phenyldiazenyl)phenyl methyl carbonate

NASA Astrophysics Data System (ADS)

Arokiasamy, A.; Manikandan, G.; Thanikachalam, V.; Gokula Krishnan, K.

2017-04-01

Synthesis and computational optimization studies have been carried out by Hartree-Fock (HF) and Density Functional Theory (DFT-B3LYP) methods with 6-31+G(d, p) basis set for 2-((E)-(2-(2-cyanoacetyl)hydrazono)methyl)-4-((E)-phenyldiazenyl)phenyl methyl carbonate (CHPMC). The stable configuration of CHPMC was confirmed theoretically by potential energy surface scan analysis. The complete vibrational assignments were performed on the basis of total energy distribution (TED) analysis. The vibrational properties studied by IR and Raman spectroscopic data complemented by quantum chemical calculations support the formation of intramolecular hydrogen bond. Furthermore, the UV-Vis spectra are interpreted in terms of TD-DFT quantum chemical calculations. The shapes of the simulated absorption spectra are in good agreement with the experimental data. The comparison between the experimental and theoretical values of FT-IR, FT-Raman vibrational spectra, NMR (1H and 13C) and UV-Vis spectra have also been discussed.

Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex.

PubMed

Téllez S, Claudio A; Costa, Anilton C; Mondragón, M A; Ferreira, Glaucio B; Versiane, O; Rangel, J L; Lima, G Müller; Martin, A A

2016-12-05

Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands. Copyright © 2016 Elsevier B.V. All rights reserved.

Non-contact assessment of COD and turbidity concentrations in water using diffuse reflectance UV-Vis spectroscopy.

PubMed

Agustsson, Jon; Akermann, Oliver; Barry, D Andrew; Rossi, Luca

2014-08-01

Water contamination is an important environmental concern underlining the need for reliable real-time information on contaminant concentrations in natural waters. Here, a new non-contact UV-Vis spectroscopic approach for monitoring contaminants in water, and especially wastewater, is proposed. Diffuse reflectance UV-Vis spectroscopy was applied to measure simultaneously the chemical oxygen demand (COD) and turbidity (TUR) concentrations in water. The measurements were carried out in the wavelength range from 200-1100 nm. The measured spectra were analysed using partial-least-squares (PLS) regression. The correlation coefficient between the measured and the reference concentrations of COD and TUR in the water samples were R(2) = 0.85 and 0.96, respectively. These results highlight the potential of non-contact UV-Vis spectroscopy for the assessment of water contamination. A system built on the concept would be able to monitor wastewater pollution continuously, without the need for laborious sample collection and subsequent laboratory analysis. Furthermore, since no parts of the system are in contact with the wastewater stream the need for maintenance is minimised.

Fluorescent bovine serum albumin interacting with the antitussive quencher dextromethorphan: a spectroscopic insight.

PubMed

Durgannavar, Amar K; Patgar, Manjanath B; Nandibewoor, Sharanappa T; Chimatadar, Shivamurti A

2016-05-01

The interaction of dextromethorphan hydrobromide (DXM) with bovine serum albumin (BSA) is studied by using fluorescence spectra, UV-vis absorption, synchronous fluorescence spectra (SFS), 3D fluorescence spectra, Fourier transform infrared (FTIR) spectroscopy and circular dichroism under simulated physiological conditions. DXM effectively quenched the intrinsic fluorescence of BSA. Values of the binding constant, K(A), are 7.159 × 10(3), 9.398 × 10(3) and 16.101 × 10(3)  L/mol; the number of binding sites, n, and the corresponding thermodynamic parameters ΔG°, ΔH° and ΔS° between DXM and BSA were calculated at different temperatures. The interaction between DXM and BSA occurs through dynamic quenching and the effect of DXM on the conformation of BSA was analyzed using SFS. The average binding distance, r, between the donor (BSA) and acceptor (DXM) was determined based on Förster's theory. The results of fluorescence spectra, UV-vis absorption spectra and SFS show that the secondary structure of the protein has been changed in the presence of DXM. Copyright © 2015 John Wiley & Sons, Ltd.

One trinucleus dimethine cyanine dye: Experimental and theoretical studies on molecular structure as well as absorption and fluorescence properties

NASA Astrophysics Data System (ADS)

Zhang, D. D.; Wang, L. Y.; Su, J. J.; Zhang, X. F.; Lei, Y. B.; Zhai, G. H.; Wen, Z. Y.

2013-05-01

A kind of trinucleus dimethine cyanine dye: 1-methyl-2,6-bis[2-(furan-2-yl)vinyl]pyridinium iodide (1) was synthesized and characterized by 1H NMR, 13C NMR, IR, MS, UV-Vis spectroscopy and elemental analysis. The crystals of dye 1, obtained from slow evaporation of solvent acetone, crystallized in the triclinic space group P - 1 with a = 9.6501(16) Å, b = 10.2308(17) Å, c = 10.7341(17) Å, V = 887.2(3) Å3, and Z = 2 (at 298(2) K), and it was stabilized by the hydrogen bonds and intermolecular face-to-face π⋯π aromatic stacking interactions. Crystallographic, IR, 1H NMR and UV-Vis data of dye 1 were compared with the results of density functional theory (DFT) method, and the calculated molecular geometries, vibrational bands, 1H NMR chemical shifts and UV-Vis maximum absorption were consistent with the experimental results. The fluorescence spectra were predicted in four different solvents with CIS/PCM methods. Compared with experimental values, the absolute deviations of emission maxima were -17.4 nm in chloroform, 6.3 nm in DMSO, 4.9 nm in methanol, and 6.8 nm in water, respectively. And the experimental fluorescence spectra were nicely reproduced by the simulated fluorescence spectra for each solvent.

Differentiation of tea varieties using UV-Vis spectra and pattern recognition techniques

NASA Astrophysics Data System (ADS)

Palacios-Morillo, Ana; Alcázar, Ángela.; de Pablos, Fernando; Jurado, José Marcos

2013-02-01

Tea, one of the most consumed beverages all over the world, is of great importance in the economies of a number of countries. Several methods have been developed to classify tea varieties or origins based in pattern recognition techniques applied to chemical data, such as metal profile, amino acids, catechins and volatile compounds. Some of these analytical methods become tedious and expensive to be applied in routine works. The use of UV-Vis spectral data as discriminant variables, highly influenced by the chemical composition, can be an alternative to these methods. UV-Vis spectra of methanol-water extracts of tea have been obtained in the interval 250-800 nm. Absorbances have been used as input variables. Principal component analysis was used to reduce the number of variables and several pattern recognition methods, such as linear discriminant analysis, support vector machines and artificial neural networks, have been applied in order to differentiate the most common tea varieties. A successful classification model was built by combining principal component analysis and multilayer perceptron artificial neural networks, allowing the differentiation between tea varieties. This rapid and simple methodology can be applied to solve classification problems in food industry saving economic resources.

Electrochemical synthesis of nanostructured Se-doped SnS: Effect of Se-dopant on surface characterizations

NASA Astrophysics Data System (ADS)

Kafashan, Hosein; Azizieh, Mahdi; Balak, Zohre

2017-07-01

SnS1-xSex nanostructures with different Se-dopant concentrations were deposited on fluorine doped tin oxide (FTO) substrate through cathodic electrodeposition technique. The pH, temperature, applied potential (E), and deposition time remained were 2.1, 60 °C, -1 V, and 30 min, respectively. SnS1-xSex nanostructures were characterized using X-ray diffraction (XRD), field emission scanning electron microcopy (FESEM), energy dispersive X-ray spectroscopy (EDX), room temperature photoluminescence (PL), and UV-vis spectroscopy. The XRD patterns revealed that the SnS1-xSex nanostructures were polycrystalline with orthorhombic structure. FESEM showed various kinds of morphologies in SnS1-xSex nanostructures due to Se-doping. PL and UV-vis spectroscopy were used to evaluate the optical properties of SnS1-xSex thin films. The PL spectra of SnS1-xSex nanostructures displayed four emission peaks, those are a blue, a green, an orange, and a red emission. UV-vis spectra showed that the optical band gap energy (Eg) of SnS1-xSex nanostructures varied between 1.22-1.65 eV, due to Se-doping.

Polyethyleneglycol/silver functionalized reduced graphene oxide aerogel for environmental application

NASA Astrophysics Data System (ADS)

Kumari, G. Vanitha; Asha, S.; Ananth, A. Nimrodh; Rajan, M. A. Jothi; Mathavan, T.

2018-04-01

Polyethylene glycol (PEG)/Silver (Ag) functionalized reduced graphene oxide aerogel (RGOA) was synthesized. PEG/Ag decorated reduced graphene oxide aerogel was characterized using XRD, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR). The surface morphology of PEG/Ag/RGOA was analyzed using scanning electron microscope. The non-covalent interaction between reduced graphene oxide layers and the interaction between PEG and Ag on RGOA were studied by FT-IR spectra. It was observed that the interaction between Ag and PEG could enhance the properties of RGOA. Methyl Orange (MO) dye degradation was observed from UV-Vis Spectra. The process was studied by monitoring the simultaneous decrease in the height of UV-Vis absorption peak of dye solution. The results show that PEG/RGOA and PEG/Ag/RGOA are an efficient catalyst for dye degradation.

A multifrequency virtual spectrometer for complex bio-organic systems: vibronic and environmental effects on the UV/Vis spectrum of chlorophyll a.

PubMed

Barone, Vincenzo; Biczysko, Malgorzata; Borkowska-Panek, Monika; Bloino, Julien

2014-10-20

The subtle interplay of several different effects means that the interpretation and analysis of experimental spectra in terms of structural and dynamic characteristics is a challenging task. In this context, theoretical studies can be helpful, and as such, computational spectroscopy is rapidly evolving from a highly specialized research field toward a versatile and widespread tool. However, in the case of electronic spectra (e.g. UV/Vis, circular dichroism, photoelectron, and X-ray spectra), the most commonly used methods still rely on the computation of vertical excitation energies, which are further convoluted to simulate line shapes. Such treatment completely neglects the influence of nuclear motions, despite the well-recognized notion that a proper account of vibronic effects is often mandatory to correctly interpret experimental findings. Development and validation of improved models rooted into density functional theory (DFT) and its time-dependent extension (TD-DFT) is of course instrumental for the optimal balance between reliability and favorable scaling with the number of electrons. However, the implementation of easy-to-use and effective procedures to simulate vibrationally resolved electronic spectra, and their availability to a wide community of users, is at least equally important for reliable simulations of spectral line shapes for compounds of biological and technological interest. Here, such an approach has been applied to the study of the UV/Vis spectra of chlorophyll a. The results show that properly tailored approaches are feasible for state-of-the-art computational spectroscopy studies, and allow, with affordable computational resources, vibrational and environmental effects on the spectral line shapes to be taken into account for large systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigating the Implementation of ZnO Nanoparticles as a Tunable UV Detector for Different Skin Types

NASA Astrophysics Data System (ADS)

Mosayebi, Pegah; Dorranian, Davoud; Behzad, Kasra

A facile chemical reduction method was used to synthesize ZnO nanoparticles (NPs) in ethylene glycol solvent at two different calcination temperatures. As a result of variation in the calcination temperature, ZnO NPs with two different sizes were achieved. The NPs were investigated for their structural and optical characteristics using X-ray diffraction and ultraviolet (UV)-Vis spectroscopy. The synthesized ZnO NPs exhibited a hexagonal structure with sizes of 46 and 65nm. The synthesized NPs were then used to investigate dye photocatalytic behavior of products as a tunable UV detector for different skin types. The dye degradation and decolorization of methylene blue in the presence of ZnO NP, following UV radiation as a function of time, were studied at different pH levels. The optical absorption spectra were then taken every 15min for all samples. The UV-Vis spectroscopy spectra revealed that optical absorption of solution was decreased upon UV exposure as a function of time. Photocatalytic reaction indicated that the dye degradation and decolorization rate were accelerated with the increase of pH level. Therefore, a tunable UV detector for different skin types could be engineered by varying the pH level of solution to avoid human skin burning.

Photocatalytic properties of Au-deposited mesoporous SiO{sub 2}–TiO{sub 2} photocatalyst under simultaneous irradiation of UV and visible light

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

Okuno, T., E-mail: t093507@edu.imc.tut.ac.jp; Kawamura, G., E-mail: gokawamura@ee.tut.ac.jp; Muto, H., E-mail: muto@ee.tut.ac.jp

Mesoporous SiO{sub 2} templates deposited TiO{sub 2} nanocrystals are synthesized via a sol–gel route, and Au nanoparticles (NPs) are deposited in the tubular mesopores of the templates by a photodeposition method (Au/SiO{sub 2}–TiO{sub 2}). The photocatalytic characteristics of Au/SiO{sub 2}–TiO{sub 2} are discussed with the action spectra of photoreactions of 2-propanol and methylene blue. Photocatalytic activities of SiO{sub 2}–TiO{sub 2} under individual ultraviolet (UV) and visible (Vis) light illumination are enhanced by deposition of Au NPs. Furthermore, Au/SiO{sub 2}–TiO{sub 2} shows higher photocatalytic activities under simultaneous irradiation of UV and Vis light compared to the activity under individual UV andmore » Vis light irradiation. Since the photocatalytic activity under simultaneous irradiation is almost the same as the total activities under individual UV and Vis light irradiation, it is concluded that the electrons and the holes generated by lights of different wavelengths are efficiently used for photocatalysis without carrier recombination. - Graphical abstract: This graphic shows the possible charge behavior in Au/SiO{sub 2}–TiO{sub 2} under independent light irradiation of ultraviolet and visible light irradiation. Both reactions under independent UV and Vis light irradiation occurred in parallel when Au/SiO{sub 2}–TiO{sub 2} photocatalyst was illuminated UV and Vis light simultaneously, and then photocatalytic activity is improved by simultaneous irradiation. - Highlights: • Au nanoparticles were deposited in mesoporous SiO{sub 2}–TiO{sub 2} by a photodeposition method. • Photocatalytic activity under UV and Vis light was enhanced by deposition of Au. • Photocatalytic activity of Au/SiO{sub 2}–TiO{sub 2} was improved by simultaneous irradiation.« less

Effect of fusion mixture treatment on the surface of low grade natural ruby

NASA Astrophysics Data System (ADS)

Sakthivel, R.; Pradhan, K. C.; Nayak, B. B.; Dash, Tapan; Sahu, R. K.; Mishra, B. K.

2017-05-01

Improvement in aesthetic look of low grade natural ruby (gemstone) surface was clearly evident after fusion mixture treatment. Surface impurities of the gemstone were significantly reduced to give it a face lift. The processing consists of heat treatment (1000 °C) of the raw gemstone with fusion mixture (sodium and potassium carbonates), followed by hydrochloric acid digestion (90 °C) and ultrasonic cleaning.Both the untreated and the treated gemstone were characterized by X-ray diffraction, UV-vis spectroscopy (diffuse reflectance),photoluminescence and X-ray photoelectron spectroscopy. The paper consolidates the results of these studies and presents the effect of the typical chemical treatment (stated above) on the low grade natural ruby. While X-ray diffraction study identifies the occurrence of alumina phase in both the treated and the untreated gemstones, the UV-vis spectra exhibit strong characteristic absorption of Cr3+at 400 and 550 nm wavelength for the treated gemstone in contrast to weak absorption observed for the untreated gemstone at such wavelengths, thus showing the beneficial effect of fusion mixture treatment. Peaks observed for the gemstone (for both treated and untreated samples) in the excitation spectra of photoluminescence show a good correlation with observed UV-vis (diffuse reflectance) spectra. Photoluminescence emission spectra of the untreated gemstone show characteristic emission at 695 nm for Cr3+ ion (as in alumina matrix), but its emission intensity significantly reduces after fusion mixture treatment. It is found that the surface of the fusion mixture treated ruby gemstone looks much brighter than the corresponding untreated surface.

Structural and spectroscopic (UV-Vis, IR, Raman, and NMR) characteristics of anisaldehydes that are flavoring food additives: A density functional study in comparison with experiments

NASA Astrophysics Data System (ADS)

Altun, Ahmet; Swesi, O. A. A.; Alhatab, B. S. S.

2017-01-01

The molecular structures, vibrational spectra (IR and Raman), electronic spectra (UV-Vis and DOS), and NMR spectra (13C and 1H) of p-anisaldehyde, m-anisaldehyde, and o-anisaldehyde have been studied by using the B3LYP density functional and the 6-311++G** basis set. While p-anisaldehyde has been found to contain two stable conformers at room temperature, m-anisaldehyde and o-anisaldehyde contain four stable conformers. In agreement with the calculated ground-state energetics and small transition barriers, the comparison of the experimental and calculated spectra of the anisaldehydes indicates equilibrium between all conformers at room temperature. However, the two conformers of o-anisaldehyde, in which the methoxy group lies out of the ring plane, are too rare at the equilibrium. The equilibrium conditions of the conformers of the anisaldehyde isomers have been shown readily accessible through UV-Vis and 13C NMR spectral studies but requiring very detailed vibrational analyses. The effect of the solvent has been found to red-shift the electronic absorption bands and to make the anisaldehydes more reactive and soft. Molecular electrostatic potential maps of the anisaldehydes show that their oxygen atoms are the sites for nucleophilic reactivity. Compared with the most sophisticated NBO method, ESP charges have been found mostly reliable while Mulliken charges fail badly with the present large 6-311++G** basis set. The present calculations reproduce not only the experimental spectral characteristics of the anisaldehydes but also reveal their several structural features.

Quantification of taurine in energy drinks using ¹H NMR.

PubMed

Hohmann, Monika; Felbinger, Christine; Christoph, Norbert; Wachter, Helmut; Wiest, Johannes; Holzgrabe, Ulrike

2014-05-01

The consumption of so called energy drinks is increasing, especially among adolescents. These beverages commonly contain considerable amounts of the amino sulfonic acid taurine, which is related to a magnitude of various physiological effects. The customary method to control the legal limit of taurine in energy drinks is LC-UV/vis with postcolumn derivatization using ninhydrin. In this paper we describe the quantification of taurine in energy drinks by (1)H NMR as an alternative to existing methods of quantification. Variation of pH values revealed the separation of a distinct taurine signal in (1)H NMR spectra, which was applied for integration and quantification. Quantification was performed using external calibration (R(2)>0.9999; linearity verified by Mandel's fitting test with a 95% confidence level) and PULCON. Taurine concentrations in 20 different energy drinks were analyzed by both using (1)H NMR and LC-UV/vis. The deviation between (1)H NMR and LC-UV/vis results was always below the expanded measurement uncertainty of 12.2% for the LC-UV/vis method (95% confidence level) and at worst 10.4%. Due to the high accordance to LC-UV/vis data and adequate recovery rates (ranging between 97.1% and 108.2%), (1)H NMR measurement presents a suitable method to quantify taurine in energy drinks. Copyright © 2013 Elsevier B.V. All rights reserved.

UV-vis spectral property of a multi-hydroxyl Schiff-base derivative and its colorimetric response to some special metal ions.

PubMed

Xing, Lin; Zheng, Xiaoyu; Sun, Wenyu; Yuan, Hua; Hu, Lei; Yan, Zhengquan

2018-06-05

A multi-hydroxyl Schiff-base derivative, N-2'-hydroxyl-1'-naphthyl methylene-2-amino phenol (HNMAP), was synthesized and characterized by FTIR, 1 H NMR and UV-vis spectroscopy. It was noted to find there was great effect for solvent and pH on the UV-vis spectroscopy of HNMAP. Especially, some metal ions could make its UV-vis spectra changed regularly with different time-resolved effects. For example, a real-time and multi-wavelength response to Fe 2+ at 520 nm, 466 nm and 447 nm and a quite slow one about 26 min to Fe 3+ at 447 nm and 466 nm, respectively. Under the optimized conditions, the changes in the corresponding absorption intensities at above wavelengths were in proportion to c Fe 2+ or c Fe 3+ during respectively partitioned linear ranges, which realized to quantitatively detect Fe 2+ or Fe 3+ with a large linear range more than two orders of magnitude. A 1:1 complex mode for HNMAP-Fe 2+ and 1:2 for HNMAP-Fe 3+ were proposed from UV-vis spectral titration and Job's plot. HNMAP would be a potential sensor for colorimetric detection of Fe 2+ and Fe 3+ in practice. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced selective photocatalytic reduction of CO2 to CH4 over plasmonic Au modified g-C3N4 photocatalyst under UV-vis light irradiation

NASA Astrophysics Data System (ADS)

Li, Hailong; Gao, Yan; Xiong, Zhuo; Liao, Chen; Shih, Kaimin

2018-05-01

A series of Au-g-C3N4 (Au-CN) catalysts were prepared through a NaBH4-reduction method using g-C3N4 (CN) from pyrolysis of urea as precursor. The catalysts' surface area, crystal structure, surface morphology, chemical state, functional group composition and optical properties were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible (UV-vis) diffuse reflectance spectra, fourier transform infrared, photoluminescence and transient photocurrent analysis. The carbon dioxide (CO2) photoreduction activities under ultraviolet visible (UV-vis) light irradiation were significantly enhanced when gold (Au) was loaded on the surface of CN. 2Au-CN catalyst with Au to CN mole ratio of 2% showed the best catalytic activity. After 2 h UV-vis light irradiation, the methane (CH4) yield over the 2Au-CN catalyst was 9.1 times higher than that over the pure CN. The CH4 selectivity also greatly improved for the 2Au-CN compared to the CN. The deposited Au nanoparticles facilitated the separation of electron-hole pairs on the CN surface. Moreover, the surface plasmon resonance effect of Au further promoted the generation of hot electrons and visible light absorption. Therefore, Au loading significantly improved CO2 photoreduction performance of CN under UV-vis light irradiation.

[Preparation and spectral analysis of a new type of blue light-emitting material delta-Alq3].

PubMed

Wang, Hua; Hao, Yu-ying; Gao, Zhi-xiang; Zhou, He-feng; Xu, Bing-she

2006-10-01

In the present article, delta-Alq3, a new type of blue light-emitting material, was synthesized and investigated by IR spectra, XRD spectra, UV-Vis absorption spectra, photoluminescence (PL) spectra, and electroluminescence (EL) spectra. The relationship between molecular spatial structure and spectral characteristics was studied by the spectral analysis of delta-Alq3 and alpha-Alq3. Results show that a new phase of Alq3 (delta-Alq3) can be obtained by vacuum heating alpha-Alq3, and the molecular spatial structure of alpha-Alq3 changes during the vacuum heating. The molecular spatial structure of delta-Alq3 lacks symmetry compared to alpha-Alq3. This transformation can reduce the electron cloud density on phenoxide of Alq3 and weaken the intermolecular conjugated interaction between adjacent Alq3 molecules. Hence, the pi--pi* electron transition absorption peak of delta-Alq3 shifts toward short wavelength in UV-Vis absorption spectra, and the maximum emission peak of delta-Alq3 (lamda max = 480 nm) blue-shifts by 35 nm compared with that of alpha-Alq3 (lamda max = 515 nm) in PL spectra. The maximum emission peaks of delta-Alq3 and alpha-Alq3 are all at 520 nm in EL spectra.

Laboratory and Field Spectroscopy of Moon analogue material

NASA Astrophysics Data System (ADS)

Offringa, Marloes; Foing, Bernard H.

2016-07-01

Samples derived from terrestrial analogue sites are studied to gain insight into lunar processes in their geological context (Foing, Stoker, Ehrenfreund, 2011). For this study samples from the volcanic region of the Eifel, Germany collected during our latest field campaigns in November 2015 and February 2016 (Foing et al., 2010), are analyzed with a variety of spectrometers. The aim is to obtain a database of analyzed samples that could be used as a reference for future in situ measurements. We also use a documented set of Moon-Mars relevant minerals curated at VU Amsterdam. We are using systematically for all samples UV-VIS and NIR reflectance spectrometers, and sporadically a Fourier Transform Infrared (FTIR) spectrometer, an X-Ray Fluorescence (XRF) spectrometer and a Raman laser spectrometer on control samples. Calibration of the UV-VIS and NIR reflectance spectrometers is the main focus of this research in order to obtain the clearest spectra. The calibration of the UV-VIS and NIR reflectance spectrometers requires the use of a good light source as well as suitable optical fibers to create a signal that covers the widest range in wavelengths available. To eliminate noise towards the edges of this range, multiple measurements are averaged and data is processed by dividing the signal by reference spectra. Obtained spectra can be tested for accuracy by comparing them with stationary laboratory spectrometers such as the FTIR spectrometer. The Raman, UV-VIS and NIR are also used in combination with the ExoGeoLab mock-up lander during field campaigns (Foing, Stoker, Ehrenfreund, 2011) also brought again to Eifel in February 2016, to prove the applicability of the equipment in the field. Acknowledgements: we thank Dominic Doyle for ESTEC optical lab support, Euan Monaghan (Leiden U) for FTIR measurement support, Wim van Westrenen for access to VU samples, Oscar Kamps (Utrecht U./ESTEC), Aidan Cowley (EAC) and Matthias Sperl (DLR) for support discussions

Determination of Diethyl Phthalate and Polyhexamethylene Guanidine in Surrogate Alcohol from Russia

PubMed Central

Monakhova, Yulia B.; Kuballa, Thomas; Leitz, Jenny; Lachenmeier, Dirk W.

2011-01-01

Analytical methods based on spectroscopic techniques were developed and validated for the determination of diethyl phthalate (DEP) and polyhexamethylene guanidine (PHMG), which may occur in unrecorded alcohol. Analysis for PHMG was based on UV-VIS spectrophotometry after derivatization with Eosin Y and 1H NMR spectroscopy of the DMSO extract. Analysis of DEP was performed with direct UV-VIS and 1H NMR methods. Multivariate curve resolution and spectra computation methods were used to confirm the presence of PHMG and DEP in the investigated beverages. Of 22 analysed alcohol samples, two contained DEP or PHMG. 1H NMR analysis also revealed the presence of signals of hawthorn extract in three medicinal alcohols used as surrogate alcohol. The simple and cheap UV-VIS methods can be used for rapid screening of surrogate alcohol samples for impurities, while 1H NMR is recommended for specific confirmatory analysis if required. PMID:21647285

Determination of diethyl phthalate and polyhexamethylene guanidine in surrogate alcohol from Russia.

PubMed

Monakhova, Yulia B; Kuballa, Thomas; Leitz, Jenny; Lachenmeier, Dirk W

2011-01-01

Analytical methods based on spectroscopic techniques were developed and validated for the determination of diethyl phthalate (DEP) and polyhexamethylene guanidine (PHMG), which may occur in unrecorded alcohol. Analysis for PHMG was based on UV-VIS spectrophotometry after derivatization with Eosin Y and (1)H NMR spectroscopy of the DMSO extract. Analysis of DEP was performed with direct UV-VIS and (1)H NMR methods. Multivariate curve resolution and spectra computation methods were used to confirm the presence of PHMG and DEP in the investigated beverages. Of 22 analysed alcohol samples, two contained DEP or PHMG. (1)H NMR analysis also revealed the presence of signals of hawthorn extract in three medicinal alcohols used as surrogate alcohol. The simple and cheap UV-VIS methods can be used for rapid screening of surrogate alcohol samples for impurities, while (1)H NMR is recommended for specific confirmatory analysis if required.

Combined In Situ Illumination-NMR-UV/Vis Spectroscopy: A New Mechanistic Tool in Photochemistry.

PubMed

Seegerer, Andreas; Nitschke, Philipp; Gschwind, Ruth M

2018-06-18

Synthetic applications in photochemistry are booming. Despite great progress in the development of new reactions, mechanistic investigations are still challenging. Therefore, we present a fully automated in situ combination of NMR spectroscopy, UV/Vis spectroscopy, and illumination to allow simultaneous and time-resolved detection of paramagnetic and diamagnetic species. This optical fiber-based setup enables the first acquisition of combined UV/Vis and NMR spectra in photocatalysis, as demonstrated on a conPET process. Furthermore, the broad applicability of combined UVNMR spectroscopy for light-induced processes is demonstrated on a structural and quantitative analysis of a photoswitch, including rate modulation and stabilization of transient species by temperature variation. Owing to the flexibility regarding the NMR hardware, temperature, and light sources, we expect wide-ranging applications of this setup in various research fields. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

NASA Astrophysics Data System (ADS)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

Design of UV-absorbing PVDF membrane via surface-initiated AGET ATRP

NASA Astrophysics Data System (ADS)

Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Zhou, Yan; Lin, Changhong; Yang, Yuming

2018-03-01

Herein, PVDF membranes with excellent UV-absorbing property were first synthesized through grafting the polymerizable low-molecular-weight organic UV-absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) onto α-bromoester-functionalized PVDF membranes via the surface-initiated activator generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The surface initiators were immobilized by the reaction between 2-bromoisobutyryl bromide (BIBB) and the hydroxylated PVDF membranes. PVDF-g-PBPMA membranes with different grafting densities were obtained by tuning the polymerization time and the modified membranes were characterized by 1H-NMR, FT-IR, XPS, SEM, UV-vis Spectrophotometer, TGA and DSC. The experimental results indicated that PBPMA chains were successfully introduced onto PVDF membranes. Most importantly, the PVDF-g-PBPMA membranes exhibited outstanding UV-shielding property. UV-vis transmittance spectra showed that most UV light below 360 nm could be absorbed by PVDF-g-PBPMA membranes and the whole UV light region (200-400 nm) can be blocked with the reaction time increased.

Spectroscopic and DFT studies of bis-3-hydroxypyridinium and bis-3-hydroxymethylpyridinium dibromides with tetramethylene linker

NASA Astrophysics Data System (ADS)

Komasa, Anna

2018-01-01

Experimental and theoretical IR, Raman, UV-Vis, 1H and 13C NMR spectra of 1,4-di(3-hydroxypyridinium)butane dibromide and 1,4-di(3-hydroxymethylpyridinium)butane dibromide were obtained and analyzed. Optimized geometrical structures of the studied compounds were calculated by B3LYP method using 6-311++G(d,p) basis set and employed to determine the theoretical wavenumbers and intensities of IR and Raman spectra. The frequency assignments were supported by the potential energy distribution (PED) analysis. The significant role of the intermolecular interactions and the hydrogen bond was revealed on the basis of IR spectra. The calculated GIAO/B3LYP/6-311++G(d,p) isotropic magnetic shielding constants were used to predict the 1H and 13C chemical shifts for the optimized structures. Accuracy of the prediction of 1H and 13C chemical shifts was significantly improved by a simulation of the solvent in calculations. On the basis of UV-Vis spectra the acid-base equilibrium in the water solution of 1,4-di(3-hydroxypyridinium)butane dibromide was found.

Theoretical studies on the structural and spectra properties of two C74 fullerenes and the chlorinated species C74Cl10

NASA Astrophysics Data System (ADS)

Zheng, Mei; Song, Xitong; Li, Xiaoqi; Qi, Jiayuan

2018-07-01

The geometrical/electronic structures, X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy of two especially C74 fullerenes (D3h-C74 and C1-C74) and the chlorinated species C1-C74Cl10, which are newly isolated in the experiment, have been calculated by means of the density functional theory (DFT) method. Effective changes in the electronic structure and simulated X-ray spectra have been observed after chlorination. Strong isomer dependence has been found in both spectra, thus the 'fingerprints' in the spectra can be employed as a tool to identify the isomers. The ultraviolet-visible (UV-vis) absorption spectrum of C1-C74Cl10 has been performed by using the time-dependent DFT method. The generated UV-vis spectrum coincides with the previous experimental counterpart. The results of this work can provide useful information especially for isomer identification and further study on fullerenes by means of the aforementioned spectroscopy techniques.

Theoretical modeling of UV-Vis absorption and emission spectra in liquid state systems including vibrational and conformational effects: explicit treatment of the vibronic transitions.

PubMed

D'Abramo, Marco; Aschi, Massimiliano; Amadei, Andrea

2014-04-28

Here, we extend a recently introduced theoretical-computational procedure [M. D'Alessandro, M. Aschi, C. Mazzuca, A. Palleschi, and A. Amadei, J. Chem. Phys. 139, 114102 (2013)] to include quantum vibrational transitions in modelling electronic spectra of atomic molecular systems in condensed phase. The method is based on the combination of Molecular Dynamics simulations and quantum chemical calculations within the Perturbed Matrix Method approach. The main aim of the presented approach is to reproduce as much as possible the spectral line shape which results from a subtle combination of environmental and intrinsic (chromophore) mechanical-dynamical features. As a case study, we were able to model the low energy UV-vis transitions of pyrene in liquid acetonitrile in good agreement with the experimental data.

Comment on ``(Au-Ag)144(SR)60 alloy nanomolecules'' by C. Kumara and A. Dass, Nanoscale, 2011, 3, 3064

NASA Astrophysics Data System (ADS)

Barcaro, Giovanni; Sementa, Luca; Fortunelli, Alessandro; Stener, Mauro

2015-04-01

A recent paper in this journal reported the synthesis and characterization via electrospray ionization mass spectroscopy and UV-vis spectroscopy of (Au-Ag)144(SR)60 alloy nanomolecules with different compositions, ranging from 1 : 0 to 1 : 0.75 Au : Ag ratios. The UV-vis spectra of such systems were found to exhibit absorption peaks at 310 nm, 425 nm and 560 nm, interpreted as reminiscent of the silver surface plasmon resonance band due to simple atomic replacement of Au by Ag atoms in a fixed structural framework. On the basis of a comparison of experimentally observed and theoretically simulated optical absorption spectra, we conclude that the experimental situation must be more complicated, and that further work is needed to achieve atomistic insight into these fascinating systems.

High temperature thermochromic polydiacetylenes: Design and colorimetric properties

NASA Astrophysics Data System (ADS)

Huo, Jingpei; Hu, Zhudong; He, Guozhang; Hong, Xiaxiao; Yang, Zhihao; Luo, Shihe; Ye, Xiufang; Li, Yanli; Zhang, Yubo; Zhang, Min; Chen, Hong; Fan, Ting; Zhang, Yuyuan; Xiong, Bangyun; Wang, Zhaoyang; Zhu, Zhibo; Chen, Dongchu

2017-11-01

Three novel polydiacetylenes (PDAs) are synthesized through the self-assembly followed by the topochemical polymerization via controllable electrophoretic deposition. All the samples could undergo a multi-step thermochromic process, turning purple and red successively over a wide range from room temperature to above 250 °C. Resulting PDAs are studied by UV-vis, IR, Raman spectroscopies, and chromoisomerism by naked eye visualization; their stabilities by thermogravimetric method, and emission behavior by fluorescence spectroscopy. To study the mechanism of the thermochromic response, temperature-dependent UV-vis spectra, the results of which successfully highlighted the close relationship between chromatic transitions and the conformational changes.

Discrimination Between Maturity and Composition from Integrated Clementine UltraViolet-Visible and Near-Infrared Data

NASA Astrophysics Data System (ADS)

Le Mouelic, S.; Langevin, Y.; Erard, S.; Pinet, P.; Daydou, Y.; Chevrel, S.

1999-01-01

The Clementine UV-VIS dataset has greatly improved our understanding of the Moon. The UV-VIS camera was limited to five spectral channels from 415 to 1000 nm. The Clementine near-infrared (NIR) camera was designed to complement this spectral coverage. The NIR filter at 2000 run allows the discrimination between olivine and pyroxene within identified mare basalts. In addition, we will show that the integration of Clementine UV-VIS and NIR datasets allows a better evaluation of the ferrous 1-micron absorption band depth and gives access to the slope of the continuum. The discrimination between maturity and FeO composition can be achieved by a principal component analysis performed on spectral parameters. We selected 952 Clementine UV-VIS and NIR images to compute a multispectral cube covering the Aristarchus Plateau. Aristarchus Plateau is one of the most heterogeneous areas on the Moon. Highland-type materials, mare basalts, and dark mantle deposits have previously been mentioned. The mosaic represents a set of about 500 x 600 nine-channel spectra. UV-VIS filters at 415, 750, 900, 950, and 1000 run were calibrated using the ISIS software. We applied the reduction method described elsewhere to reduce the NIR filters at 1100, 1250, 1500 and 2000 nm. Absolute gain and offset values were refined for the NIR images by using eight telescopic spectra acquired as references. With this calibration test, we were able to reproduce the eight telescopic spectra with a maximum error of 1.8%. The integration of UV-VIS and NIR spectral channels allows the visualization of complete low-resolution spectra. In order to investigate the spectral effects of the space-weathering processes, we focused our analysis on a small mare crater and its immediate surroundings. According to the small size of the crater (about 2-km) and its location on an homogeneous mare area, we can reasonably assume that the content in FeO is homogeneous. The impact event has induced a variation of the maturity of the soil by excavating fresh material. Graphs displays five absolute reflectance spectra extracted from this area. One graph displays the same spectra divided by a continuum, which is considered to be a right line fitting the spectra at 0.75 and 1.5 micron. Spectrum 1 is extracted from the brightest part of the crater interior, and spectrum 5 is extracted from the surrounding mare material. Spectra 2, 3, and 4 are extracted from intermediate distances between the two areas. The 1-and-2 micron absorption band depths and the overall reflectance increase from spectrum 5 (corresponding to a mature area) to spectrum 1 (the most immature area). Conversely, the continuum slope decreases from spectrum 5 to spectrum 1. These three spectral effects of maturity have also been identified on laboratory spectra of lunar samples. Most of the lunar soils exhibit a signature near 1 micron. This absorption band is due to the presence of Fe2+ in mafic minerals such as orthopyroxene, clinopyroxene, and olivine. In the case of Clementine UV-VIS data alone, the depth of the 1-micron feature is evaluated by the 950/750-nm reflectance ratio. This ratio combined to the reflectance at 750nm has been used to evaluate the global content in FeO of the lunar surface. Near-infrared data makes a more precise evaluation of the 1 micron band depth possible by providing the right side of the band. The continuum in the vicinity of the band can be evaluated by an arithmetic mean or a geometric interpolation of both sides of the band, which are taken at 750 and 1500nm. The geometric interpolation is less sensitive to residual calibration uncertainties. With this method, the 1-micron absorption band depth for the Aristarchus; Plateau can be refined by as much as 10%. The difference is maximum on Fe-poor, highland-type materials. Similarly, the NIR data provide the possibility to investigate the continuum slope of the spectra. The continuum slope is a key parameter in any spectral analysis. The continuum slope variations seem to be mainly dominated by maturity effects, as suggested by the high correlation with the independent evaluation of maturity (OMAT parameter). We have also found a good correlation between the continuum slope and the OMAT parameter on laboratory spectra of lunar samples of the J. B. Adams collection. The discrimination between maturity effects and composition effects can be achieved by using a principal component analysis (PCA) on three spectral parameters, which are the reflectance at 0.75 micron the depth of the 1-micron feature, and the continuum slope. These parameters are mostly affected by maturity and FeO content. The effects of various glass content are assimilated to maturity. The aim of the PCA is to decorrelate the FeO content and maturity effects in the three input parameters. The integration of UV-VIS and NIR datasets allows for a better understanding of the spectral properties of the lunar surface by giving access to key parameters such as the 1 and 2-micron band depths and the continuum slope. The continuum slope can be combined with the depth of the mafic 1-micron absorption feature and the reflectance at 750 nm to discriminate between maturity and composition. NIR images of the sample return stations will be very interesting to refine absolute FeO content and maturity evaluations. Additional information is available in original.

Experimental and theoretical investigation on the molecular structure, spectroscopic and electric properties of 2,4-dinitrodiphenylamine, 2-nitro-4-(trifluoromethyl)aniline and 4-bromo-2-nitroaniline

NASA Astrophysics Data System (ADS)

Hernández-Paredes, Javier; Hernández-Negrete, Ofelia; Carrillo-Torres, Roberto C.; Sánchez-Zeferino, Raúl; Duarte-Moller, Alberto; Alvarez-Ramos, Mario E.

2015-10-01

2,4-Dinitrodiphenylamine (I), 2-nitro-4-(trifluoromethyl)aniline (II) and 4-bromo-2-nitroaniline (III) have been investigated by DFT and experimental FTIR, Raman and UV-Vis spectroscopies. The gas-phase molecular geometries were consistent with similar compounds already reported in the literature. From the vibrational analysis, the main functional groups were identified and their absorption bands were assigned. Some differences were found between the calculated and the experimental UV-Vis spectra. These differences were analyzed and explained in terms of the TD-DFT/B3LYP limitations, which were mainly attributed to charge-transfer (CT) effects. These findings were in agreement with previous works, which reported that TD-DFT/B3LYP calculations diverge from experimental results when the electronic transitions involve CT. Despite this, TD-DFT/B3LYP calculations provided satisfactory results and a detailed description of the electronic transitions involved in the absorption bands of the UV-Vis spectra. In terms of the NLO properties, it was found that compound (I) is a good candidate for NLO applications and deserves further study due to its good β values. However, the β values for compounds (II) and (III) were negatively affected compared to those found on o-nitroaniline.

UV-Vis, infrared, and mass spectroscopy of electron irradiated frozen oxygen and carbon dioxide mixtures with water

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

Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

2014-02-01

Ozone has been detected on the surface of Ganymede via observation of the Hartley band through the use of ultraviolet spectroscopy and is largely agreed upon to be formed by radiolytic processing via interaction of magnetospheric energetic ions and/or electrons with oxygen-bearing ices on Ganymede's surface. Interestingly, a clearly distinct band near 300 nm within the shoulder of the UV-Vis spectrum of Ganymede was also observed, but currently lacks an acceptable physical or chemical explanation. Consequently, the primary motivation behind this work was the collection of UV-Vis absorption spectroscopy of ozone formation by energetic electron bombardment of a variety ofmore » oxygen-bearing ices (oxygen, carbon dioxide, water) relevant to this moon as well as other solar system. Ozone was indeed synthesized in pure ices of molecular oxygen, carbon dioxide and a mixture of water and oxygen, in agreement with previous studies. The Hartley band of the ozone synthesized in these ice mixtures was observed in the UV-Vis spectra and compared with the spectrum of Ganymede. In addition, a solid state ozone absorption cross section of 6.0 ± 0.6 × 10{sup –17} cm{sup 2} molecule{sup –1} was obtained from the UV-Vis spectral data. Ozone was not produced in the irradiated carbon dioxide-water mixtures; however, a spectrally 'red' UV continuum is observed and appears to reproduce well what is observed in a large number of icy moons such as Europa.« less

Reaction pathways of proton transfer in hydrogen-bonded phenol-carboxylate complexes explored by combined UV-vis and NMR spectroscopy.

PubMed

Koeppe, Benjamin; Tolstoy, Peter M; Limbach, Hans-Heinrich

2011-05-25

Combined low-temperature NMR/UV-vis spectroscopy (UVNMR), where optical and NMR spectra are measured in the NMR spectrometer under the same conditions, has been set up and applied to the study of H-bonded anions A··H··X(-) (AH = 1-(13)C-2-chloro-4-nitrophenol, X(-) = 15 carboxylic acid anions, 5 phenolates, Cl(-), Br(-), I(-), and BF(4)(-)). In this series, H is shifted from A to X, modeling the proton-transfer pathway. The (1)H and (13)C chemical shifts and the H/D isotope effects on the latter provide information about averaged H-bond geometries. At the same time, red shifts of the π-π* UV-vis absorption bands are observed which correlate with the averaged H-bond geometries. However, on the UV-vis time scale, different tautomeric states and solvent configurations are in slow exchange. The combined data sets indicate that the proton transfer starts with a H-bond compression and a displacement of the proton toward the H-bond center, involving single-well configurations A-H···X(-). In the strong H-bond regime, coexisting tautomers A··H···X(-) and A(-)···H··X are observed by UV. Their geometries and statistical weights change continuously when the basicity of X(-) is increased. Finally, again a series of single-well structures of the type A(-)···H-X is observed. Interestingly, the UV-vis absorption bands are broadened inhomogeneously because of a distribution of H-bond geometries arising from different solvent configurations.

DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid

NASA Astrophysics Data System (ADS)

Karabacak, M.; Kose, E.; Sas, E. B.; Kurt, M.; Asiri, A. M.; Atac, A.

2015-02-01

The spectroscopic (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm-1 and 3500-10 cm-1, respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts (1H and 13C) were recorded in DMSO solution. The 1H and 13C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing.

DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid.

PubMed

Karabacak, M; Kose, E; Sas, E B; Kurt, M; Asiri, A M; Atac, A

2015-02-05

The spectroscopic (FT-IR, FT-Raman, (1)H and (13)C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts ((1)H and (13)C) were recorded in DMSO solution. The (1)H and (13)C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of geographical origin of alcoholic beverages using ultraviolet, visible and infrared spectroscopy: A review

NASA Astrophysics Data System (ADS)

Uríčková, Veronika; Sádecká, Jana

2015-09-01

The identification of the geographical origin of beverages is one of the most important issues in food chemistry. Spectroscopic methods provide a relative rapid and low cost alternative to traditional chemical composition or sensory analyses. This paper reviews the current state of development of ultraviolet (UV), visible (Vis), near infrared (NIR) and mid infrared (MIR) spectroscopic techniques combined with pattern recognition methods for determining geographical origin of both wines and distilled drinks. UV, Vis, and NIR spectra contain broad band(s) with weak spectral features limiting their discrimination ability. Despite this expected shortcoming, each of the three spectroscopic ranges (NIR, Vis/NIR and UV/Vis/NIR) provides average correct classification higher than 82%. Although average correct classification is similar for NIR and MIR regions, in some instances MIR data processing improves prediction. Advantage of using MIR is that MIR peaks are better defined and more easily assigned than NIR bands. In general, success in a classification depends on both spectral range and pattern recognition methods. The main problem still remains the construction of databanks needed for all of these methods.

Charge-Transfer Complexes and Photochemistry of Ozone with Ferrocene and n-Butylferrocene: A UV-vis Matrix-Isolation Study.

PubMed

Pinelo, Laura F; Kugel, Roger W; Ault, Bruce S

2015-10-15

The reactions of ozone with ferrocene (cp2Fe) and with n-butylferrocene (n-butyl cp2Fe) were studied using matrix isolation, UV-vis spectroscopy, and theoretical calculations. The codeposition of cp2Fe with O3 and of n-butyl cp2Fe with O3 into an argon matrix led to the production of 1:1 charge-transfer complexes with absorptions at 765 and 815 nm, respectively. These absorptions contribute to the green matrix color observed upon initial deposition. The charge-transfer complexes underwent photochemical reactions upon irradiation with red light (λ ≥ 600 nm). Theoretical UV-vis spectra of the charge-transfer complexes and photochemical products were calculated using TD-DFT at the B3LYP/6-311G++(d,2p) level of theory. The calculated UV-vis spectra were in good agreement with the experimental results. MO analysis of these long-wavelength transitions showed them to be n→ π* on the ozone subunit in the complex and indicated that the formation of the charge-transfer complex between ozone and cp2Fe or n-butyl cp2Fe affects how readily the π* orbital on O3 is populated when red light (λ ≥ 600 nm) is absorbed. 1:1 complexes of cp2Fe and n-butyl cp2Fe with O2 were also observed experimentally and calculated theoretically. These results support and enhance previous infrared studies of the mechanism of photooxidation of ferrocene by ozone, a reaction that has considerable significance for the formation of iron oxide thin films for a range of applications.

A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices.

PubMed

Kofman, V; Witlox, M J A; Bouwman, J; Ten Kate, I L; Linnartz, H

2018-05-01

This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools-UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry-can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, n λ , of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

A multifunctional setup to record FTIR and UV-vis spectra of organic molecules and their photoproducts in astronomical ices

NASA Astrophysics Data System (ADS)

Kofman, V.; Witlox, M. J. A.; Bouwman, J.; ten Kate, I. L.; Linnartz, H.

2018-05-01

This article describes a new, multi-functional, high-vacuum ice setup that allows to record the in situ and real-time spectra of vacuum UV (VUV)-irradiated non-volatile molecules embedded in a low-temperature (10 K) amorphous solid water environment. Three complementary diagnostic tools—UV-visible (UV-vis) and Fourier Transform Infrared (FTIR) spectroscopy and temperature-programmed desorption quadrupole mass spectrometry—can be used to simultaneously study the physical and chemical behavior of the organic molecules in the ice upon VUV irradiation. The setup is equipped with a temperature-controlled sublimation oven that enables the controlled homogeneous deposition of solid species such as amino acids, nucleobases, and polycyclic aromatic hydrocarbons (PAHs) in ice mixtures prepared from precursor gases and/or liquids. The resulting ice is photo-processed with a microwave discharge hydrogen lamp, generating VUV radiation with a spectral energy distribution representative for the interstellar medium. The characteristics, performance, and future potential of the system are discussed by describing three different applications. First, a new method is introduced, which uses broadband interference transmission fringes recorded during ice deposition, to determine the wavelength-dependent refractive index, nλ, of amorphous solid water. This approach is also applicable to other solids, pure and mixed. Second, the UV-vis and FTIR spectroscopy of an VUV-irradiated triphenylene:water ice mixture is discussed, monitoring the ionization efficiency of PAHs in interstellar ice environments. The third and final example investigates the stability of solid glycine upon VUV irradiation by monitoring the formation of dissociation products in real time.

Evaluation of the optical characteristics of c-axis oriented zinc oxide thin films grown by sol gel spin coating technique

NASA Astrophysics Data System (ADS)

Baisakh, K.; Behera, S.; Pati, S.

2018-03-01

In this work we have systematically studied the optical characteristics of synthesized wurzite zinc oxide thin films exhibiting (002) orientation. Using sol gel spin coating technique zinc oxide thin films are grown on pre cleaned fused quartz substrates. Structural properties of the films are studied using X-ray diffraction analysis. Micro structural analysis and thickness of the grown samples are analyzed using field emission scanning electron microscopy. With an aim to investigate the optical characteristics of the grown zinc oxide thin films the transmission and reflection spectra are evaluated in the ultraviolet-visible (UV-VIS) range. Using envelope method, the refractive index, extinction coefficient, absorption coefficient, band gap energy and the thickness of the synthesized films are estimated from the recorded UV-VIS spectra. An attempt has also been made to study the influence of crystallographic orientation on the optical characteristics of the grown films.

Study of the interaction of deoxynivalenol with human serum albumin by spectroscopic technique and molecular modelling.

PubMed

Li, Yuqin; Wang, Hao; Jia, Baoxiu; Liu, Caihong; Liu, Ke; Qi, Yongxiu; Hu, Zhide

2013-01-01

The mechanism of interaction between deoxynivalenol (DON) and human serum albumin (HSA) was studied using spectroscopic methods including fluorescence spectra, UV-VIS, Fourier transform infrared (FT-IR) and circular dichroism (CD). The quenching mechanism was investigated in terms of the association constants, number of binding sites and basic thermodynamic parameters. The distance between the HSA donor and the acceptor DON was 2.80 nm as derived from fluorescence resonance energy transfer. The secondary structure compositions of free HSA and its DON complexes were estimated by the FT-IR spectra. Alteration of the secondary protein structure in the presence of DON was confirmed by UV-VIS and CD spectroscopy. Molecular modelling revealed that a DON-protein complex was stabilised by hydrophobic forces and hydrogen bonding. It was potentially useful for elucidating the toxigenicity of DON when combined with biomolecular function effect, transmembrane transport, toxicological testing and the other experiments.

Library of UV-Vis-NIR reflectance spectra of modern organic dyes from historic pattern-card coloured papers.

PubMed

Montagner, Cristina; Bacci, Mauro; Bracci, Susanna; Freeman, Rachel; Picollo, Marcello

2011-09-01

An accurate characterisation of the organic dyes used in artworks, especially those made of paper, is an important factor in designing safe conservation treatments. In the case of synthetic organic dyes used in modern works of art, for example, one frequently encountered difficulty is that some of these dyes are not still commercially available. Recognizing this problem, the authors of this paper present the results of an analysis of UV-Vis-NIR fibre optic reflectance spectra of 82 samples of dyed paper prepared with 41 dyes. The samples come from a historic book, The Dyeing of Paper in the Pulp, which was published by Interessen-Gemeinschaft (I.G.) Farbenindustrie in 1925. The dyes used in the paper pulp belong to the azo compounds, acridine, anthraquinone, azine, diphenylmethane, indigoid, methine, nitro, quinoline, thiazine, triphenylmethane, sulphur and xanthene classes. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic properties and theoretical studies of bis-Schiff bases derived from polyamine and pyrazolones.

PubMed

Ren, Tiegang; Liu, Shuyun; Li, Guihui; Zhang, Jinglai; Guo, Jia; Li, Weijie; Yang, Lirong

2012-11-01

A series of novel bis-Schiff base were synthesized from 1-aryl-3-methyl-4-benzoyl-5-pyrazolones and diethylenetriamine (or triethylenetetramine) as the starting materials. All of these bis-Schiff bases were characterized by means of NMR, IR, and MS. The UV-vis absorption spectra and fluorescent spectra of these bis-Schiff bases were also measured. Moreover, the B3LYP/6-31G(d) method was used to optimize the ground state geometry of the bis-Schiff bases; and the UV-vis spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVDZ basis set of TD-B3LYP method. It has been found that all of these bis-Schiff bases show a remarkable absorption peak in a wavelength range of 270-340 nm; and their maximum emission peaks are around 348 nm. Copyright © 2012 Elsevier B.V. All rights reserved.

Method for outlier detection: a tool to assess the consistency between laboratory data and ultraviolet-visible absorbance spectra in wastewater samples.

PubMed

Zamora, D; Torres, A

2014-01-01

Reliable estimations of the evolution of water quality parameters by using in situ technologies make it possible to follow the operation of a wastewater treatment plant (WWTP), as well as improving the understanding and control of the operation, especially in the detection of disturbances. However, ultraviolet (UV)-Vis sensors have to be calibrated by means of a local fingerprint laboratory reference concentration-value data-set. The detection of outliers in these data-sets is therefore important. This paper presents a method for detecting outliers in UV-Vis absorbances coupled to water quality reference laboratory concentrations for samples used for calibration purposes. Application to samples from the influent of the San Fernando WWTP (Medellín, Colombia) is shown. After the removal of outliers, improvements in the predictability of the influent concentrations using absorbance spectra were found.

UV-Vis absorption spectra and electronic structure of merocyanines in the gas phase

NASA Astrophysics Data System (ADS)

Ishchenko, Alexander A.; Kulinich, Andrii V.; Bondarev, Stanislav L.; Raichenok, Tamara F.

2018-02-01

Gas-phase absorption spectra of a merocyanine vinylogous series have been studied for the first time. In vapour, their long-wavelength absorption bands were found to be considerably shifted hypsochromically, broader, more symmetrical, less intense, and their vinylene shift much smaller than even in low-polarity n-hexane. This indicates that in the gas phase their electronic structure closely approaches the nonpolar polyene limiting structure. The TDDFT calculations of the long-wavelength electronic transitions in the studied merocyanines in vacuo demonstrated good-to-excellent correlation - depending on the functional used - with the obtained experimental data. For comparison, the solvent effects was accounted for using the polarizable continuum model (PCM) with n-hexane and ethanol as low-polarity and high-polarity media, and compared with the UV-Vis spectral data in these solvents. In this case, the discrepancy between theory and experiment was much greater, increasing at that with the polymethine chain length.

Microstructure and optical properties of nanocrystalline Cu2O thin films prepared by electrodeposition.

PubMed

Jiang, Xishun; Zhang, Miao; Shi, Shiwei; He, Gang; Song, Xueping; Sun, Zhaoqi

2014-01-01

Cuprous oxide (Cu2O) thin films were prepared by using electrodeposition technique at different applied potentials (-0.1, -0.3, -0.5, -0.7, and -0.9 V) and were annealed in vacuum at a temperature of 100°C for 1 h. Microstructure and optical properties of these films have been investigated by X-ray diffractometer (XRD), field-emission scanning electron microscope (SEM), UV-visible (vis) spectrophotometer, and fluorescence spectrophotometer. The morphology of these films varies obviously at different applied potentials. Analyses from these characterizations have confirmed that these films are composed of regular, well-faceted, polyhedral crystallites. UV-vis absorption spectra measurements have shown apparent shift in optical band gap from 1.69 to 2.03 eV as the applied potential becomes more cathodic. The emission of FL spectra at 603 nm may be assigned as the near band-edge emission.

Insights into dissociative electron transfer in esterified shikonin semiquinones by in situ ESR/UV-Vis spectroelectrochemistry.

PubMed

Armendáriz-Vidales, G; Frontana, C

2015-11-21

In this work, electrogenerated anion and dianion species from shikonin and its ester derivative isovalerylshikonin were characterized by means of ESR/UV-Vis spectroelectrochemistry. Analysis of the spectra supported the proposal that stepwise dissociative electron transfer (DET) takes place during the second reduction process of the esterified compound. Quantum chemical calculations were performed for validating the occurrence of this mechanistic pathway and for obtaining thermodynamic information on the electron transfer process; ΔG(cleavage)(0) was estimated to be -0.45 eV, considering that the two possible products of the overall reaction scheme are both a quinone and carboxylate anions.

Computational Design of Tunable UV-Vis-IR Filters Based on Silver Nanoparticle Arrays

NASA Astrophysics Data System (ADS)

Waters, Michael; Shi, Guangsha; Kioupakis, Emmanouil

We propose design strategies to develop selective optical filters in the UV-Vis-IR spectrum using the surface plasmon response of silver nanoparticle arrays. Our finite-difference time-domain simulations allow us to rapidly evaluate many nanostructures comprising simple geometries while varying their shape, height, width, and spacing. Our results allow us to identify trends in the filtering spectra as well as the relative amount of absorption and reflection. Optical filtering with nanoparticles is applicable to any transparent substrate and can be easily adapted to existing manufacturing processes while keeping the total cost of materials low. This work was supported by Guardian Industries Corp.

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.

PubMed

Pires-Oliveira, Rafael; Joekes, Inés

2014-11-01

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38 °C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. Copyright © 2014 Elsevier B.V. All rights reserved.

[Measurement of Water COD Based on UV-Vis Spectroscopy Technology].

PubMed

Wang, Xiao-ming; Zhang, Hai-liang; Luo, Wei; Liu, Xue-mei

2016-01-01

Ultraviolet/visible (UV/Vis) spectroscopy technology was used to measure water COD. A total of 135 water samples were collected from Zhejiang province. Raw spectra with 3 different pretreatment methods (Multiplicative Scatter Correction (MSC), Standard Normal Variate (SNV) and 1st Derivatives were compared to determine the optimal pretreatment method for analysis. Spectral variable selection is an important strategy in spectrum modeling analysis, because it tends to parsimonious data representation and can lead to multivariate models with better performance. In order to simply calibration models, the preprocessed spectra were then used to select sensitive wavelengths by competitive adaptive reweighted sampling (CARS), Random frog and Successive Genetic Algorithm (GA) methods. Different numbers of sensitive wavelengths were selected by different variable selection methods with SNV preprocessing method. Partial least squares (PLS) was used to build models with the full spectra, and Extreme Learning Machine (ELM) was applied to build models with the selected wavelength variables. The overall results showed that ELM model performed better than PLS model, and the ELM model with the selected wavelengths based on CARS obtained the best results with the determination coefficient (R2), RMSEP and RPD were 0.82, 14.48 and 2.34 for prediction set. The results indicated that it was feasible to use UV/Vis with characteristic wavelengths which were obtained by CARS variable selection method, combined with ELM calibration could apply for the rapid and accurate determination of COD in aquaculture water. Moreover, this study laid the foundation for further implementation of online analysis of aquaculture water and rapid determination of other water quality parameters.

Synthesis of Ni nanoparticles decorated SiO2/TiO2 magnetic spheres for enhanced photocatalytic activity towards the degradation of azo dye

NASA Astrophysics Data System (ADS)

Mahesh, K. P. O.; Kuo, Dong-Hau

2015-12-01

Highly photocatalytic active Ni magnetic nanoparticles-decorated SiO2 core/TiO2 shell (Ni-SiO2/TiO2) particles have been prepared by the simultaneous hydrolysis and condensation of titanium tetra-isopropoxide on SiO2 sphere of ∼300 nm in size followed by the reduction of nickel chloride using hydrazine hydrate as a reducing agent. The crystalline nature, surface morphology, electrochemical impedance spectra and UV-vis diffuse reflectance spectra of the Ni-SiO2/TiO2 magnetic spheres were characterized by PXRD, FE-SEM, TEM, EIS and UV-vis DRS. The Ni-SiO2/TiO2 magnetic photocatalyst was used for the degradation of Acid Black 1 (AB 1) dye under UV irradiation. The effects of different concentrations of the Ni nanoparticles deposited on the SiO2/TiO2 composite spheres for the photo-mineralization of AB 1 dye were analyzed. The results showed the Ni-SiO2/TiO2 magnetic photocatalyst to be efficient and reusable.

Synthesis and characterization of photo-crosslinkable 4-styryl-pyridine modified alginate.

PubMed

Elsayed, Nadia H; Monier, M; Alatawi, Raedah A S

2016-07-10

In this article photo-crosslinkablestyryl-pyridine modified alginate (ASP-Alg) was prepared and entirely investigated utilizing different instrumental techniques such as Elemental analysis, Fourier transform infrared (FTIR),(13)C and (1)H nuclear magnetic resonance (NMR), ultraviolet-visible light (UV-vis), X-ray diffraction (XRD) spectra and scanning electron microscope (SEM). Upon irradiation in the UV region, the casted ASP-Alg membranes were cross-linked through the [2π+2π] cycloaddition reaction of the inserted photo-active styryl pyridine moieties. Both cross-linking density and kinetics were monitored by examining the UV-vis light spectra of the irradiated membrane at predetermined time intervals and the obtained results were found to fit with the second order mathematical kinetic model, revealing the performance of the cross-linking via bimolecular [2π+2π] cycloaddition reaction. Also, the swelling behaviors along with biodegradability were also studied, and the results indicated the decrease of the swelling ratio and degradation rate by increasing the cross-linking density. Moreover, the mechanical properties were also examined under both wet and dry conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis, thermogravimetric, spectroscopic and theoretical characterization of copper(II) complex with 4-chloro-2-nitrobenzenosulfonamide

NASA Astrophysics Data System (ADS)

Camí, G.; Chacón Villalba, E.; Di Santi, Y.; Colinas, P.; Estiu, G.; Soria, D. B.

2011-05-01

4-Chloro-2-nitrobenzenesulfonamide (ClNbsa) was purified and characterized. A new copper(II) complex, [Cu(ClNbsa) 2(NH 3) 2], has been prepared using the sulfonamide as ligand. The thermal behavior of both, the ligand and the Cu(II) complex, was investigated by thermogravimetric analyses (TG) and differential thermal analysis (DT), and the electronic characteristics analyzed by UV-VIS, FTIR, Raman and 1H NMR spectroscopies. The experimental IR, Raman and UV-VIS spectra have been assigned on the basis of DFT calculations at the B3LYP level of theory using the standard (6-31 + G ∗∗) basis set. The geometries have been fully optimized in vacuum and in modeled dimethylsulfoxide (DMSO) solvent, using for the latter a continuum solvation model that reproduced the experimental conditions of the UV-VIS spectroscopy. The theoretical results converged to stable conformations for the free sulfonamide and for the complex, suggesting for the latter a distorted square planar geometry in both environments.

Chemistry WebBook

National Institute of Standards and Technology Data Gateway

SRD 69 NIST Chemistry WebBook (Web, free access)   The NIST Chemistry WebBook contains: Thermochemical data for over 7000 organic and small inorganic compounds; thermochemistry data for over 8000 reactions; IR spectra for over 16,000 compounds; mass spectra for over 33,000 compounds; UV/Vis spectra for over 1600 compounds; electronic and vibrational spectra for over 5000 compounds; constants of diatomic molecules(spectroscopic data) for over 600 compounds; ion energetics data for over 16,000 compounds; thermophysical property data for 74 fluids.

Vibrational analysis, NBO analysis, NMR, UV-VIS, hyperpolarizability analysis of Trimethadione by density functional theory

NASA Astrophysics Data System (ADS)

Vijayachamundeeswari, S. P.; Yagna Narayana, B.; Jone Pradeepa, S.; Sundaraganesan, N.

2015-11-01

Trimethadione (TMD) is an anticonvulsant drug widely used against absences seizures. We have characterised the TMD by various spectra including UV-VIS, IR, Raman, GC-MS and NMR. In this work, we made use of Density Functional Theory (DFT) B3LYP method with 6-31G (d, p) basis set, to calculate the molecular structure of TMD, and predicted its infrared, Raman and ultraviolet spectra for the first time. FT-IR and FT-Raman spectra were recorded in the region 4000-400 cm-1 and 3500-50 cm-1, respectively. The vibrational frequencies were calculated and scaled values were compared with the experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes. The optimized geometry parameters were calculated. NMR chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. The predicted first hyperpolarizibility also shows that the molecule might have convincingly good nonlinear optical (NLO) activities. The calculated HOMO-LUMO energy gap discloses that charge transfer occurs within the molecule.

Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices.

PubMed

Saş, E Babur; Kurt, M; Can, M; Okur, S; İçli, S; Demiç, S

2014-12-10

The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV-Vis, (1)H and (13)C NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. (1)H and (13)C NMR spectra and UV-Vis spectrum were recorded in DMSO solution. HOMO-LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices

NASA Astrophysics Data System (ADS)

Saş, E. Babur; Kurt, M.; Can, M.; Okur, S.; İçli, S.; Demiç, S.

2014-12-01

The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV-Vis, 1H and 13C NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. 1H and 13C NMR spectra and UV-Vis spectrum were recorded in DMSO solution. HOMO-LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.

Characterization and activity of Pd-modified TiO2 catalysts for photocatalytic oxidation of NO in gas phase.

PubMed

Wu, Zhongbiao; Sheng, Zhongyi; Liu, Yue; Wang, Haiqiang; Tang, Nian; Wang, Jie

2009-05-30

Pd-modified TiO(2) prepared by thermal impregnation method was used in this study for photocatalytic oxidation of NO in gas phase. The physico-chemical properties of Pd/TiO(2) catalysts were characterized by X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller measurements (BET), X-ray photoelectron spectrum analysis (XPS), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), UV-vis diffuse reflectance spectra (UV-vis DRS) and photoluminescence spectra (PL). It was found that Pd dopant existed as PdO particles in as-prepared photocatalysts. The results of PL spectra indicated that the photogenerated electrons and holes were efficiently separated after Pd doping. During in situ XPS study, it was found that the content of hydroxyl groups on the surface of Pd/TiO(2) increased when the catalyst was irradiated by UV light, which could result in the improvement of photocatalytic activity. The activity test showed that the optimum Pd dopant content was 0.05 wt.%. And the maximum conversion of NO was about 72% higher than that of P25 when the initial concentration of NO was 200 ppm, which showed that Pd/TiO(2) photocatalysts could be potentially applied to oxidize higher concentration of NO.

Field test of a new instrument to measure UV/Vis (300-700 nm) ambient aerosol extinction spectra in Colorado during DISCOVER-AQ

NASA Astrophysics Data System (ADS)

Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Dibb, J. E.; Greenslade, M. E.; Martin, R.; Scheuer, E. M.; Shook, M.; Thornhill, K. L., II; Troop, D.; Winstead, E.; Ziemba, L. D.

2014-12-01

An optical instrument has been developed to investigate aerosol extinction spectra in the ambient atmosphere. Based on a White-type cell design and using a differential optical approach, aerosol extinction spectra over the 300-700 nm ultraviolet and visible (UV/Vis) wavelength range are obtained. Laboratory tests conducted at NASA Langley Research Center (NASA LaRC) in March 2014 showed good agreement with Cavity Attenuated Phase Shift (CAPS PMex, Aerodyne Research) extinction measurements (at 450, 530, and 630 nm) for a variety of aerosols, e.g., scatterers such as polystyrene latex spheres and ammonium sulfate; absorbers such as dust (including pigmented minerals), smoke (generated in a miniCAST burning propane) and laboratory smoke analogs (e.g., fullerene soot and aquadag). The instrument was field tested in Colorado in July and August 2014 aboard the NASA mobile laboratory at various ground sites during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign. A description of the instrument, results from the laboratory tests, and summer field data will be presented. The instrument provides a new tool for probing in situ aerosol optical properties that may help inform remote sensing approaches well into the UV range.

UV-Vis-NIR luminescence properties and energy transfer mechanism of LiSrPO4:Eu2+, Pr3+ suitable for solar spectral convertor.

PubMed

Chen, Yan; Wang, Jing; Liu, Chunmeng; Tang, Jinke; Kuang, Xiaojun; Wu, Mingmei; Su, Qiang

2013-02-11

An efficient near-infrared (NIR) phosphor LiSrPO(4):Eu(2+), Pr(3+) is synthesized by solid-state reaction and systematically investigated using x-ray diffraction, diffuse reflection spectrum, photoluminescence spectra at room temperature and 3 K, and the decay curves. The UV-Vis-NIR energy transfer mechanism is proposed based on these results. The results demonstrate Eu(2+) can be an efficient sensitizer for harvesting UV photon and greatly enhancing the NIR emission of Pr(3+) between 960 and 1060 nm through efficient energy feeding by allowed 4f-5d absorption of Eu(2+) with high oscillator strength. Eu(2+)/Pr(3+) may be an efficient donor-acceptor pair as solar spectral converter for Si solar cells.

Impact of vanadium ions in barium borate glass

NASA Astrophysics Data System (ADS)

Abdelghany, A. M.; Hammad, Ahmed H.

2015-02-01

Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data.

Experimental and theoretical investigation on the molecular structure, spectroscopic and electric properties of 2,4-dinitrodiphenylamine, 2-nitro-4-(trifluoromethyl)aniline and 4-bromo-2-nitroaniline.

PubMed

Hernández-Paredes, Javier; Hernández-Negrete, Ofelia; Carrillo-Torres, Roberto C; Sánchez-Zeferino, Raúl; Duarte-Moller, Alberto; Alvarez-Ramos, Mario E

2015-10-05

2,4-Dinitrodiphenylamine (I), 2-nitro-4-(trifluoromethyl)aniline (II) and 4-bromo-2-nitroaniline (III) have been investigated by DFT and experimental FTIR, Raman and UV-Vis spectroscopies. The gas-phase molecular geometries were consistent with similar compounds already reported in the literature. From the vibrational analysis, the main functional groups were identified and their absorption bands were assigned. Some differences were found between the calculated and the experimental UV-Vis spectra. These differences were analyzed and explained in terms of the TD-DFT/B3LYP limitations, which were mainly attributed to charge-transfer (CT) effects. These findings were in agreement with previous works, which reported that TD-DFT/B3LYP calculations diverge from experimental results when the electronic transitions involve CT. Despite this, TD-DFT/B3LYP calculations provided satisfactory results and a detailed description of the electronic transitions involved in the absorption bands of the UV-Vis spectra. In terms of the NLO properties, it was found that compound (I) is a good candidate for NLO applications and deserves further study due to its good β values. However, the β values for compounds (II) and (III) were negatively affected compared to those found on o-nitroaniline. Copyright © 2015 Elsevier B.V. All rights reserved.

Biosynthesis and computational analysis of amine-ended dual thiol ligand functionalized gold nanoparticles for conventional spectroscopy detection of melamine.

PubMed

Anand, K; Singh, Thishana; Madhumitha, G; Phulukdaree, A; Gengan, Robert M; Chuturgoon, A A

2017-04-01

The bio-synthesized DTAuNPs have an average size of 21nm. The aggregation extent depends on the concentration of melamine, which was validated by UV-vis spectra and visual method of melamine detection was developed. The major observation in this method was the color change of DTAuNPs from red to purple due to the aggregation of ligand capped gold nanoparticles instigated by melamine. The reaction of color changes were processed due to the shifting of bonding in hydrogen in between nanoparticles and melamine. The aggregation extent depends on the concentration of melamine, which can be validated UV-vis spectra and visual method of detecting melamine is developed. The electron density and conventional UV-vis, FTIR spectroscopy and DFT studies on the ligand was performed using computational methods. The theoretical and experimental data for the energy transitions and the molar extinction coefficients of the ligands studied has been obtained. Further, the ligand capped gold nanoparticles was assessed for cytotoxicity against A549 cells which resulted in significant decrease in cell viability was noted in 50μg/mL DTAu, 4-ATP and AXT treated cells at 2h (85% and 66%) and 6h (83% and 36%) respectively, (p<0.01) were studied and reported in this manuscript. Copyright © 2017 Elsevier B.V. All rights reserved.

Color change of tourmaline by heat treatment and electron beam irradiation: UV-Visible, EPR, and Mid-IR spectroscopic analyses

NASA Astrophysics Data System (ADS)

Maneewong, Apichate; Seong, Baek Seok; Shin, Eun Joo; Kim, Jeong Seog; Kajornrith, Varavuth

2016-01-01

The color of pink tourmaline gemstone changed to colorless when heating at temperature of 600 °C in air. This colorless tourmaline recovered its pink color when irradiated with an electron beam (e-beam) of 800 kGy. The origin of the color change was investigated in three types of tourmaline gemstones, two pink are from Afghanistan and one green are from Nigeria, by using Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and Energy Dispersive X-ray Fluorescence (EDXRF). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: two absorption bands centered at wavelength of 396 and 520 nm, respectively. Both absorption bands disappeared when heated in air at 600 °C and then reappeared when irradiated with an e-beam at 800 kGy. EPR T2 spectra showed that the color change was related to the valence change of Mn3+ to Mn2+ and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also became colorless when heated, but the color was not recovered when the gemstone underwent e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from a decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with either heat treatment or e-beam irradiation.

Assessing pearl quality using reflectance UV-Vis spectroscopy: does the same donor produce consistent pearl quality?

PubMed

Mamangkey, Noldy Gustaf F; Agatonovic, Snezana; Southgate, Paul C

2010-09-20

Two groups of commercial quality ("acceptable") pearls produced using two donors, and a group of "acceptable" pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters.

Detection of Maillard reaction products by a coupled HPLC-Fraction collector technique and FTIR characterization of Cu(II)-complexation with the isolated species

NASA Astrophysics Data System (ADS)

Ioannou, Aristos; Daskalakis, Vangelis; Varotsis, Constantinos

2017-08-01

The isolation of reaction products of asparagine with reducing sugars at alkaline pH and high temperature has been probed by a combination of high performance liquid chromatography (HPLC) coupled with a Fraction Collector. The UV-vis and FTIR spectra of the isolated Maillard reaction products showed structure-sensitive changes as depicted by deamination events and formation of asparagine-saccharide conjugates. The initial reaction species of the Asn-Gluc reaction were also characterized by Density Functional Theory (DFT) methods. Evidence for Cu (II) metal ion complexation with the Maillard reaction products is supported by UV-vis and FTIR spectroscopy.

Optical absorption and photoluminescence study of nanocrystalline Zn0.92M0.08O (M: Li & Gd)

NASA Astrophysics Data System (ADS)

Punia, Khushboo; Lal, Ganesh; Kumar, Sudhish

2018-05-01

Nanocrystalline samples of Zn0.92Li0.08O and Zn0.92Gd0.08O have been synthesized using citrate sol-gel route without post synthesis annealing and characterized using powder X-ray diffraction (XRD), UV-Vis-NIR and Photoluminescence spectroscopic measurements. Analysis of XRD pattern and PL spectra revealed single phase formation of the nanocrystalline Zn0.92Li0.08O and Zn0.92Gd0.08O in the wurtzite type hexagonal structure with intrinsic crystal and surface defects. UV-Vis-NIR optical absorption measurements show that the maximum photo absorption occurs below 600nm in the UV& visible band. The estimated values of band gap energy were found to be 2.53eV and 2.73eV for Zn0.92Li0.08O and Zn0.92Gd0.08O respectively. The photoluminescence spectra excited at the wavelength 325nm displays two broad peaks in the UV and visible bands centered at ˜416 nm & ˜602 nm for Zn0.92Gd0.08O and ˜406nm & ˜598nm for Zn0.92Li0.08O. Both Gd and Li doping in ZnO leads to considerable decrease in the optical band gap energy and red shifting of the UV emission band towards the visible band.

UV-vis spectroscopic studies of CaF2 photo-thermo-refractive glass

NASA Astrophysics Data System (ADS)

Stoica, Martina; Herrmann, Andreas; Hein, Joachim; Rüssel, Christian

2016-12-01

A photo-thermo-refractive glass based on the system Na2O/K2O/CaO/CaF2/Al2O3/ZnO/SiO2 doped with Ag2O, CeO2, SnO2, Sb2O3 and KBr was investigated. This glass undergoes a permanent refractive index change after UV irradiation and subsequent two step heat treatment at temperatures above Tg. This is due to the formation of Ag metal clusters which act as nucleation centers for CaF2 crystallization. Oxidation of Ce3+ by UV light is the initial reaction and acts as photosensitizer in the glass. The UV-vis absorption spectra during this photo-induced crystallization process were measured. The spectral components that form the absorption spectra of cerium were studied in detail by a band separation with Gaussian functions. Deconvolution of the cerium absorption bands shows an envelope of five spectral components for the trivalent cerium due to the 4f-5d transitions and two spectral components for the tetravalent cerium caused by charge transfer transitions. The effect of different dopants and melting conditions on the photo-thermal process were studied to investigate the influence of glass technology on the photoprocess.

Synthesis, characterization, and spectroscopic investigation of benzoxazole conjugated Schiff bases.

PubMed

Santos, Fabiano S; Costa, Tania M H; Stefani, Valter; Gonçalves, Paulo F B; Descalzo, Rodrigo R; Benvenutti, Edilson V; Rodembusch, Fabiano S

2011-11-24

Two Schiff bases were synthesized by reaction of 2-(4'-aminophenyl)benzoxazole derivatives with 4-N,N-diethylaminobenzaldehyde. UV-visible (UV-vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes' shift. The UV-vis data indicates that each dye behaves as two different chromophores in solution in the ground state. The fluorescence emission spectra of the dye 5a show that an intramolecular proton transfer (ESIPT) mechanism takes place in the excited state, whereas a twisted internal charge transfer (TICT) state is observed for the dye 5b. Theoretical calculations were performed in order to study the conformation and polarity of the molecules at their ground and excited electronic states. Using density functional theory (DFT) methods at theoretical levels BLYP/Aug-SV(P) for geometry optimizations and B3LYP/6-311++G(2d,p) for single-point energy evaluations, the calculations indicate that the lowest energy conformations are in all cases nonplanar and that the dipole moments of the excited state relaxed structures are much larger than those of the ground state structures, which corroborates the experimental UV-vis absorption results.

FT-IR, UV-vis, 1H and 13C NMR spectra and the equilibrium structure of organic dye molecule disperse red 1 acrylate: a combined experimental and theoretical analysis.

PubMed

Cinar, Mehmet; Coruh, Ali; Karabacak, Mehmet

2011-12-01

This study reports the characterization of disperse red 1 acrylate compound by spectral techniques and quantum chemical calculations. The spectroscopic properties were analyzed by FT-IR, UV-vis, (1)H NMR and (13)C NMR techniques. FT-IR spectrum in solid state was recorded in the region 4000-400 cm(-1). The UV-vis absorption spectrum of the compound that dissolved in methanol was recorded in the range of 200-800 nm. The (1)H and (13)C NMR spectra were recorded in CDCl(3) solution. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. A satisfactory consistency between the experimental and theoretical spectra was obtained and it shows that the hybrid DFT method is very useful in predicting accurate vibrational structure, especially for high-frequency region. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. A study on the electronic properties were performed by timedependent DFT (TD-DFT) and CIS(D) approach. To investigate non linear optical properties, the electric dipole moment μ, polarizability α, anisotropy of polarizability Δα and molecular first hyperpolarizability β were computed. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the compound can be a good candidate of nonlinear optical materials. Copyright © 2011 Elsevier B.V. All rights reserved.

Green synthesis of stabilized spherical shaped gold nanoparticles using novel aqueous Elaeis guineensis (oil palm) leaves extract

NASA Astrophysics Data System (ADS)

Ahmad, Tausif; Bustam, Mohamad Azmi; Irfan, Muhammad; Moniruzzaman, Muhammad; Anwaar Asghar, Hafiz Muhammad; Bhattacharjee, Sekhar

2018-05-01

In the last decade, development of bioinspired protocols to synthesize gold nanoparticles (AuNPs) using plants and their extracts have been dealt by researchers due to their low cost, renewability and non-toxic features. A simple, cheap and ecofriendly method is reported to synthesize stabilized AuNPs of size 35-75 nm at room temperature using aqueous Elaeis guineensis (oil palm) leaves extract without addition of any external agent. Oil palm leaves mediated AuNPs were characterized using FTIR, UV-vis spectrophotometer, EDAX, XPS, FESEM, TEM, DLS and TGA. FTIR spectra results revealed contribution of phenolic, carboxylic, amines and amides in reduction of trivalent gold ions and stabilization of formed gold atoms. Reaction solution color change and UV-vis spectra confirmed reduction of gold ions to generate gold atoms. Reaction mechanism explained the role of phenolic compounds in reduction reaction using FTIR and UV-vis spectra results. EDAX and XPS results further validated the formation of metallic gold particles through bioreduction of gold ions. Crystal structure of metallic gold particles was confirmed through XRD peaks indexing to (111), (200), (220) and (311) planes. TEM and FESEM particles size measurements exhibited the formation of nanostructured AuNPs. Synthesis of well scattered and spherical shaped AuNPs was revealed through FESEM and TEM images. The excellent stability of AuNPs was shown through high negative zeta potential value (-14.7 ± 4.68 mV) and uniform dispersion in aqueous media. Our results disclosed the excellent potential of Elaeis guineensis (oil palm) leaves as reducing and stabilizing agents in green synthesis of well scattered spherical shaped AuNPs, which can be employed as strong candidates in medical drug delivery and industrial applications.

Artificial neural network associated to UV/Vis spectroscopy for monitoring bioreactions in biopharmaceutical processes.

PubMed

Takahashi, Maria Beatriz; Leme, Jaci; Caricati, Celso Pereira; Tonso, Aldo; Fernández Núñez, Eutimio Gustavo; Rocha, José Celso

2015-06-01

Currently, mammalian cells are the most utilized hosts for biopharmaceutical production. The culture media for these cell lines include commonly in their composition a pH indicator. Spectroscopic techniques are used for biopharmaceutical process monitoring, among them, UV-Vis spectroscopy has found scarce applications. This work aimed to define artificial neural networks architecture and fit its parameters to predict some nutrients and metabolites, as well as viable cell concentration based on UV-Vis spectral data of mammalian cell bioprocess using phenol red in culture medium. The BHK-21 cell line was used as a mammalian cell model. Off-line spectra of supernatant samples taken from batches performed at different dissolved oxygen concentrations in two bioreactor configurations and with two pH control strategies were used to define two artificial neural networks. According to absolute errors, glutamine (0.13 ± 0.14 mM), glutamate (0.02 ± 0.02 mM), glucose (1.11 ± 1.70 mM), lactate (0.84 ± 0.68 mM) and viable cell concentrations (1.89 10(5) ± 1.90 10(5) cell/mL) were suitably predicted. The prediction error averages for monitored variables were lower than those previously reported using different spectroscopic techniques in combination with partial least squares or artificial neural network. The present work allows for UV-VIS sensor development, and decreases cost related to nutrients and metabolite quantifications.

Mineralogy and chemistry of Ti-bearing lunar soils: Effects on reflectance spectra and remote sensing observations

NASA Astrophysics Data System (ADS)

Coman, Ecaterina O.; Jolliff, Bradley L.; Carpenter, Paul

2018-05-01

This paper presents results of coordinated ultraviolet and visible wavelength reflectance measurements, X-ray diffraction analyses of mineral components, and micro X-ray fluorescence analyses of Ti concentrations of 13 lunar soil samples (<210 μm) that span a range of maturity and TiO2 contents. Results of these analyses are used to determine the effects of soil maturity, TiO2 concentration, and specific mineralogical makeup, especially ilmenite content, on the ultraviolet/visible (UV/VIS) ratio for application to remote sensing observations of the Moon and other airless bodies. We find that measured ilmenite weight percent correlates highly with measured TiO2 concentrations. Thus, the ilmenite content is a good predictor of TiO2 concentration. Ilmenite is the main contributor of TiO2 for soils with greater than about 2 wt.% TiO2, so we take the effects of TiO2 on reflectance spectra to be essentially those of ilmenite. Constraining the data set to eight mature Apollo soils, we find that among the UV/VIS ratios from laboratory-measured spectra, the 321/415 nm ratio shows the best correlation with TiO2 and ilmenite. Moreover, for soils with similar maturity in the submature to mature range, those with higher TiO2 have higher 321/415 UV/VIS ratios. Finally, the correlation between TiO2 content and 321/415 ratio in samples measured in the lab appears weaker than for the same relationship using the Lunar Reconnaissance Orbiter (LRO) Wide Angle Camera (WAC) spectral data for the 321/415 ratio of Apollo ground-truth sites. The correlation between lab-derived 321/415 ratios and TiO2 content for measured samples improves when low-maturity samples are excluded from the dataset, implying that the LROC WAC spectra at 400 m/pix spatial resolution senses mostly mature soil.

Aqueous synthesis of III-V semiconductor GaP and InP exhibiting pronounced quantum confinement.

PubMed

Gao, Shanmin; Lu, Jun; Chen, Nan; Zhao, Yan; Xie, Yi

2002-12-21

A mild aqueous synthesis route was successfully established to synthesize well crystallized and monodisperse GaP and InP nanocrystals, which were proved to exhibit pronounced quantum confinement by room-temperature UV/Vis adsorption and photoluminescence (PL) spectra.

Spectroscopic studies of anthracyclines: Structural characterization and in vitro tracking

NASA Astrophysics Data System (ADS)

Szafraniec, Ewelina; Majzner, Katarzyna; Farhane, Zeineb; Byrne, Hugh J.; Lukawska, Malgorzata; Oszczapowicz, Irena; Chlopicki, Stefan; Baranska, Malgorzata

2016-12-01

A broad spectroscopic characterization, using ultraviolet-visible (UV-vis) and Fourier transform infrared absorption as well as Raman scattering, of two commonly used anthracyclines antibiotics (DOX) daunorubicin (DNR), their epimers (EDOX, EDNR) and ten selected analogs is presented. The paper serves as a comprehensive spectral library of UV-vis, IR and Raman spectra of anthracyclines in the solid state and in solution. The particular advantage of Raman spectroscopy for the measurement and analysis of individual antibiotics is demonstrated. Raman spectroscopy can be used to monitor the in vitro uptake and distribution of the drug in cells, using both 488 nm and 785 nm as source wavelengths, with submicrometer spatial resolution, although the cellular accumulation of the drug is different in each case. The high information content of Raman spectra allows studies of the drug-cell interactions, and so the method seems very suitable for monitoring drug uptake and mechanisms of interaction with cellular compartments at the subcellular level.

Synthesis of gold nanorods with a longitudinal surface plasmon resonance peak of around 1250 nm

NASA Astrophysics Data System (ADS)

Nguyen, Thi Nhat Hang; Le Trinh Nguyen, Thi; Thanh Tuyen Luong, Thi; Thang Nguyen, Canh Minh; Nguyen, Thi Phuong Phong

2016-03-01

We prepared gold nanorods and joined them to chemicals such as tetrachloauric (III) acid trihydrate, silver nitrate, hydroquinone, hexadecyltrimethylammonium bromide, sodium hydroxide and sodium borohydride using the seed-mediated method. The combination of hydroquinone, with or without salicylic acid, influences the size of the gold nanorods, and this is demonstrated by the results of TEM images, UV-vis spectra and the value of the longitudinal surface plasmon resonance peak with respect to the UV-vis spectra. By changing the Ag+ ion and hydroquinone concentration and the combination of hydroquinone and salicylic acid, the size of the gold nanorods can be controlled and this is manifested by longitudinal surface plasmon resonance peaks forming between 875 and 1278 nm. In particular, sample E2 achieved a longitudinal surface plasmon peak at 1273 nm and an aspect ratio of more than 10 by modifying the hydroquinone to 2.5 mM and salicylic acid to 0.5 mM concentration in the growth solution.

Synthesis and characterization of CdS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Fang, Pengfei; Chen, Zhe; Wang, Shaojie

2007-08-01

A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd 2+-dispersed poly vinyl-alcohol (PVA) with H 2S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd sbnd S bond at 405 cm -1 was observed, which further testified the generation of CdS nanoparticles. The TGA results showed incorporation of CdS nanoparticles significantly altered the thermal properties of PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that the CdS/PVA films showed quantum confinement effect.

Electrochemical and spectroscopic study on the interaction between isoprenaline and DNA using multivariate curve resolution-alternating least squares.

PubMed

Ni, Yongnian; Wei, Min; Kokot, Serge

2011-11-01

Interaction of isoprenaline (ISO) with calf-thymus DNA was studied by spectroscopic and electrochemical methods. The behavior of ISO was investigated at a glassy carbon electrode (GCE) by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV); ISO was oxidized and an irreversible oxidation peak was observed. The binding constant K and the stoichiometric coefficient m of ISO with DNA were evaluated. Also, with the addition of DNA, hyperchromicity of the UV-vis absorption spectra of ISO was noted, while the fluorescence intensity decreased significantly. Multivariate curve resolution-alternating least squares (MCR-ALS) chemometrics method was applied to resolve the combined spectroscopic data matrix, which was obtained by the UV-vis and fluorescence methods. Pure spectra of ISO, DNA and ISO-DNA complex, and their concentration profiles were then successfully obtained. The results indicated that the ISO molecule intercalated into the base-pairs of DNA, and the complex of ISO-DNA was formed. Copyright © 2011 Elsevier B.V. All rights reserved.

Spectroscopic Studies on the Effect of Some Ferrocene Derivatives in the Formation of Silver Nanoparticles.

PubMed

Sanyal, Manik Kumar; Biswas, Bipul; Chowdhury, Avijit; Mallik, Biswanath

2016-06-01

Silver nanoparticles were prepared by microwave assisted method using silver nitrate as precursor in the presence of some ferrocene derivatives. The formation of the silver nanoparticles was monitored using UV-Vis spectroscopy. The UV-Vis spectroscopy revealed the formation of silver nanoparticles by exhibiting typical surface plasmon absorption band. The position of plasmon band (406-429 nm) was observed to depend on the nature of a particular ferrocene derivative used. TEM images indicated that the nanoparticles were spherical in shape and well-dispersed. Quantum dots (3.2 nm) were prepared by using ferrocenecarboxylic acid. The surface plasmon absorption band has shown red shift with increasing concentration of ferrocene derivative. For different duration of microwave heating time, intensity of absorption spectra in general was found to increase except in presence of ferrocene carbaldehyde where it decreased. Time-dependent spectra have indicated almost stable position of the surface plasmon band with increasing time of observation confirming that the as prepared silver nanoparticles did not aggregate with lapse of time.

Experimental and theoretical description of the optical properties of Myrcia sylvatica essential oil.

PubMed

Silva Prado, Andriele da; Leal, Luciano Almeida; de Brito, Patrick Pascoal; de Almeida Fonseca, Antonio Luciano; Blawid, Stefan; Ceschin, Artemis Marti; Veras Mourão, Rosa Helena; da Silva Júnior, Antônio Quaresma; Antonio da Silva Filho, Demétrio; Ribeiro Junior, Luiz Antonio; Ferreira da Cunha, Wiliam

2017-07-01

We present an extensive study of the optical properties of Myrcia sylvatica essential oil with the goal of investigating the suitability of its material system for uses in organic photovoltaics. The methods of extraction, experimental analysis, and theoretical modeling are described in detail. The precise composition of the oil in our samples is determined via gas chromatography, mass spectrometry, and X-ray scattering techniques. The measurements indicate that, indeed, the material system of Myrcia sylvatica essential oil may be successfully employed for the design of organic photovoltaic devices. The optical absorption of the molecules that compose the oil are calculated using time-dependent density functional theory and used to explain the measured UV-Vis spectra of the oil. We show that it is sufficient to consider the α-bisabolol/cadalene pair, two of the main constituents of the oil, to obtain the main features of the UV-Vis spectra. This finding is of importance for future works that aim to use Myrcia sylvatica essential oil as a photovoltaic material.

UV-vis spectroscopy and colorimetric models for detecting anthocyanin-metal complexes in plants: An overview of in vitro and in vivo techniques.

PubMed

Fedenko, Volodymyr S; Shemet, Sergiy A; Landi, Marco

2017-05-01

Although anthocyanin (ACN) biosynthesis is one of the best studied pathways of secondary metabolism in plants, the possible physiological and ecological role(s) of these pigments continue to intrigue scientists. Like other dihydroxy B-ring substituted flavonoids, ACNs have an ability to bind metal and metalloid ions, a property that has been exploited for a variety of purposes. For example, the metal binding ability may be used to stabilize ACNs from plant food sources, or to modify their colors for using them as food colorants. The complexation of metals with cyanidin derivatives can also be used as a simple, sensitive, cheap, and rapid method for determination concentrations of several metals in biological and environmental samples using UV-vis spectroscopy. Far less information is available on the ecological significance of ACN-metal complexes in plant-environment interactions. Metalloanthocyanins (protocyanin, nemophilin, commelinin, protodelphin, cyanosalvianin) are involved in the copigmentation phenomenon that leads to blue-pigmented petals, which may facilitate specific plant-pollinator interactions. ACN-metal formation and compartmentation into the vacuole has also been proposed to be part of an orchestrated detoxification mechanism in plants which experience metal/metalloid excess. However, investigations into ACN-metal interactions in plant biology may be limited because of the complexity of the analytical techniques required. To address this concern, here we describe simple methods for the detection of ACN-metal both in vitro and in vivo using UV-vis spectroscopy and colorimetric models. In particular, the use of UV-vis spectra, difference absorption spectra, and colorimetry techniques will be described for in vitro determination of ACN-metal features, whereas reflectance spectroscopy and colorimetric parameters related to CIE L * a * b * and CIE XYZ systems will be detailed for in vivo analyses. In this way, we hope to make this high-informative tool more accessible to plant physiologists and ecologists. Copyright © 2017 Elsevier GmbH. All rights reserved.

UV-vis and Raman spectroelectrochemical investigation of the redox behavior of poly(5-cyanoindole) in acidic aqueous solutions.

PubMed

Talbi, H; Billaud, D; Louarn, G; Pron, A

2000-03-01

Spectroelectrochemical properties of conducting poly(5-cyanoindole) films deposited on indium tin oxide (ITO) and platinum electrodes are investigated using UV-vis and resonant Raman spectroscopies. The transitions from undoped to semi-conducting state of P5CN require the partial oxidation of the polymer to create radical-cations by insertion of charge-neutralizing anions into the polymer. In order to obtain detailed structural information from the vibrational spectra, it is necessary to know the vibrational modes of oxidation-sensitive bands. Vibrational assignments were made on the basis of the results obtained on polyindole and P5CN in acetonitrile solution. The drastic changes in optical absorption and Raman spectra observed at various stage of oxidation were explained by the conversions between at least three different structures. On the basis of the Raman spectra, we have identified the vibrational modes associated with neutral and polaronic segments. The perturbation associated with the coexistence of these polaronic segments has been described as a quinoid structure growing on the expense of the benzoid one. The results obtained indicate that the molecular properties of the conducting polymers at various stages of an oxidation are better revealed by in-situ Raman spectra than by ex-situ studies.

Spectral analysis, vibrational assignments, NBO analysis, NMR, UV-Vis, hyperpolarizability analysis of 2-aminofluorene by density functional theory.

PubMed

Jone Pradeepa, S; Sundaraganesan, N

2014-05-05

In this present investigation, the collective experimental and theoretical study on molecular structure, vibrational analysis and NBO analysis has been reported for 2-aminofluorene. FT-IR spectrum was recorded in the range 4000-400 cm(-1). FT-Raman spectrum was recorded in the range 4000-50 cm(-1). The molecular geometry, vibrational spectra, and natural bond orbital analysis (NBO) were calculated for 2-aminofluorene using Density Functional Theory (DFT) based on B3LYP/6-31G(d,p) model chemistry. (13)C and (1)H NMR chemical shifts of 2-aminofluorene were calculated using GIAO method. The computed vibrational and NMR spectra were compared with the experimental results. The total energy distribution (TED) was derived to deepen the understanding of different modes of vibrations contributed by respective wavenumber. The experimental UV-Vis spectra was recorded in the region of 400-200 nm and correlated with simulated spectra by suitably solvated B3LYP/6-31G(d,p) model. The HOMO-LUMO energies were measured with time dependent DFT approach. The nonlinearity of the title compound was confirmed by hyperpolarizabilty examination. Using theoretical calculation Molecular Electrostatic Potential (MEP) was investigated. Copyright © 2014 Elsevier B.V. All rights reserved.

Fusion of Ultraviolet-Visible and Infrared Transient Absorption Spectroscopy Data to Model Ultrafast Photoisomerization.

PubMed

Debus, Bruno; Orio, Maylis; Rehault, Julien; Burdzinski, Gotard; Ruckebusch, Cyril; Sliwa, Michel

2017-08-03

Ultrafast photoisomerization reactions generally start at a higher excited state with excess of internal vibrational energy and occur via conical intersections. This leads to ultrafast dynamics which are difficult to investigate with a single transient absorption spectroscopy technique, be it in the ultraviolet-visible (UV-vis) or infrared (IR) domain. On one hand, the information available in the UV-vis domain is limited as only slight spectral changes are observed for different isomers. On the other hand, the interpretation of vibrational spectra is strongly hindered by intramolecular relaxation and vibrational cooling. These limitations can be circumvented by fusing UV-vis and IR transient absorption spectroscopy data in a multiset multivariate curve resolution analysis. We apply this approach to describe the spectrodynamics of the ultrafast cis-trans photoisomerization around the C-N double bond observed for aromatic Schiff bases. Twisted intermediate states could be elucidated, and isomerization was shown to occur through a continuous complete rotation. More broadly, data fusion can be used to rationalize a vast range of ultrafast photoisomerization processes of interest in photochemistry.

Quantitative and qualitative studies of silica in different rice samples grown in north of Iran using UV-vis, XRD and IR spectroscopy techniques.

PubMed

Samadi-Maybodi, Abdolraouf; Atashbozorg, Ebrahim

2006-11-15

Silicon is an essential trace element and is found in vegetables, fruits, cereals, water, pasta and rice (Oryza sativa). In this work, the silica content of different types of rice grains were measured. Here, we used the heteropoly blue photometric method with a double beam UV-vis spectrophotometer to determine the amount of silicon in rice samples (n=7) that were collected in the north of Iran. The samples were digested with wet-ashing method by microwave-assisted heating and then treated with ammonium molybdate to produce a yellow color compound in acidic solution (ca. pH 1.2) and then reduced to give a heteropoly compound with a blue color. Analyses were performed using standard addition method and absorbance values were measured with double beam UV-vis spectrophotometer at lambda(max)=815nm. Results indicated that the silica content was 307-451mg/kg for the samples. X-ray diffraction patterns and infra-red spectra were obtained from rice samples without any sample treatment.

Investigation on interaction between Ligupurpuroside A and pepsin by spectroscopic and docking methods.

PubMed

Shen, Liangliang; Xu, Hong; Huang, Fengwen; Li, Yi; Xiao, Huafeng; Yang, Zhen; Hu, Zhangli; He, Zhendan; Zeng, Zheling; Li, Yinong

2015-01-25

Ligupurpuroside A is one of the major glycoside in Ku-Din-Cha, a type of Chinese functional tea. In order to better understand its digestion and metabolism in humans, the interaction between Ligupurpuroside A and pepsin has been investigated by fluorescence spectra, UV-vis absorption spectra and synchronous fluorescence spectra along with molecular docking method. The fluorescence experiments indicate that Ligupurpuroside A can effectively quench the intrinsic fluorescence of pepsin through a combined quenching way at the low concentration of Ligupurpuroside A, and a static quenching procedure at the high concentration. The binding constant, binding sites of Ligupurpuroside A with pepsin have been calculated. The thermodynamic analysis suggests that non-covalent reactions, including electrostatic force, hydrophobic interaction and hydrogen bond are the main forces stabilizing the complex. According to the Förster's non-radiation energy transfer theory, the binding distance between pepsin and Ligupurpuroside A was calculated to be 3.15 nm, which implies that energy transfer occurs between pepsin and Ligupurpuroside A. Conformation change of pepsin was observed from UV-vis absorption spectra and synchronous fluorescence spectra under experimental conditions. In addition, all these experimental results have been validated by the protein-ligand docking studies which show that Ligupurpuroside A is located in the cleft between the domains of pepsin. Copyright © 2014 Elsevier B.V. All rights reserved.

Emission spectra of photoionized plasmas induced by intense EUV pulses: Experimental and theoretical investigations

NASA Astrophysics Data System (ADS)

Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemysław; Jarocki, Roman; Fiedorowicz, Henryk

2017-03-01

Experimental measurements and numerical modeling of emission spectra in photoionized plasma in the ultraviolet and visible light (UV/Vis) range for noble gases have been investigated. The photoionized plasmas were created using laser-produced plasma (LPP) extreme ultraviolet (EUV) source. The source was based on a gas puff target; irradiated with 10ns/10J/10Hz Nd:YAG laser. The EUV radiation pulses were collected and focused using grazing incidence multifoil EUV collector. The laser pulses were focused on a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of gases resulted in a formation of low temperature photoionized plasmas emitting radiation in the UV/Vis spectral range. Atomic photoionized plasmas produced this way consisted of atomic and ionic with various ionization states. The most dominated observed spectral lines originated from radiative transitions in singly charged ions. To assist in a theoretical interpretation of the measured spectra, an atomic code based on Cowan's programs and a collisional-radiative PrismSPECT code have been used to calculate the theoretical spectra. A comparison of the calculated spectral lines with experimentally obtained results is presented. Electron temperature in plasma is estimated using the Boltzmann plot method, by an assumption that a local thermodynamic equilibrium (LTE) condition in the plasma is validated in the first few ionization states. A brief discussion for the measured and computed spectra is given.

Electronic structure and spectroscopic properties of mononuclear manganese(III) Schiff base complexes: a systematic study on [Mn(acen)X] complexes by EPR, UV/vis, and MCD spectroscopy (X = Hal, NCS).

PubMed

Westphal, Anne; Klinkebiel, Arne; Berends, Hans-Martin; Broda, Henning; Kurz, Philipp; Tuczek, Felix

2013-03-04

The manganese(III) Schiff base complexes [Mn(acen)X] (H2acen: N,N'-ethylenebis(acetylacetone)imine, X: I(-), Br(-), Cl(-), NCS(-)) are considered as model systems for a combined study of the electronic structure using vibrational, UV/vis absorption, parallel-mode electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectroscopy. By variation of the co-ligand X, the influence of the axial ligand field within a given square-pyramidal coordination geometry on the UV/vis, EPR, and MCD spectra of the title compounds is investigated. Between 25000 and 35000 cm(-1), the low-temperature MCD spectra are dominated by two very intense, oppositely signed pseudo-A terms, referred to as "double pseudo-A terms", which change their signs within the [Mn(acen)X] series dependent on the axial ligand X. Based on molecular orbital (MO) and symmetry considerations, these features are assigned to π(n.b.)(s, a) → yz, z(2) ligand-to-metal charge transfer transitions. The individual MCD signs are directly determined from the calculated MOs of the [Mn(acen)X] complexes. The observed sign change is explained by an inversion of symmetry among the π(n.b.)(s, a) donor orbitals which leads to an interchange of the positive and negative pseudo-A terms constituting the "double pseudo-A term".

Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy.

PubMed

Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P; Nguyen, Huong T H; Dang, Andy; Tureček, František

2018-01-16

Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z 4 + H] +● fragment ion-radicals of the R-C ● H-CONH- type, initially formed by N-C α bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [ ● DAAR + H] + isomers and used to assign structures to the action spectra. The potential energy surface of [ ● DAAR + H] + isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [ ● XAAR + H] + ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone C α positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H] ● -ETD fragments containing Asp, Asn, Glu, and Gln residues. Graphical Abstract ᅟ.

Spontaneous Isomerization of Peptide Cation Radicals Following Electron Transfer Dissociation Revealed by UV-Vis Photodissociation Action Spectroscopy

NASA Astrophysics Data System (ADS)

Imaoka, Naruaki; Houferak, Camille; Murphy, Megan P.; Nguyen, Huong T. H.; Dang, Andy; Tureček, František

2018-01-01

Peptide cation radicals of the z-type were produced by electron transfer dissociation (ETD) of peptide dications and studied by UV-Vis photodissociation (UVPD) action spectroscopy. Cation radicals containing the Asp (D), Asn (N), Glu (E), and Gln (Q) residues were found to spontaneously isomerize by hydrogen atom migrations upon ETD. Canonical N-terminal [z4 + H]+● fragment ion-radicals of the R-C●H-CONH- type, initially formed by N-Cα bond cleavage, were found to be minor components of the stable ion fraction. Vibronically broadened UV-Vis absorption spectra were calculated by time-dependent density functional theory for several [●DAAR + H]+ isomers and used to assign structures to the action spectra. The potential energy surface of [●DAAR + H]+ isomers was mapped by ab initio and density functional theory calculations that revealed multiple isomerization pathways by hydrogen atom migrations. The transition-state energies for the isomerizations were found to be lower than the dissociation thresholds, accounting for the isomerization in non-dissociating ions. The facile isomerization in [●XAAR + H]+ ions (X = D, N, E, and Q) was attributed to low-energy intermediates having the radical defect in the side chain that can promote hydrogen migration along backbone Cα positions. A similar side-chain mediated mechanism is suggested for the facile intermolecular hydrogen migration between the c- and [z + H]●-ETD fragments containing Asp, Asn, Glu, and Gln residues. [Figure not available: see fulltext.

Impact of vanadium ions in barium borate glass.

PubMed

Abdelghany, A M; Hammad, Ahmed H

2015-02-25

Combined optical and infrared spectral measurements of prepared barium borate glasses containing different concentrations of V2O5 were carried out. Vanadium containing glasses exhibit extended UV-visible (UV/Vis.) bands when compared with base binary borate glass. UV/Vis. spectrum shows the presence of an unsymmetrical strong UV broad band centered at 214 nm attributed to the presence of unavoidable trace iron impurities within the raw materials used for the preparation of such glass. The calculated direct and indirect optical band gaps are found to decrease with increasing the vanadium content (2.9:137 for indirect and 3.99:2.01 for direct transition). This change was discussed in terms of structural changes in the glass network. Infrared absorption spectra of the glasses reveal the appearance of both triangular and tetrahedral borate units. Electron spin resonance analyses indicate the presence of unpaired species in sufficient quantity to be identified and to confirm the spectral data. Copyright © 2014 Elsevier B.V. All rights reserved.

The photocatalytic investigation of methylene blue dye with Cr doped zinc oxide nanoparticles

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

Ray, Rajeev; Kumar, Ashavani, E-mail: ashavani@yahoo.com

2015-08-28

The present work reports eco-friendly and cost effective sol-gel technique for synthesis of Chromium doped ZnO nanoparticles at room temperature. In this process Zinc nitrate, Chromium nitrate were used as precursor. Structural as well as optical properties of Cr induced ZnO samples were analysed by X-ray diffraction technique (XRD), SEM, PL and UV-Visible spectroscopy (UV-Vis) respectively. XRD analysis shows that the samples have hexagonal (wurtzite) structure with no additional peak which suggests that Cr ions fit into the regular Zn sites of ZnO crystal structure. By using Scherrer’s formula for pure and Cr doped ZnO samples the average grain sizemore » was found to be 32 nm. Further band gap of pure and doped ZnO samples have been calculated by using UV-Vis spectra. The photo-catalytic degradation of methyl blue dye under UV irradiation was examined for synthesized samples. The results show that the concentration plays an important role in photo-catalytic activity.« less

Dithia[3.3]paracyclophane-based monometal ruthenium acetylide complexes: synthesis, characterization and substituent effects.

PubMed

Zhu, Xingxun; Ou, Yaping; Zhang, Jing; Xia, Jian-Long; Yin, Jun; Yu, Guang-Ao; Liu, Sheng Hua

2013-05-21

A series of dithia[3.3]metaparacyclophane-based monometal ruthenium acetylide complexes have been synthesized. All of the complexes have been fully characterised by NMR spectrometry, X-ray crystallography and elemental analyses. At the same time, their basic optical properties, such as UV/Vis absorption spectra, and electrochemical properties have been determined. (1)H NMR and X-ray crystal structure studies reveal that there are intramolecular C-H···π interactions in these ruthenium complexes, in both solution and solid states. Electrochemical studies reveal that the substituted groups on the dithia[3.3]paracyclophane ring can clearly affect the oxidation activities of the ruthenium center by way of the intramolecular C-H···π interaction. In addition, electron-donating groups facilitate the oxidation of the ruthenium center compared with electron-deficient groups. UV/Vis absorption and IR spectra of some complexes in neutral and oxidized states also have been studied. IR spectra studies indicated that the substituents in the cyclophane have some effects on the ν(C≡C) bands of these complexes in the neutral state and little effect on ν(C≡C) of these complexes in the oxidized state.

Quantum chemical calculations and analysis of FTIR, FT-Raman and UV-Vis spectra of temozolomide molecule

NASA Astrophysics Data System (ADS)

Bhat, Sheeraz Ahmad; Ahmad, Shabbir

2015-11-01

A combined experimental and theoretical study of the structure, vibrational and electronic spectra of temozolomide molecule, which is largely used in the treatment of brain tumours, is presented. FTIR (4000-400 cm-1) and FT-Raman spectra (4000‒50 cm-1) have been recorded and analysed using anharmonic frequency calculations using VPT2, VSCF and CC-VSCF levels of theory within B3LYP/6-311++G(d,p) framework. Anharmonic methods give accurate frequencies of fundamental modes, overtones as well as Fermi resonances and account for coupling of different modes. The anharmonic frequencies calculated using VPT2 and CC-VSCF methods show better agreement with the experimental data. Harmonic frequencies including solvent effects are also computed using IEF-PCM model. The magnitudes of coupling between pair of modes have been calculated using coupling integral based on 2MR-QFF approximation. Intermolecular interactions are discussed for three possible dimers of temozolomide. UV-Vis spectrum, examined in ethanol solvent, is compared with the calculated spectrum at TD-DFT/6-311++G(d,p) level of theory. The electronic properties, such as excitation energy, frontier molecular orbital energies and the assignments of the absorption bands are also discussed.

Comparative theoretical and experimental study on novel tri-quinoline system and its anticancer studies

NASA Astrophysics Data System (ADS)

Gayathri, Kasirajan; Radhika, Ramachandran; Shankar, Ramasamy; Malathi, Mahalingam; Savithiri, Krishnaswamy; Sparkes, Hazel A.; Howard, Judith A. K.; Mohan, Palathurai Subramaniam

2017-04-01

A novel compound 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline 3 bearing a tri-quinoline moiety has been synthesized from 2-chloro-3,6-dimethyl quinoline 1 and 8-hydroxy quinoline 2 using dry acetone and K2CO3 as a base. 3 has been characterized by using FT-IR, FT-Raman, UV-Vis, 1H NMR, 13C NMR spectra and single crystal X-ray diffraction methods. We have also made a combined experimental and theoretical study on the molecular structure, vibrational spectra, NMR, FT-IR, FT-Raman and UV-Vis spectra of 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline. The theoretical studies of the title compound have been evaluated by using density functional theory calculations using B3LYP/6-31+G(d,p) and M06-2X/6-31+G(d,p) level of theories. The calculated theoretical values were found to be in good agreement with the experimental findings. The single crystal structure 3 crystallized in the orthorhombic space group Pna21. The compound 3 exhibits higher cytotoxicity in human cervical cancer cell lines (HeLa) than human breast cancer cell lines (MCF7).

Spectral and quantum chemical studies on 1,3-bis(N(1)-4-amino-6-methoxypyrimidinebenzenesulfonamide-2,2,4,4-ethane-1,2-dithiol)-2,4-dichlorocyclodiphosph(V)azane and its erbium complex.

PubMed

Al-Mogren, Muneerah M; Alaghaz, Abdel-Nasser M A; El-Gogary, Tarek M

2014-01-24

Novel 1,3-bis(N(1)-4-amino-6-methoxypyrimidine-benzenesulfonamide-2,2,4,4-ethane-1,2-dithiol)-2,4-dichlorocyclodiphosph(V)azane (L), was prepared and their coordinating behavior towards the lanthanide ion Er(III) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-VIS., (1)H NMR, (13)C NMR, (31)P NMR, SEM, XRD, mass spectra, effective magnetic susceptibility measurements and thermogravimetric analysis (TGA). Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of L and its binuclear Er(III) complex. Different tautomers of the ligand were optimized at the ab initio DFT level. Keto-form structure is about 17.7 kcal/mol more stable than the enol form (taking zpe correction into account). Simulated IR frequencies were scaled and compared with that experimentally measured. TD-DFT method was used to compute the UV-VIS spectra which compared by the measured electronic spectra. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Gawai, U. P.; Dole, B. N.; Khawal, H. A.

Ag doped ZnO nanocrystals were synthesized by co-precipitation method with the nominal compositions (x=0.00, 0.02, 0.04, 0.06). The as-synthesized Ag doped ZnO nanocrystals were characterized by X-ray diffraction (XRD), FTIR and UV-Vis. From XRD patterns samples shows hexagonal structure. The average crystallite size is in the range of 41-47 nm. All as synthesized Zn{sub 1−x}Ag{sub x}O nanocrystals are highly textured, with wurtzite structure along the (101) growth direction. The energy band gap of pure and Ag doped ZnO were calculated from UV-Vis spectra. FTIR spectra were confirmed that Ag substituted into ZnO. Chemical species of the samples were detected using FTIRmore » spectra An increase in the hexagonal lattice parameters of ZnO is observed on increasing the Ag concentration. An optical absorption study shows an increment in the band gap with increasing Ag content. From optical study the samples determines blue shift. Atomic packing fraction (APF) and c/a ratio were calculated using XRD data. It confirms the formation of ZnO with the stretching vibrational mode around at 506 to 510 cm{sup −1}.« less

Design of geometry, synthesis, spectroscopic (FT-IR, UV/Vis, excited state, polarization) and anisotropy (thermal conductivity and electrical) properties of new synthesized derivatives of (E,E)-azomethines in colored stretched poly (vinyl alcohol) matrix

NASA Astrophysics Data System (ADS)

Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Dikusar, Evgenij; Yahyaei, Hooriye; Kumar, Rakesh; Khaleghian, Mehrnoosh

2018-04-01

In the present work, the molecular structures of two new azomethine dyes: have been predicted and investigated using Density Functional Theory (DFT) in dimethylformamide (DMF). The geometries of the azomethine dyes were optimized by B3LYP/6-31+G* level of theory. The electronic spectra of these azomethine dyes in a DMF solvent was carried out by using TD-B3LYP/6-31+G* method. After quantum-chemical calculations two new azomethine dyes for optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. The computed absorption spectral data of the azomethine dyes are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for visible region of spectrum were developed. The main optical parameters of the polarizing PVA-films (Transmittance, Polarization Efficiency and Dichroic Ratio) have been measured and discussed. Anisotropy of thermal and electrical conductivity of the PVA-films have been studied and explained.

Additive assisted hydrothermal synthesis, characterization and optical properties of one dimensional DyPO4:Ce3+ nanostructures

NASA Astrophysics Data System (ADS)

Khajuria, H.; Kumar, M.; Singh, R.; Ladol, J.; Nawaz Sheikh, H.

2018-05-01

One dimensional nanostructures of cerium doped dysprosium phosphate (DyPO4:Ce3+) were synthesized via hydrothermal route in the presence of different surfactants [sodium dodecyl sulfate (SDS), dodecyl sulfosuccinate (DSS), polyvinyl pyrollidone (PVP)] and solvent [ethylene glycol and water]. The prepared nanostructures were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-VIS-NIR absorption spectrophotometer and photoluminescence (PL) studies. The PXRD and FTIR results indicate purity, good crystallinity and effective doping of Ce3+ in nanostructures. SEM and TEM micrographs display nanorods, nanowires and nanobundles like morphology of DyPO4:Ce3+. Energy-dispersive X-ray spectra (EDS) of DyPO4:Ce3+nanostructures confirm the presence of dopant. UV-VIS-NIR absorption spectra of prepared compounds are used to calculate band gap and explore their optical properties. Luminescent properties of DyPO4:Ce3+ was studied by using PL emission spectra. The effect of additives and solvents on the uniformity, morphology and optical properties of the nanostructures were studied in detail.

Preparation, characterization, physical properties, and photoconducting behaviour of anthracene derivative nanowires

NASA Astrophysics Data System (ADS)

Xiao, Jinchong; Yin, Zongyou; Yang, Bo; Liu, Yi; Ji, Li; Guo, Jun; Huang, Ling; Liu, Xuewei; Yan, Qingyu; Zhang, Hua; Zhang, Qichun

2011-11-01

Organic nanowires of 9,10-dibromoanthracene (DBA) and 9,10-dicyanoanthracene (DCNA) were obtained by adding the THF solution of DBA/DCNA into water containing P123 surfactants. The as-prepared nanowires were characterized by UV-vis, fluorescence spectra, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). We found that DBA and DCNA nanowires emitted green light rather than blue light for molecules in THF solution. The red-shift UV and fluorescent spectra of DBA and DCNA nanowires implied that these nanowires were formed through J-aggregation. The photoconducting study of DBA/DCNA nanowire-based network on rGO/SiO2/Si shows different photocurrent behaviors upon irradiation, which displayed that electron transfer from DCNA nanowire to rGO was stronger than that of DBA nanowires to rGO.Organic nanowires of 9,10-dibromoanthracene (DBA) and 9,10-dicyanoanthracene (DCNA) were obtained by adding the THF solution of DBA/DCNA into water containing P123 surfactants. The as-prepared nanowires were characterized by UV-vis, fluorescence spectra, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). We found that DBA and DCNA nanowires emitted green light rather than blue light for molecules in THF solution. The red-shift UV and fluorescent spectra of DBA and DCNA nanowires implied that these nanowires were formed through J-aggregation. The photoconducting study of DBA/DCNA nanowire-based network on rGO/SiO2/Si shows different photocurrent behaviors upon irradiation, which displayed that electron transfer from DCNA nanowire to rGO was stronger than that of DBA nanowires to rGO. Electronic supplementary information (ESI) available: XRD patterns and simulations, and FT-IR spectra. CCDC reference numbers 840471. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c1nr10655d

Assessment of spectroscopic parameters of solvated Eu(dmh)3 phen organometallic complex in various basic and acidic solvents.

PubMed

Chitnis, Dipti; Kalyani, N Thejo; Dhoble, Sanjay

2018-05-31

We report on the comprehension of novel europium activated hybrid organic Eu(dmh) 3 phen (Eu: europium, dmh: 2,6-dimethyl-3,5-heptanedione, phen: 1,10 phenanthroline) organo-metallic complexes, synthesized at different pH values by the solution technique. Photo physical properties of these complexes in various basic and acidic solvents were probed by UV-vis optical absorption and photoluminescence (PL) spectra. Minute differences in optical absorption peaks with variable optical densities were encountered with the variation in solvent from basic (chloroform, toluene, tetrahydrofuran) to acidic (acetic acid) media, revealing bathochromic shift in the absorption peaks. The PL spectra of the complex in various acidic and basic organic solvents revealed the position of the emission peak at 613 nm irrespective of the changes in solvents whereas the excitation spectrum almost matched with that of the UV-vis absorption data. The optical density was found to be maximum for the complex with pH 7.0 whereas it gradually decreased when pH was lowered to 6.0 or raised to 8.0 at an interval of 0.5, demonstrating its pH sensitive nature. Several spectroscopic parameters related to probability of transition such as absorbance A(λ), Napierian absorption coefficient α(λ), molecular absorption cross-section σ(λ), radiative lifetime (τ 0 ) and oscillator strength (f) were calculated from UV-vis spectra. The relative intensity ratio (R-ratio), calculated from the emission spectra was found to be almost the same in all the organic solvents. The optical energy gap, calculated for the designed complexes were found to be well in accordance with the ideal acceptance value of energy gap of the emissive materials used for fabrication of red organic light-emitting diode (OLED). The relation between Stoke's shift and solvent polarity function was established by Lippert-Mataga plot. This remarkable independence of the electronic absorption spectra of Eu complexes on the nature of the solvent with unique emission wavelength furnishes its potential to serve as a red light emitter for solution processed OLEDs, display panels and solid-state lighting. Copyright © 2018 John Wiley & Sons, Ltd.

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

Doménech, J. L.; Herrero, V. J.; Tanarro, I.

The chloroniumyl cation, HCl{sup +}, has been recently identified in space from Herschel 's spectra. A joint analysis of extensive vis-UV spectroscopy emission data together with a few high-resolution and high-accuracy millimeter-wave data provided the necessary rest frequencies to support the astronomical identification. Nevertheless, the analysis did not include any infrared (IR) vibration–rotation data. Furthermore, with the end of the Herschel mission, IR observations from the ground may be one of the few available means to further study this ion in space. In this work, we provide a set of accurate rovibrational transition wavenumbers, as well as a new andmore » improved global fit of vis-UV, IR, and millimeter-wave spectroscopy laboratory data, that will aid in future studies of this molecule.« less

Determination of successive complexation constants in an ionic liquid: complexation of UO(2)(2+) with NO(3)(-) in C(4)-mimTf(2)N studied by UV-Vis spectroscopy.

PubMed

Georg, Sylvia; Billard, Isabelle; Ouadi, Ali; Gaillard, Clotilde; Petitjean, Laetitia; Picquet, Michel; Solov'ev, Vitaly

2010-04-01

The complexation of UO(2)(2+) with NO(3)(-) has been investigated in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by UV-vis spectroscopy at T = 18.5 degrees C. The complexation is evidenced through the appearance of four peaks at 425, 438, 453, and 467 nm. EXAFS data indicate that the trinitrato complex, UO(2)(NO(3))(3)(-), is dominating the speciation for a reagent ratio of [NO(3)(-)]/[UO(2)(2+)] > 3. Assuming three successive complexation steps, the conditional stability constants are calculated, the individual absorption spectra are derived, and a speciation plot is presented.

Photoluminescence study of carbon dots from ginger and galangal herbs using microwave technique

NASA Astrophysics Data System (ADS)

Isnaeni; Rahmawati, I.; Intan, R.; Zakaria, M.

2018-03-01

Carbon dots are new type of fluorescent nanoparticle that can be synthesis easily from natural sources. We have synthesized carbon dots from ginger and galangal herbs using microwave technique and studied their optical properties. We synthesized colloidal carbon dots in water solvent by varying microwave processing time. UV-Vis absorbance, photoluminescence, time-resolved photoluminescence, and transmission electron microscope were utilized to study properties of carbon dots. We found that microwave processing time significantly affect optical properties of synthesized carbon dots. UV-Vis absorbance spectra and time-resolved photoluminescence results show that luminescent of carbon dots is dominated by recombination process from n-π* surface energy level. With further development, these carbon dots are potential for several applications.

EPR, optical absorption and luminescence studies of Cr3+-doped antimony phosphate glasses

NASA Astrophysics Data System (ADS)

De Vicente, F. S.; Santos, F. A.; Simões, B. S.; Dias, S. T.; Siu Li, M.

2014-12-01

Antimony phosphate glasses (SbPO) doped with 3 and 6 mol% of Cr3+ were studied by Electron Paramagnetic Resonance (EPR), UV-VIS optical absorption and luminescence spectroscopy. The EPR spectra of Cr3+-doped glasses showed two principal resonance signals with effective g values at g = 5.11 and g = 1.97. UV-VIS optical absorption spectra of SbPO:Cr3+ presented four characteristics bands at 457, 641, 675, and 705 nm related to the transitions from 4A2(F) to 4T1(F), 4T2(F), 2T1(G), and 2E(G), respectively, of Cr3+ ions in octahedral symmetry. Optical absorption spectra of SbPO:Cr3+ allowed evaluating the crystalline field Dq, Racah parameters (B and C) and Dq/B. The calculated value of Dq/B = 2.48 indicates that Cr3+ ions in SbPO glasses are in strong ligand field sites. The optical band gap for SbPO and SbPO:Cr3+ were evaluated from the UV optical absorption edges. Luminescence measurements of pure and Cr3+-doped glasses excited with 350 nm revealed weak emission bands from 400 to 600 nm due to the 3P1 → 1S0 electronic transition from Sb3+ ions. Cr3+-doped glasses excited with 415 nm presented Cr3+ characteristic luminescence spectra composed by two broad bands, one band centered at 645 nm (2E → 4A2) and another intense band from 700 to 850 nm (4T2 → 4A2).

Discrimination of various paper types using diffuse reflectance ultraviolet-visible near-infrared (UV-Vis-NIR) spectroscopy: forensic application to questioned documents.

PubMed

Kumar, Raj; Kumar, Vinay; Sharma, Vishal

2015-06-01

Diffuse reflectance ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy is applied as a means of differentiating various types of writing, office, and photocopy papers (collected from stationery shops in India) on the basis of reflectance and absorbance spectra that otherwise seem to be almost alike in different illumination conditions. In order to minimize bias, spectra from both sides of paper were obtained. In addition, three spectra from three different locations (from one side) were recorded covering the upper, middle, and bottom portions of the paper sample, and the mean average reflectivity of both the sides was calculated. A significant difference was observed in mean average reflectivity of Side A and Side B of the paper using Student's pair >t-test. Three different approaches were used for discrimination: (1) qualitative features of the whole set of samples, (2) principal component analysis, and (3) a combination of both approaches. On the basis of the first approach, i.e., qualitative features, 96.49% discriminating power (DP) was observed, which shows highly significant results with the UV-Vis-NIR technique. In the second approach the discriminating power is further enhanced by incorporating the principal component analysis (PCA) statistical method, where this method describes each UV-Vis spectrum in a group through numerical loading values connected to the first few principal components. All components described 100% variance of the samples, but only the first three PCs are good enough to explain the variance (PC1 = 51.64%, PC2 = 47.52%, and PC3 = 0.54%) of the samples; i.e., the first three PCs described 99.70% of the data, whereas in the third approach, the four samples, C, G, K, and N, out of a total 19 samples, which were not differentiated using qualitative features (approach no. 1), were therefore subjected to PCA. The first two PCs described 99.37% of the spectral features. The discrimination was achieved by using a loading plot between PC1 and PC2. It is therefore concluded that maximum discrimination of writing, office, and photocopy paper could be achieved on the basis of the second approach. Hence, the present inexpensive analytical method can be appropriate for application to routine questioned document examination work in forensic laboratories because it provides nondestructive, quantitative, reliable, and repeatable results.

Labeling Cells with Silver/Dendrimer Nanocomposites

DTIC Science & Technology

2005-01-01

used in further studies without additional purification. Potentiometric titrations were performed manually, under nitrogen atmosphere, at room...transmits light between 465 and 485 nm. Results and Discussion Figure IA presents potentiometric titration curves of Ag+-PAMAM_E5.NH 2 systems mixed at 15:1... Potentiometric titration curves of PAMAM_E5.NH 2 (circles) Ag+-PAMAME5.NH 2 30:1 (squares) and Ag+-PAMAME5.NH2 45:1 systems (triangles). B - UV-vis spectra of UV

The manifestation of optical centers in UV-Vis absorption and luminescence spectra of white blood human cells

NASA Astrophysics Data System (ADS)

Terent'yeva, Yu G.; Yashchuk, V. M.; Zaika, L. A.; Snitserova, O. M.; Losytsky, M. Yu

2016-12-01

A white blood human cells spectral investigation is presented. The aim of this series of experiments was to obtain and analyze the absorption and luminescence (fluorescence and phosphorescence) spectra at room temperature and at 78 K of newly isolated white blood human cells and their organelles. As a result the optical centers and possible biochemical components that form the studied spectra where identified. Also the differences between the spectra of abnormal cells (B-cell chronic lymphocytic leukemia BCLL) and normal ones were studied for the whole cells and individual organelles.

Effects of iron on optical properties of dissolved organic matter.

PubMed

Poulin, Brett A; Ryan, Joseph N; Aiken, George R

2014-09-02

Iron is a source of interference in the spectroscopic analysis of dissolved organic matter (DOM); however, its effects on commonly employed ultraviolet and visible (UV-vis) light adsorption and fluorescence measurements are poorly defined. Here, we describe the effects of iron(II) and iron(III) on the UV-vis absorption and fluorescence of solutions containing two DOM fractions and two surface water samples. In each case, regardless of DOM composition, UV-vis absorption increased linearly with increasing iron(III). Correction factors were derived using iron(III) absorption coefficients determined at wavelengths commonly used to characterize DOM. Iron(III) addition increased specific UV absorbances (SUVA) and decreased the absorption ratios (E2:E3) and spectral slope ratios (SR) of DOM samples. Both iron(II) and iron(III) quenched DOM fluorescence at pH 6.7. The degree and region of fluorescence quenching varied with the iron:DOC concentration ratio, DOM composition, and pH. Regions of the fluorescence spectra associated with greater DOM conjugation were more susceptible to iron quenching, and DOM fluorescence indices were sensitive to the presence of both forms of iron. Analyses of the excitation-emission matrices using a 7- and 13-component parallel factor analysis (PARAFAC) model showed low PARAFAC sensitivity to iron addition.

Elaboration, structural and optical investigations of ZnO/epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Moussa, S.; Namouchi, F.; Guermazi, H.

2015-07-01

Hybrid nanocomposites were elaborated by incorporating ZnO nanoparticles into a transparent epoxy polymer matrix, using the direct dispersion method. The effect of the nanoparticles on the structural and optical properties of the polymer matrix was investigated using Fourier transform infrared (FTIR), Raman and UV-Visible spectroscopies. Nanocomposites FTIR spectra showed a variation of band intensities attributed to nanoparticles agglomeration within the polymer. The UV-Visible measurements showed a redshift on the band gap energy of the nanocomposites differently from neat epoxy resin, caused by interactions between ZnO NPs and polymer chains. Raman spectra confirm these interactions and the formation of hydrogen bonds in the nanocomposites. The UV-Visible transmittance spectra revealed that addition of a very low concentration (0.2wt%) of ZnO nanoparticles to a transparent epoxy matrix would maintain high visible-light transparency. The decrease of transmittance with increasing ZnO percentage is due to light scattering which originates from the agglomeration of nanoparticles in the matrix, the mismatch between the refractive index of ZnO and that of the epoxy matrix, and the increase of the surface roughness of the nanocomposite with increasing ZnO addition. Moreover, the UV-vis absorption spectra revealed that adding more than 1wt% ZnO leads to the improvement of the UV shielding properties of the nanocomposites. These results prove that the elaborated ZnO/epoxy nanocomposites can be used as UV shielding materials.

Quantification of Coffea arabica and Coffea canephora var. robusta concentration in blends by means of synchronous fluorescence and UV-Vis spectroscopies.

PubMed

Dankowska, A; Domagała, A; Kowalewski, W

2017-09-01

The potential of fluorescence, UV-Vis spectroscopies as well as the low- and mid-level data fusion of both spectroscopies for the quantification of concentrations of roasted Coffea arabica and Coffea canephora var. robusta in coffee blends was investigated. Principal component analysis was used to reduce data multidimensionality. To calculate the level of undeclared addition, multiple linear regression (PCA-MLR) models were used with lowest root mean square error of calibration (RMSEC) of 3.6% and root mean square error of cross-validation (RMSECV) of 7.9%. LDA analysis was applied to fluorescence intensities and UV spectra of Coffea arabica, canephora samples, and their mixtures in order to examine classification ability. The best performance of PCA-LDA analysis was observed for data fusion of UV and fluorescence intensity measurements at wavelength interval of 60nm. LDA showed that data fusion can achieve over 96% of correct classifications (sensitivity) in the test set and 100% of correct classifications in the training set, with low-level data fusion. The corresponding results for individual spectroscopies ranged from 90% (UV-Vis spectroscopy) to 77% (synchronous fluorescence) in the test set, and from 93% to 97% in the training set. The results demonstrate that fluorescence, UV, and visible spectroscopies complement each other, giving a complementary effect for the quantification of roasted Coffea arabica and Coffea canephora var. robusta concentration in blends. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessing Pearl Quality Using Reflectance UV-Vis Spectroscopy: Does the Same Donor Produce Consistent Pearl Quality?

PubMed Central

Mamangkey, Noldy Gustaf F.; Agatonovic, Snezana; Southgate, Paul C.

2010-01-01

Two groups of commercial quality (“acceptable”) pearls produced using two donors, and a group of “acceptable” pearls from other donors were analyzed using reflectance UV-Vis spectrophotometry. Three pearls with different colors produced by the same donor showed different absorption spectra. Cream and gold colored pearls showed a wide absorption from 320 to about 460 nm, while there was just slight reflectance around 400 nm by the white pearl with a pink overtone. Cream and gold pearls reached a reflectance peak at 560 to 590 nm, while the white pearl with pink overtone showed slightly wider absorption in this region. Both cream and gold pearls showed an absorption peak after the reflectance peak, at about 700 nm for the cream pearl and 750 nm for the gold pearl. Two other pearls produced by the same donor (white with cream overtone and cream with various overtones) showed similar spectra, which differed in their intensity. One of these pearls had very high lustre and its spectrum showed a much higher percentage reflectance than the second pearl with inferior lustre. This result may indicate that reflectance is a useful quantitative indicator of pearl lustre. The spectra of two white pearls resulting from different donors with the same color nacre (silver) showed a reflectance at 260 nm, followed by absorption at 280 nm and another reflectance peak at 340 nm. After this peak the spectra for these pearls remained flat until a slight absorption peak around 700 nm. Throughout the visible region, all white pearls used in this study showed similar reflectance spectra although there were differences in reflectance intensity. Unlike the spectral results from white pearls, the results from yellow and gold pearls varied according to color saturation of the pearl. The results of this study show that similarities between absorption and reflectance spectra of cultured pearls resulting from the same saibo donor are negligible and could not be detected with UV-Vis spectrophotometry. Nevertheless, this technique could have a role to play in developing less subjective methods of assessing pearl quality and in further studies of the relationships between pearl quality and that of the donor and recipient oysters. PMID:20948903

Inversion of the 11Bu and 21Ag electronic states of all-trans-1,6-diphenyl-1,3,5-hexatriene in carbon disulfide.

PubMed

Catalán, Javier

2017-10-11

From the analysis of UV/Vis absorption spectra, emission and excitation emission spectra of solutions of all-trans-1,6-diphenyl-1,3,5-hexatriene (DPH) in carbon disulfide (CS 2 ) within a wide range of temperatures, we can conclude that these spectra do not support the inversion of excited electronic states in DPH by an increased polarizability of the solvent as proposed by Kohler and Itoh. The proposal by Kohler and Itoh is widely accepted as an elegant demonstration of the inversion of the 1 1 Bu and 2 1 Ag states in the polyene DPH by a mere increase in the solvent polarizability. The evidence provided in this paper confirms, as has recently been proposed, that a ghost state as the first electronic state, 2 1 Ag, is not necessary to explain the photophysics of DPH. The photophysics of DPH is plausibly explicable with the 1 1 Bu state, which is directly excitable by photonic absorption from the fundamental electronic state of the compound. In this paper, we provide evidence that the UV/Vis spectra of DPH in CS 2 at 77 K are most likely generated from a molecular structure of DPH constrained by solid CS 2 , which is clearly distinct from that present in liquid CS 2 .

Structural, optical and dielectric properties of Ce0.9Nd0.1O1.95 nanocrystalline oxygen ion conductors: Effect of sintering temperature

NASA Astrophysics Data System (ADS)

Anirban, Sk.; Dutta, A.

2015-01-01

Neodymium doped nanocrystalline ceria [Ce0.9Nd0.1O1.95] was prepared through citrate auto-ignition method. The prepared samples were sintered at five different temperatures starting from 400 °C up to 1200 °C. Rietveld's powder structure refinement analysis of XRD data confirmed the single phase cubic fluorite structure of the prepared samples with space group Fm 3 barm and the obtained particle size and lattice parameter values were found to vary with sintering temperature from 6.68 nm to 39.51 nm and from 5.39077 Å to 5.42317 Å respectively. The optical properties were studied using FT-IR and UV-vis absorption spectra. The FT-IR spectra confirm the presence of functional groups and chemical bonding in the material. The optical band gap was calculated from UV-vis spectra and its value was found to decrease from 3.70 eV to 2.46 eV with increase in sintering temperature. The dc conductivity was found to be thermally activated and decreased with increase in sintering temperature. The nature of impedance spectra reveals the presence of both grain and grain boundary effect. The tangent loss exhibited the presence of relaxation peaks due to the presence of defect pair in the synthesized samples.

Component Analysis and Identification of Black Tahitian Cultured Pearls From the Oyster Pinctada margaritifera Using Spectroscopic Techniques

NASA Astrophysics Data System (ADS)

Shi, L.; Wang, Y.; Liu, X.; Mao, J.

2018-03-01

Raman spectroscopy, ultraviolet, visible, and near infrared (UV-Vis-NIR) reflectance spectroscopy, and X-ray fluorescence (XRF) spectroscopy were used to characterize black Tahitian cultured pearls and imitations of these saltwater cultured pearls produced by γ-irradiation, and by coloring of cultured pearls with silver nitrate or organic dyes. Raman spectra indicated that aragonite was the major constituent of these four types of pearl. Using Raman spectroscopy at an excitation wavelength of 514 nm, black Tahitian cultured pearls exhibited characteristic 1100-1700 cm-1 bands. These bands were attributed to various organic components, including conchiolin and other black biological pigments. The peaks shown by saltwater cultured pearls colored with organic dyes varied with the type of dye used. Tahitian cultured and organic-dye-treated saltwater cultured pearls were easily identified by Raman spectroscopy. UV-Vis-NIR reflectance spectra showed bands at 408, 497, and 700 nm derived from porphyrin pigment and other black pigments. The spectra of dye-treated black saltwater pearls showed absorption peaks at 216, 261, 300, and 578 nm. The 261-nm absorption band disappeared from the spectra of γ-irradiated saltwater cultured pearls. This suggests the degradation of conchiolin in the γ-irradiated saltwater cultured pearls. XRF analysis revealed the presence of Ag on the surface of silver nitrate-dyed saltwater cultured pearls.

A computational perspective of vibrational and electronic analysis of potential photosensitizer 2-chlorothioxanthone

NASA Astrophysics Data System (ADS)

Ali, Narmeen; Mansha, Asim; Asim, Sadia; Zahoor, Ameer Fawad; Ghafoor, Sidra; Akbar, Muhammad Usman

2018-03-01

This paper deals with combined theoretical and experimental study of geometric, electronic and vibrational properties of 2-chlorothioxanthone (CTX) molecule which is potential photosensitizer. The FT-IR spectrum of CTX in solid phase was recorded in 4000-400 cm-1 region. The UV-Vis. absorption spectrum was also recorded in the laboratory as well as computed at DFT/B3LYP level in five different phases viz. gas, water, DMSO, acetone and ethanol. The quantum mechanics based theoretical IR and Raman spectra were also calculated for the title compound employing HF and DFT functional with 3-21G+, 6-31G+ and 6-311G+, 6-311G++ basis sets, respectively, and assignment of each vibrational frequency has been done on the basis of potential energy distribution (PED). A comparison has been made between theoretical and experimental vibrational spectra as well as for the UV-Vis. absorption spectra. The computed infra red & Raman spectra by DFT compared with experimental spectra along with reliable vibrational assignment based on PED. The calculated electronic properties, results of natural bonding orbital (NBO) analysis, charge distribution, dipole moment and energies have been reported in the paper. Bimolecular quenching of triplet state of CTX in the presence of triethylamine, 2-propanol triethylamine and diazobicyclooctane (DABCO) reflect the interactions between them. The bimolecular quenching rate constant is fastest for interaction of 3CTX in the presence of DABCO reflecting their stronger interactions.

Modeling the chemistry of plasma polymerization using mass spectrometry.

PubMed

Ihrig, D F; Stockhaus, J; Scheide, F; Winkelhake, Oliver; Streuber, Oliver

2003-04-01

The goal of the project is a solvent free painting shop. The environmental technologies laboratory is developing processes of plasma etching and polymerization. Polymerized thin films are first-order corrosion protection and primer for painting. Using pure acetylene we get very nice thin films which were not bonded very well. By using air as bulk gas it is possible to polymerize, in an acetylene plasma, well bonded thin films which are stable first-order corrosion protections and good primers. UV/Vis spectroscopy shows nitrogen oxide radicals in the emission spectra of pure nitrogen and air. But nitrogen oxide is fully suppressed in the presence of acetylene. IR spectroscopy shows only C=O, CH(2) and CH(3) groups but no nitrogen species. With the aid of UV/Vis spectra and the chemistry of ozone formation it is possible to define reactive traps and steps, molecule depletion and processes of proton scavenging and proton loss. Using a numerical model it is possible to evaluate these processes and to calculate theoretical mass spectra. Adjustment of theoretical mass spectra to real measurements leads to specific channels of polymerization which are driven by radicals especially the acetyl radical. The estimated theoretical mass spectra show the specific channels of these chemical processes. It is possible to quantify these channels. This quantification represents the mass flow through this chemical system. With respect to these chemical processes it is possible to have an idea of pollutant production processes.

Microalga Scenedesmus sp.: A potential low-cost green machine for silver nanoparticle synthesis.

PubMed

Jena, Jayashree; Pradhan, Nilotpala; Nayak, Rati Ranjan; Dash, Bishnu P; Sukla, Lala Behari; Panda, Prasanna K; Mishra, Barada K

2014-04-01

Bionanotechnology has revolutionized nanomaterial synthesis by providing a green synthetic platform using biological systems. Among such biological systems, microalgae have tremendous potential to take up metal ions and produce nanoparticles by a detoxification process. The present study explores the intracellular and extracellular biogenic syntheses of silver nanoparticles (SNPs) using the unicellular green microalga Scenedesmus sp. Biosynthesized SNPs were characterized by AAS, UV-Vis spectroscopy, TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activity. Intracellular nanoparticle biosynthesis was initiated by a high rate of Ag(+) ion accumulation in the microalgal biomass and subsequent formation of spherical crystalline SNPs (average size, 15-20 nm) due to the biochemical reduction of Ag(+) ions. The synthesized nanoparticles were intracellular, as confirmed by the UV-Vis spectra of the outside medium. Furthermore, extracellular synthesis using boiled extract showed the formation of well scattered, highly stable, spherical SNPs with an average size of 5-10 nm. The size and morphology of the nanoparticles were confirmed by TEM. The crystalline nature of the SNPs was evident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilization of SNPs. Furthermore, the synthesized nanoparticles exhibited high antimicrobial activity against pathogenic gram-negative and gram-positive bacteria. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials in a large-scale system that could be of great use in biomedical applications.

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine.

PubMed

Mohamed, Gehad G; El-Gamel, Nadia E A

2004-11-01

The ternary piroxicam (Pir; 4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA chelates were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine

NASA Astrophysics Data System (ADS)

Mohamed, Gehad G.; El-Gamel, Nadia E. A.

2004-11-01

The ternary piroxicam (Pir; 4-hydroxy-2-methyl- N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide) complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with various amino acids (AA) such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized by elemental analyses, molar conductance, IR, UV-Vis, magnetic moment, diffuse reflectance and X-ray powder diffraction. The UV-Vis spectra of Pir and the effect of metal chelation on the different interligand transitions are discussed in detailed manner. IR and UV-Vis spectra confirm that Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its carboxylic group, in addition PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its carboxylic and amino groups. All the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. The molar conductance data reveal that most of these chelates are non electrolytes, while Fe(III)-Pir-Gly, Co(II)-, Ni(II)-, Cu(II)- and Zn(II)-Pir-PhA cheletes were 1:1 electrolytes. X-ray powder diffraction is used as a new tool to estimate the crystallinity of chelates as well as to elucidate their geometrical structures.

Preparation of manganese doped cadmium sulfide nanoparticles in zincblende phase and their magnetic properties.

PubMed

Nakaya, Masafumi; Tanaka, Itaru; Muramatsu, Atsushi

2012-12-01

In this study, the random dope of Mn into CdS nanoparticles in zincblende phase has been carried out under the mild reaction condition. The resulting nanoparticles were characterized by energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV-Vis spectrometer, PL spectrometer, and SQUID. EDX showed that the compositions of Mn doped CdS nanoparticles were readily controlled. TEM showed the particle sizes were not significantly affected by the compositions, retaining to be ca. 3 nm with a narrow size distribution. UV-Vis and PL spectra of the resulting nanoparticles showed the intra-Mn level may be affected by the quantum size effect. SQUID measurement showed that the resulting nanoparticles showed diamagnetism, paramagnetism and superparamagnetism dependent on Mn content.

Dopant occupancy and UV-VIS-NIR spectroscopy of Mg (0, 4, 5 and 6 mol.%):Dy:LiNbO3 crystal

NASA Astrophysics Data System (ADS)

Dai, Li; Liu, Chunrui; Han, Xianbo; Wang, Luping; Tan, Chao; Yan, Zhehua; Xu, Yuheng

2017-09-01

A series of Dy:LiNbO3 crystals with x mol.% Mg2+ ions (x =0, 4, 5 and 6 mol.%) were grown by the Czochralski method. The effective segregation coefficient of Mg2+ and Dy3+ ions was studied by the inductively coupled plasma-atomic emission spectrometry (ICP-AES). UV-VIS-NIR absorption spectra and Judd-Ofelt theory were used to investigate their spectroscopic properties. J-O intensity parameters (Ω2 = 7.53 × 10-20cm2, Ω4 = 6.98 × 10-20cm2, and Ω6 = 3.09 × 10-20cm2) and larger spectroscopic quality factor (X = 2.26) for Mg:(6 mol.%)Dy:LiNbO3 crystals were obtained.

Spectroscopic and quantum chemical studies on bromopyrazone.

PubMed

Gökce, Halil; Bahçeli, Semiha

2014-12-10

In this study, the FT-IR, micro-Raman and UV-vis. spectra of bromopyrazone molecule, C10H8BrN3O, (with synonym,1-phenyl-4-amino-5-bromopyridazon-(6) or 5-amino-4-bromo-2-phenyl-3(2H)-pyridazinone) were recorded experimentally. The molecular structure, vibrational wavenumbers, electronic transition absorption wavelengths in ethanol solvent, HOMOs and LUMOs analyses, molecular electrostatic potential (MEP), natural bond orbitals (NBO), nonlinear optical (NLO) properties and atomic charges of bromopyrazone molecule have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. The obtained results show that the calculated vibrational frequencies and UV-vis. values are in a good agreement with experimental data. Copyright © 2014 Elsevier B.V. All rights reserved.

Solvent and structural effects on the spectral shifts of 5-(substituted phenylazo)-3-cyano-6-hydroxy-1-(2-hydroxyethyl)-4-methyl-2-pyridones

NASA Astrophysics Data System (ADS)

Mirković, Jelena M.; Božić, Bojan Đ.; Mutavdžić, Dragosav R.; Ušćumlić, Gordana S.; Mijin, Dušan Ž.

2014-11-01

Spectral properties, solvatochromism and azo-hydrazone tautomerism of ten 5-(substituted phenylazo)-3-cyano-6-hydroxy-1-(2-hydroxyethyl)-4-methyl-2-pyridones in twenty-two solvents are investigated. For quantitative evaluation of the solvent effects on the UV-vis absorption maxima, the principles of the linear solvation energy relationships are used, i.e. models proposed by Kamlet-Taft and Catalán. Linear free energy relationships are applied to the UV-vis absorption spectra and correlation of absorption frequencies with Hammett substituent constants are performed. Furthermore, the influence of the electronic nature of the substituents on 1H and 13C NMR shifts is investigated by simple and extended Hammett equations, as well as by Swain-Lupton equation.

Optical properties of γ-irradiated Bombyx mori silk fibroin films

NASA Astrophysics Data System (ADS)

Madhukumar, R.; Asha, S.; Lakshmeesha Rao, B.; Sarojini, B. K.; Byrappa, K.; Wang, Youjiang; Sangappa, Y.

2015-11-01

In the present work the Bombyx mori silk fibroin (SF) films were prepared by the solution casting method and effects of γ-irradiation on the optical properties and optical constants of the films have been studied by using Ultra Violet-Visible (UV-Vis) spectrophotometer. The recorded UV-Vis absorption and transmission spectra have been used to determine the optical band gap (Eg), refractive index (n), extinction coefficient (k), optical conductivity (σopt) and dielectric constants (ε*) of virgin and γ-irradiated films. Reduction in optical band gap and increase in refractive index with increasing radiation dosage were observed. It is also found that there is an increase in dielectric constants with increasing photon energy. The obtained results reveal that the refractive index of the SF films may be efficiently changed by γ-irradiation.

Synthesis and characterization of PVK/AgNPs nanocomposites prepared by laser ablation.

PubMed

Abd El-Kader, F H; Hakeem, N A; Elashmawi, I S; Menazea, A A

2015-03-05

Nanocomposites of Poly (n-vinylcarbazole) PVK/Ag nanoparticles were prepared by laser ablation of a silver plate in aqueous solution of chlorobenzene. The influences of laser parameters such as; time of irradiation, source power and wavelength (photon energy) on structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) and Photoluminescence (PL). A correlation between the investigated properties has been discussed. XRD, TEM and PL indicated that the complexation between AgNPs and PVK in the composite system is possible. Only the reflection peak at 2θ=38° of AgNPs appeared in the composite nanoparticles while the other reflection peaks were destroyed. The nanoparticles shape and size distribution were evaluated from TEM images. TEM analysis revealed a lower average particle size at long laser irradiation time 40min and short laser wavelength 532nm together with high laser power 570mW. From UV-Visible spectra the values of absorption coefficient, absorption edge and energy tail were calculated. The reduction of band tail value with increasing the laser ablation parameters confirms the decrease of the disorder in such composite system. The PL and UV-Vis. spectra confirm that nanocomposite samples showed quantum confinement effect. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced UV-visible response of bismuth subcarbonate nanowires for degradation of xanthate and photocatalytic reaction mechanism.

PubMed

Cui, Kuixin; He, Yuehui; Jin, Shengming

2016-04-01

(BiO)2CO3 nanowires were prepared by simple hydrothermal treatment of commercial Bi2O3 powders and characterized by X-ray diffractometry, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of (BiO)2CO3 nanowires was studied through degradation of sodium isopropyl xanthate. Photocatalytic experimental results indicated that the as-prepared (BiO)2CO3 nanowires show high photocatalytic efficiency. Photocatalytic activity increased after two cycles. Time-dependent UV-vis spectra demonstrated that the final degradation products included isopropyl alcohol and carbon disulfide. UV-vis diffuse reflection spectra showed that the band gap of the as-prepared (BiO)2CO3 nanowires and recycled (BiO)2CO3 nanowires were 2.75 eV and 1.15 eV, respectively. XPS results indicated that formation of Bi2S3@(BiO)2CO3 core-shell nanowires occurred after recycled photodegradation of isopropyl xanthate owing to existence of two types of Bi configurations in the recycled (BiO)2CO3 nanowires. A probable degradation mechanism of isopropyl xanthate was also proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Binding of caffeine with caffeic acid and chlorogenic acid using fluorescence quenching, UV/vis and FTIR spectroscopic techniques.

PubMed

Belay, Abebe; Kim, Hyung Kook; Hwang, Yoon-Hwae

2016-03-01

The interactions of caffeine (CF) with chlorogenic acid (CGA) and caffeic acid (CFA) were investigated by fluorescence quenching, UV/vis and Fourier transform infrared (FTIR) spectroscopic techniques. The results of the study indicated that the fluorescence quenching between caffeine and hydroxycinnamic acids could be rationalized in terms of static quenching or the formation of non-fluorescent CF-CFA and CF-CGA complexes. From fluorescence quenching spectral analysis, the quenching constant (KSV), quenching rate constant (kq), number of binding sites (n), thermodynamic properties and conformational changes of the interaction were determined. The quenching constants (KSV) between CF and CGA, CFA are 1.84 × 10(4) and 1.04 × 10(4) L/mol at 298 K and their binding site n is ~ 1. Thermodynamic parameters determined using the Van't Hoff equation indicated that hydrogen bonds and van der Waal's forces have a major role in the reaction of caffeine with caffeic acid and chlorogenic acid. The 3D fluorescence, UV/vis and FTIR spectra also showed that the binding of CF with CFA and CGA induces conformational changes in CFA and CGA. Copyright © 2015 John Wiley & Sons, Ltd.

Quality of Rapeseed Bio-Fuel Waste: Optical Properties

NASA Astrophysics Data System (ADS)

Sujak, Agnieszka; Muszyñski, Siemowit; Kachel-Jakubowska, Magdalena

2014-04-01

The objective of the presented work was to examine the optical properties of selected bio-fuel waste. Three independent optical methods: UV-Vis spectroscopy, infrared spectroscopy and chromametric measurements were applied to establish the possible quality control test for the obtained substances. The following by-products were tested: distilled glycerine, technical glycerine and matter organic non glycerine fraction from rapeseed oil bio-fuel production. The results show that analysis of UV-Vis spectra can give rapid information about the purity of distilled glycerine, while no direct information can be obtained concerning the concentration and kind of impurities. Transmission mode is more useful as compared to absorption, concerning the detection abilities of average UV-Vis spectrometers. Infrared spectroscopy can be used as a complementary method for determining impurities/admixtures in samples. Measurements of chroma give the quickest data to compare the colour of biofuel by-products obtained by different producers. The condition is, however, that the products are received through the same or similar chemical processes. The other important factor is application of well defined measuring background. All the discussed analyses are quick, cheap and non-destructive, and can help to compare the quality of products.

Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by 13C NMR and UV-Vis Absorption Spectroscopy and High-Performance Liquid Chromatography.

PubMed

Liu, Tong; Abrahams, Isaac; Dennis, T John S

2018-04-26

The molecular structures of 19 purified isomers of bis-phenyl-C 62 -butyric acid methyl ester were identified by a combination of 13 C NMR and UV-vis absorption spectroscopies and high-performance liquid chromatography (HPLC) retention time analysis. All 19 isomers are dicyclopropafullerenes (none are homofullerenes). There were seven isomers with C 1 molecular point-group symmetry, four with C s , six with C 2 , one with C 2 v , and one with C 2 h symmetry. The C 2 h , C 2 v , and all five nonequatorial C 1 isomers were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13 C NMR and UV-vis spectra placed them in six groups of two same-symmetry isomers. On the basis of the widely spaced HPLC retention times of the two isomers within each of these six groups, and the empirical inverse correlation between retention time and addend spacing, each isomer was assigned to its corresponding HPLC fraction. In addition, the missing trans-1 isomer was found, purified, and characterized.

The characterization of the concentration of the single-walled carbon nanotubes in aqueous dispersion by UV-Vis-NIR absorption spectroscopy.

PubMed

Yang, Bing; Ren, Lingling; Li, Luming; Tao, Xingfu; Shi, Yunhua; Zheng, Yudong

2013-11-07

Current and future applications of single-wall carbon nanotubes (SWCNTs) depend on the dispersion of the SWCNTs in aqueous solution and their quantitation. The concentration of SWCNTs is an important indicator to evaluate the dispersibility of the surfactant-dispersed SWCNTs suspension. Due to the complexity of the SWCNTs suspension, it is necessary to determine both the total concentration of the dispersed SWCNTs and the concentration of individually dispersed SWCNTs in aqueous suspensions, and these were evaluated through the absorbance and the resonance ratios of UV-Vis-NIR absorption spectra, respectively. However, there is no specific and reliable position assigned for either calculation of the absorbance or the resonance ratio of the UV-Vis-NIR absorption spectrum. In this paper, different ranges of wavelengths for these two parameters were studied. From this, we concluded that the wavelength range between 300 nm and 600 nm should be the most suitable for evaluation of the total concentration of dispersed SWCNTs in the suspension; also, wavelengths below 800 nm should be most suitable for evaluation of the concentration of individually dispersed SWCNTs in the suspension. Moreover, these wavelength ranges are verified by accurate dilution experiments.

Optical property analysis of thermally and photolytically aged Eucalyptus Camaldulensis chemithermomechanical pulp (CTMP)

Treesearch

Yao Chen; Yongming Fan; Mandla A. Tshabalala; Nicole M. Stark; Jianmin Gao

2012-01-01

To investigate the optical properties of chemithermomechanical pulp (CTMP) from Eucalyptus camaldulensis, one group of samples of CTMP was aged by heating, and another group was first subjected to bleaching with different bleaching agents, and then aging by exposure to sunlight. Chromophores were analyzed using diffuse reflectance UV-Vis spectra (...

A Better Sunscreen: Structural Effects on Spectral Properties

ERIC Educational Resources Information Center

Huck, Lawrence A.; Leigh, William J.

2010-01-01

A modification of the mixed-aldol synthesis of dibenzylideneacetone, prepared from acetone and benzaldehyde, is described wherein acetone is replaced with a series of cyclic ketones with ring sizes of 5-7 carbons. The structural variations in the resulting conjugated ketones produce regular variations in the UV-vis absorption spectra. The choice…

Fe(Ⅲ) ions enhanced catalytic properties of (BiO)2CO3 nanowires and mechanism study for complete degradation of xanthate.

PubMed

Guo, Yujiao; Cui, Kuixin; Hu, Mingyi; Jin, Shengming

2017-08-01

The wire-like Fe 3+ -doped (BiO) 2 CO 3 photocatalyst was synthesized by a hydrothermal method. The photocatalytic property of Fe 3+ -doped (BiO) 2 CO 3 nanowires was evaluated through degradation of sodium isopropyl xanthate under UV-visible light irradiation. The as-prepared Fe 3+ -doped (BiO) 2 CO 3 nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) in detail. The results of XRD showed that the crystallinity of (BiO) 2 CO 3 nanowires decreased when Fe 3+ ions were introduced into the solution system. XPS results illustrated that xanthate could be absorbed on the surface of Fe 3+ -doped (BiO) 2 CO 3 nanowires to produce BiS bond at the beginning of the reaction, which could broaden the visible light absorption. FTIR spectra confirmed the formation of SO 4 2- after photocatalytic decomposition of xanthate solution. The Fe 3+ -doped (BiO) 2 CO 3 nanowires showed an enhanced photocatalytic activity for decomposition of xanthate due to the narrower band gap and larger BET surface area, comparing with pure (BiO) 2 CO 3 nanowires. By the results of UV-vis spectra of the solution and FTIR spectra of recycled Fe 3+ -doped (BiO) 2 CO 3 , the xanthate was oxidized completely into CO 2 and SO 4 2- . The photocatalytic degradation process of xanthate followed a pseudo-second-order kinetics model. The mechanism of enhanced photocatalytic activity was proposed as well. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new μ3-oxo-centered tri-nuclear carboxyl bridged iron (III) complex with thio-methyl groups in the periphery: Structural, spectroscopic and electrochemical studies

NASA Astrophysics Data System (ADS)

Lu, Maofeng; Chen, Tingting; Wang, Miao; Jiang, Guomin; Lu, Tianhong; Jiang, Guoqing; Du, Jiangyan

2014-02-01

A tri-nuclear iron (III) complex [Fe3(μ3-O)(O2CC6H4SCH3)6(Py)3]FeCl4 has been synthesized and characterized by X-ray crystallography, Surface enhanced Raman Scattering (SERS), Fourier Transform Infra Red (FT-IR), Ultraviolet-Visible (UV-Vis) spectroscopy and Thermogravimetric analysis (TGA)/Differential scanning calorimetry (DSC). The functionalized thio-methyl groups around the periphery of the complex 1 may provide binding sites to the surface of some specific materials, such as noble metals. The Ag sols and complex 1-Ag sol had been characterized by SERS and UV-Vis spectroscopy. The complex 1 were also self-assembled on gold electrode by AuS bond, exhibiting an irreversible process at E1/2 = 0.967 V (ΔE = 0.525 V). Meanwhile the Raman spectra were compared with FT-IR, and the results indicated that the strong Raman lines either correspond to weak Infrared absorptions or are absent in the Infrared spectra.

Spectroscopic investigation on the efficient organic nonlinear crystals of pure and diethanolamine added DAST.

PubMed

Karthikeyan, C; Haja Hameed, A S; Sagaya Agnes Nisha, J; Ravi, G

2013-11-01

4-N,N'-dimethylamino-N-methyl-4-stilbazolium toyslate (DAST) and diethanolamine (DEA) added DAST crystals are grown by slow cooling method. The corresponding powder samples are examined by characterization studies such as XRD, FT-IR, FT-Raman, UV-Vis-NIR and photoluminescence studies. From the powder X-ray diffraction, their lattice parameter values are found out. Since the vibrational spectra of the molecules are considerably contributed to their linear and nonlinear optical effects, Infrared and Raman spectroscopic studies are carried out for the samples. The UV-Vis-NIR absorption spectra of the samples are used to find the nature of transitions occurred in the samples. Using the density functional theory, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) analyses are done in order to explain the transition and density of states (DOS). The first order hyperpolarizability is calculated by HF and B3LYP/6-311 G(d,p) basis sets for the DAST molecule. From the photoluminescence (PL) spectral studies, the strong excitation emissions are observed. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication and electrocatalytic properties of chitosan and keplerate-type polyoxometalate {Mo72Fe30} hybrid films.

PubMed

Fan, Dawei; Hao, Jingcheng

2009-05-28

Hybrid films composed of chitosan and Keplerate-type polyoxometalate, {Mo72Fe30} (Mo72VIFe30IIIO252L102.ca.180H2O, L=H2O/CH3COO-/Mo2O8/9n-), were fabricated on quartz, silicon, and ITO substrates by layer-by-layer (LbL) method. The LbL films were characterized by UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and cyclic voltammetry (CV). UV-vis spectra show that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of chitosan/{Mo72Fe30} bilayers. XPS spectra confirm the incorporation of chitosan and {Mo72Fe30} into the films. The electrocatalytic reduction of ClO3-, BrO3-, and IO3- by chitosan/{Mo72Fe30} hybrid films in an acidic aqueous solution shows an electrocatalytic reduction activity of IO3->BrO3->ClO3-. In particular, the modified electrodes exhibited high electrocatalytic activity for reduction of IO3-.

Solar photocatalytic degradation of isoproturon over TiO2/H-MOR composite systems.

PubMed

Sharma, Mangalampalli V Phanikrishna; Durgakumari, Valluri; Subrahmanyam, Machiraju

2008-12-30

The photocatalytic degradation and mineralization of isoproturon herbicide was investigated in aqueous solution containing TiO2 over H-mordenite (H-MOR) photocatalysts under solar light. The catalysts are characterized by X-ray diffraction (XRD), UV-Vis diffused reflectance spectra (UV-Vis DRS), Fourier transform-infra red spectra (FT-IR) and scanning electron microscopy (SEM) techniques. The effect of TiO2, H-MOR support and different wt% of TiO2 over the support on the photocatalytic degradation and influence of parameters such as TiO2 loading, catalyst amount, pH and initial concentration of isoproturon on degradation are evaluated. 15wt% TiO2/H-MOR composite is found to be optimum. The degradation reaction follows pseudo-first order kinetics and is discussed in terms of Langmuir-Hinshelwood (L-H) kinetic model. The extent of isoproturon mineralization studied with chemical oxygen demand (COD) and total organic carbon (TOC) measurements and approximately 80% mineralization occurred in 5h. A plausible mechanism is proposed based on the intermediates identified by liquid chromatography-mass spectroscopy (LC-MS).

Vibrational spectral investigation, NBO, first hyperpolarizability and UV-Vis spectral analysis of 3,5-dichlorobenzonitrile and m-bromobenzonitrile by ab initio and density functional theory methods.

PubMed

Senthil kumar, J; Jeyavijayan, S; Arivazhagan, M

2015-02-05

The FT-IR and FT-Raman spectra of 3,5-dichlorobenzonitrile and m-bromobenzonitrile have been recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The optimized geometry, wave numbers and intensity of vibrational bonds of title molecules are obtained by ab initio and DFT level of theory with complete relaxation in the potential energy surface using 6-311++G(d, p) basis set. A complete vibrational assignments aided by the theoretical harmonic frequency, analysis have been proposed. The harmonic vibrational frequencies calculated have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The UV-Vis spectral analysis of the molecules has also been done which confirms the charge transfer of the molecules. Furthermore, the first hyperpolarizability and total dipole moment of the molecules have been calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential prospects in archaeological research by using optical spectroscopy through a black glass ocular

NASA Astrophysics Data System (ADS)

Cosyns, P.; Meulebroeck, W.; Thienpont, H.; Nys, K.

The aim of this paper is to draw attention to the potential usefulness of optical spectroscopy within the archaeological discourse. We therefore use the standardized color coordinates and the transmittance spectra in the region between 350- 1650 nm of nine fragmented Roman black glass artifacts from archaeological contexts in Avenches (Switzerland) and an intact piece from Tongeren (Belgium). Firstly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help the archaeologist in understanding the various excavated features containing glass artifacts. The analysis of the optical spectra of Roman black glass artifacts demonstrates in the first place that an object has a very homogenous composition. The clustering of the different fragments with characteristic spectra permits to connect the pieces from various areas of an excavation to one single object or to several objects from the same batch. These results provide the archaeologist the possibility to merge recognized layers or to connect different features in the surrounding area. Secondly, we demonstrate how the use of UV-Vis-NIR spectroscopy can help improve the analysis process. This inexpensive method can facilitate a more convenient and purposive sampling by means of a preliminary inquiry, selecting the most interesting pieces out of a large group of artifacts suitable for chemical analysis.

Quantum chemical modeling of new derivatives of (E,E)-azomethines: Synthesis, spectroscopic (FT-IR, UV/Vis, polarization) and thermophysical investigations

NASA Astrophysics Data System (ADS)

Shahab, Siyamak; Sheikhi, Masoome; Filippovich, Liudmila; Anatol'evich, Dikusar Evgenij; Yahyaei, Hooriye

2017-06-01

In the present work, the molecular structures of three new azomethine dyes: N-benzylidene-4-((E)-phenyldiazenyl)aniline (PAZB-1), 2-methoxy-4-(((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-2) and 2-methoxy-5-((E)-((4-((E)- phenyldiazenyl)phenyl)imino)methyl)phenol (PAZB-8) have been predicted and investigated using Density Functional Theory (DFT) in dimethylformamide (DMF). The geometries of the azomethine dyes were optimized by PBE0/6-31 + G* level of theory. The electronic spectra of these azomethine dyes in a DMF solution was carried out by TDPBE0/6-31 + G* method. After quantum-chemical calculations three new azomethine dyes for optoelectronic applications were synthesized. FT-IR spectra of the title compounds are recorded and discussed. The computed absorption spectral data of the azomethine dyes are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films for Visible region of spectrum were developed. The main optical parameters of polarizing PVA-films (Transmittance, Polarization Efficiency and Dichroic Ratio) have been measured and discussed. Anisotropy of thermal conductivity of the PVA-films has been studied.

Quantification of Material Fluorescence and Light Scattering Cross Sections Using Ratiometric Bandwidth-Varied Polarized Resonance Synchronous Spectroscopy.

PubMed

Xu, Joanna Xiuzhu; Hu, Juan; Zhang, Dongmao

2018-05-25

Presented herein is the ratiometric bandwidth-varied polarized resonance synchronous spectroscopy (BVPRS2) method for quantification of material optical activity spectra. These include the sample light absorption and scattering cross-section spectrum, the scattering depolarization spectrum, and the fluorescence emission cross-section and depolarization spectrum in the wavelength region where the sample both absorbs and emits. This ratiometric BVPRS2 spectroscopic method is a self-contained technique capable of quantitatively decoupling material fluorescence and light scattering signal contribution to its ratiometric BVPRS2 spectra through the linear curve-fitting of the ratiometric BVPRS2 signal as a function of the wavelength bandwidth used in the PRS2 measurements. Example applications of this new spectroscopic method are demonstrated with materials that can be approximated as pure scatterers, simultaneous photon absorbers/emitters, simultaneous photon absorbers/scatterers, and finally simultaneous photon absorbers/scatterers/emitters. Because the only instruments needed for this ratiometric BVPRS2 technique are the conventional UV-vis spectrophotometer and spectrofluorometer, this work should open doors for routine decomposition of material UV-vis extinction spectrum into its absorption and scattering component spectra. The methodology and insights provided in this work should be of broad significance to all chemical research that involves photon/matter interactions.

Stabilizing subnanometer Ag(0) nanoclusters by thiolate and diphosphine ligands and their crystal structures

NASA Astrophysics Data System (ADS)

Yang, Huayan; Wang, Yu; Zheng, Nanfeng

2013-03-01

The combined use of thiolate and diphosphine as surface ligands helps to stabilize subnanometer Ag(0) nanoclusters, resulting in the successful crystallization of two Ag(0)-containing nanoclusters (Ag16 and Ag32) for X-ray single crystal analysis. Both clusters have core-shell structures with Ag86+ and Ag2212+ as their cores, which are not simply either fragments of face-centered cubic metals or their five-fold twinned counterparts. The clusters display UV-Vis absorption spectra consisting of molecule-like optical transitions.The combined use of thiolate and diphosphine as surface ligands helps to stabilize subnanometer Ag(0) nanoclusters, resulting in the successful crystallization of two Ag(0)-containing nanoclusters (Ag16 and Ag32) for X-ray single crystal analysis. Both clusters have core-shell structures with Ag86+ and Ag2212+ as their cores, which are not simply either fragments of face-centered cubic metals or their five-fold twinned counterparts. The clusters display UV-Vis absorption spectra consisting of molecule-like optical transitions. Electronic supplementary information (ESI) available: Experimental details, more pictures of the structure and XPS spectra of the clusters. CCDC 916463 and 916464. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3nr34328f

Novel acid mono azo dye compound: Synthesis, characterization, vibrational, optical and theoretical investigations of 2-[(E)-(8-hydroxyquinolin-5-yl)-diazenyl]-4,5-dimethoxybenzoic acid

NASA Astrophysics Data System (ADS)

Saçmacı, Mustafa; Çavuş, Hatice Kanbur; Arı, Hatice; Şahingöz, Recep; Özpozan, Talat

2012-11-01

Novel acid mono azo dye, 2-[(E)-(8-hydroxyquinolin-5yl)-diazenyl]-4,5-dimethoxybenzoic acid (HQD), was synthesized by coupling diazonium salt solution of 2-amino-4,5-dimethoxybenzoic acid (DMA) with 8-hydroxyquinoline (HQ). This dye was characterized by UV-vis, IR & Raman, 1H and 13C NMR spectroscopic techniques and elemental analysis. The normal coordinate analysis of HQD was also performed to assign each band in vibrational spectra. DFT (B3LYP and B3PW91) calculations were employed to optimize the geometry, to interpret NMR spectra, to calculate and to determine the stable tautomeric structure of the compound. Natural Bond Orbital (NBO) analysis was performed to investigate intramolecular interactions. The vibrational spectral data obtained from solid phase IR & Raman spectra were assigned based on the results of the theoretical calculations. UV-vis spectroscopic technique was employed to obtain the optical band gap of HQD. The analysis of the optical absorption data revealed the existence of direct and indirect transitions in the optical band gaps. The optical band gaps of HQD have been found 1.95 and 1.90 eV for direct and indirect transitions, respectively.

An investigation onto the molecular structure of 5-chloro-3-(2-(4-ethylpiperazine-1-il)-2-oxoethyl)benzo[d]thiazole-2(3H)-on drug molecule before and after atmospheric pressure plasma treatment

NASA Astrophysics Data System (ADS)

Tanışlı, Murat; Taşal, Erol; Şahin, Neslihan; Dikmen, Gökhan

2018-05-01

The spectra of molecular structure for the 5-chloro-3-(2-(4-ethylpiperazine-1-il)-2-oxoethyl)benzo[d]thiazole-2(3H)-on drug molecule (abbreviated as 5KEB) before and after the atmospheric pressure plasma treatments (APPTs) of neon (Ne) and argon (Ar) were investigated. The Fourier transform infrared (FT-IR), ultraviolet visible (UV-Vis) spectra and NMR measurements of the 5KEB drug molecule dissolved in toluene and ethanol solvents were recorded and examined for liquid phases. Then FT-IR, UV-Vis spectra and NMR measurements were analysed. It is seen that some bonds of 5KEB molecule were decomposed. There were also unobserved vibrational modes. After the Ne plasma at the atmospheric pressure applied to 5KEB drug molecule dissolved in toluene, the bonds as 9Ssbnd 8C; 9Ssbnd 8C = 10 O, 8Csbnd 7N, 7Nsbnd 8C = 10O were vanished, and then the new bonds of the 7N = 8C, 7N = 8C = 10 O, 9Ssbnd 5Csbnd 4Csbnd 7N = 8C = 10O were observed. New photoproducts may be defined as the stretching peaks, stretching vibrational modes for 5KEB drug molecule in liquid phase prepared with ethanol and toluene solvents after APPT. Also, after Ar plasma at atmospheric pressure applied here, the 9Ssbnd 8C bond of the 5KEB drug molecule dissolved in toluene was broken. The isomerization process in UV-Vis was defined by π-π* and n-π* electronic transitions. According to NMR results, protons of pyridine ring, protons of CH2 group bonded to carbonyl group and protons of CH3 group more affected than other protons from Ar and Ne APPTs and these protons were eliminated by Ar and Ne APPTs.

Indonesian palm civet coffee discrimination using UV-visible spectroscopy and several chemometrics methods

NASA Astrophysics Data System (ADS)

Yulia, M.; Suhandy, D.

2017-05-01

Indonesian palm civet coffee or kopi luwak (Indonesian words for coffee and palm civet) is well known as the world’s priciest and rarest coffee. To protect the authenticity of luwak coffee and protect consumer from luwak coffee adulteration, it is very important to develop a simple and inexpensive method to discriminate between civet and non-civet coffee. The discrimination between civet and non-civet coffee in ground roasted (powder) samples is very challenging since it is very difficult to distinguish between the two by using conventional method. In this research, the use of UV-Visible spectra combined with two chemometric methods, SIMCA and PLS-DA, was evaluated to discriminate civet and non-civet ground coffee samples. The spectral data of civet and non-civet coffee were acquired using UV-Vis spectrometer (Genesys™ 10S UV-Vis, Thermo Scientific, USA). The result shows that using both supervised discrimination methods: SIMCA and PLS-DA, all samples were correctly classified into their corresponding classes with 100% rate for accuracy, sensitivity and specificity, respectively.

Organic/Organometallic Hybrids as Broadband Nonlinear Transmission Materials

DTIC Science & Technology

2010-06-01

Distribution Statement checked below. The current distribution for this document can be found in the DTIC® Technical Report Database. h...device applications. The details of these studies were reported in publications #9 and #10. The UV-vis absorption spectra, emission spectra, triplet...11300) 76 596 (400; 0.08; 589 (100; 0.025; 385(86), 585(87, 0.51 2.00x10s) 2.50x10s) 493 3 )e e a Radiative decay rate constant (k, = O/r). b Emission

Synthesis and antibacterial properties of water-dispersible silver nanoparticles stabilized by metal-carbon σ-bonds

NASA Astrophysics Data System (ADS)

Kawai, Koji; Narushima, Takashi; Kaneko, Kotaro; Kawakami, Hayato; Matsumoto, Miyuki; Hyono, Atsushi; Nishihara, Hiroshi; Yonezawa, Tetsu

2012-12-01

The synthesis of 4-diazoniumcarboxylbenzene fluoroborate, a new water-soluble stabilizer for metal nanoparticles (NPs), is described. A stable dispersion of Ag NPs in water was successfully produced by a simultaneous aqueous reduction of this diazonium salt and silver nitrate by NaBH4. UV-vis spectra, TEM images, XRD patterns, and XPS spectra of the obtained Ag NPs revealed that they were stabilized by Ag-C σ-bonds. These NPs showed excellent antimicrobial properties against Staphylococcus aureus.

Modified Fe3O4- hydroxyapatite nanocomposites as heterogeneous catalysts in three UV, Vis and Fenton like degradation systems

NASA Astrophysics Data System (ADS)

Valizadeh, S.; Rasoulifard, M. H.; Dorraji, M. S. Seyed

2014-11-01

The magnetite-hydroxyapatite (M-HAP) nanocomposites were prepared by a chemical co- precipitation procedure and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance spectra (DRS). The ability of the synthesized catalyst for photocatalytic degradation of Acid Blue 25 (AB25), as an organic dye, under UV irradiation was studied. The catalyst was modified employing transition metals (Mn, Fe, Co, Ni, Cu and Zn) trying to improve the catalytic performance of HAP in absence of UV irradiation and in the presence of hydrogen peroxide i.e. a Fenton like reaction. The best results obtained for Cu and Co modified M-HAPs and the effect of operational parameters such pH, amount of catalyst and hydrogen peroxide concentration was studied. In order to investigate the performance of HAP based photocatalyst in visible light region, M-HAP was modified with silver ions. At the end, Langmuir-Hinshelwood kinetic expression used to evaluate and compare the catalytic systems. The strongest degradation activity was observed for Ag-M-HAP/Vis system because of Ag3PO4 formation. Apparent reaction rate constant (Kapp) by Ag-M-HAP/Vis was 63, 36 and 19 times faster than Cu-M-HAP(II)/H2O2, Co-M-HAP(II)/H2O2 and M-HAP (I)/UV systems, respectively.

Vacancy-Rich Monolayer BiO 2-x as a Highly Efficient UV, Visible, and Near-Infrared Responsive Photocatalyst

DOE PAGES

Li, Jun; Wu, Xiaoyong; Pan, Wenfeng; ...

2017-09-08

Here in this paper, a full-spectrum responsive vacancy-rich monolayer BiO 2-x has been synthesized. The increased density of states at the conduction band (CB) minimum in the monolayer BiO 2-x is responsible for the enhanced photon response and photo-absorption, which were confirmed by UV/Vis-NIR diffuse reflectance spectra (DRS) and photocurrent measurements. Compared to bulk BiO 2-x, monolayer BiO 2-x has exhibited enhanced photocatalytic performance for rhodamine B and phenol removal under UV, visible, and near-infrared light (NIR) irradiation, which can be attributed to the vacancy VBi-O"' as confirmed by the positron annihilation spectra. The presence of V Bi-O"' defects inmore » monolayer BiO 2-x promoted the separation of electrons and holes. This finding provides an atomic level understanding for developing highly efficient UV, visible, and NIR light responsive photocatalysts.« less

Vacancy-Rich Monolayer BiO 2-x as a Highly Efficient UV, Visible, and Near-Infrared Responsive Photocatalyst

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

Li, Jun; Wu, Xiaoyong; Pan, Wenfeng

Here in this paper, a full-spectrum responsive vacancy-rich monolayer BiO 2-x has been synthesized. The increased density of states at the conduction band (CB) minimum in the monolayer BiO 2-x is responsible for the enhanced photon response and photo-absorption, which were confirmed by UV/Vis-NIR diffuse reflectance spectra (DRS) and photocurrent measurements. Compared to bulk BiO 2-x, monolayer BiO 2-x has exhibited enhanced photocatalytic performance for rhodamine B and phenol removal under UV, visible, and near-infrared light (NIR) irradiation, which can be attributed to the vacancy VBi-O"' as confirmed by the positron annihilation spectra. The presence of V Bi-O"' defects inmore » monolayer BiO 2-x promoted the separation of electrons and holes. This finding provides an atomic level understanding for developing highly efficient UV, visible, and NIR light responsive photocatalysts.« less

Explaining Space-Weathering Effects on UV-Vis-NIR Spectra with Light-Scattering Methods

NASA Astrophysics Data System (ADS)

Penttilä, Antti; Väisänen, Timo; Martikainen, Julia; Kohout, Tomas; Muinonen, Karri

2015-11-01

Space-weathering (SW) introduces changes to the asteroid reflectance spectra. In silicate minerals, SW is known to darken the spectra and reduce the silicate absorption band depths. In olivine, the neutral slope in Vis and NIR wavelengths is becoming positive [1]. In pyroxene, the positive slope over the 1 µm absorption band is decreasing, and the negative slope over the 2 µm band is increasing towards positive values with increasing SW [2].The SW process generates small nanophase iron (npFe0) inclusions in the surface layers of mineral grains. The inclusions are some tens of nm in size. This mechanism has been linked to the Moon and to a certain extent also to the silicate-rich S-complex asteroids.We offer two simple explanations from light-scattering theory to explain the SW effects on the spectral slope. First, the npFe0 will introduce a posititive general slope (reddening) to the spectra. The npFe0 inclusions (~10 nm) are in the Rayleigh domain with the wavelength λ in the UV-Vis-NIR range. Their absorption cross-section follows approximately the 1/λ-relation from the Rayleigh theory. Absorption is more efficient in the UV than in the NIR wavelengths, therefore the spectra are reddening.Second, the effect of npFe0 absorption is more efficient for originally brighter reflectance values. Explanation combines the effective medium theory and the exponential attenuation in the medium. When adding a small amount of highly absorbing npFe0, the effective absorption coefficient k will increase approximately the same Δk for the typical values of silicates. This change will increase more effectively the exponential attenuation if the original k was very small, and thus the reflectance high. Therefore, both positive and negative spectral slopes will approach zero with SW.We conclude that the SW will introduce a general reddening, and neutralize local slopes. This is verified using the SIRIS code [3], which combines geometric optics with small internal diffuse scatterers in the radiative transfer domain.[1] Kohout T. et al. (2014), Icarus 237(15), 75-83.[2] Kohout T. et al. (2015), Workshop on Space Weathering of Airless Bodies, Abstract.[3] Muinonen K. et al. (2009), JQSRT 110, 1628-1639.

Geographical identification of saffron (Crocus sativus L.) by linear discriminant analysis applied to the UV-visible spectra of aqueous extracts.

PubMed

D'Archivio, Angelo Antonio; Maggi, Maria Anna

2017-03-15

We attempted geographical classification of saffron using UV-visible spectroscopy, conventionally adopted for quality grading according to the ISO Normative 3632. We investigated 81 saffron samples produced in L'Aquila, Città della Pieve, Cascia, and Sardinia (Italy) and commercial products purchased in various supermarkets. Exploratory principal component analysis applied to the UV-vis spectra of saffron aqueous extracts revealed a clear differentiation of the samples belonging to different quality categories, but a poor separation according to the geographical origin of the spices. On the other hand, linear discriminant analysis based on 8 selected absorbance values, concentrated near 279, 305 and 328nm, allowed a good distinction of the spices coming from different sites. Under severe validation conditions (30% and 50% of saffron samples in the evaluation set), correct predictions were 85 and 83%, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of Heck-cross coupling 4-(4-nitrostyryl) aniline as potential precursor in Schiff-base synthesis

NASA Astrophysics Data System (ADS)

Hassan, Norhafiefa; Izwani, Fatin; Yusoff, H. M.

2017-09-01

This is a preliminary study of alkoxy substituted Heck-schiff base compound as recognition layer in electrochemical DNA sensor for liver cancer. 4-(4-nitrostyryl)aniline was synthesized by bis (triphenylphosphine) palladium (II) dichloride as catalyst and has been characterized by using Fourier transform-infrared spectrometer (FTIR), UV-Vis spectrophotometer and Nuclear Magnetic Resonance (NMR) spectra. The result obtained from FTIR show that there are formation of N=O (NO2) asymmetric stretching vibrations 1340 cm-1. In UV-vis, absorbance of NO2 can be observed at peak 410 nm. While in the 1H NMR and 13C NMR the peak of C-C coupling was found in the range of δH 6.84-7.09 ppm and δC 125.23 ppm.

Investigation on intermolecular interaction between berberine and β-cyclodextrin by 2D UV-Vis asynchronous spectra

NASA Astrophysics Data System (ADS)

He, Anqi; Kang, Xiaoyan; Xu, Yizhuang; Noda, Isao; Ozaki, Yukihiro; Wu, Jinguang

2017-10-01

The interaction between berberine chloride and β-cyclodextrin (β-CyD) is investigated via 2D asynchronous UV-Vis spectrum. The occurrence of cross peaks around (420 nm, 420 nm) in 2D asynchronous spectrum reveals that specific intermolecular interaction indeed exists between berberine chloride and β-CyD. In spite of the difficulty caused by overlapping of cross peaks, we manage to confirm that the 420 nm band of berberine undergoes a red-shift, and its bandwidth decreases under the interaction with β-CyD. The red-shift of the 420 nm band that can be assigned to n-π* transition indicates the environment of berberine becomes more hydrophobic. The above spectral behavior is helpful in understanding why the solubility of berberine is enhanced by β-CyD.

Synthesis, structural characterization and DFT calculation on a square-planar Ni(II) complex of a compartmental Schiff base ligand

NASA Astrophysics Data System (ADS)

Biswas, Surajit; Dolai, Malay; Dutta, Arpan; Ali, Mahammad

2016-12-01

Reaction of a symmetric compartmental Schiff-base ligand, (H2L) with nickel(II) perchlorate hexahydrate in 1:1 M ratio in methanol gives rise to a mononuclear nickel(II) compound, NiL (1). The compound has been characterized by C, H, N microanalyses and UV-Vis spectra. The single crystal X-ray diffraction studies reveal a square planar geometry around the Ni(II) center. The compound crystallizes in monoclinic system with space group C2/c with a = 21.6425(6), b = 9.9481(3), c = 13.1958(4) Å, β = 107.728(2)°, V = 2706.16(14) Å3 and Z = 4. Ground state DFT optimization and TDDFT calculations on the ligand and complex were performed to get their UV-Vis spectral pattern.

[Rapid determination of COD in aquaculture water based on LS-SVM with ultraviolet/visible spectroscopy].

PubMed

Liu, Xue-Mei; Zhang, Hai-Liang

2014-10-01

Ultraviolet/visible (UV/Vis) spectroscopy was studied for the rapid determination of chemical oxygen demand (COD), which was an indicator to measure the concentration of organic matter in aquaculture water. In order to reduce the influence of the absolute noises of the spectra, the extracted 135 absorbance spectra were preprocessed by Savitzky-Golay smoothing (SG), EMD, and wavelet transform (WT) methods. The preprocessed spectra were then used to select latent variables (LVs) by partial least squares (PLS) methods. Partial least squares (PLS) was used to build models with the full spectra, and back- propagation neural network (BPNN) and least square support vector machine (LS-SVM) were applied to build models with the selected LVs. The overall results showed that BPNN and LS-SVM models performed better than PLS models, and the LS-SVM models with LVs based on WT preprocessed spectra obtained the best results with the determination coefficient (r2) and RMSE being 0. 83 and 14. 78 mg · L(-1) for calibration set, and 0.82 and 14.82 mg · L(-1) for the prediction set respectively. The method showed the best performance in LS-SVM model. The results indicated that it was feasible to use UV/Vis with LVs which were obtained by PLS method, combined with LS-SVM calibration could be applied to the rapid and accurate determination of COD in aquaculture water. Moreover, this study laid the foundation for further implementation of online analysis of aquaculture water and rapid determination of other water quality parameters.

Revision of iron(III)-citrate speciation in aqueous solution. Voltammetric and spectrophotometric studies.

PubMed

Vukosav, Petra; Mlakar, Marina; Tomišić, Vladislav

2012-10-01

A detailed study of iron (III)-citrate speciation in aqueous solution (θ=25°C, I(c)=0.7 mol L(-1)) was carried out by voltammetric and UV-vis spectrophotometric measurements and the obtained data were used for reconciled characterization of iron (III)-citrate complexes. Four different redox processes were registered in the voltammograms: at 0.1 V (pH=5.5) which corresponded to the reduction of iron(III)-monocitrate species (Fe:cit=1:1), at about -0.1 V (pH=5.5) that was related to the reduction of FeL(2)(5-), FeL(2)H(4-) and FeL(2)H(2)(3-) complexes, at -0.28 V (pH=5.5) which corresponded to the reduction of polynuclear iron(III)-citrate complex(es), and at -0.4V (pH=7.5) which was probably a consequence of Fe(cit)(2)(OH)(x) species reduction. Reversible redox process at -0.1 V allowed for the determination of iron(III)-citrate species and their stability constants by analyzing E(p) vs. pH and E(p) vs. [L(4-)] dependence. The UV-vis spectra recorded at varied pH revealed four different spectrally active species: FeLH (logβ=25.69), FeL(2)H(2)(3-) (log β=48.06), FeL(2)H(4-) (log β=44.60), and FeL(2)(5-) (log β=38.85). The stability constants obtained by spectrophotometry were in agreement with those determined electrochemically. The UV-vis spectra recorded at various citrate concentrations (pH=2.0) supported the results of spectrophotometric-potentiometric titration. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of heating time on the growth and behavior of amorphous carbon nanostructures from ferrocene

NASA Astrophysics Data System (ADS)

Rafiqul Islam, Md; Rashid, A. K. M. B.; Ferdous, Md; Shafiul Azam, Md

2017-05-01

Heating time is one of the crucial factors in various methods employed for the synthesis of carbon nanostructures (CNSs) from ferrocene. However, the effects of heating time on the growth and morphology of the nanostructured materials has not been well explored yet, particularly for amorphous carbon. Herein, we investigate how the variation of heating time impacts the growth of CNSs by carrying out the reaction between ferrocene and ammonium chloride in a solvent free condition at 250 °C. Several different forms of carbon nanostructures yielded from this reaction at 25 min (CNS-25), 30 min (CNS-30), 35 min (CNS-35) and 40 min (CNS-40) were analyzed by means of field emission scanning electron microscopy (FESEM) coupled with energy-dispersive x-ray (EDX), Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The final product CNS-40 was washed several times with concentrated hydrochloric acid solution to remove the impurities and then characterized by the means of similar techniques. FTIR spectra of all the nanostructures confirmed the presence of several functional groups such as C  =  C, C-O and -OH etc, which are common in carbonaceous nanostructures. However, the FESEM images obtained are significantly different and suggest a gradual growth of the carbon nanostructures ending up with long carbon nanotubes after 40 min. No absorption peak in the visible region of the UV-Vis spectra of the final product confirms the amorphous nature, which is also supported by XRD of the synthesized nanotube. Moreover, a noteworthy redshift in the UV-Vis peaks reflecting a huge increase in length and diameter of the nanostructures indicates the maximum longitudinal growth of the carbon nanotubes occurs during 35 min to 40 min.

Redox and photoinduced electron-transfer properties in short distance organoboryl ferrocene-subphthalocyanine dyads.

PubMed

Maligaspe, Eranda; Hauwiller, Matthew R; Zatsikha, Yuriy V; Hinke, Jonathan A; Solntsev, Pavlo V; Blank, David A; Nemykin, Victor N

2014-09-02

Reaction between ferrocene lithium or ethynylferrocene magnesium bromide and (chloro)boronsubphthalocyanine leads to formation of ferrocene- (2) and ethynylferrocene- (3) containing subphthalocyanine dyads with a direct organometallic B-C bond. New donor-acceptor dyads were characterized using UV-vis and magnetic circular dichroism (MCD) spectroscopies, NMR method, and X-ray crystallography. Redox potentials of the rigid donor-acceptor dyads 2 and 3 were studied using the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) approaches and compared to the parent subphthalocyanine 1 and conformationally flexible subphthalocyanine ferrocenenylmethoxide (4) and ferrocenyl carboxylate (5) dyads reported earlier. It was found that the first oxidation process in dyads 2 and 3 is ferrocene-centered, while the first reduction as well as the second oxidation are centered at the subphthalocyanine ligand. Density functional theory-polarized continuum model (DFT-PCM) and time-dependent (TD) DFT-PCM methods were used to probe the electronic structures and explain the UV-vis and MCD spectra of complexes 1-5. DFT-PCM calculations suggest that the LUMO, LUMO+1, and HOMO-3 in new dyads 2 and 3 are centered at the subphthalocyanine ligand, while the HOMO to HOMO-2 in both dyads are predominantly ferrocene-centered. TDDFT-PCM calculations on compounds 1-5 are indicative of the π → π* transitions dominance in their UV-vis spectra, which is consistent with the experimental data. The excited state dynamics of the parent subphthalocyanine 1 and dyads 2-5 were investigated using time-resolved transient spectroscopy. In the dyads 2-5, the initially excited state is rapidly (<2 ps) quenched by electron transfer from the ferrocene ligand. The lifetime of the charge transfer state demonstrates a systematic dependence on the structure of the bridge between the subphthalocyanine and ferrocene.

Co-assembly of Zn(SPh){sub 2} and organic linkers into helical and zig-zag polymer chains

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

Liu Yi; Yu Lingmin; Loo, Say Chye Joachim

2012-07-15

Two novel one-dimensional coordination polymers, single helicate [Zn(SPh){sub 2}(TPyTA)(EG)]{sub n} (EG=ethylene glycol) (1) and zig-zag structure [Zn(SPh){sub 2}(BPyVB)]{sub n} (2), were synthesized under solvothermal conditions at 150 Degree-Sign C or room temperature by the co-assembly of Zn(SPh){sub 2} and organic linkers such as 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPyTA) and 1,3-bis(trans-4-pyridylvinyl)benzene (BPyVB). X-ray crystallography study reveals that both polymers 1 and 2 crystallize in space group P2{sub 1}/c of the monoclinic system. The solid-state UV-vis absorption spectra show that 1 and 2 have maxium absorption onsets at 400 nm and 420 nm, respectively. TGA analysis indicates that 1 and 2 are stable up tomore » 110 Degree-Sign C and 210 Degree-Sign C. - Graphical abstract: Two novel one-dimensional coordination polymers, single helicate [Zn(SPh){sub 2}(TPyTA)(EG)]{sub n} (1) and zig-zag structure [Zn(SPh){sub 2}(BPyVB)]{sub n} (2), were synthesized. Solid-state UV-vis absorptions show that 1 and 2 have maxium absorption onsets at 400 nm and 420 nm, respectively. TGA analysis indicates that 1 and 2 are stable up to 110 Degree-Sign C and 210 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Two novel one-dimensional coordination polymers have been synthesized. Black-Right-Pointing-Pointer TPyTA results in helical structures in 1 while BPyVB leads to zig-zag chains in 2. Black-Right-Pointing-Pointer Solid-state UV-vis absorption spectra and TGA analysis of the title polymers were studied.« less

Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV-vis spectra, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis, thermodynamic properties of benzophenone 2,4-dicarboxylic acid by ab initio HF and density functional method

NASA Astrophysics Data System (ADS)

Chaitanya, K.

2012-02-01

The FT-IR (4000-450 cm -1) and FT-Raman spectra (3500-100 cm -1) of benzophenone 2,4-dicarboxylic acid (2,4-BDA) have been recorded in the condensed state. Density functional theory calculation with B3LYP/6-31G(d,p) basis set have been used to determine ground state molecular geometries (bond lengths and bond angles), harmonic vibrational frequencies, infrared intensities, Raman activities and bonding features of the title compounds. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability ( β0) and related properties ( β, α0 and Δ α) of 2,4-BDA is calculated using HF/6-31G(d,p) method on the finite-field approach. The stability of molecule has been analyzed by using NBO analysis. The calculated first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. Mulliken population analysis on atomic charges is also calculated. Because of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the UV-vis spectra and electronic absorption properties were explained and illustrated from the frontier molecular orbitals.

Raman, IR, UV-vis and EPR characterization of two copper dioxolene complexes derived from L-dopa and dopamine

NASA Astrophysics Data System (ADS)

Barreto, Wagner J.; Barreto, Sônia R. G.; Ando, Rômulo A.; Santos, Paulo S.; DiMauro, Eduardo; Jorge, Thiago

2008-12-01

The anionic complexes [Cu(L 1-) 3] 1-, L - = dopasemiquinone or L-dopasemiquinone, were prepared and characterized. The complexes are stable in aqueous solution showing intense absorption bands at ca. 605 nm for Cu(II)-L-dopasemiquinone and at ca. 595 nm for Cu(II)-dopasemiquinone in the UV-vis spectra, that can be assigned to intraligand transitions. Noradrenaline and adrenaline, under the same reaction conditions, did not yield Cu-complexes, despite the bands in the UV region showing that noradrenaline and adrenaline were oxidized during the process. The complexes display a resonance Raman effect, and the most enhanced bands involve ring modes and particularly the νCC + νCO stretching mode at ca. 1384 cm -1. The free radical nature of the ligands and the oxidation state of the Cu(II) were confirmed by the EPR spectra that display absorptions assigned to organic radicals with g = 2.0005 and g = 2.0923, and for Cu(II) with g = 2.008 and g = 2.0897 for L-dopasemiquinone and dopasemiquinone, respectively. The possibility that dopamine and L-dopa can form stable and aqueous-soluble copper complexes at neutral pH, whereas noradrenaline and adrenaline cannot, may be important in understanding how Cu(II)-dopamine crosses the cellular membrane as proposed in the literature to explain the role of copper in Wilson disease.

Tropospheric Ozone Profiling Using Simulated GEO-CAPE Measurement

NASA Technical Reports Server (NTRS)

Natraj, Vijay; Li, Xiong; Kulawik, Susan; Chance, Kelly; Chatfield, Robert; Edwards, David P .; Eldering, Annmarie; Francis, Gene; Kurosu, Thomas; Pickering, Kenneth;

Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

NASA Astrophysics Data System (ADS)

Gautam, C. R.; Das, Sangeeta; Gautam, S. S.; Madheshiya, Abhishek; Singh, Anod Kumar

2018-04-01

In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of Gesbnd Osbnd Ge, Bsbnd Osbnd Ge, Sisbnd Osbnd Ge, Sisbnd Osbnd Si, and Pbsbnd Osbnd Ge. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV-Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV-Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

Modifications of hemoglobin and myoglobin by Maillard reaction products (MRPs).

PubMed

Ioannou, Aristos; Varotsis, Constantinos

2017-01-01

High performance liquid chromatography (HPLC) coupled with a Fraction Collector was employed to isolate Maillard reaction products (MRPs) formed in model systems comprising of asparagine and monosaccharides in the 60-180°C range. The primary MRP which is detected at 60°C is important for Acrylamide content and color/aroma development in foods and also in the field of food biotechnology for controlling the extent of the Maillard reaction with temperature. The discrete fractions of the reaction products were reacted with Hemoglobin (Hb) and Myoglobin (Mb) at physiological conditions and the reaction adducts were monitored by UV-vis and Attenuated Total Reflection-Fourier transform infrared (FTIR) spectrophotometry. The UV-vis kinetic profiles revealed the formation of a Soret transition characteristic of a low-spin six-coordinated species and the ATR-FTIR spectrum of the Hb-MRP and Mb-MRP fractions showed modifications in the protein Amide I and II vibrations. The UV-vis and the FTIR spectra of the Hb-MRPs indicate that the six-coordinated species is a hemichrome in which the distal E7 Histidine is coordinated to the heme Fe and blocks irreversibly the ligand binding site. Although the Mb-MRPs complex is a six-coordinated species, the 1608 cm-1 FTIR band characteristic of a hemichrome was not observed.

Optical, Magnetic and Photocatalytic Activity Studies of Li, Mg and Sr Doped and Undoped Zinc Oxide Nanoparticles.

PubMed

Shanthi, S I; Poovaragan, S; Arularasu, M V; Nithya, S; Sundaram, R; Magdalane, C Maria; Kaviyarasu, K; Maaza, M

2018-08-01

Nanoparticles of Li, Mg and Sr doped and undoped zinc oxide was prepared by simple precipitation method. The structural, optical, and magnetic properties of the samples were investigated by the Powder X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Fourier Transform Infrared (FTIR) spectroscopy, Ultra-violet Visible spectroscopy (UV-vis) spectra, Photoluminescence (PL) and Vibrational Sample Magnetometer (VSM). The Powder X-ray diffraction data confirm the formation of hexagonal wurtzite structure of all doped and undoped ZnO. The SEM photograph reveals that the pores availability and particles size in the range of 10 nm-50 nm. FTIR and UV-Visible spectra results confirm the incorporation of the dopant into the ZnO lattice nanostructure. The UV-Visible spectra indicate that the shift of blue region (lower wavelength) due to bandgap widening. Photoluminescence intensity varies with doping due to the increase of oxygen vacancies in prepared ZnO. The pure ZnO exist paramagnetic while doped (Li, Mg and Sr) ZnO exist ferromagnetic property. The photocatalytic activity of the prepared sample also carried out in detail.

Effects of Space Weathering on Reflectance Spectra of Ureilites: First Studies

NASA Technical Reports Server (NTRS)

Goodrich, C. A.; Gillis-Davis, J.; Cloutis, E.; Applin, D.; Takir, D.; Hibbitts, C.; Christoffersen, R.; Fries, M.; Klima, R.; Decker, S.

2018-01-01

Ureilites are differentiated meteorites (ultramafic rocks interpreted to be mantle residues) that contain as much carbon as the most carbon-rich carbonaceous chondrites (CCs). Reflectance spectra of ureilites are similar to those of some CCs. Hence, ureilitic asteroids may accidentally be categorized as primitive because their spectra could resemble those of C-complex asteroids, which are thought to be CC-like. We began spectral studies of progressively laser-weathered ureilites with the goals of predicting UV-VIS-IR spectra of ureilitic asteroids, and identifying features that could distinguish differentiated from primitive dark asteroids. Space weathering has not previously been studied for ureilites, and, based on space weathering studies of CCs and other C-rich materials, it could significantly alter their reflectance spectra.

Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy

PubMed Central

Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

2016-01-01

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin–Ciocalteu method (R2 of 0.97 in calibration and R2 of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R2 of 0.93 in calibration and R2 of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R2 of 0.99 in calibration and R2 of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R2 of 0.96 in calibration and R2 of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content—the most important parameters to be measured in this type of liqueurs.  PMID:27735832

Discrimination of Apple Liqueurs (Nalewka) Using a Voltammetric Electronic Tongue, UV-Vis and Raman Spectroscopy.

PubMed

Śliwińska, Magdalena; Garcia-Hernandez, Celia; Kościński, Mikołaj; Dymerski, Tomasz; Wardencki, Waldemar; Namieśnik, Jacek; Śliwińska-Bartkowiak, Małgorzata; Jurga, Stefan; Garcia-Cabezon, Cristina; Rodriguez-Mendez, Maria Luz

2016-10-09

The capability of a phthalocyanine-based voltammetric electronic tongue to analyze strong alcoholic beverages has been evaluated and compared with the performance of spectroscopic techniques coupled to chemometrics. Nalewka Polish liqueurs prepared from five apple varieties have been used as a model of strong liqueurs. Principal Component Analysis has demonstrated that the best discrimination between liqueurs prepared from different apple varieties is achieved using the e-tongue and UV-Vis spectroscopy. Raman spectra coupled to chemometrics have not been efficient in discriminating liqueurs. The calculated Euclidean distances and the k-Nearest Neighbors algorithm (kNN) confirmed these results. The main advantage of the e-tongue is that, using PLS-1, good correlations have been found simultaneously with the phenolic content measured by the Folin-Ciocalteu method (R² of 0.97 in calibration and R² of 0.93 in validation) and also with the density, a marker of the alcoholic content method (R² of 0.93 in calibration and R² of 0.88 in validation). UV-Vis coupled with chemometrics has shown good correlations only with the phenolic content (R² of 0.99 in calibration and R² of 0.99 in validation) but correlations with the alcoholic content were low. Raman coupled with chemometrics has shown good correlations only with density (R² of 0.96 in calibration and R² of 0.85 in validation). In summary, from the three holistic methods evaluated to analyze strong alcoholic liqueurs, the voltammetric electronic tongue using phthalocyanines as sensing elements is superior to Raman or UV-Vis techniques because it shows an excellent discrimination capability and remarkable correlations with both antioxidant capacity and alcoholic content-the most important parameters to be measured in this type of liqueurs.

Combination of UV-vis spectroscopy and chemometrics to understand protein-nanomaterial conjugate: a case study on human serum albumin and gold nanoparticles.

PubMed

Wang, Yong; Ni, Yongnian

2014-02-01

Study of the interactions between proteins and nanomaterials is of great importance for understanding of protein nanoconjugate. In this work, we choose human serum albumin (HSA) and citrate-capped gold nanoparticles (AuNPs) as a model of protein and nanomaterial, and combine UV-vis spectroscopy with multivariate curve resolution by an alternating least squares (MCR-ALS) algorithm to present a new and efficient method for comparatively comprehensive study of evolution of protein nanoconjugate. UV-vis spectroscopy coupled with MCR-ALS allows qualitative and quantitative extraction of the distribution diagrams, spectra and kinetic profiles of absorbing pure species (AuNPs and AuNPs-HSA conjugate are herein identified) and undetectable species (HSA) from spectral data. The response profiles recovered are converted into the desired thermodynamic, kinetic and structural parameters describing the protein nanoconjugate evolution. Analysis of these parameters for the system gives evidence that HSA molecules are very likely to be attached to AuNPs surface predominantly as a flat monolayer to form a stable AuNPs-HSA conjugate with a core-shell structure, and the binding process takes place mainly through electrostatic and hydrogen-bond interactions between the positively amino acid residues of HSA and the negatively carboxyl group of citrate on AuNPs surface. The results obtained are verified by transmission electron microscopy, zeta potential, circular dichroism spectroscopy and Fourier transform infrared spectroscopy, showing the potential of UV-vis spectroscopy for study of evolution of protein nanoconjugate. In parallel, concentration evolutions of pure species resolved by MCR-ALS are used to construct a sensitive spectroscopic biosensor for HSA with a linear range from 1.8 nM to 28.1 nM and a detection limit of 0.8 nM. © 2013 Published by Elsevier B.V.

40 CFR 796.1050 - Absorption in aqueous solution: Ultraviolet/visible spectra.

Code of Federal Regulations, 2011 CFR

2011-07-01

....50 λ in nm 235 257 313 350 (2) Fluoranthene (in methanol) from C.R.C. Atlas of Spectral Data...-nitrophenol (in methanol) from C.R.C. Atlas of Spectral Data, paragraph (d)(3) of this section: log ε 3.88 4... to obtain the UV-VIS spectrum of the test compound. Such an instrument should have a photometric...

Exploring the site-selective binding of jatrorrhizine to human serum albumin: spectroscopic and molecular modeling approaches.

PubMed

Mi, Ran; Hu, Yan-Jun; Fan, Xiao-Yang; Ouyang, Yu; Bai, Ai-Min

2014-01-03

This paper exploring the site-selective binding of jatrorrhizine to human serum albumin (HSA) under physiological conditions (pH=7.4). The investigation was carried out using fluorescence spectroscopy, UV-vis spectroscopy, and molecular modeling. The results of fluorescence quenching and UV-vis absorption spectra experiments indicated the formation of the complex of HSA-jatrorrhizine. Binding parameters calculating from Stern-Volmer method and Scatchard method were calculated at 298, 304 and 310 K, with the corresponding thermodynamic parameters ΔG, ΔH and ΔS as well. Binding parameters calculating from Stern-Volmer method and Scatchard method showed that jatrorrhizine bind to HSA with the binding affinities of the order 10(4) L mol(-1). The thermodynamic parameters studies revealed that the binding was characterized by negative enthalpy and positive entropy changes and the electrostatic interactions play a major role for jatrorrhizine-HSA association. Site marker competitive displacement experiments and molecular modeling calculation demonstrating that jatrorrhizine is mainly located within the hydrophobic pocket of the subdomain IIIA of HSA. Furthermore, the synchronous fluorescence spectra suggested that the association between jatrorrhizine and HSA changed molecular conformation of HSA. Copyright © 2013. Published by Elsevier B.V.

Spectroscopic ellipsometry study of N+ ion-implanted ethylene-norbornene films

NASA Astrophysics Data System (ADS)

Šiljegović, M.; Kačarević-Popović, Z. M.; Stchakovsky, M.; Radosavljević, A. N.; Korica, S.; Novaković, M.; Popović, M.

2014-05-01

The optical properties of 150 keV N+ implanted ethylene-norbornene (TOPAS 6017S-04) copolymer were investigated using phase modulated spectroscopic ellipsometry (PMSE) and ultraviolet-visible (UV-Vis) spectroscopy in the ranges of 0.6-6.5 eV and of 1.5-6.2 eV, respectively. The single-effective-oscillator model was used to fit the calculated data to the experimental ellipsometric spectra. The results show that the oscillator and dispersion energies decrease with increasing ion fluence up to 1015 cm-2, and then these parameters increase with further fluence increasing. Analysis of the UV-Vis absorption spectra revealed the presence of indirect electronic transitions with the band gap energy in the range of 1.3 to 2.8 eV. It was found that both the band gap energy and the energy width of the distribution of localized band tail states decrease, while the values of Tauc coefficient increase with increasing the ion fluence. From the ellipsometric data we found that the real part of the dielectric function increased about 7% after irradiation with 1015 cm-2, and decreased about 10% in samples modified with 1016 cm-2.

Binding properties of food colorant allura red with human serum albumin in vitro.

PubMed

Wang, Langhong; Zhang, Guowen; Wang, Yaping

2014-05-01

Allura red (AR) is a widely used colorant in food industry, but may have a potential security risk. In this study, the properties of interaction between AR and human serum albumin (HSA) in vitro were determined by fluorescence, UV-Vis absorption and circular dichroism (CD) spectroscopy combining with multivariate curve resolution-alternating least squares (MCR-ALS) chemometrics and molecular modeling approaches. An expanded UV-Vis data matrix was resolved by MCR-ALS method, and the concentration profiles and pure spectra for the three reaction components (AR, HSA, and AR-HSA complex) of the system were then successfully obtained to evaluate the progress interaction of AR with HSA. The calculated thermodynamic parameters indicated that hydrogen binding and hydrophobic interactions played major roles in the binding process, and the interaction induced a decrease in the protein surface hydrophobicity. The competitive experiments revealed that AR mainly located in Sudlow's site I of HSA, and this result was further supported by molecular modeling studies. Analysis of CD spectra found that the addition of AR induced the conformational changes of HSA. This study have provided new insight into the mechanism of interaction between AR and HSA.

Experimental and theoretical study of p-nitroacetanilide

NASA Astrophysics Data System (ADS)

Gnanasambandan, T.; Gunasekaran, S.; Seshadri, S.

2014-01-01

The spectroscopic properties of the p-nitroacetanilide (PNA) were examined by FT-IR, FT-Raman and UV-Vis techniques. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400 cm-1 and 3500-100 cm-1, respectively. The UV-Vis absorption spectrum of the compound that dissolved in ethanol was recorded in the range of 200-400 nm. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional theory (DFT) employing B3LYP methods with the 6-31G(d,p) and 6-311+G(d,p) basis sets. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Thermodynamic properties like entropy, heat capacity and enthalpy have been calculated for the molecule. HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear optical (NLO) properties such as electric dipole moment and first hyperpolarizability have been computed using B3LYP quantum chemical calculation.

Elaboration of nano titania-magnetic reduced graphene oxide for degradation of tartrazine dye in aqueous solution

NASA Astrophysics Data System (ADS)

Nada, Amr A.; Tantawy, Hesham R.; Elsayed, Mohamed A.; Bechelany, Mikhael; Elmowafy, Mohamed E.

2018-04-01

In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts. The structural and magnetic features of the prepared composite photocatalysts were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS), Raman and vibrating sample magnetometer (VSM). The resulting TiO2/magnetite reduced graphene oxide (MRGT) composite demonstrated intrinsic visible light photocatalytic activity, on degradation of tartrazine (TZ) dye from a synthetic aqueous solution. Specifically, it exhibits higher photocatalytic activity than magnetite reduced graphene oxide (MRG) and TiO2 nanoparticles. The photocatalytic degradation of TZ dye when using MRG and TiO2 for 3 h under visible light was 35% and 10% respectively, whereas for MRGT it was more than 95%. The higher photocatalytic efficiency of MRGT is due to the existence of reduced graphene oxide and magnetite which enhances the photocatalytic efficiency of the composite in visible light towards the degradation of harmful soluble azo dye (tartrazine).

Where Is the Electronic Oscillator Strength? Mapping Oscillator Strength across Molecular Absorption Spectra.

PubMed

Zheng, Lianjun; Polizzi, Nicholas F; Dave, Adarsh R; Migliore, Agostino; Beratan, David N

2016-03-24

The effectiveness of solar energy capture and conversion materials derives from their ability to absorb light and to transform the excitation energy into energy stored in free carriers or chemical bonds. The Thomas-Reiche-Kuhn (TRK) sum rule mandates that the integrated (electronic) oscillator strength of an absorber equals the total number of electrons in the structure. Typical molecular chromophores place only about 1% of their oscillator strength in the UV-vis window, so individual chromophores operate at about 1% of their theoretical limit. We explore the distribution of oscillator strength as a function of excitation energy to understand this circumstance. To this aim, we use familiar independent-electron model Hamiltonians as well as first-principles electronic structure methods. While model Hamiltonians capture the qualitative electronic spectra associated with π electron chromophores, these Hamiltonians mistakenly focus the oscillator strength in the fewest low-energy transitions. Advanced electronic structure methods, in contrast, spread the oscillator strength over a very wide excitation energy range, including transitions to Rydberg and continuum states, consistent with experiment. Our analysis rationalizes the low oscillator strength in the UV-vis spectral region in molecules, a step toward the goal of oscillator strength manipulation and focusing.

Synthesis and Elucidation Structure of Tetrakis-diphenylaminecopper(II) Chloride Hexahydrate

NASA Astrophysics Data System (ADS)

Syaima, H.; Rahardjo, S. B.; Suciningrum, E.

2017-11-01

CuCl2·2H2O with diphenylamine formed a complex compound in 1:4-mole ratio of metal to the ligand in methanol. Its structural properties were investigated by employing metal content analysis by Atomic Absorption Spectroscopy (AAS), magnetic susceptibility, UV-vis and FTIR spectroscopy. The forming of the complex was indicated by shifting of UV-Vis spectra. The result of analysis Cu(II) in the complex showed empirical formula of the complex were Cu(diphenylamine)4Cl2(H2O)6. The electrical conductivity of complex showed the charge ratio of cation and anion = 2:1. Finally, the proposed formula of the complex was [Cu(diphenylamine)4]Cl2·6H2O. Based on infrared spectra, it was revealed that diphenylamine existed as monodentate bind to copper(II) through the functional group of N-H. The electronic spectral study of the complex showed three transition peaks on 861, 592, and 419 nm corresponding to the 2B1g → 2A1g, 2B1g → 2B2g dan 2B1g → 2Eg transitions. The complex was paramagnetic and indicated that ligands form square planar geometry around the Cu(II).

Precursor effect on the property and catalytic behavior of Fe-TS-1 in butadiene epoxidation

NASA Astrophysics Data System (ADS)

Wu, Mei; Zhao, Huahua; Yang, Jian; Zhao, Jun; Song, Huanling; Chou, Lingjun

2017-11-01

The effect of iron precursor on the property and catalytic behavior of iron modified titanium silicalite molecular sieve (Fe-TS-1) catalysts in butadiene selective epoxidation has been studied. Three Fe-TS-1 catalysts were prepared, using iron nitrate, iron chloride and iron sulfate as precursors, which played an important role in adjusting the textural properties and chemical states of TS-1. Of the prepared Fe-TS-1 catalysts, those modified by iron nitrate (FN-TS-1) exhibited a significant enhanced performance in butadiene selective epoxidation compared to those derived from iron sulfate (FS-TS-1) or iron chloride (FC-TS-1) precursors. To obtain a deep understanding of their structure-performance relationship, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Temperature programmed desorption of NH3 (NH3-TPD), Diffuse reflectance UV-Vis spectra (DR UV-Vis), Fourier transformed infrared spectra (FT-IR) and thermal gravimetric analysis (TGA) were conducted to characterize Fe-TS-1 catalysts. Experimental results indicated that textural structures and acid sites of modified catalysts as well as the type of Fe species influenced by the precursors were all responsible for the activity and product distribution.

Spectral enhancement of leucocrystal violet treated footwear impression evidence in blood.

PubMed

Spence, Lindsay; Asmussen, Gary

2003-03-27

The results presented demonstrate the capacity for spectral enhancement to substantially improve the forensic examination of footwear impressions in blood treated with leucocrystal violet (LCV). The UV-Vis absorption spectra were generated of (i) an aqueous solution of leucocrystal violet, (ii) leucocrystal violet in 3% H(2)O(2), (iii) LCV working solution and (iv) whole blood added to LCV working solution. The resultant fluorescence emission spectra were subsequently generated (lambda(ex)=630nm, lambda(em)=661-900nm). The results indicate that the UV-Vis absorption spectra of an unbuffered solution of whole blood with LCV working solution produces a strong absorbance curve with a maxima at 630nm. Subsequent excitation at this wavelength and generation of the emission spectrum in the fluorescence mode indicates that a solution of whole blood added to LCV working solution is an extremely weak fluorophore. Therefore, to enable an adequate and timely enhancement of blood impression evidence treated with LCV utilising either visible fluorescence or infrared luminescence requires (i) selection of the most appropriate excitation wavelength (lambda(ex)) and emission wavelength (lambda(em)) with extremely narrow band pass filters, which in the absence of substrate matrix interference is excitation at 630nm producing the emission maxima at 665nm and (ii) a visual enhancement system such as a CCD colour IR video camera with image integration.

Modification of fluorescence and optical properties of Rhodamine B dye doped PVA/Chitosan polymer blend films

NASA Astrophysics Data System (ADS)

Padmakumari, R.; Ravindrachary, V.; Mahantesha, B. K.; Sagar, Rohan N.; Sahanakumari, R.; Bhajantri, R. F.

2018-05-01

Pure and Rhodamine B doped Poly (vinyl alcohol)/Chitosan composite films are prepared using solution casting method. Fourier transforms infrared spectra (FTIR), Ultraviolet-Visible (UV-Vis), fluorescence studies were used to characterize the prepared polymer films. The FT-IR results show that the appearance of new peaks along with shift in peak positions indicates the interaction of Rhodamine B with PVA-CS blend. Optical absorption edge, band gap and activation energy were determined from UV-Visible studies. The optical absorption edge increases, band gap decreases and activation energy increases with dopant concentration respectively. The corresponding emission spectra were studied using fluorescence spectroscopy. From the fluorescence study the quenching phenomena are observed in emission wavelength range of 607nm-613nm upon excitation with absorption maxima 443nm.

Study on the behavior and mechanism of polycarbonate with hot-water aging

NASA Astrophysics Data System (ADS)

Kong, L. P.; Zhao, Y. X.; Zhou, C. H.; Huang, Y. H.; Tang, M.; Gao, J. G.

2016-07-01

The present work was concerned with hot-water aging behavior and mechanism of Bisphenol A polycarbonate (PC) used as food and packaging materials. It indicated that with the aging time prolonged, PC sample had internal defects and the mechanical properties of PC materials changed not too much, molecular weight decreased, thermal stability declined. Phenolic hydroxyl absorption intensity enhanced in IR spectra and the maximum absorption wavelength red shift of benzene in UV-Vis spectra, the level of BPA increased. The color change of PC sample was not apparent.

Dihydronaphthalenone Carboxylates - Spectral Characteristics and Structure

NASA Astrophysics Data System (ADS)

Bakalova, Sn.; Georgieva, A.; Nikolov, P.; Stanoeva, E.

1997-05-01

The absorption and luminescence characteristics of a group of newly synthesized methyl esters of 2-alkyl (p-substituted-aryl) -aminomethylene-3,4-dihydro-1(2 H)-naphthalenone-4-carboxylic acids have been investigated. The studied compounds may exist in three tautomeric forms. On the basis of comparison of their electronic spectra to those of similar substances, the observed substituent effect on the position of the UV-VIS absorption bands, the IR spectra and the results of PPP-SCF-CI quantum-chemical calculations it is concluded that the keto tautomer predominates in solution.

Novel ZrO2 based ceramics stabilized by Fe2O3, SiO2 and Y2O3

NASA Astrophysics Data System (ADS)

Rada, S.; Culea, E.; Rada, M.

2018-03-01

Samples in the 5Fe2O3·10SiO2·xY2O3·(85-x)ZrO2 composition where x = 5, 10 and 15 mol% Y2O3 were synthesized and investigated by XRD, SEM, density measurements, FTIR, UV-Vis, EPR and PL spectroscopies. X-ray diffraction patterns confirm the presence of the tetragonal and cubic ZrO2 crystalline phases in all samples. The IR data show the overlaps of absorption bands assigned to Zrsbnd Osbnd Zr and Sisbnd Osbnd linkages in samples. UV-Vis and PL data indicate higher concentrations of intrinsic defects by doping with Y2O3 concentrations. The EPR spectra are characterized by two resonance lines situated at about g ∼ 4.3 and g ∼ 2 for lower Y2O3 contents.

Biosynthesis of silver nanoparticles using Ocimum sanctum (Tulsi) leaf extract and screening its antimicrobial activity

NASA Astrophysics Data System (ADS)

Singhal, Garima; Bhavesh, Riju; Kasariya, Kunal; Sharma, Ashish Ranjan; Singh, Rajendra Pal

2011-07-01

Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles. In this study, biosynthesis of stable silver nanoparticles was done using Tulsi ( Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV-vis spectrophotometer, Atomic Absorption Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV-vis absorption spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4-30 nm possessing antimicrobial activity suggesting their possible application in medical industry.

Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

NASA Astrophysics Data System (ADS)

Tripathi, R. M.; Gupta, Rohit Kumar; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.; Singh, Priti

2013-09-01

The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV-Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8-24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity.

Interaction of three new tetradentates Schiff bases containing N2O2 donor atoms with calf thymus DNA.

PubMed

Ajloo, Davood; Shabanpanah, Sajede; Shafaatian, Bita; Ghadamgahi, Maryam; Alipour, Yasin; Lashgarbolouki, Taghi; Saboury, Ali Akbar

2015-01-01

Interaction of 1,3-bis(2-hydroxy-benzylidene)-urea (H2L1), 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea (H2L2) and 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea nickel(II) (NiL2) with calf-thymus DNA were investigated by UV-vis absorption, fluorescence emission and circular dichroism (CD) spectroscopy as well as cyclic voltammetry, viscosity measurements, molecular docking and molecular dynamics simulation. Binding constants were determined using UV-vis absorption and fluorescence spectra. The results indicated that studied Schiff-bases bind to DNA in the intercalative mode in which the metal derivative is more effective than non metals. Their interaction trend is further determined by molecular dynamics (MD) simulation. MD results showed that Ni derivative reduces oligonucleotide intermolecular hydrogen bond and increases solvent accessible surface area more than other compounds. Copyright © 2015 Elsevier B.V. All rights reserved.

Discrimination of whisky brands and counterfeit identification by UV-Vis spectroscopy and multivariate data analysis.

PubMed

Martins, Angélica Rocha; Talhavini, Márcio; Vieira, Maurício Leite; Zacca, Jorge Jardim; Braga, Jez Willian Batista

2017-08-15

The discrimination of whisky brands and counterfeit identification were performed by UV-Vis spectroscopy combined with partial least squares for discriminant analysis (PLS-DA). In the proposed method all spectra were obtained with no sample preparation. The discrimination models were built with the employment of seven whisky brands: Red Label, Black Label, White Horse, Chivas Regal (12years), Ballantine's Finest, Old Parr and Natu Nobilis. The method was validated with an independent test set of authentic samples belonging to the seven selected brands and another eleven brands not included in the training samples. Furthermore, seventy-three counterfeit samples were also used to validate the method. Results showed correct classification rates for genuine and false samples over 98.6% and 93.1%, respectively, indicating that the method can be helpful for the forensic analysis of whisky samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation on intermolecular interaction between berberine and β-cyclodextrin by 2D UV-Vis asynchronous spectra.

PubMed

He, Anqi; Kang, Xiaoyan; Xu, Yizhuang; Noda, Isao; Ozaki, Yukihiro; Wu, Jinguang

2017-10-05

The interaction between berberine chloride and β-cyclodextrin (β-CyD) is investigated via 2D asynchronous UV-Vis spectrum. The occurrence of cross peaks around (420nm, 420nm) in 2D asynchronous spectrum reveals that specific intermolecular interaction indeed exists between berberine chloride and β-CyD. In spite of the difficulty caused by overlapping of cross peaks, we manage to confirm that the 420nm band of berberine undergoes a red-shift, and its bandwidth decreases under the interaction with β-CyD. The red-shift of the 420nm band that can be assigned to n-π* transition indicates the environment of berberine becomes more hydrophobic. The above spectral behavior is helpful in understanding why the solubility of berberine is enhanced by β-CyD. Copyright © 2017. Published by Elsevier B.V.

Catalytic hydrogenation rate of polycyclic aromatic hydrocarbons in supercritical carbon dioxide containing polymer-stabilized palladium nanoparticles.

PubMed

Liao, Weisheng; Liu, Hsin-Wang; Chen, Hsing-Jung; Chang, Wen-Yen; Chiu, Kong-Hwa; Wai, Chien M

2011-01-01

Catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs) with up to four fused benzene rings over high-density-polyethylene-stabilized palladium nanoparticles in supercritical carbon dioxide via in situ UV/Vis spectroscopy is presented. PAHs can be efficiently converted to saturated polycyclic hydrocarbons using this green technique under mild conditions at 20 MPa of CO₂ containing 1 MPa of H₂ at 40-50°C. Kinetic studies based on in situ UV/Vis spectra of the CO₂ phase reveal that the initial hydrogenation of a given PAH and the subsequent hydrogenations of its intermediates are pseudo-first-order. The hydrogenation rate of the latter is always much smaller than that of the former probably due to increasing steric hindrance introduced by the hydrogenated benzene rings of PAHs which impedes the adsorption process and hydrogen access to PAHs on catalyst surfaces. Copyright © 2010 Elsevier Ltd. All rights reserved.

Novel Iron-oxide Catalyzed CNT Formation on Semiconductor Silicon Nanowire

PubMed Central

Adam, Tijjani; U, Hashim

2014-01-01

An aqueous ferric nitrate nonahydrate (Fe(NO3)3.9H2O) and magnesium oxide (MgO) were mixed and deposited on silicon nanowires (SiNWs), the carbon nanotubes (CNTs) formed by the concentration of Fe3O4/MgO catalysts with the mole ratio set at 0.15:9.85 and 600°C had diameter between 15.23 to 90nm with high-density distribution of CNT while those with the mole ratio set at 0.45:9.55 and 730°C had diameter of 100 to 230nm. The UV/Vis/NIR and FT-IR spectroscopes clearly confirmed the presence of the silicon-CNTs hybrid structure. UV/Vis/NIR, FT-IR spectra and FESEM images confirmed the silicon-CNT structure exists with diameters ranging between 15-230nm. Thus, the study demonstrated cost effective method of silicon-CNT composite nanowire formation via Iron-oxide Catalyze synthesis. PMID:25237290

Non-rigid molecule of copper(II) diiminate Cu[CF3C(NH)C(F)C(NH)CF3]2, its conformational polymorphism in crystal and structure in solutions (Raman, UV-vis and quantum chemistry study)

NASA Astrophysics Data System (ADS)

Bukalov, Sergey S.; Aysin, Rinat R.; Leites, Larissa A.; Kurykin, Mikhail A.; Khrustalev, Victor N.

2015-10-01

Calculation of potential energy surface (PES) of isolated molecule of copper(II) diiminate Cu[CF3С(NH)C(F)C(NH)CF3]2 (1) resulted a double-well curve with the minima corresponding to equivalent screwed conformations. The low barrier leads to molecular non-rigidity which seems to be the reason of conformational polymorphism in crystals, reported in [1]. For one of newly found polymorphs, the X-ray structure was determined. The differences in the Raman and UV-vis spectra between differently colored species and their solutions were revealed, they are determined by different geometries of Cu(II) coordination polyhedron and different systems of intermolecular interactions in crystals. Transformations of the polymorphs under thermal, mechanical and photo exposures were studied.

Conformational analysis, UV-VIS, MESP, NLO and NMR studies of 6-methoxy-1,2,3,4-tetrahydronaphthalene.

PubMed

Arivazhagan, M; Kavitha, R; Subhasini, V P

2014-07-15

The detailed HF and B3LYP/6-311++G(d,p) comparative studies on the complete FT-IR and FT-Raman spectra of 6-methoxy-1,2,3,4-tetrahydronaphthalene [MTHN] have been studied. In view of the special properties and uses, the present investigation has been undertaken to provide a satisfactorily vibrational analysis of 6-methoxy-1,2,3,4-tetrahydronaphthalene. Therefore, a thorough Raman, IR, molecular electrostatic potential (MESP), non-linear optical (NLO) properties, UV-VIS, HOMO-LUMO and NMR spectroscopic investigation are reported complemented by B3LYP theoretical predictions with basis set 6-311++G(d,p) to provide novel insight on vibrational assignments and conformational stability of MTHN. Potential energy surface scans (PES) of the CH3 group are undertaken to shed light on the rather complicated conformational interchanges in the compound under investigation. Copyright © 2014 Elsevier B.V. All rights reserved.

Substituent and solvent effects on the UV/vis absorption spectra of 5-(3- and 4-substituted arylazo)-4,6-dimethyl-3-cyano-2-pyridones

NASA Astrophysics Data System (ADS)

Mijin, Dušan Ž.; Ušćumlić, Gordana S.; Perišić-Janjić, Nada U.; Valentić, Nataša V.

2006-01-01

Absorption spectra of seventeen 5-(3- and 4-substituted arylazo)-4,6-dimethyl-3-cyano-2-pyridones have been recorded in 12 protic and aprotic solvents in the range 200-600 nm. The effects of substituents on the absorption spectra of these new azo dyes are interpreted by correlation of absorption frequencies with Hammett equation. The solute-solvent interactions were clarified on the basis of linear solvation energy relationships concept proposed by Kamlet and Taft. The 2-pyridone/2-hydroxypiridine tautomeric equilibration is found to depend upon substituents as well as on solvents.

Synthesis and photocatalytic activity of ytterbium-doped titania/diatomite composite photocatalysts

NASA Astrophysics Data System (ADS)

Tang, Wenjian; Qiu, Kehui; Zhang, Peicong; Yuan, Xiqiang

2016-01-01

Ytterbium-doped titanium dioxide (Yb-TiO2)/diatomite composite materials with different Yb concentrations were prepared by sol-gel method. The phase structure, morphology, and chemical composition of the as-prepared composites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) diffuse reflection spectroscopy. The XRD and Raman spectroscopy analysis indicated that the TiO2 existed in the form of pure anatase in the composites. The SEM images exhibited the well deposition and dispersion of TiO2 nanoparticles with little agglomeration on the surfaces of diatoms. The UV-vis diffuse reflection spectra showed that the band gap of TiO2 could be narrowed by the introduction of Yb species, which was further affected by doping concentration of Yb. The photocatalytic activity of synthesized samples was investigated by the degradation of methylene blue (MB) under UV light irradiation. It was observed that the photocatalytic degradation followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Compared to TiO2 and TiO2/diatomite, the Yb-TiO2/diatomite composites exhibited higher photocatalytic activity toward degradation of MB using UV light irradiation.

VizieR Online Data Catalog: Solar spectral irradiance (Marchenko+, 2014)

NASA Astrophysics Data System (ADS)

Marchenko, S. V.; Deland, M. T.

2017-03-01

Combining the contemporaneous Ozone Monitoring Instrument (OMI) and GOME-2 observations with the records from previous solar cycles, we construct the normalized (to the Mg II doublet at 280 nm) solar variability spectrum in the 170-795 nm spectral range, which could be used in combination with a reference spectrum (e.g., Thuillier et al. 2004, Solar Variability and its Effects on Climate (Geophysical Monograph 141), ed. J. M. Pup et al. (Washington, DC: AGU Geophysical Monograph Series), 171) to reproduce a dynamical solar spectrum at any epoch.The remote-sensing OMI (part of the Aura instrumental suite; Levelt et al., 2006ITGRS..44.1093L) has collected information about trace gases in the Earth's atmosphere since 2004 July. OMI comprises three different spectral channels, UV1 (264-311 nm spectral domain, resolution δλ = 0.63 nm), UV2 (307-383 nm, δλ = 0.42 nm), and VIS (349-504 nm, δλ = 0.63 nm), each acquiring data through partially shared optical pathways (Dobber et al., 2006ITGRS..44.1209D). The UV1 and UV2 light falls on the same CCD detector while VIS spectra are recorded by a different CCD. (1 data file).

Studies of surface morphology and optical properties of ZnO nanostructures grown on different molarities of TiO{sub 2} seed layer

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

Asib, N. A. M., E-mail: amierahasib@yahoo.com; Afaah, A. N.; Aadila, A.

Titanium dioxide (TiO{sub 2}) seed layer was prepared by using sol-gel spin-coating technique, followed by growth of 0.01 M of Zinc oxide (ZnO) nanostructures by solution-immersion. The molarities of TiO{sub 2} seed layer were varied from 1.1 M to 0.100 M on glass substrates. The nanostructures thin films were characterized by Field Emission Scanning Electrons Microscope (FESEM), Photoluminescence (PL) spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. FESEM images demonstrate that needle-like ZnO nanostructures are formed on all TiO{sub 2} seed layer. The smallest diameter of needle-like ZnO nanostructures (90.3 nm) were deposited on TiO{sub 2} seed layer of 0.100 M. PL spectramore » of the TiO{sub 2}: ZnO nanostructures thin films show the blue shifted emissions in the UV regions compared to the ZnO thin film. Meanwhile, UV-vis spectra of films display high absorption in the UV region and high trasparency in the visible region. The highest absorbance at UV region was recorded for sample which has 0.100 M of TiO{sub 2} seed layer.« less

Synthesis and photocatalytic activity of N-doped TiO2 produced in a solid phase reaction

NASA Astrophysics Data System (ADS)

Xin, Gang; Pan, Hongfei; Chen, Dan; Zhang, Zhihua; Wen, Bin

2013-02-01

N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light.

Hydrogen incorporation and the oxidation state of iron in ringwoodite - a spectroscopic study

NASA Astrophysics Data System (ADS)

Mrosko, M.; Lenz, S.; McCammon, C. A.; Taran, M.; Wirth, R.; Koch-Mueller, M.

2011-12-01

Ringwoodite is the most abundant mineral in the lower transition zone in the Earth's mantle. It is the high-pressure γ-polymorph of (Mg,Fe)2SiO4 and occurs in spinel structure. Although it is nominally anhydrous it can incorporate up to 3 wt% water as OH- via point defects. In general the OH-incorporation depends on pressure, temperature, composition, and oxygen fugacity. To learn more about the H incorporation in ringwoodite we conducted several Multi-Anvil-experiments to synthesize iron-bearing (0.10≤xFe≤0.25) hydrous ringwoodite under oxidizing (Re/ReO2 buffer) and reducing (Fe/FeO buffer) conditions. The experiments were performed at 1200°C and pressures between 16.5 and 18.3 GPa. For 57Fe-Mössbauer spectroscopy ringwoodite enriched in 57Fe was synthesized. We investigated the samples by FTIR spectroscopy at room temperature as well as in-situ by increasing the temperature. Doing so we observed a remarkable color change of ringwoodite from blue to green at 500°C and brown at 600°C. All samples, treated and untreated, were then investigated by UV-VIS-, Mössbauer- and Energy-Electron-Loss-Spectroscopy. These methods enable us to investigate the local environment of incorporated elements even in ranges of trace amounts. The IR-spectra of the untreated samples show a broad OH band around 3150 cm-1 and two shoulders on the high-energy side: one intense at 3675 and a weak one at around 3460 cm-1. The water content of the samples was determined using FTIR spectroscopy to a max. value of app. 2 wt% H2O. UV-VIS spectra display a broad band around 12700 and a shoulder at 9900 cm-1 representing the spin allowed dd-transitions of VIFe2+. The weaker band around 18000 cm-1 is a distinct feature of Fe2+ - Fe3+ intervalence charge transfer indicating the presence of Fe3+ in the samples. FTIR and UV-VIS spectra of the samples synthesized at different fO2 were very similar. The analyses of EEL-spectra, however, yield Fe3+ fractions ranging from 10 (4) at reducing to 19 (7) % at oxidizing conditions. According to the Mössbauer spectrum the 57Fe-enriched sample contains 5 (2) % Fe3+ that could solely be assigned to the octahedral site. The heat treated samples displayed hydrogen loss, a rearrangement of a part of the hydrogens (FITR) as well as oxidation of Fe2+ to Fe3+ proven by the appearance of the spin forbidden dd-transition band for Fe3+ and the ligand-metal (O2- - Fe3+) transition band in the optical spectra. These modifications of the UV-VIS features explain the color change of the crystals. Likewise EEL-spectra reveal an oxidation of Fe2+ as the amount of Fe3+ increases in FIB-foils of annealed ringwoodite crystals up to nearly twice the number of the untempered samples. All these information lead to a reinterpretation of the broad OH band since the rearrangement of H visible as OH absorption feature obviously is Fe3+-related at least for the higher energy bands as the fraction of ferric iron rises while the intensity of these OH-bands also increases.

Fuzzy clustering evaluation of the discrimination power of UV-Vis and (±) ESI-MS detection system in individual or coupled RPLC for characterization of Ginkgo Biloba standardized extracts.

PubMed

Medvedovici, Andrei; Albu, Florin; Naşcu-Briciu, Rodica Domnica; Sârbu, Costel

2014-02-01

Discrimination power evaluation of UV-Vis and (±) electrospray ionization/mass spectrometric techniques, (ESI-MS) individually considered or coupled as detectors to reversed phase liquid chromatography (RPLC) in the characterization of Ginkgo Biloba standardized extracts, is used in herbal medicines and/or dietary supplements with the help of Fuzzy hierarchical clustering (FHC). Seventeen batches of Ginkgo Biloba commercially available standardized extracts from seven manufacturers were measured during experiments. All extracts were within the criteria of the official monograph dedicated to dried refined and quantified Ginkgo extracts, in the European Pharmacopoeia. UV-Vis and (±) ESI-MS spectra of the bulk standardized extracts in methanol were acquired. Additionally, an RPLC separation based on a simple gradient elution profile was applied to the standardized extracts. Detection was made through monitoring UV absorption at 220 nm wavelength or the total ion current (TIC) produced through (±) ESI-MS analysis. FHC was applied to raw, centered and scaled data sets, for evaluating the discrimination power of the method with respect to the origins of the extracts and to the batch to batch variability. The discrimination power increases with the increase of the intrinsic selectivity of the spectral technique being used: UV-Vis

Laser-induced optical breakdown spectroscopy of polymer materials based on evaluation of molecular emission bands

NASA Astrophysics Data System (ADS)

Trautner, Stefan; Jasik, Juraj; Parigger, Christian G.; Pedarnig, Johannes D.; Spendelhofer, Wolfgang; Lackner, Johannes; Veis, Pavel; Heitz, Johannes

2017-03-01

Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157 nm F2 laser and 532 nm Nd:YAG laser ablation in nitrogen and argon gas background or in air. The optical detection reaches from ultraviolet (UV) over the visible (VIS) to the near infrared (NIR) spectral range. In the UV/VIS range, intense molecular emissions, C2 Swan and CN violet bands, are measured with an Echelle spectrometer equipped with an intensified CCD camera. The measured molecular emission spectra can be fitted by vibrational-rotational transitions by open access programs and data sets with good agreement between measured and fitted spectra. The fits allow determining vibrational-rotational temperatures. A comparison to electronic temperatures Te derived earlier from atomic carbon vacuum-UV (VUV) emission lines show differences, which can be related to different locations of the atomic and molecular species in the expanding plasma plume. In the NIR spectral region, we also observe the CN red bands with a conventional CDD Czerny Turner spectrometer. The emission of the three strong atomic sulfur lines between 920 and 925 nm is overlapped by these bands. Fitting of the CN red bands allows a separation of both spectral contributions. This makes a quantitative evaluation of sulfur contents in the start material in the order of 1 wt% feasible.

Spectroscopic (FT-IR, FT-Raman, FT-NMR and UV-Vis) investigation on benzil dioxime using quantum computational methods

NASA Astrophysics Data System (ADS)

Bakkiyaraj, D.; Periandy, S.; Xavier, S.

2016-03-01

The spectral analysis of benzil dioxime is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum computations by density functional theories. The FT-IR (4000 - 400 cm-1) and FT-Raman (4000-100 cm-1) spectra are recorded in solid phase, the 1H and 13C NMR spectra in DMSO phase and the UV spectrum (200-400 nm) in ethanol phase. The different conformers of the compound and their minimum energies are studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure the molecule is analyzed interms of parameters like bond length, bond angle and dihedral angles predicted byB3LYP and CAM-B3LYP methods with cc-pVDZ basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non -linear optical property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts and the same is discussed in comparison with atomic charges, predicted by Mullikan and APT charge analysis. NBO analysis is carried out to picture the probable electronic transitions in the molecule.

Correlation between the structure modification and conductivity of 3 MeV Si ion-irradiated polyimide

NASA Astrophysics Data System (ADS)

Sun, Youmei; Zhu, Zhiyong; Li, Changlin

2002-05-01

The surface modification of the polyimide (PI/Kapton) films was carried out by 3 MeV Si + implantation to fluences ranging from 1×10 12 to 1.25×10 15 ions/cm 2. Fourier transform infrared (FTIR), Raman and ultraviolet/visible (UV/Vis) spectroscopes were employed to investigate the chemical degradation of function groups in the irradiated layer. FTIR results show that the absorbance of typical function group decreases exponentially as a function of fluence. The damage cross-section of typical bonds of PI was evaluated from the FTIR spectra. Raman analysis shows the absorbed dose for destruction of all function groups is above 218 MGy. The red shifting of the absorption edge from UV to visible reveals the band gap closing which results from increase of the cluster size. The production efficiency of the chromophores was discussed according to UV/Vis analysis. Irradiation dramatically enhances the electrical conductivity and the sheet resistivity in our experiment descends nearly 10 orders of magnitude compared with its intrinsic value.

Stability, cytotoxicity and cell uptake of water-soluble dendron–conjugated gold nanoparticles with 3, 12 and 17 nm cores† †Electronic supplementary information (ESI) available: Additional characterization methods and procedures in addition to the data for the characterization of glutathione-capped gold nanoparticles and dendron-conjugated gold nanoparticles including FT-IR spectra (Fig. S1 and S2), UV-vis spectra (Fig. S3 and S6), TEM images (Fig. S4), MALDI-TOF/TOF spectra (Fig. S5), fluorescence spectra (Fig. S6 and S7), In vitro cytotoxic assay results (Fig. S9) and ICP-MS results (Tables 1 and 2). DOI: 10.1039/c5tb00608b Click here for additional data file.

PubMed Central

Deol, Suprit; Weerasuriya, Nisala

2015-01-01

This article describes the synthesis of water-soluble dendron–conjugated gold nanoparticles (Den–AuNPs) with various average core sizes and the evaluation of stability, cytotoxicity, cell permeability and uptake of these materials. The characterization of Den–AuNPs using various techniques including transmission electron microscopy (TEM), matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS), 1H NMR, FT-IR, and UV-vis spectroscopy confirms the dendron conjugation to the glutathione-capped gold nanoparticles (AuNPs). The stability of AuNPs and Den–AuNPs in solutions of different pH and salt concentration is determined by monitoring the changes in surface plasmon bands of gold using UV-vis spectroscopy. The stability of Den–AuNPs at different pH remained about the same compared to that of AuNPs. In comparison, the Den–AuNPs are found to be more stable than the precursor AuNPs maintaining their solubility in the aqueous solution with the salt concentration of up to 100 mM. The improved stability of Den–AuNPs suggests that the post-functionalization of thiol-capped gold nanoparticle surfaces with dendrons can further improve the physiological stability and biocompatibility of gold nanoparticle-based materials. Cytotoxicity studies of AuNPs and Den–AuNPs with and without fluorophores are also performed by examining cell viability for 3T3 fibroblasts using a MTT cell proliferation assay. The conjugation of dendrons to the AuNPs with a fluorophore is able to decrease the cytotoxicity brought about by the fluorophore. The successful uptake of Den–AuNPs in mouse fibroblast 3T3 cells shows the physiological viability of the hybrid materials. PMID:26366289

Vacancy-Rich Monolayer BiO2-x as a Highly Efficient UV, Visible, and Near-Infrared Responsive Photocatalyst.

PubMed

Li, Jun; Wu, Xiaoyong; Pan, Wenfeng; Zhang, Gaoke; Chen, Hong

2018-01-08

Vacancy-rich layered materials with good electron-transfer property are of great interest. Herein, a full-spectrum responsive vacancy-rich monolayer BiO 2-x has been synthesized. The increased density of states at the conduction band (CB) minimum in the monolayer BiO 2-x is responsible for the enhanced photon response and photo-absorption, which were confirmed by UV/Vis-NIR diffuse reflectance spectra (DRS) and photocurrent measurements. Compared to bulk BiO 2-x , monolayer BiO 2-x has exhibited enhanced photocatalytic performance for rhodamine B and phenol removal under UV, visible, and near-infrared light (NIR) irradiation, which can be attributed to the vacancy V Bi-O ''' as confirmed by the positron annihilation spectra. The presence of V Bi-O ''' defects in monolayer BiO 2-x promoted the separation of electrons and holes. This finding provides an atomic level understanding for developing highly efficient UV, visible, and NIR light responsive photocatalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple route to (NH4)xWO3 nanorods for near infrared absorption

NASA Astrophysics Data System (ADS)

Guo, Chongshen; Yin, Shu; Dong, Qiang; Sato, Tsugio

2012-05-01

Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows.Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30612c

Interrelating meteorite and asteroid spectra at UV-Vis-NIR wavelengths using novel multiple-scattering methods

NASA Astrophysics Data System (ADS)

Martikainen, Julia; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

2017-10-01

Asteroids have remained mostly the same for the past 4.5 billion years, and provide us information on the origin, evolution and current state of the Solar System. Asteroids and meteorites can be linked by matching their respective reflectance spectra. This is difficult, because spectral features depend strongly on the surface properties, and meteorite surfaces are free of regolith dust present in asteroids. Furthermore, asteroid surfaces experience space weathering which affects their spectral features.We present a novel simulation framework for assessing the spectral properties of meteorites and asteroids and matching their reflectance spectra. The simulations are carried out by utilizing a light-scattering code that takes inhomogeneous waves into account and simulates light scattering by Gaussian-random-sphere particles large compared to the wavelength of the incident light. The code uses incoherent input and computes phase matrices by utilizing incoherent scattering matrices. Reflectance spectra are modeled by combining olivine, pyroxene, and iron, the most common materials that dominate the spectral features of asteroids and meteorites. Space weathering is taken into account by adding nanoiron into the modeled asteroid spectrum. The complex refractive indices needed for the simulations are obtained from existing databases, or derived using an optimization that utilizes our ray-optics code and the measured spectrum of the material.We demonstrate our approach by applying it to the reflectance spectrum of (4) Vesta and the reflectance spectrum of the Johnstown meteorite measured with the University of Helsinki integrating-sphere UV-Vis-NIR spectrometer.Acknowledgments. The research is funded by the ERC Advanced Grant No. 320773 (SAEMPL).

Laser synthesis and spectroscopy of acetonitrile/silver nanoparticles

NASA Astrophysics Data System (ADS)

Akin, S. T.; Liu, X.; Duncan, M. A.

2015-11-01

Silver nanoparticles with acetonitrile ligands are produced in a laser ablation flow reactor. Excimer laser ablation produces gas phase metal clusters which are thermalized with helium or argon collisions in the flowtube, and reactions with acetonitrile vapor coordinate this ligand to the particle surface. The gaseous mixture is captured in a cryogenic trap; warming produces a solution of excess ligand and coated particles. TEM images reveal particle sizes of 10-30 nm diameter. UV-vis absorption and fluorescence spectra are compared to those of standard silver nanoparticles with surfactant coatings. Deep-UV ligand absorption is strongly enhanced by nanoparticle adsorption.

Optical properties of La{sub 2}CuO{sub 4} and La{sub 2-x}Ca{sub x}CuO{sub 4} crystallites in UV-vis-NIR region synthesized by sol-gel process

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

Li Yifeng; Huang Jianfeng, E-mail: hjfnpu@163.com; Cao Liyun

2012-02-15

La{sub 2}CuO{sub 4} and La{sub 2-x}Ca{sub x}CuO{sub 4} crystallites were prepared via a simple sol-gel process. The as-prepared La{sub 2}CuO{sub 4} and La{sub 2} {sub -x}Ca{sub x}CuO{sub 4} crystallites were characterized by X-ray diffraction, transmission electron microscope and UV-vis-NIR spectra. Results show that the grain size of La{sub 2}CuO{sub 4} crystallites increases with the increase of heat treatment temperature from 600 Degree-Sign C to 800 Degree-Sign C. Optical properties show that La{sub 2}CuO{sub 4} crystallites have broad absorption both in the UV-vis region and in the NIR region. The band gap of the as-prepared crystallites decreases from 1.367 eV tomore » 1.284 eV with the increase of calcination temperature from 600 Degree-Sign C to 800 Degree-Sign C. In the series of La{sub 2-x}Ca{sub x}CuO{sub 4} compounds (x = 0.05, 0.08, 0.10, 0.12, 0.15 and 0.20), all of the samples exhibit an orthogonal crystal structure and the solubility limit of Ca{sup 2+} in La{sub 2}CuO{sub 4} is within the range of x = 0.12-0.15. In the whole UV-vis-NIR region, La{sub 2-x}Ca{sub x}CuO{sub 4} crystallites exhibit a broad absorption and the corresponding band gap first increases and then decreases with increasing of Ca{sup 2+} content. - Highlights: Black-Right-Pointing-Pointer The optical band gap can be tuned by adjusting the grain size and Ca{sup 2+} content. Black-Right-Pointing-Pointer La{sub 2}CuO{sub 4} crystallites exhibit a broad absorption band both in the UV-vis region and in the NIR region. Black-Right-Pointing-Pointer The band gap increases from 1.284 eV to 1.319 eV with the decrease of heat treatment temperature. Black-Right-Pointing-Pointer In the whole UV-vis-NIR region, the La{sub 2-x}Ca{sub x}CuO{sub 4} crystallites displayed a broad absorption. Black-Right-Pointing-Pointer The band gap of La{sub 2-x}Ca{sub x}CuO{sub 4} increases linearly with doping level when 0 {<=} x {<=} 0.12.« less

Modification of indole by electron-rich atoms and their application in novel electron donor materials

NASA Astrophysics Data System (ADS)

Zhang, Maolin; Qin, Guangjiong; Liu, Jialei; Zhen, Zhen; Fedorchuk, A. A.; Lakshminarayana, G.; Albassam, A. A.; El-Naggar, A. M.; Ozga, Katarzyna; Kityk, I. V.

2017-08-01

Novel nonlinear optical (NLO) chromophore based on 6-(pyrrolidin-1-yl)-1H-indole as the electron donor group was designed and synthesized. The molecular structure of this chromophore was characterized by 1H NMR spectra, 13C NMR spectra, and MS spectra. The delocalized energy level was estimated by UV-Vis. spectra. The thermal property was studied by thermogravimetric analysis (TGA). The poled films containing chromophores ZML-1 with a loading density of 10 wt% in amorphous polycarbonate (APC) afford an average electro-optic (EO) coefficient (r33) of 19 pm/V at 1310 nm. Compared to the reported aniline-based chromophore (r33 = 12 pm/V) analogues, chromophore ZML-1 exhibits enhanced electro-optical activity.

Spectral investigations and DFT studies of 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (caffeine) interaction and recognition by single amino acid derived self-assembled nanostructures

NASA Astrophysics Data System (ADS)

Govindhan, R.; Karthikeyan, B.

2018-03-01

Recognition of xanthine alkaloid caffeine with 3,5-bis(trifluoromethyl)benzylamine derived peptide nanotubes (BTTPNTs) through chemical interaction have been achieved through the host-guest like interaction. DFT simulation is carried out for caffeine interacted with BTTPNTs system and also experimentally characterized by ultraviolet-visible (UV-vis) absorbance, confocal Raman spectra (CRS) with microscopic imaging (CRM), FT-Raman, surface enhanced Raman scattering (SERS), UV-diffuse reflectance spectra (UV-DRS), high resolution transmission electron microscopy (HR-TEM) and cyclic voltammetry (CV) studies. The results are used to examine the morphologies, size of the nanostructure and study of its interaction with the caffeine molecule. The results show that BTTPNTs is having potential for sensing the caffeine molecules through the binding occurred from the NH2 of tyrosine moiety of the BTTPNTs. This intermolecular association through face-to-face stacking of BTTPNTs is explained by detailed DFT calculations.

Structures, molecular orbitals and UV-vis spectra investigations on methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate: a computational study.

PubMed

Wang, Tsang-Hsiu; Chu, Hsing-Yu; Wang, I-Teng

2014-10-15

The methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate (C11H11N3O2) has been studied by theoretically methods. The structure of this compound is optimized by density functional theory (DFT), the second-order Møller-Plesset perturbation theory (MP2) and G3 theory (G3(MP2)) levels. Our calculation results are in very good agreement with experimental values. Compared to a perfect pentagonal structure, the geometrical structures of C11H11N3O2 show a little distortion of 1,2,3-triazole ring due to the highly electronegativity of substitution groups. In addition, dipole moment and frontier molecular orbitals (FMOs) of the C11H11N3O2 are calculated as well. Because of solvent effect, the HOMO-LUMO energy gap in methanol is predicted to be smaller than in gas phase by 0.367eV. The simulated UV-vis spectra are investigated by time-dependent density functional theory (TD-DFT), and two obviously absorption features have been predicted. These two absorption features are located between 170nm and 210nm, which is in ultraviolet C range. Moreover, the UV absorption features in methanol are predicted to be more intense than in gas phase; besides, the red shift is predicted in methanol as well. Copyright © 2014 Elsevier B.V. All rights reserved.

Photodegradation of microcystin-LR catalyzed by metal phthalocyanines immobilized on TiO2-SiO2 under visible-light irradiation.

PubMed

Peng, Guotao; Fan, Zhengqiu; Wang, Xiangrong; Sui, Xin; Chen, Chen

2015-01-01

Microcystins (MCs) are a group of monocyclic heptapeptide toxins produced by species of cyanobacteria. Since MCs exhibit acute and chronic effects on humans and wildlife by damaging the liver, they are of increasing concern worldwide. In this study, we investigated the ability of the phthalocyanine compound (ZnPc-TiO2-SiO2) to degrade microcystin-LR (MC-LR) in the presence of visible light. X-ray diffraction (XRD) and UV-Visible diffuse reflectance spectra (UV-Vis DRS) were utilized to characterize the crystalline phase and the absorption behavior of this catalyst. According to the results, XRD spectra of ZnPc-TiO2-SiO2 powders taken in the 2θ configuration exhibited the peaks characteristic of the anatase phase. UV-Vis DRS showed that the absorption band wavelength shifted to the visible range when ZnPc was supported on the surface of TiO2-SiO2. Subsequently, several parameters including catalyst dose, MC-LR concentrations and pH were investigated. The MC-LR was quantified in each sample through high-performance liquid chromatography (HPLC). The maximum MC-LR degradation rate of 80.2% can be obtained within 300 minutes under the following conditions: catalyst dose of 7.50 g/L, initial MC-LR concentration of 17.35 mg/L, pH 6.76 and the first cycling run of the photocatalytic reaction. Moreover, the degradation process fitted well with the pseudo-first-order kinetic model.

New Measurement of Singly Ionized Selenium Spectra by High Resolution Fourier Transform and Grating Spectroscopy

NASA Astrophysics Data System (ADS)

Hala, Noman; Nave, G.; Kramida, A.; Ahmad, T.; Nahar, S.; Pradhan, A.

2015-05-01

We report new measurements of singly ionised selenium, an element of the iron group detected in nearly twice as many planetary nebulae as any other trans-iron element. We use the NIST 2 m UV/Vis/IR and FT700 UV/Vis Fourier transform spectrometers over the wavelength range of 2000 Å-2.5 μm, supplemented in the lower wavelength region 300-2400 Å with grating spectra taken on a 3-m normal incidence vacuum spectrograph. The analysis of Se II is being extended, covering the wide spectral region from UV to IR. From our investigation, we found serious inconsistency and incompleteness in the previously published results, where several levels were reported without any designation. The analysis is being revised and extended with the help of semiempirical quasi-relativistic Hartree-Fock calculations, starting with the 4s24p3- [4s24p2(4d +5d +5s +6s) +4s4p4] transition array. Out of fifty-two previously reported levels, we rejected thirteen and found several new level values. With the new measurements, we expect to observe transitions between 4s24p2(4d +5s) and 4s24p2(5p +4f), lying in the visible and IR region. A complete interpretation of the level system of both parities will be assisted by least squares fitted parametric calculations. In all, we have already classified about 450 observed lines involving 89 energy levels.

Spectroscopic characterization of the quantum wires in titanosilicates ETS-4 and ETS-10

NASA Astrophysics Data System (ADS)

Yilmaz, Bilge; Warzywoda, Juliusz; Sacco, Albert, Jr.

2006-08-01

Titanosilicates ETS-4 and ETS-10 contain octahedrally coordinated monatomic semiconductor \\cdots \\mathrm {Ti} -O-Ti-O-\\mathrm {Ti}\\cdots (titania) chains in their frameworks. Titania chains are isolated from one another by a siliceous matrix. Thus, these chains can be regarded as one-dimensional nanostructures, i.e., 'quantum wires'. Diffuse reflectance UV-vis (DR-UV-vis) spectroscopy analysis demonstrated a significant blue-shift of the optical absorption edge (>60 nm) for both ETS-4 and ETS-10 compared to bulk titania. This blue-shift is consistent with the hypothesis that the titania chains in ETS-4 and ETS-10 are acting as quantum wires. A broad range of ETS-4 and ETS-10 samples with diverse crystallo-chemical characteristics was prepared. The DR-UV-vis and Raman spectra of various ETS-4 and ETS-10 samples exhibited different characteristics, which were hypothesized to be related to the titania chain 'quality'. Detailed investigation of the spectroscopic bands associated with the titania chains in ETS-4 was performed for the first time. The 'quality' of these titania chains/quantum wires in ETS-4 and ETS-10 was correlated with the crystal growth mechanisms of these materials. Comparison of the growth mechanisms and the spectroscopic behaviour for ETS-4 and ETS-10 suggests that the control of 'quantum wire quality' via hydrothermal synthesis is possible in ETS-4 but would be difficult in ETS-10.

New insights on the spectrophotometric determination of melatonin pKa values and melatonin-βCD inclusion complex formation constant

NASA Astrophysics Data System (ADS)

Zafra-Roldán, A.; Corona-Avendaño, S.; Montes-Sánchez, R.; Palomar-Pardavé, M.; Romero-Romo, M.; Ramírez-Silva, M. T.

2018-02-01

Using UV-Vis spectrophotometry a stability study of melatonin at different pH values was done in aqueous media, finding that at acidic pH melatonin is unstable when interacting with the environment, however it becomes stable protecting it from light and oxygen. From the UV-Vis spectra and SQUAD software, melatonin pKa values, in a completely protected aqueous medium, were estimated as 5.777 ± 0.011 and 10.201 ± 0.024. Using the same techniques, the melatonin and β-cyclodextrin inclusion complex formation constants were assessed at pH 3, 7 and 11.5, giving the values of log β = (3.07 ± 0.06), (2.94 ± 0.01) and (3.07 ± 0.06) M- 1, respectively. From the global acidity formation constants and the complexes' formation constants, the molar fractions were determined for each species of MT and MT - βCD, to build the molar fraction-[βCD]-pH 3D diagram and the molar fraction-pH 2D diagrams, where it was possible to observe the predominance of the MT species with and without βCD. A voltammetric study at pH 3, allowed obtaining a value of log β = (3.15 ± 0.01) M- 1, which corroborates that obtained through UV-Vis spectrophotometry, supporting strongly the rationale behind using simple, straightforward techniques.

A combined Surface Enhanced Raman Spectroscopy (SERS)/UV-vis approach for the investigation of dye content in commercial felt tip pens inks.

PubMed

Saviello, Daniela; Trabace, Maddalena; Alyami, Abeer; Mirabile, Antonio; Giorgi, Rodorico; Baglioni, Piero; Iacopino, Daniela

2018-05-01

The development of protocols for the protection of the large patrimony of works of art created by felt tip pen media since the 1950's requires detailed knowledge of the main dyes constituting commercial ink mixtures. In this work Surface Enhanced Raman Scattering (SERS) and UV-vis spectroscopy were used for the first time for the systematic identification of dye composition in commercial felt tip pens. A large selection of pens comprising six colors of five different brands was analyzed. Intense SERS spectra were obtained for all colors, allowing identification of main dye constituents. Poinceau 4R and Eosin dyes were found to be the main constituents of red and pink colors; Rhodamine and Tartrazine were found in orange and yellow colors; Erioglaucine was found in green and blue colors. UV-vis analysis of the same inks was used to support SERS findings but also to unequivocally assign some uncertain dye identifications, especially for yellow and orange colors. The spectral data of all felt tip pens collected through this work were assembled in a database format. The data obtained through this systematic investigation constitute the basis for the assembly of larger reference databases that ultimately will support the development of conservation protocols for the long term preservation of modern art collections. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic (UV-Vis, FT-IR and NMR), single crystal XRD of 3,5-diethyl -2,6-di(thiophen-2-yl)piperidin-4-on-1-ium picrate: A comprehensive experimental and computational study

NASA Astrophysics Data System (ADS)

Arockia doss, M.; Rajarajan, G.; Thanikachalam, V.; Selvanayagam, S.; Sridhar, B.

2017-01-01

A piperidin-4-one containing picrate 3,5-diethyl -2,6-di(thiophen-2-yl)piperidin-4-on-1-ium picrate [3,5-DPPP] was synthesized. The molecular structure of 3,5-DPPP was confirmed by FT-IR, NMR, Uv-Vis, single crystal XRD analysis and DFT and HF methods with 6-31G(d,p) basis set. The XRD data confirm the transfer of protons from picric acid (O2) to piperidin-4-one ring (N1). The 3,5-DPPP compound is stabilized by the presence of intermolecular and intramolecular hydrogen bonds (N-H⋯O, C-H⋯S and C-H⋯O). Density functional theory and HF calculations have been used widely for calculating a wide variety of molecular properties such as optimized structure, FT-IR and Uv-Vis spectra, and provided reliable results which are in agreement with experimental data. The charge density data have been used to understand the properties of molecular systems. Furthermore, several quantum chemical insights have been obtained in the form of the total and partial density of states, the HOMO-LUMO energy gap and electrostatic potential map etc. In addition, the polarizability and first hyperpolarizability were calculated to show the potential applications of 3,5-DPPP in nonlinear optics.

Structural, absorption, and molecular properties of o,o'-dihydroxyazo resorcinol dyes bearing an acryloyloxy group

NASA Astrophysics Data System (ADS)

Özkınalı, Sevil; Çavuş, M. Serdar; Ceylan, Abdullah; Gür, Mahmut

2017-12-01

To the best of our knowledge, this is the first study reporting the synthesis and characterization of o,o‧-dihydroxyazo dyes bearing an acryloyl group. The o,o‧-dihydroxyazo dyes were synthesized through coupling of resorcinol with the diazonium salts of 2-amino-4-methylphenol, 2-aminophenol, 2-amino-4-chlorophenol, and 2-amino-4-nitrophenol. Their acryloyl derivatives were synthesized using metallic sodium and acryloyl chloride under an inert atmosphere. Characterization of the compounds was conducted using infrared (IR), ultraviolet-visible (UV-vis), proton nuclear magnetic resonance (1H NMR), and carbon nuclear magnetic resonance (13C NMR) spectroscopic methods. The tautomerism of the synthesized compounds' was also evaluated. The results were compared with theoretical results obtained by density functional theory (DFT). The DFT calculations were performed to obtain ground-state optimized geometries and calculate the relevant electronic and chemical reactivity parameters. Furthermore, possible tautomers deduced from the UV-vis spectra were investigated using theoretical calculations. Both the IR and NMR spectral data showed that azo tautomers predominate in the solid state and DMSO solvent. The effects of pH, solvent, and substituent on the predominant tautomers were further investigated through UV-vis spectroscopy. The results indicate that hydrazone tautomers were dominant at pH 12 in dimethylformamide (DMF), whereas azo tautomers were dominant at pH 2 in EtOH or CHCl3.

Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

PubMed

Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V K; Singh, Bachcha; Singh, Ranjan K

2016-02-05

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

The spectroscopic (FTIR, FT-Raman and UV-Vis spectra), DFT and normal coordinate computations of m-nitromethylbenzoate

NASA Astrophysics Data System (ADS)

Gnanasambandan, T.; Gunasekaran, S.; Seshadri, S.

2013-08-01

A combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of m-nitromethylbenzoate (MNMB) has been reported in the present work. The FT-IR solid phase (4000-400 cm-1) and FT-Raman spectra (3500-100 cm-1) of MNMB was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of MNMB in the ground-state have been calculated by using the density functional method B3LYP with 6-31G (d,p) and 6-31+G(d,p) basis sets. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethyl acetate solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Preparation and characterization of Bi-doped TiO{sub 2} and its solar photocatalytic activity for the degradation of isoproturon herbicide

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

Reddy, Police Anil Kumar; Srinivas, Basavaraju; Kala, Pruthu

Highlights: {yields} Visible active Bi-TiO{sub 2} photocatalyst preparation and thorough charaterization. {yields} Bi-TiO{sub 2} shows high activity for isoproturon degradation under solar light irradiation. {yields} The spectral response of TiO{sub 2} shifts from UV to visible light region by Bi doping. {yields} Bi{sup 3+{delta}+} species are playing a vital role in minimizing e{sup -}/h{sup +} recombination. -- Abstract: Bi-doped TiO{sub 2} catalyst was prepared by sol-gel method and was characterized by thermo gravimetric analysis (TGA), X-ray diffraction spectra (XRD), X-ray photo electronic spectroscopy (XPS), UV-Vis diffused reflectance spectra (DRS), photoluminescence spectra (PLS), transmission electron microscopy (TEM), energy dispersive analysis ofmore » X-rays (EDAX) and BET surface area. The photocatalytic activity of the catalysts were evaluated for the degradation of isoproturon herbicide under solar light irradiation. The UV-Visible DRS of Bi-doped TiO{sub 2} showed red shift in optical absorption. The presence of Bi{sup 3+{delta}+} species are playing a vital role in minimizing the electron hole recombination resulting higher activity compared to bare TiO{sub 2}.« less

Studies on the binding behavior of prodigiosin with bovine hemoglobin by multi-spectroscopic techniques

NASA Astrophysics Data System (ADS)

Tang, Jing; Yang, Chao; Zhou, Lin; Ma, Fei; Liu, Shuchao; Wei, Shaohua; Zhou, Jiahong; Zhou, Yanhuai

2012-10-01

In this article, the interaction mechanism of prodigiosin (PG) with bovine hemoglobin (BHb) is studied in detail using various spectroscopic technologies. UV-vis absorption and fluorescence spectra demonstrate the interaction process. The Stern-Volmer plot and the time-resolved fluorescence study suggest the quenching mechanism of fluorescence of BHb by PG is a static quenching procedure, and the hydrophobic interactions play a major role in binding of PG to BHb. Furthermore, synchronous fluorescence studies, Fourier transform infrared (FTIR) and circular dichroism (CD) spectra reveal that the conformation of BHb is changed after conjugation with PG.

Nano/microstructure and optical properties of ZnO particles precipitated from zinc acetylacetonate

NASA Astrophysics Data System (ADS)

Petrović, Željka; Ristić, Mira; Musić, Svetozar; Fabián, Martin

2015-06-01

The influence of experimental conditions on the nano/microstructure and optical properties of ZnO particles produced by rapid hydrolysis of zinc acetylacetonate, followed by aging of the precipitation system at 160 °C, was investigated. Samples were characterized by XRD, FE scanning electron microscopy (FE-SEM), FT-IR, UV/Vis/NIR and photoluminescence (PL) spectroscopies. XRD patterns of all samples were assigned to the hexagonal ZnO phase (wurtzite-type), as well as the corresponding FT-IR spectra. FE-SEM inspection showed a high dependence of the ZnO nano/microstructure on the chemical composition of the reaction mixture and autoclaving time after the rapid hydrolysis of zinc acetylacetonate. Microstructural differences were noticed between C2H5OH/H2O and H2O media, as well as under the influence of NH4OH addition. Measurements of nanocrystallite sizes showed no significant preferential orientation in the (1 0 0) and (0 0 2) directions relative to the (1 0 1) and (1 1 0) directions. Somewhat smaller crystallite sizes were noticed for ZnO samples synthesized by adding the NH4OH solution. Dissolution/recrystallization of ZnO particles played an important role in the formation of different ZnO nano/microstructures. The band gap values for prepared ZnO samples were calculated on the basis of recorded UV/Vis spectra. PL spectra were recorded for ZnO samples in powder form and their suspensions in pure ethanol. Noticed differences are discussed.

Improving UV Resistance of High Performance Fibers

NASA Astrophysics Data System (ADS)

Hassanin, Ahmed

High performance fibers are characterized by their superior properties compared to the traditional textile fibers. High strength fibers have high modules, high strength to weight ratio, high chemical resistance, and usually high temperature resistance. It is used in application where superior properties are needed such as bulletproof vests, ropes and cables, cut resistant products, load tendons for giant scientific balloons, fishing rods, tennis racket strings, parachute cords, adhesives and sealants, protective apparel and tire cords. Unfortunately, Ultraviolet (UV) radiation causes serious degradation to the most of high performance fibers. UV lights, either natural or artificial, cause organic compounds to decompose and degrade, because the energy of the photons of UV light is high enough to break chemical bonds causing chain scission. This work is aiming at achieving maximum protection of high performance fibers using sheathing approaches. The sheaths proposed are of lightweight to maintain the advantage of the high performance fiber that is the high strength to weight ratio. This study involves developing three different types of sheathing. The product of interest that need be protected from UV is braid from PBO. First approach is extruding a sheath from Low Density Polyethylene (LDPE) loaded with different rutile TiO2 % nanoparticles around the braid from the PBO. The results of this approach showed that LDPE sheath loaded with 10% TiO2 by weight achieved the highest protection compare to 0% and 5% TiO2. The protection here is judged by strength loss of PBO. This trend noticed in different weathering environments, where the sheathed samples were exposed to UV-VIS radiations in different weatheromter equipments as well as exposure to high altitude environment using NASA BRDL balloon. The second approach is focusing in developing a protective porous membrane from polyurethane loaded with rutile TiO2 nanoparticles. Membrane from polyurethane loaded with 4% rutile TiO2 nanoparticles showed excellent protection of braid from PBO. Only 7.5% strength loss was observed. To optimize the degree of protection of the sheath loaded with UV blocker particles, computational models were developed to optimize the protective layer thickness/weight and the amount of UV particles that provide the maximum protection with lightest weight of the protective layer and minimum amount of UV particles. The simulated results were found to be higher that the experimental results due to the tendency of nanoparticles to be agglomerated in real experiments. The third approach to achieve a maximum protection with the minimum weight added is constructing a sleeve from SpectraRTM (Ultra High Molecular Weight Polyethylene (UHMWPE) high performance fiber), which is known to resist UV, woven fabric. Covering the braid from PBO fiber with Spectra RTM woven fabric provide hybrid structure with two compatible components that can share the load and thus maintain the high strength to weight ratio. Although the SpectraRTM fabric had maximum cover factor, 20 % of visible light and about 15 % of UV were able to penetrate the fabric. This transmittance of UV-VIS light negatively affected the protection performance of the SpectraRTM woven fabric layer. It is thought that SpectraRTM fabric be coated with a thin layer (mentioned earlier) containing UV blocker for additional protection while maintain strength contribution to the hybrid structure. To maximize the strength to weight ratio of the hybrid structure (with core from PBO braid and sheath from SpectraRTM woven fabric) an established finite element model was utilized. The theoretical results using the finite element theory indicated that by controlling the bending rigidity of the filling yarn of the SpectraRTM fabric, the extension at peak load of woven fabric in warp direction (loading direction) could be controlled to match the braid extension at peak load. The match in the extension at peak load of the two components of the hybrid structure allowed the maximum strength to weight ratio. Thus, the SpectraRTM woven layer could achieve both the protection from UV and the load share in the hybrid structure.

Structure of new carotenoids with the 6-oxo-kappa end group from the fruits of paprika, Capsicum annuum.

PubMed

Maoka, Takashi; Akimoto, Naoshige; Fujiwara, Yasuhiro; Hashimoto, Keiji

2004-01-01

New carotenoids 1 and 2 were isolated as minor components from the ripe fruits of paprika (Capsicum annuum). The structures of 1 and 2 were determined to be (3R,5'R)-3-hydroxy-beta,kappa-caroten-6'-one and (5'R)-3,4-didehydro-beta,kappa-caroten-6'-one, respectively, from UV-vis, NMR, CD, HRFABMS, and FABMS/MS spectra.

Hydrogen content estimation of hydrogenated amorphous carbon by visible Raman spectroscopy

NASA Astrophysics Data System (ADS)

Adamopoulos, G.; Robertson, J.; Morrison, N. A.; Godet, C.

2004-12-01

In the present study, we report the hydrogen content estimation of the hydrogenated amorphous carbon (a-C:H) films using visible Raman spectroscopy in a fast and nondestructive way. Hydrogenated diamondlike carbon films were deposited by the plasma enhanced chemical vapor deposition, plasma beam source, and integrated distributed electron cyclotron resonance techniques. Methane and acetylene were used as source gases resulting in different hydrogen content and sp2/sp3 fraction. Ultraviolet-visible (UV-Vis) spectroscopic ellipsometry (1.5-5eV ) as well as UV-Vis spectroscopy were provided with the optical band gap (Tauc gap). The sp2/sp3 fraction and the hydrogen content were independently estimated by electron energy loss spectroscopy and elastic recoil detection analysis-Rutherford back scattering, respectively. The Raman spectra that were acquired in the visible region using the 488nm line shows the superposition of Raman features on a photoluminescence (PL) background. The direct relationship of the sp2 content and the optical band gap has been confirmed. The difference in the PL background for samples of the same optical band gap (sp2 content) and different hydrogen content was demonstrated and an empirical relationship between the visible Raman spectra PL background slope and the corresponding hydrogen content was extracted.

Spectroscopic studies on diamond like carbon films synthesized by pulsed laser ablation

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

Panda, Madhusmita; Krishnan, R., E-mail: krish@igcar.gov.in; Ravindran, T. R.

2016-05-23

Hydrogen free Diamond like Carbon (DLC) thin films enriched with C-C sp{sup 3} bonding were grown on Si (111) substrates at laser pulse energies varying from 100 to 400 mJ (DLC-100, DLC-200, DLC-300, DLC-400), by Pulsed Laser Ablation (PLA) utilizing an Nd:YAG laser operating at fundamental wavelength. Structural, optical and morphological evolutions as a function of laser pulse energy were studied by micro Raman, UV-Vis spectroscopic studies and Atomic Force Microscopy (AFM), respectively. Raman spectra analysis provided critical clues for the variation in sp{sup 3} content and optical energy gap. The sp{sup 3} content was estimated using the FWHM ofmore » the G peak and found to be in the range of 62-69%. The trend of evolution of sp{sup 3} content matches well with the evolution of I{sub D}/I{sub G} ratio with pulse energy. UV-Vis absorption study of DLC films revealed the variation of optical energy gap with laser pulse energy (1.88 – 2.23 eV), which matches well with the evolution of G-Peak position of the Raman spectra. AFM study revealed that roughness, size and density of particulate in DLC films increase with laser pulse energy.« less

Synthesis of Hierarchical Self-Assembled CuO and Their Structure-Enhanced Photocatalytic Performance

NASA Astrophysics Data System (ADS)

Wang, Dagui; Yan, Bing; Song, Caixiong; Ye, Ting; Wang, Yongqian

2018-01-01

Hierarchical self-assembled CuO hollow microspheres with superior photocatalytic performance are synthesized via a simple hydrothermal process in the presence of cationic surfactants (cetyltrimethylammonium bromide, CTAB). The structure, morphology, and optical absorption performance of CuO samples prepared with different surfactants including CTAB, nonionic surfactant (polyvinylpyrrolidone, PVP) and anionic surfactant (sodium dodecyl sulfate, SDS) are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-vis) absorption spectra. Moreover, the photocatalytic performances of the CuO samples are evaluated by the photo-degradation of a simulative contaminant methylene blue. The XRD patterns and FESEM images demonstrate that the category of surfactants have effects on the phase structure and morphology of CuO. Compared with bulk CuO (1.20 eV at room temperature), the band gap of CuO microspheres prepared with different surfactants including CTAB, PVP and SDS are measured at 2.16 eV, 2.29 eV, 2.44 eV, respectively, which exhibits a blue shift in the UV-vis spectra. The synthesized hierarchical self-assembled CuO hollow microspheres reveal commendable photocatalytic activity, in which the photo-degradation rate could rise to 94.1%. Additionally, a reasonable growth mechanism of CuO microspheres synthesized with different surfactants is discussed in detail.

Experimental and theoretical study of p-nitroacetanilide.

PubMed

Gnanasambandan, T; Gunasekaran, S; Seshadri, S

2014-01-03

The spectroscopic properties of the p-nitroacetanilide (PNA) were examined by FT-IR, FT-Raman and UV-Vis techniques. FT-IR and FT-Raman spectra in solid state were observed in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The UV-Vis absorption spectrum of the compound that dissolved in ethanol was recorded in the range of 200-400 nm. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional theory (DFT) employing B3LYP methods with the 6-31G(d,p) and 6-311+G(d,p) basis sets. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Thermodynamic properties like entropy, heat capacity and enthalpy have been calculated for the molecule. HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Important non-linear optical (NLO) properties such as electric dipole moment and first hyperpolarizability have been computed using B3LYP quantum chemical calculation. Copyright © 2013 Elsevier B.V. All rights reserved.

A combined experimental (IR, Raman and UV-Vis) and quantum chemical study of canadine

NASA Astrophysics Data System (ADS)

Joshi, Bhawani Datt; Srivastava, Anubha; Tandon, Poonam; Jain, Sudha; Ayala, A. P.

2018-02-01

Plant based natural products cover a major sector of the medicinal field, as such focus on plant research has been increased all over the world. As an attempt to aid that research, we have performed structural and spectroscopic analysis of a natural product, an alkaloid: canadine. Both ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP using 6-311 ++G(d,p) basis set were used for the calculations. The calculated vibrational frequencies were scaled and compared with the experimental infrared and Raman spectra. The complete vibrational assignments were made using potential energy distribution. The structure-activity relation has also been interpreted by mapping electrostatic potential surface and evaluating the reactivity descriptors, which are valuable information for quality control of medicines and drug-receptor interactions. Natural bond orbital analysis has also been performed to understand the stability and hyperconjugative interactions of the molecule. Furthermore, UV-Vis spectra have been recorded in an ethanol solvent (EtOH) and the electronic property has been analyzed employing TD-DFT for both gaseous and solvent phase. The HOMO and LUMO calculation with their energy gap show that charge transfer occurs within the molecule. Additionally, the nonlinear optical properties of the title compound have been interpreted that predicts it's the best candidate for the NLO materials.

Synthesis, characterization and biological activities of some Ru(II) complexes with substituted chalcones and their applications as chemotherapeutics against breast cancer

NASA Astrophysics Data System (ADS)

Singh, Ashok K.; Saxena, Gunjan; Dixit, Shivani; Hamidullah; Singh, Sachin K.; Singh, Sudheer K.; Arshad, M.; Konwar, Rituraj

2016-05-01

Four new Ru(II) DMSO complexes with substituted chalcone ligands viz. (E)-1-(2-hydroxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one (HL1), (E)-1-(2-hydroxyphenyl)-3-(4-nitrophenyl)prop-2-en-1-one (HL2), (E)-3-(4-(dimethylamino)phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (HL3) and (E)-1-(2-hydroxyphenyl)-3-(4-Chlorophenyl)prop-2-en-1-one (HL4) have been synthesized, and characterized by micro-analyses, IR, 1H NMR, UV-Vis and ESI-MS and screened for anti-cancer activity against breast cancer cell lines (MCF-7 and MDA MB-231). Compounds HL4 and [Ru(HL1) (O-DMSO)3(S-DMSO)]Cl (M1R) showed significant anti-breast cancer activity as evident from cytotoxicity, morphological and nuclear changes, DNA fragmentation and cell cycle arrest in breast cancer cells. UV-Vis and CD-spectra analysis showed HL4 and M1R interfered with DNA absorption spectra possibly due to DNA binding whereas these compounds were devoid of DNA topoisomerase inhibiting activity. Thus, these Ru(II) compounds have been established as new leads for future optimization by improving anti-cancer potency and safety.

Experimental and theoretical elucidation of structural and antioxidant properties of vanillylmandelic acid and its carboxylate anion

NASA Astrophysics Data System (ADS)

Dimić, Dušan; Milenković, Dejan; Ilić, Jelica; Šmit, Biljana; Amić, Ana; Marković, Zoran; Dimitrić Marković, Jasmina

2018-06-01

Vanillylmandelic acid (VMA), an important metabolite of catecholamines that is routinely screened as tumor marker, was investigated by the various spectroscopic techniques (IR, Raman, UV-Vis, antioxidant decolorization assay and NMR). Structures optimized by the employment of five common functionals (M05-2X, M06-2X, B3LYP, CAM-B3LYP, B3LYP-D3) were compared with the crystallographic data. The M05-2X functional reproduced the most reliable experimental bond lengths and angles (correlation coefficient >0.999). The importance of intramolecular hydrogen bonds for structural stability was discussed and quantified by the NBO analysis. The most prominent bands in vibrational spectrum were analyzed and compared to the experimental data. The positions of the carbon and hydrogen atoms in NMR spectra were well reproduced. The differences in UV-Vis spectrum were investigated by adding the explicit solvent and by performing NBO and QTAIM analyses. The discrepancy in the two spectra of about 50 nm could be explained by the solvent effect on carboxyl group. The most probable antioxidant activity mechanism was discussed for VMA and its carboxylate anion. The Molecular Docking study with the C - reactive protein additionally proved that variety of functional groups present in VMA and its anion allowed strong hydrogen and hydrophobic interactions.

ZnS, CdS and HgS nanoparticles via alkyl-phenyl dithiocarbamate complexes as single source precursors.

PubMed

Onwudiwe, Damian C; Ajibade, Peter A

2011-01-01

The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively.

ZnS, CdS and HgS Nanoparticles via Alkyl-Phenyl Dithiocarbamate Complexes as Single Source Precursors

PubMed Central

Onwudiwe, Damian C.; Ajibade, Peter A.

2011-01-01

The synthesis of II-VI semiconductor nanoparticles obtained by the thermolysis of certain group 12 metal complexes as precursors is reported. Thermogravimetric analysis of the single source precursors showed sharp decomposition leading to their respective metal sulfides. The structural and optical properties of the prepared nanoparticles were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) UV-Vis and photoluminescence spectroscopy. The X-ray diffraction pattern showed that the prepared ZnS nanoparticles have a cubic sphalerite structure; the CdS indicates a hexagonal phase and the HgS show the presence of metacinnabar phase. The TEM image demonstrates that the ZnS nanoparticles are dot-shaped, the CdS and the HgS clearly showed a rice and spherical morphology respectively. The UV-Vis spectra exhibited a blue-shift with respect to that of the bulk samples which is attributed to the quantum size effect. The band gap of the samples have been calculated from absorption spectra and werefound to be about 4.33 eV (286 nm), 2.91 eV (426 nm) and 4.27 eV (290 nm) for the ZnS, CdS and HgS samples respectively. PMID:22016607

Synthesis and molecular structure of a zinc complex of the vitamin K3 analogue phthiocol

NASA Astrophysics Data System (ADS)

Kathawate, Laxmi; Sproules, Stephen; Pawar, Omkar; Markad, Ganesh; Haram, Santosh; Puranik, Vedavati; Salunke-Gawali, Sunita

2013-09-01

The complex [Zn(phthiocol)2(H2O)2]; 1, where phthiocol is 2-hydroxy-3-methyl-1,4-naphthoquinone, has been synthesized and characterized by elemental analysis, FT-IR, 1H NMR, UV-vis spectroscopy, thermogravimetric (TG) analysis, electrochemical and single crystal X-ray diffraction studies. The νCO stretch shifts to lower frequencies upon complexation of phthiocol to Zn2+. 1H NMR spectra show an upfield shift of the benzenoid ring protons in 1. There is a bathochromic shift of the LMCT band in the UV-vis spectra of 1. Single crystal X-ray structure of 1 show distorted octahedral geometry around Zn2+. Two phthiocol ligands are in plane with the metal, while water molecules are trans to this plane. Coordination of deprotonated phthiocol ligands is 'trans, trans' to Zn2+. Intra as well as intermolecular interactions are observed in 1. Molecules of 1 show three dimensional network through CH⋯O and OH⋯O interactions. Additional anodic peaks are observed in cyclic voltammogram of phthiocol ligand due to oxidation of reduced species formed during reduction. One-electron reduction of 1 is shown to be reversible and DFT studies define this redox event as ligand-centered.

Simultaneous determination of vitamin B12 and its derivatives using some of multivariate calibration 1 (MVC1) techniques

NASA Astrophysics Data System (ADS)

Samadi-Maybodi, Abdolraouf; Darzi, S. K. Hassani Nejad

2008-10-01

Resolution of binary mixtures of vitamin B12, methylcobalamin and B12 coenzyme with minimum sample pre-treatment and without analyte separation has been successfully achieved by methods of partial least squares algorithm with one dependent variable (PLS1), orthogonal signal correction/partial least squares (OSC/PLS), principal component regression (PCR) and hybrid linear analysis (HLA). Data of analysis were obtained from UV-vis spectra. The UV-vis spectra of the vitamin B12, methylcobalamin and B12 coenzyme were recorded in the same spectral conditions. The method of central composite design was used in the ranges of 10-80 mg L -1 for vitamin B12 and methylcobalamin and 20-130 mg L -1 for B12 coenzyme. The models refinement procedure and validation were performed by cross-validation. The minimum root mean square error of prediction (RMSEP) was 2.26 mg L -1 for vitamin B12 with PLS1, 1.33 mg L -1 for methylcobalamin with OSC/PLS and 3.24 mg L -1 for B12 coenzyme with HLA techniques. Figures of merit such as selectivity, sensitivity, analytical sensitivity and LOD were determined for three compounds. The procedure was successfully applied to simultaneous determination of three compounds in synthetic mixtures and in a pharmaceutical formulation.

The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest

NASA Astrophysics Data System (ADS)

Keller-Rudek, H.; Moortgat, G. K.; Sander, R.; Sörensen, R.

2013-12-01

We present the MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules, which is a large collection of absorption cross sections and quantum yields in the ultraviolet and visible (UV/VIS) wavelength region for gaseous molecules and radicals primarily of atmospheric interest. The data files contain results of individual measurements, covering research of almost a whole century. To compare and visualize the data sets, multicoloured graphical representations have been created. The MPI-Mainz UV/VIS Spectral Atlas is available on the Internet at http://www.uv-vis-spectral-atlas-mainz.org. It now appears with improved browse and search options, based on new database software. In addition to the Web pages, which are continuously updated, a frozen version of the data is available under the doi:10.5281/zenodo.6951.

Preparation and characterization of PVP-PVA–ZnO blend polymer nano composite films

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

Divya, S., E-mail: divi.fysics@gmail.com; Saipriya, G.; Hemalatha, J., E-mail: hemalatha@nitt.edu

Flexible self-standing films of PVP-PVA blend composites are prepared by using ZnO as a nano filler at different concentrations. The structural, compositional, morphological and optical studies made with the help of X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Scanning electron microscope (SEM), Atomic Force Microscopy (AFM), Ultraviolet-visible spectroscopy (UV-vis) and Photoluminescence (PL) spectra are presented in this paper. The results of XRD indicate that ZnO nanoparticles are formed with hexagonal phase in the polymeric matrix. SEM images show the dispersion of ZnO nano filler in the polymer matrix. UV–vis spectra reveal that the absorption peak is centered around 235more » nm and 370 nm for the nano composite films. The blue shift is observed with decrease in the concentration of the nano filler. PL spectra shows the excitation wavelength is given at 320 nm.The emission peaks were observed at 383 nm ascribing to the electronic transitions between valence band and conduction band and the peak at 430 nm.« less

Catalytic reduction of NO to N2O by a designed heme copper center in myoglobin: implications for the role of metal ions.

PubMed

Zhao, Xuan; Yeung, Natasha; Russell, Brandy S; Garner, Dewain K; Lu, Yi

2006-05-31

The effects of metal ions on the reduction of nitric oxide (NO) with a designed heme copper center in myoglobin (F43H/L29H sperm whale Mb, CuBMb) were investigated under reducing anaerobic conditions using UV-vis and EPR spectroscopic techniques as well as GC/MS. In the presence of Cu(I), catalytic reduction of NO to N2O by CuBMb was observed with turnover number of 2 mol NO.mol CuBMb-1.min-1, close to 3 mol NO.mol enzyme-1.min-1 reported for the ba3 oxidases from T. thermophilus. Formation of a His-heme-NO species was detected by UV-vis and EPR spectroscopy. In comparison to the EPR spectra of ferrous-CuBMb-NO in the absence of metal ions, the EPR spectra of ferrous-CuBMb-NO in the presence of Cu(I) showed less-resolved hyperfine splitting from the proximal histidine, probably due to weakening of the proximal His-heme bond. In the presence of Zn(II), formation of a five-coordinate ferrous-CuBMb-NO species, resulting from cleavage of the proximal heme Fe-His bond, was shown by UV-vis and EPR spectroscopic studies. The reduction of NO to N2O was not observed in the presence of Zn(II). Control experiments using wild-type myoglobin indicated no reduction of NO in the presence of either Cu(I) or Zn(II). These results suggest that both the identity and the oxidation state of the metal ion in the CuB center are important for NO reduction. A redox-active metal ion is required to deliver electrons, and a higher oxidation state is preferred to weaken the heme iron-proximal histidine toward a five-coordinate key intermediate in NO reduction.

Formation, structural and optical characterization of neodymium doped-zinc soda lime silica based glass

NASA Astrophysics Data System (ADS)

Zamratul, M. I. M.; Zaidan, A. W.; Khamirul, A. M.; Nurzilla, M.; Halim, S. A.

New glass system of neodymium - doped zinc soda lime silica glass has been synthesized for the first time by melt-quenching of glass waste soda lime silica (SLS) with zinc oxide (ZnO) as precursor glass and Nd2O3 as dopant. In order to examine the effect of Nd3+ on the structural and optical properties, the prepared sample of structure [(ZnO)0.5(SLS)0.5](Nd2O3)x (x = 0, 1, 2, 3, 4 and 5 wt%) was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy (UV-Vis) and the photoluminescence (PL). XRD pattern justifies the amorphous nature of synthesized glasses. FTIR spectroscopy has been used to observe the structural evolution of ZnO4 and SiO4 groups. The UV-Vis-NIR absorption spectra reveals seven peaks centered at excitation of electron from ground state 4I9/2 to 4D3/2 + 4D5/2 (∼360 nm), 2G9/2 + 2D3/2 + 2P3/2(∼470 nm), 2K13/2 + 4G7/2 + 4G9/2 (∼523 nm), 4G5/2 + 2G7/2 (∼583 nm), 4F9/2 (∼678 nm), 4S3/2 + 4F7/2 (∼748 nm) and 4F5/2 + 2H9/2 (∼801 nm). PL spectra under the excitation of 800 nm display four emission bands centered at 531 nm, 598 nm, 637 nm and 671 nm corresponding to 4G7/2 → 4I9/2, (4G7/2 → 4I11/2, 4G5/2 → 4I9/2), (4G5/2 → 4I11/2) and (4G7/2 → 4I13/2, 4G5/2 → 4I11/2) respectively.

Stability Characterization of Quinazoline Derivative BG1188 by Optical Methods

NASA Astrophysics Data System (ADS)

Militaru, Andra; Smarandache, Adriana; Mahamoud, Abdallah; Damian, Victor; Ganea, Paul; Alibert, Sandrine; Pagès, Jean-Marie; Pascu, Mihail-Lucian

2011-08-01

3-[2-(dimethylamino)ethyl]-6-nitroquinazolin-4(3H)-one, labeled BG1188, is a new synthesized compound, out of a series of quinazoline derivatives developed to fight the multidrug resistance of antibiotics acquired by bacteria. A characterization of the BG1188 powder was made using FTIR spectra in order to evidence the functional groups in the medicine's molecule. The ultraviolet-visible (UV-Vis) absorption spectra were used to study the stability of the BG1188 solutions in two solvents and at different temperatures. BG1188 concentration in ultrapure water was varied between 2×10-3 M (stock solution) and 10-6 M. The concentration recommended by higher activity on bacteria was 10-3 M. For the same reason, this was the utilized concentration of BG1188 in dimethyl sulfoxide (DMSO). Time stability was characterized by comparing the time evolution of the UV-Vis absorption spectra of the BG1188 solutions in ultrapure de-ionized water or in DMSO. The spectra were recorded daily for about 4 months after the preparation for the BG1188 solutions in ultrapure water. Generally, samples are stable within the experimental errors at concentrations higher than 10-5 M, but the stability time interval may vary from 119 days at 10-4 M to 34 days at 10-5 M. Time evolution of the absorption spectra at 10-3 M in ultrapure water shows reproducibility within the measuring errors (±1.045%) for time intervals up to 1032 hours (more than 40 days) after preparation. On the other hand, BG1188 solutions in DMSO may be considered unstable because the absorption spectra modify in terms of peak shapes and intensities, indicating that the samples exhibit modifications immediately after preparation. Regardless the solvent used, some aggregation phenomena took place and wire-like aggregates were observed in all the solutions with the naked eye. These aggregates were analyzed, tentatively, using optical microscopy and FTIR.

Potentiometric and Conductometric Study of Aqueous Solutions of Lithium and Sodium Salts of Poly(thiophen-3-ylacetic acid).

PubMed

Hostnik, Gregor; Vlachy, Vojko; Bondarev, Dmitrij; Jiří, Vohlídal; Cerar, Janez

2012-09-01

The title polymer, PTAA, practically free of ester groups was obtained by oxidative polymerization of methyl thiophen-3-ylacetate and subsequent basic hydrolysis of primary polymer. Poly(thiophen-3-ylacetic acid) has been thoroughly characterized by NMR, IR, Raman, and UV/Vis spectroscopy. The polyacid behavior during neutralization titrations with lithium and sodium hydroxides, carried out under nitrogen atmosphere, has been studied by conductometry and potentiometry. Henderson-Hasselbach plots of potentiometric titration curves show a break point at pH around 6, where the curve slope drops from 1.8 (at lower pH) to a value from 1.05 to 1.3 (at higher pH values). The UV/Vis spectra monitored during back titration show: (i) monotonous decrease of both λmax and εmax as pH decreases, (ii) the presence of the isosbestic point at 401 nm that can be ascribed to conformational transition of PTAA chains, and (iii) absence of the isosbestic point at 392 nm reported previously by other authors.

Wastewater quality monitoring system using sensor fusion and machine learning techniques.

PubMed

Qin, Xusong; Gao, Furong; Chen, Guohua

2012-03-15

A multi-sensor water quality monitoring system incorporating an UV/Vis spectrometer and a turbidimeter was used to monitor the Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and Oil & Grease (O&G) concentrations of the effluents from the Chinese restaurant on campus and an electrocoagulation-electroflotation (EC-EF) pilot plant. In order to handle the noise and information unbalance in the fused UV/Vis spectra and turbidity measurements during the calibration model building, an improved boosting method, Boosting-Iterative Predictor Weighting-Partial Least Squares (Boosting-IPW-PLS), was developed in the present study. The Boosting-IPW-PLS method incorporates IPW into boosting scheme to suppress the quality-irrelevant variables by assigning small weights, and builds up the models for the wastewater quality predictions based on the weighted variables. The monitoring system was tested in the field with satisfactory results, underlying the potential of this technique for the online monitoring of water quality. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spectroscopic studies on the interaction of sodium benzoate, a food preservative, with calf thymus DNA.

PubMed

Zhang, Guowen; Ma, Yadi

2013-11-01

The interaction between sodium benzoate (SB) and calf thymus DNA in simulated physiological buffer (pH 7.4) using acridine orange (AO) dye as a fluorescence probe, was investigated by UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopy along with DNA melting studies and viscosity measurements. An expanded UV-Vis spectral data matrix was resolved by multivariate curve resolution-alternating least squares (MCR-ALS) approach. The equilibrium concentration profiles and the pure spectra for SB, DNA and DNA-SB complex from the high overlapping composite response were simultaneously obtained. The results indicated that SB could bind to DNA, and hydrophobic interactions and hydrogen bonds played a vital role in the binding process. Moreover, SB was able to quench the fluorescence of DNA-AO complex through a static procedure. The quenching observed was indicative of an intercalative mode of interaction between SB and DNA, which was supported by melting studies, viscosity measurements and CD analysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Spectroscopic investigation of different concentrations of the vapour deposited copper phthalocyanine as a "guest" in polyimide matrix.

PubMed

Georgiev, Anton; Yordanov, Dancho; Dimov, Dean; Assa, Jacob; Spassova, Erinche; Danev, Gencho

2015-04-05

Nanocomposite layers 250 nm copper phthalocyanine/polyimide prepared by simultaneous vapour deposition of three different sources were studied. Different concentrations of copper phthalocyanine as a "guest" in polyimide matrix as a function of conditions of the preparation have been determined by FTIR (Fourier Transform Infrared) and UV-VIS (Ultraviolet-Visible) spectroscopies. The aim was to estimate the possibility of the spectroscopic methods for quantitative determination of the "guest" and compare with the quality of the polyimide thin films in relation to the "guest" concentration. The band at 1334 cm(-1) has been used for quantitative estimation of "guest" in polyimide matrix. The concentrations of the copper phthalocyanine less than 20% require curve fitting techniques with Fourier self deconvolution. The relationship between "guest" concentrations and degree of imidization, as well as the electronic UV-VIS spectra are discussed in relation to the composition, imidization degree and the two crystallographic modification of the embedded chromophore. Copyright © 2015 Elsevier B.V. All rights reserved.

Degradability studies of PLA nanocomposites under controlled water sorption and soil burial conditions

NASA Astrophysics Data System (ADS)

Norazlina, H.; Hadi, A. A.; Qurni, A. U.; Amri, M.; Mashelmie, S.; Kamal, Y.

2018-04-01

Polymer blended nanocomposites based on polylactic acid (PLA) were prepared via a simple melting process and investigated for its biodegradation behaviour. The treated CNTs were surface modified by using acid treatment and characterisations of composites were done by using Fourier Transform Infra-Red (FTIR) and UV-Vis. FTIR spectra and UV-Vis peak confirmed the surface modification of CNTs. The water uptake and weight loss behaviour based on CNTs and m-CNTs loading at different temperatures (25° and 45°C) were studied. It was found that the water absorption and weight loss of nanocomposites increased by the incorporation of CNTs and m-CNTs. Moisture induced degradation of composite samples was significant at elevated temperature. The addition of treated CNTs successfully reduced the water uptake and weight loss of nanocomposites due to less hydrolytic effect of water on nanocomposites. In soil burial test, the weight loss increases with addition of nanofiller. The loading of m-CNT reduced the ability of nanocomposites degradation.

Bimetallic ruthenium complexes bridged by divinylphenylene bearing oligo(ethylene glycol)methylether: synthesis, (spectro)electrochemistry and the lithium cation effect.

PubMed

Tian, Li Yan; Liu, Yuan Mei; Tian, Guang-Xuan; Wu, Xiang Hua; Li, Zhen; Kou, Jun-Feng; Ou, Ya-Ping; Liu, Sheng Hua; Fu, Wen-Fu

2014-03-14

A series of 1,4-disubstituted ruthenium-vinyl complexes, (E,E)-[{(PMe3)3(CO)ClRu}2(μ-HC=CH-Ar-CH=CH)], in which the 1,4-diethenylphenylene bridge bears two oligo(ethylene glycol)methyl ether side chains at different positions (2,5- and 2,3-positions), were prepared. The respective products were characterized by elemental analyses and NMR spectroscopy. The structures of complexes 1b and 1e were established by X-ray crystallography. The electronic properties of the complexes were investigated by cyclic voltammetry, and IR and UV-vis/NIR spectroscopies. Electrochemical studies showed that the 2,5-substituents better stabilized the mixed-valence states; the electrochemical behavior was greatly affected by lithium cations, especially complex 1g with 2,3-substituents, which was further supported by IR and UV-vis/NIR spectra changes. Spectroelectrochemical studies showed that the redox chemistry was dominated by the non-innocent character of the bridging fragment.

Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions.

PubMed

Güder, Aytaç; Korkmaz, Halil; Gökce, Halil; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

2014-12-10

In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, β-carotene and vitamin E contents were carried out. In addition, the FT-IR, (13)C and (1)H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data. Copyright © 2014 Elsevier B.V. All rights reserved.

Intelligent pH indicator film composed of agar/potato starch and anthocyanin extracts from purple sweet potato.

PubMed

Choi, Inyoung; Lee, Jun Young; Lacroix, Monique; Han, Jaejoon

2017-03-01

A new colorimetric pH indicator film was developed using agar, potato starch, and natural dyes extracted from purple sweet potato, Ipomoea batatas. Both agar and potato starch are solid matrices used to immobilize natural dyes, anthocyanins. The ultraviolet-visible (UV-vis) spectrum of anthocyanin extract solutions and agar/potato starch films with anthocyanins showed color variations to different pH values (pH 2.0-10.0). Fourier transform infrared (FT-IR) and UV-vis region spectra showed compatibility between agar, starch, and anthocyanin extracts. Color variations of pH indicator films were measured by a colorimeter after immersion in different pH buffers. An application test was conducted for potential use as a meat spoilage sensor. The pH indicator films showed pH changes and spoilage point of pork samples, changing from red to green. Therefore, the developed pH indicator films could be used as a diagnostic tool for the detection of food spoilage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Isolation, characterization, spectroscopic properties and quantum chemical computations of an important phytoalexin resveratrol as antioxidant component from Vitis labrusca L. and their chemical compositions

NASA Astrophysics Data System (ADS)

Güder, Aytaç; Korkmaz, Halil; Gökce, Halil; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

2014-12-01

In this study, isolation and characterization of trans-resveratrol (RES) as an antioxidant compound were carried out from VLE, VLG and VLS. Furthermore, antioxidant activities were evaluated by using six different methods. Finally, total phenolic, flavonoid, ascorbic acid, anthocyanin, lycopene, β-carotene and vitamin E contents were carried out. In addition, the FT-IR, 13C and 1H NMR chemical shifts and UV-vis. spectra of trans-resveratrol were experimentally recorded. Quantum chemical computations such as the molecular geometry, vibrational frequencies, UV-vis. spectroscopic parameters, HOMOs-LUMOs energies, molecular electrostatic potential (MEP), natural bond orbitals (NBO) and nonlinear optics (NLO) properties of title molecule have been calculated by using DFT/B3PW91 method with 6-311++G(d,p) basis set in ground state for the first time. The obtained results show that the calculated spectroscopic data are in a good agreement with experimental data.

Solvent Dependency of the UV-Vis Spectrum of Indenoisoquinolines: Role of Keto-Oxygens as Polarity Interaction Probes

PubMed Central

Coletta, Andrea; Castelli, Silvia; Chillemi, Giovanni; Sanna, Nico; Cushman, Mark; Pommier, Yves; Desideri, Alessandro

2013-01-01

Indenoisoquinolines are the most promising non-campthotecins topoisomerase IB inhibitors. We present an integrated experimental/computational investigation of the UV-Vis spectra of the IQNs parental compound (NSC314622) and two of its derivatives (NSC724998 and NSC725776) currently undergoing Phase I clinical trials. In all the three compounds a similar dependence of the relative absorption intensities at 270 nm and 290 nm on solvent polarity is found. The keto-oxygens in positions 5 and 11 of the molecular scaffold of the molecule are the principal chromophores involved in this dependence. Protic interactions on these sites are also found to give rise to absorptions at wavelength <250 nm observed in water solution, due to the stabilization of highly polarized tautomers of the molecule. These results suggest that the keto-oxygens are important polarizable groups that can act as useful interactors with the molecular receptor, providing at the same time an useful fingerprint for the monitoring of the drug binding to topoisomerase IB. PMID:24086299

Synthesis and different optical properties of Gd2O3 doped sodium zinc tellurite glasses

NASA Astrophysics Data System (ADS)

Samanta, Buddhadev; Dutta, Dibakar; Ghosh, Subhankar

2017-06-01

A series of Gd2O3 doped sodium zinc tellurite [xGd2O3-(0.8-x) TeO2-0.1Na2O-0.1ZnO] glasses are prepared by the conventional melt quenching method and their optical properties have been studied. UV-vis spectrophotometric studies within the wavelength range from 230 nm-800 nm are carried out in the integrating sphere mode to study the effect of Gd2O3 doping on the optical band gap (Eg), refractive index (n), dielectric constant (εr) and susceptibility (χ). Other physical properties like molar volume, molar refraction, polarizability, metallization criterion, number density of rare-earth ions (N), polaron radius (rp), inter ionic distance (ri), molar cation polarizability (∑αi), number of oxide ions in chemical composition (NO2-), optical band gap based electronic oxide ion polarizability (αO2-) and optical basicity (Λ) of glass samples have been studied on the basis of UV-vis spectra and density profile of the different glasses.

Synthesis, structural and optical properties of PVP coated transition metal doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Desai, N. V.; Shaikh, I. A.; Rawal, K. G.; Shah, D. V.

2018-05-01

The room temperature photoluminescence (PL) of transition metal doped ZnS nanoparticles is investigated in the present study. The PVP coated ZnS nanoparticles doped with transition metals are synthesized by facile wet chemical co-precipitation method with the concentration of impurity 1%. The UV-Vis absorbance spectra have a peak at 324nm which shifts slightly to 321nm upon introduction of the impurity. The incorporation of the transition metal as dopant is confirmed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The particle size and the morphology are characterized by scanning electron microscopy (SEM), XRD and UV-Vis spectroscopy. The average size of synthesized nanoparticles is about 2.6nm. The room temperature photoluminescence (PL) of undoped and doped ZnS nanoparticles show a strong and sharp peak at 782nm and 781.6nm respectively. The intensity of the PL changes with the type of doping having maximum for manganese (Mn).

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

NASA Astrophysics Data System (ADS)

Deborah, M.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

2015-03-01

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (0 0 2) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

An Octanuclear Metallosupramolecular Cage Designed To Exhibit Spin-Crossover Behavior.

PubMed

Struch, Niklas; Bannwarth, Christoph; Ronson, Tanya K; Lorenz, Yvonne; Mienert, Bernd; Wagner, Norbert; Engeser, Marianne; Bill, Eckhard; Puttreddy, Rakesh; Rissanen, Kari; Beck, Johannes; Grimme, Stefan; Nitschke, Jonathan R; Lützen, Arne

2017-04-24

By employing the subcomponent self-assembly approach utilizing 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or its zinc(II) complex, 1H-4-imidazolecarbaldehyde, and either zinc(II) or iron(II) salts, we were able to prepare O-symmetric cages having a confined volume of ca. 1300 Å 3 . The use of iron(II) salts yielded coordination cages in the high-spin state at room temperature, manifesting spin-crossover in solution at low temperatures, whereas corresponding zinc(II) salts led to the corresponding diamagnetic analogues. The new cages were characterized by synchrotron X-ray crystallography, high-resolution mass spectrometry, and NMR, Mössbauer, IR, and UV/Vis spectroscopy. The cage structures and UV/Vis spectra were independently confirmed by state-of-the-art DFT calculations. A remarkably high-spin-stabilizing effect through encapsulation of C 70 was observed. The spin-transition temperature T 1/2 is lowered by 20 K in the host-guest complex. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectrometric studies on the interaction of fluoroquinolones and bovine serum albumin

NASA Astrophysics Data System (ADS)

Ni, Yongnian; Su, Shaojing; Kokot, Serge

2010-02-01

The interaction between fluoroquinolones (FQs), ofloxacin and enrofloxacin, and bovine serum albumin (BSA) was investigated by fluorescence and UV-vis spectroscopy. It was demonstrated that the fluorescence quenching of BSA by FQ is a result of the formation of the FQ-BSA complex stabilized, in the main, by hydrogen bonds and van der Waals forces. The Stern-Volmer quenching constant, KSV, and the corresponding thermodynamic parameters, Δ H, Δ S and Δ G, were estimated. The distance, r, between the donor, BSA, and the acceptor, FQ, was estimated from fluorescence resonance energy transfer (FRET). The effect of FQ on the conformation of BSA was analyzed with the aid of UV-vis absorbance spectra and synchronous fluorescence spectroscopy. Spectral analysis showed that the two FQs affected the conformation of the BSA but in a different manner. Thus, with ofloxacin, the polarity around the tryptophan residues decreased and the hydrophobicity increased, while for enrofloxacin, the opposite effect was observed.

Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

PubMed

Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

2015-11-20

In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

Combined MCD/DFT/TDDFT Study of the Electronic Structure of Axially Pyridine Coordinated Metallocorroles.

PubMed

Rhoda, Hannah M; Crandall, Laura A; Geier, G Richard; Ziegler, Christopher J; Nemykin, Victor N

2015-05-18

A series of metallocorroles were investigated by UV-vis and magnetic circular dichroism spectroscopies. The diamagnetic distorted square-pyramidal main-group corrole Ga(tpfc)py (2), the diamagnetic distorted octahedral transition-metal adduct Co(tpfc)(py)2 (3), and paramagnetic distorted octahedral transition-metal complex Fe(tpfc)(py)2 (4) [H3tpfc = tris(perfluorophenyl)corrole] were studied to investigate similarities and differences in the electronic structure and spectroscopy of the closed- and open-shell metallocorroles. Similar to the free-base H3tpfc (1), inspection of the MCD Faraday B-terms for all of the macrocycles presented in this report revealed that a ΔHOMO < ΔLUMO [ΔHOMO is the energy difference between two highest energy corrole-centered π-orbitals and ΔLUMO is the energy difference between two lowest energy corrole-centered π*-orbitals originating from ML ± 4 and ML ± 5 pairs of perimeter] condition is present for each complex, which results in an unusual sign-reversed sequence for π-π* transitions in their MCD spectra. In addition, the MCD spectra of the cobalt and the iron complexes were also complicated by a number of charge-transfer states in the visible region. Iron complex 4 also exhibits a low-energy absorption in the NIR region (1023 nm). DFT and TDDFT calculations were used to elaborate the electronic structures and provide band assignments in UV-vis and MCD spectra of the metallocorroles. DFT and TDDFT calculations predict that the orientation of the axial pyridine ligand(s) has a very minor influence on the calculated electronic structures and absorption spectra in the target systems.

Study on molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM, HOMO-LUMO energies and docking studies of 5-fluorouracil, a substance used to treat cancer

NASA Astrophysics Data System (ADS)

Almeida, Michell O.; Barros, Daiane A. S.; Araujo, Sheila C.; Faria, Sergio H. D. M.; Maltarollo, Vinicius G.; Honorio, Kathia M.

2017-09-01

Cancer cells can expand to other parts of body through blood system and nodes from a mechanism known as metastasis. Due to the large annual growth of cancer cases, various biological targets have been studied and related to this disorder. A very interesting target related to cancer is human epidermal growth factor receptor 2 (HER2). In this study, we analyzed the main intermolecular interactions between a drug used in the cancer treatment (5-fluorouracil) and HER2. Molecular modeling methods were also employed to assess the molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM and HOMO-LUMO energies of 5-FU. From the docking simulations it was possible to analyze the interactions that occur between some residues in the binding site of HER2 and 5-FU. To validate the choice of basis set that was used in the NBO and QTAIM analyses, theoretical calculations were performed to obtain FT-IR and UV/Vis spectra, and the theoretical results are consistent with the experimental data, showing that the basis set chosen is suitable. For the maximum λ from the theoretical calculation (254.89 nm) of UV/Vis, the electronic transition from HOMO to LUMO occurs at 4.89 eV. From NBO analyses, we observed interactions between Asp863 and 5-FU, i.e. the orbitals with high transfer of electrons are LP O15 (donor NBO) and BD* (π) N1-H10 (acceptor NBO), being that the value of this interaction is 7.72 kcal/mol. Results from QTAIM indicate one main intermolecular H bond, which is necessary to stabilize the complex formed between the ligands and the biological target. Therefore, this study allowed a careful evaluation on the main structural, spectroscopic and electronic properties involved in the interaction between 5-FU and HER2, an important biological complex related to the cancer treatment.

Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex.

PubMed

Girvan, Hazel M; Bradley, Justin M; Cheesman, Myles R; Kincaid, James R; Liu, Yilin; Czarnecki, Kazimierz; Fisher, Karl; Leys, David; Rigby, Stephen E J; Munro, Andrew W

2016-09-13

DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the "Microprocessor") is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet-visible (UV-vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys(-)) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme iron ligation, with conversion from bis-thiolate (Cys(-)/Cys(-)) axial coordination in ferric DGCR8 to bis-thiol (CysH/CysH) coordination in ferrous DGCR8. Pri-miRNA binding does not perturb ferric DGCR8's optical spectrum, consistent with the axial ligand environment being separated from the substrate-binding site. UV-vis absorption spectra of the Fe(II) and Fe(II)-CO forms indicate discrete species exhibiting peaks with absorption coefficients substantially larger than those for ferric DGCR8 and that previously reported for a ferrous form of DGCR8. Electron-nuclear double resonance spectroscopy data exclude histidine or water as axial ligands for ferric DGCR8 and favor bis-thiolate coordination in this form. UV-vis MCD and near-infrared MCD provide data consistent with this conclusion. UV-vis MCD data for ferrous DGCR8 reveal features consistent with bis-thiol heme iron coordination, and resonance Raman data for the ferrous-CO form are consistent with a thiol ligand trans to the CO. These studies support retention of DGCR8 cysteine coordination upon reduction, a conclusion distinct from those of previous studies of a different ferrous DGCR8 isoform.

Compositional and surface characterization of HULIS by UV-Vis, FTIR, NMR and XPS: Wintertime study in Northern India

NASA Astrophysics Data System (ADS)

Kumar, Varun; Goel, Anubha; Rajput, Prashant

2017-09-01

This study (first attempt) characterizes HULIS (Humic Like Substances) in wintertime aerosols (n = 12 during day and nighttime each) from Indo-Gangetic Plain (IGP, at Kanpur) by using various state-of-the art techniques such as UV-VIS, FTIR, 1H NMR and XPS. Based on UV-Vis analysis the absorption coefficient at 365 nm (babs-365) of HULIS was found to average at 13.6 and 28.8 Mm-1 during day and nighttime, respectively. Relatively high babs-365 of HULIS during the nighttime is attributed to influence of fog-processing. However, the power fit of UV-Vis spectrum provided near similar AAE (absorption Angstrom exponent) value of HULIS centering at 4.9 ± 1.4 and 5.1 ± 1.3 during daytime and nighttime, respectively. FTIR spectra and its double derivative revealed the presence of various functional groups viz. alcohols, ketones aldehydes, carboxylic acids as well as unsaturated and saturated carbon bonds. 1H NMR spectroscopy was applied to quantify relative percentage of various types of hydrogen atoms contained in HULIS, whereas XPS technique provided information on surface composition and oxidation states of various elements present. A significantly high abundance of H‒C‒O group has been observed in HULIS (based on 1H NMR); 41.4± 2.7% and 30.9± 2.4% in day and nighttime, respectively. However, aromatic protons (Ar-H) were higher in nighttime samples (19.3± 1.8%) as compared to that in daytime samples (7.5 ± 1.9). XPS studies revealed presence of various species on the surface of HULIS samples. Carbon existed in 7 different chemical states while total nitrogen and sulfur exhibited 3 and 2 different oxidation states (respectively) on the surface of HULIS. This study reports structural information and absorption properties of HULIS which has implications to their role as cloud condensation nuclei and atmospheric direct radiative forcing.

Platinum CCC-NHC benzimidazolyl pincer complexes: synthesis, characterization, photostability, and theoretical investigation of a blue-green emitter.

PubMed

Huckaba, Aron J; Cao, Bei; Hollis, T Keith; Valle, Henry U; Kelly, John T; Hammer, Nathan I; Oliver, Allen G; Webster, Charles Edwin

2013-06-28

The recently reported metallation/transmetallation route for the synthesis of CCC-bis(NHC) pincer ligand architectures was extended to 1,3-bis(3'-(trimethylsilylmethyl)-benzimidizol-1'-yl)benzene. The precursor was metallated with Zr(NMe2)4 and transmetallated to Pt using [Pt(COD)Cl2]. This Pt complex was found to resist photobleaching under UV irradiation in ambient conditions. Density functional theory (DFT) computations were used to generate the emission spectrum of the complex and reveal that this spectrum is the result of a transition from the triplet excited state (T1) to the ground state (S0). The Pt complex's molecular structure was determined by X-ray crystallography. The UV-vis absorption and emission spectra in solution and the solid-state emission spectra are reported. The solid-state photostability data and the radiative lifetime is also reported.

Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

NASA Astrophysics Data System (ADS)

Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

2015-07-01

Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

The use of UV-visible reflectance spectroscopy as an objective tool to evaluate pearl quality.

PubMed

Agatonovic-Kustrin, Snezana; Morton, David W

2012-07-01

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl's quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry.

A Real-Time Ultraviolet Radiation Imaging System Using an Organic Photoconductive Image Sensor†

PubMed Central

Okino, Toru; Yamahira, Seiji; Yamada, Shota; Hirose, Yutaka; Odagawa, Akihiro; Kato, Yoshihisa; Tanaka, Tsuyoshi

2018-01-01

We have developed a real time ultraviolet (UV) imaging system that can visualize both invisible UV light and a visible (VIS) background scene in an outdoor environment. As a UV/VIS image sensor, an organic photoconductive film (OPF) imager is employed. The OPF has an intrinsically higher sensitivity in the UV wavelength region than those of conventional consumer Complementary Metal Oxide Semiconductor (CMOS) image sensors (CIS) or Charge Coupled Devices (CCD). As particular examples, imaging of hydrogen flame and of corona discharge is demonstrated. UV images overlapped on background scenes are simply made by on-board background subtraction. The system is capable of imaging weaker UV signals by four orders of magnitude than that of VIS background. It is applicable not only to future hydrogen supply stations but also to other UV/VIS monitor systems requiring UV sensitivity under strong visible radiation environment such as power supply substations. PMID:29361742

Cobalt ferrite nano-composite coated on glass by Doctor Blade method for photo-catalytic degradation of an azo textile dye Reactive Red 4: XRD, FESEM and DRS investigations.

PubMed

Habibi, Mohammad Hossein; Parhizkar, Janan

2015-11-05

Cobalt ferrite nano-composite was prepared by hydrothermal route using cobalt nitrate, iron nitrate and ethylene glycol as chelating agent. The nano-composite was coated on glass by Doctor Blade method and annealed at 300 °C. The structural, optical, and photocatalytic properties have been studied by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy (UV-Vis DRS). Powder XRD analysis confirmed formation of CoFe2O4 spinel phase. The estimated particle size from FESEM data was 50 nm. The calculated energy band gaps, obtained by Tauc relation from UV-Vis absorption spectra was 1.3 eV. Photocatalytic degradation of Reactive Red 4 as an azo textile was investigated in aqueous solution under irradiation showed 68.0% degradation of the dye within 100 min. The experimental enhanced activity compare to pure Fe2O3 can be ascribed to the formation of composite, which was mainly attributable to the transfer of electron and hole to the surface of composite and hinder the electron hole recombination. Copyright © 2015 Elsevier B.V. All rights reserved.

Tuning the optical properties of ZnO nanorods by variation of precursor concentration through hydrothermal method

NASA Astrophysics Data System (ADS)

Kumari, Lakshmi; Kar, Asit Kumar

2018-05-01

ZnO nanorods with varying precursor concentration have been successfully synthesized by the hydrothermal method. The effect of the precursor concentration on the structural, morphological and optical properties of the resulting nanorods was investigated by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. The crystalline structural characterization demonstrated that the synthesized materials crystallize in pure ZnO wurtzite structure without any other secondary phase. SEM micrographs demonstrate nanorod type features in all the samples. In addition, they show that increase of precursor concentration changes the length and diameter of nanorods. The UV-Vis studies show a strong absorption band in UV region at 373 nm attributed to the band-edge absorption of wurtzite hexagonal ZnO, blue shifted relative to its bulk form (380 nm). The PL spectra of obtained nanorods excited at 360 nm present broad visible emission. Moreover, as the visible region (from 510 to 550 nm) is concerned, it is speculated that the increase of the precursor concentration affects strongly the kind of interstitial defects (Oi, Zni and Vo) formed in ZnO nanorods. The luminescence intensity decreases with the increase of precursor concentration.

Assessment of organic pollution of an industrial river by synchronous fluorescence and UV-vis spectroscopy: the Fensch River (NE France).

PubMed

Assaad, Aziz; Pontvianne, Steve; Pons, Marie-Noëlle

2017-05-01

To rapidly monitor the surface water quality in terms of organic pollution of an industrial river undergoing restoration, optical methods (UV-visible spectrometry and fluorescence) were applied in parallel to classical physical-chemical analyses. UV-visible spectra were analyzed using the maximum of the second derivative at 225 nm (related to nitrates), specific absorbance at 254 nm (SUVA 254 ), and the spectral slope between 275 and 295 nm (S 275-295 ) (related to the aromaticity and molecular weight of dissolved organic carbon). The synchronous fluorescence spectra (wavelength difference = 50 nm) exhibited a high variability in the composition of dissolved organic material between the upstream and downstream sections and also versus time. The principal components analysis of the entire set of synchronous fluorescence spectra helped to define three river sections with different pollution characteristics. Spectral decomposition was applied to the two most upstream sections: five fluorophores, classical in rivers impacted by domestic sewage and related to protein-like (λ ex  = 280 nm) and humic-like fluorescence (M-type with λ ex  ≈ 305-310 nm and C-type with λ ex  ≥ 335 nm), were identified. The irregular shape of the synchronous fluorescence spectra in the most downstream section is likely due to organic pollutants of industrial origin; however, their variability and the complexity of the spectra did not allow the further elucidation of their nature.

Photoionization and Electron Transfer of Biphenyl within the Channels of Al-ZSM-5 Zeolites.

PubMed

Gener, Isabelle; Buntinx, Guy; Brémard, Claude

1999-06-14

Evidence of the photogenerated long-lived biphenyl radical and a trapped electron in the void space of aluminated nonacidic ZSM-5 zeolites has been obtained from the time-resolved UV/Vis absorption, Raman scattering, and EPR spectra. The restoration of the ground states implicates the existence of long-lived positive holes in the framework. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing

DTIC Science & Technology

2007-09-30

have attempted to develop methods based on chemical structural modification to prevent galvanically-induced composite corrosion. [9, 10-12] These...of the two metallopolymers 11 and 12 show characteristic MLCT (metal-to-ligand charge transfer) absorption band of tris(bipyridyl)Ru(II) unit at k...showed absorption band at 450 nm and emission band at 325 nm of tris(bipyridyl)Ru(II) units in its respective UV-vis and fluorescence spectra. Very

Synthesis and optical properties of silver nanoparticles

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

Singh, Jaiveer; Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk; Choudhary, K. K.

The preparation of stable, uniform silver nanoparticles by reduction of silver acetate by ethylene glycol (EG) is reported in the present paper. It is a simple process of recent interest for obtaining silver nanoparticles. The samples were characterized by X-Ray diffraction (XRD), which reveals an average particle size (D) of 38 nm. The UV/Vis spectra show that an absorption peak, occurring due to surface plasmon resonance (SPR), exists at 319 nm.

Various DC-driven point-to-plain discharges as non-thermal plasma sources and their bactericidal effects

NASA Astrophysics Data System (ADS)

Khun, Josef; Scholtz, Vladimír; Hozák, Pavel; Fitl, Přemysl; Julák, Jaroslav

2018-06-01

The appearance of several types of ballast serial impedance-stabilized DC-driven electric corona discharges in the point-to-plane configuration is described. In addition to well-known corona discharges, new ones were observed, namely curved transient spark, interrupted channel and branched transient spark. Their properties are described by volt-ampere characteristics and UV-vis emission spectra. Their bactericidal ability for two bacterial species is also given.

Absorption spectra of PTCDI: A combined UV-Vis and TD-DFT study

NASA Astrophysics Data System (ADS)

Oltean, Mircea; Calborean, Adrian; Mile, George; Vidrighin, Mihai; Iosin, Monica; Leopold, Loredana; Maniu, Dana; Leopold, Nicolae; Chiş, Vasile

2012-11-01

Absorption spectra of PTCDI (3,4,9,10-perylene-tetracarboxylic-diimide) have been investigated in chloroform, N,N'-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). While no signature of assembled PTCDI molecules is observed in chloroform solution, distinct bands assigned to their aggregation have been identified in DMF and DMSO solutions. PTCDI monomers show very similar absorption patterns in chloroform and DMSO solutions. Experimental data, including the vibronic structure of the absorption spectra were explained based on the Franck-Condon approximation and quantum chemical results obtained at PBE0-DCP/6-31+G(d,p) level of theory. Geometry optimization of the first excited state leads to a nice agreement between the calculated adiabatic transition energies and experimental data.

On-line database of voltammetric data of immobilized particles for identifying pigments and minerals in archaeometry, conservation and restoration (ELCHER database).

PubMed

Doménech-Carbó, Antonio; Doménech-Carbó, María Teresa; Valle-Algarra, Francisco Manuel; Gimeno-Adelantado, José Vicente; Osete-Cortina, Laura; Bosch-Reig, Francisco

2016-07-13

A web-based database of voltammograms is presented for characterizing artists' pigments and corrosion products of ceramic, stone and metal objects by means of the voltammetry of immobilized particles methodology. Description of the website and the database is provided. Voltammograms are, in most cases, accompanied by scanning electron microphotographs, X-ray spectra, infrared spectra acquired in attenuated total reflectance Fourier transform infrared spectroscopy mode (ATR-FTIR) and diffuse reflectance spectra in the UV-Vis-region. For illustrating the usefulness of the database two case studies involving identification of pigments and a case study describing deterioration of an archaeological metallic object are presented. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication and optical nonlinearities of composite films derived from the water-soluble Keplerate-type polyoxometalate and chloroform-soluble porphyrin.

PubMed

Shi, Zonghai; Zhou, Yunshan; Zhang, Lijuan; Yang, Di; Mu, Cuncun; Ren, Haizhou; Shehzad, Farooq Khurum; Li, Jiaqi

2015-03-07

Composite films derived from the water-soluble Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72]·ca. 300H2O·ca. 10CH3COONH4 (denoted (NH4)42{Mo132}) and chloroform-soluble tetraphenylporphyrin perchlorate [H2TPP](ClO4)2 are successfully fabricated by a layer-by-layer self-assembly method and characterized by UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The structure of the {Mo132} and [H2TPP](2+) in the films remain intact in light of the results of UV-vis spectroscopy and XPS. UV-vis spectra measurements reveal that the amounts of deposition of {Mo132} and [H2TPP](2+) remain constant in every adsorption cycle in the composite films assembly process. Nonlinear optical properties of the composite films have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 7 ns. The results show that the composite films have notable nonlinear saturated absorption and self-defocusing effects. The combination of {Mo132} with [H2TPP](2+) can result in composite films with remarkably enhanced optical nonlinearities. The interfacial charge transfer induced by laser from porphyrin to POM in the films is thought to play a key role in the enhancement of NLO response. The third-order NLO susceptibility χ((3)) of the composite films increases with the increase of film thickness.

Optical, electrical, thermal properties of cadmium chloride doped PVA – PVP blend

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

Baraker, Basavarajeshwari M.; Hammannavar, Preeti B.; Lobo, Blaise, E-mail: blaise.lobo@gmail.com

2015-06-24

Films of polyvinylalcohol (PVA) – polyvinylpyrrolidone (PVP) blend doped with Cadmium Chloride (CdCl{sub 2}) in the doping range 1 wt% to 40 wt% were prepared by solution casting technique. These films were characterized using optical/UV-Vis- NIR spectroscopy, Differential Scanning Calorimetry (DSC) and DC electrical measurements. The UV-Visible spectra were quantitatively analyzed to yield the optical parameters. The UV-Visible Spectra show intermediate absorption bands (before the final absorption edge) due to formation of energy bands in the forbidden gap of PVA-PVP. There is a prominent absorption band at 2.9 eV, from 0.5 wt% up to 1.8 wt% doping level (DL) causedmore » by the dopant (CdCl{sub 2}). The DC electrical studies showed an increase in activation energy from 2.8 eV at 0.5 wt% DL up to 3.5 eV at 4.4 wt% DL, reaching a low of 2.4 eV at 11.2 wt% DL. DSC scans show evidence of formation of chain fragments, at doping levels beyond 8 wt%.« less

The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest

NASA Astrophysics Data System (ADS)

Keller-Rudek, H.; Moortgat, G. K.; Sander, R.; Sörensen, R.

2013-08-01

We present the MPI-Mainz UV/VIS Spectral Atlas, which is a large collection of absorption cross sections and quantum yields in the ultraviolet and visible (UV/VIS) wavelength region for gaseous molecules and radicals primarily of atmospheric interest. The data files contain results of individual measurements, covering research of almost a whole century. To compare and visualize the data sets, multicoloured graphical representations have been created. The Spectral Atlas is available on the internet at http://www.uv-vis-spectral-atlas-mainz.org. It now appears with improved browse and search options, based on new database software. In addition to the web pages, which are continuously updated, a frozen version of the data is available under the doi:10.5281/zenodo.6951.

Theoretical and spectroscopic studies of a tricyclic antidepressant, imipramine hydrochloride

NASA Astrophysics Data System (ADS)

Sagdinc, S. G.; Azkeskin, Caner; Eşme, A.

2018-06-01

Imipramine hydrochloride ([H-IMI]Cl), C19H24N2.HCl, is the prototypic tricyclic antidepressant (TCA) inhibitor of norepinephrine and serotonin neuronal reuptake. The molecular structure, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, linear and non-linear optical (NLO) properties of [H-IMI]Cl have been investigated using the density functional theory (DFT) calculations with the B3LYP level at the 6‒311++G(d,p) basis set. The UV-Vis spectra for [H-IMI]Cl were experimentally studied in water and methanol. TD‒DFT calculations in water and methanol were employed to investigate the absorption wavelengths (λ), excitation energies (E), and oscillator strengths (f) for the UV-Vis analysis and the major contributions to the electronic transitions. From NBO analysis, the orbitals with the stabilization energy E(2) of 192.15 kcal/mol are π*(C5sbnd C18) as donor NBO and π*(C19sbnd C20) as acceptor NBO. The FT‒IR (4000‒400 cm-1) and FT‒Raman (3500-50 cm-1) spectra have been measured and analyzed. The assignment of bands observed vibrational spectra have been made by comparison of its calculated theoretical vibrational frequencies obtained using the DFT/B3LYP/6‒311++G(d,p) method. The detailed vibrational assignments were performed with the DFT calculation, and the potential energy distribution (PED) of [H-IMI]Cl was obtained by the Vibrational Energy Distribution Analysis 4 (VEDA4) program. The scaled frequencies resulted in good agreement with the observed spectral patterns.

Absolute configurations of phytotoxins seiricardine A and inuloxin A obtained by chiroptical studies.

PubMed

Santoro, Ernesto; Mazzeo, Giuseppe; Petrovic, Ana G; Cimmino, Alessio; Koshoubu, Jun; Evidente, Antonio; Berova, Nina; Superchi, Stefano

2015-08-01

The absolute configuration (AC) of the plant phytotoxin inuloxin A, produced by Inula viscosa, and of the fungal phytotoxin seiricardine A, obtained from Seiridium fungi, pathogen for cypress, has been determined by experimental measurements and theoretical simulations of chiroptical properties of three related methods, namely, Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD). Computational prediction by Density Functional Theory (DFT) of VCD spectra and by Time-dependent DFT (TDDFT) of ORD and ECD spectra allowed to assign (7R,8R,10S) AC to naturally occurring (+)-inuloxin A. In the case of compound (-)-seiricardine A, which lacks useful for the analysis UV-Vis absorption, and thus provides a hardly detectable ECD spectrum and quite low ORD values, an introduction of a suitable chromophore by chemical derivatization was performed. The corresponding derivative, 2-O-p-bromobenzoate ester, gave rise to an intense ECD spectrum and higher ORD and VCD values. The comparison of computed spectra with the experimental ones allowed to assign (1S,2R,3aS,4S,5R,7aS) AC to (-)-2-O-p-bromobenzoate ester of seiricardine A and then to (-)-seiricardine A. This study further supports a recent trend of concerted application of more than a single chiroptical technique toward an unambiguous assignment of AC of flexible and complex natural products. Moreover, the use of chemical derivatization, with insertion of suitable chromophoric moieties has allowed to treat also UV-Vis transparent molecules by ECD and ORD spectroscopies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vibrational, UV spectra, NBO, first order hyperpolarizability and HOMO-LUMO analysis of carvedilol

NASA Astrophysics Data System (ADS)

Swarnalatha, N.; Gunasekaran, S.; Nagarajan, M.; Srinivasan, S.; Sankari, G.; Ramkumaar, G. R.

2015-02-01

In this work, we have investigated experimentally and theoretically on the molecular structure, vibrational spectra, UV spectral analysis and NBO studies of cardio-protective drug carvedilol. The FT-Raman and FT-IR spectra for carvedilol in the solid phase have been recorded in the region 4000-100 cm-1 and 4000-400 cm-1 respectively. Theoretical calculations were performed by using density functional theory (DFT) method at B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p) basis set levels. The harmonic vibrational frequencies, the optimized geometric parameters have been interpreted and compared with the reported experimental values. The complete vibrational assignments were performed on the basis of potential energy distribution (PED) of the vibrational modes. The thermodynamic properties and molecular electrostatic potential surfaces of the molecule were constructed. The electronic absorption spectrum was recorded in the region 400-200 nm and electronic properties such as HOMO and LUMO energies were calculated. The stability of the molecule arising from hyper conjugative interactions and charge delocalization have been analyzed from natural bond orbital (NBO) analysis. The first order hyperpolarizability of the title molecule was also calculated. The photo stability of carvedilol under different storage conditions were analyzed using UV-Vis spectral technique.

Aerosol radiative effect in UV, VIS, NIR, and SW spectra under haze and high-humidity urban conditions

NASA Astrophysics Data System (ADS)

Zhang, Ming; Ma, Yingying; Gong, Wei; Wang, Lunche; Xia, Xiangao; Che, Huizheng; Hu, Bo; Liu, Boming

2017-10-01

Aerosol properties derived from sun-photometric observations at Wuhan during a haze period were analyzed and used as input in a radiative transfer model to calculate the aerosol radiative effect (ARE) in ultraviolet (UV), visible (VIS), near-infrared (NIR), and shortwave (SW) spectra. The results showed that the aerosol optical depth (AOD) at 440 nm increased from 0.32 under clear-air conditions to 0.85 during common haze and 1.39 during severe haze. An unusual inverse relationship was found between the Ångström exponent (AE) and AOD during the haze period at Wuhan. Under high-humidity conditions, the fine-mode median radius of aerosols increased from 0.113 μm to approximately 0.2-0.5 μm as a result of hygroscopic growth, which led to increases in the AOD and decreases in the AE simultaneously. These changes were responsible for the inverse relationship between AE and AOD at Wuhan. The surface ARE in the UV (AREUV), VIS (AREVIS), NIR (ARENIR), and SW (ARESW) spectra changed from -4.46, -25.37, -12.15, and -41.99 W/m2 under clear-air conditions to -9.48, -53.96, -29.81, and -93.25 W/m2 during common hazy days and -12.89, -80.16, -55.17, and -148.22 W/m2 during severe hazy days, respectively, and the percentages of AREUV, AREVIS, and ARENIR in ARESW changed from 11%, 61%, and 28%-9%, 54%, and 37%, respectively. Meanwhile, the ARE efficiencies (REE) in SW varied from -206.5 W/m2 under clear-air conditions to -152.94 W/m2 during the common haze period and -131.47 W/m2 during the severe haze period. The smallest decreasing rate of the REE in NIR was associated with the increase of ARENIR. The weakened REE values were related to the strong forward scattering and weak backward scattering of fine aerosol particles with increasing size resulting from hygroscopic growth, while the variation of the single scattering albedo showed less impact. Source region analysis by back trajectories and the concentration weighted trajectory (CWT) method showed that black carbon came from nearby regions with low trajectories, and the surrounding haze areas were major sources of fine-mode particles in the haze in Wuhan.

Grain Spectroscopy

NASA Technical Reports Server (NTRS)

Allamandola, L. J.

1992-01-01

Our fundamental knowledge of interstellar grain composition has grown substantially during the past two decades thanks to significant advances in two areas: astronomical infrared spectroscopy and laboratory astrophysics. The opening of the mid-infrared, the spectral range from 4000-400 cm(sup -1) (2.5-25 microns), to spectroscopic study has been critical to this progress because spectroscopy in this region reveals more about a materials molecular composition and structure than any other physical property. Infrared spectra which are diagnostic of interstellar grain composition fall into two categories: absorption spectra of the dense and diffuse interstellar media, and emission spectra from UV-Vis rich dusty regions. The former will be presented in some detail, with the latter only very briefly mentioned. This paper summarized what we have learned from these spectra and presents 'doorway' references into the literature. Detailed reviews of many aspects of interstellar dust are given.

FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: Vigabatrin

NASA Astrophysics Data System (ADS)

Edwin, Bismi; Joe, I. Hubert

2013-10-01

Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the Csbnd C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system.

Synthesis, physical properties and self-assembly behavior of azole-fused pyrene derivatives

NASA Astrophysics Data System (ADS)

Xiao, Jinchong; Xiao, Xuyu; Zhao, Yanlei; Wu, Bo; Liu, Zhenying; Zhang, Xuemin; Wang, Sujuan; Zhao, Xiaohui; Liu, Lei; Jiang, Li

2013-05-01

A novel selenadiazole-fused pyrene derivative PySe was successfully synthesized and characterized. Its single structure is almost planar and adopts a sandwich-herringbone packing model. The self-assembly behaviors based on compound PySe and its analogue thiadiazole-fused pyrene derivative PyS were studied in detail and the as-formed nanostructures were fully characterized by means of UV-vis absorption, emission spectra, X-ray diffraction, field emission SEM and TEM. We attribute the bathochromic shift absorption and emission spectra of PyS and PySe in aqueous solution to the formation of J-type aggregation. In addition, our investigation demonstrated that the shape and size of the as-prepared nanostructures could be tuned by different chalcogen analogues and the volume ratio of water to organic solvent.A novel selenadiazole-fused pyrene derivative PySe was successfully synthesized and characterized. Its single structure is almost planar and adopts a sandwich-herringbone packing model. The self-assembly behaviors based on compound PySe and its analogue thiadiazole-fused pyrene derivative PyS were studied in detail and the as-formed nanostructures were fully characterized by means of UV-vis absorption, emission spectra, X-ray diffraction, field emission SEM and TEM. We attribute the bathochromic shift absorption and emission spectra of PyS and PySe in aqueous solution to the formation of J-type aggregation. In addition, our investigation demonstrated that the shape and size of the as-prepared nanostructures could be tuned by different chalcogen analogues and the volume ratio of water to organic solvent. Electronic supplementary information (ESI) available: TGA analysis, spectra characterization data for compound 1, 2, 3 and X-ray crystallographic data for compound PySe (2, CIF). CCDC 917821. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3nr00523b

UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

PubMed

Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

2014-03-07

The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

Applications of UV/Vis Spectroscopy in Characterization and Catalytic Activity of Noble Metal Nanoparticles Fabricated in Responsive Polymer Microgels: A Review.

PubMed

Begum, Robina; Farooqi, Zahoor H; Naseem, Khalida; Ali, Faisal; Batool, Madeeha; Xiao, Jianliang; Irfan, Ahmad

2018-11-02

Noble metal nanoparticles loaded smart polymer microgels have gained much attention due to fascinating combination of their properties in a single system. These hybrid systems have been extensively used in biomedicines, photonics, and catalysis. Hybrid microgels are characterized by using various techniques but UV/Vis spectroscopy is an easily available technique for characterization of noble metal nanoparticles loaded microgels. This technique is widely used for determination of size and shape of metal nanoparticles. The tuning of optical properties of noble metal nanoparticles under various stimuli can be studied using UV/Vis spectroscopic method. Time course UV/Vis spectroscopy can also be used to monitor the kinetics of swelling and deswelling of microgels and hybrid microgels. Growth of metal nanoparticles in polymeric network or growth of polymeric network around metal nanoparticle core can be studied by using UV/Vis spectroscopy. This technique can also be used for investigation of various applications of hybrid materials in catalysis, photonics, and sensing. This tutorial review describes the uses of UV/Vis spectroscopy in characterization and catalytic applications of responsive hybrid microgels with respect to recent research progress in this area.

Vibrational spectra, UV and NMR, first order hyperpolarizability and HOMO-LUMO analysis of 2-amino-4-chloro-6-methylpyrimidine.

PubMed

Jayavarthanan, T; Sundaraganesan, N; Karabacak, M; Cinar, M; Kurt, M

2012-11-01

The solid phase FTIR and FT-Raman spectra of 2-amino-4-chloro-6-methylpyrimidine (2A4Cl6MP) have been recorded in the regions 400-4000 and 50-4,000 cm(-1), respectively. The spectra have been interpreted interms of fundamentals modes, combination and overtone bands. The structure of the molecule has been optimized and the structural characteristics have been determined by density functional theory (B3LYP) method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra have also been predicted from the calculated intensities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-Vis spectrum of the compound was recorded in the region 200-400 nm and the electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Nonlinear optical and thermodynamic properties were interpreted. All the calculated results were compared with the available experimental data of the title molecule. Copyright © 2012 Elsevier B.V. All rights reserved.

Facile and fast synthesis of SnS2 nanoparticles by pulsed laser ablation in liquid

NASA Astrophysics Data System (ADS)

Johny, J.; Sepulveda-Guzman, S.; Krishnan, B.; Avellaneda, D.; Shaji, S.

2018-03-01

Nanoparticles (NPs) of tin disulfide (SnS2) were synthesized using pulsed laser ablation in liquid (PLAL) technique. Effects of different liquid media and ablation wavelengths on the morphology and optical properties of the nanoparticles were studied. Nd: YAG laser wavelengths of 532 nm and 1064 nm (frequency 10 Hz and pulse width 10 ns) were used to irradiate SnS2 target immersed in liquid for the synthesis of SnS2 nanoparticles. Here PLAL was a fast synthesis technique, the ablation was only for 30 s. Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-vis absorption spectroscopy and photoluminescence spectroscopy were used to characterize the SnS2 NPs. TEM images showed that the liquid medium and laser wavelength influence the morphology of the NPs. SAED patterns and high resolution TEM (HRTEM) images confirmed the crystallinity of the particles. XRD and XPS analyses confirmed that SnS2 NPs were having exact crystalline structure and chemical states as that of the target. Raman analysis also supported the results obtained by XRD and XPS. Optical band gaps of the nanocolloids evaluated from their UV-vis absorption spectra were 2.4-3.05 eV. SnS2 NPs were having luminescence spectra in the blue-green region irrespective of the liquid media and ablation wavelength.

Studies on the interaction of BDE-47 and BDE-209 with acetylcholinesterase (AChE) based on the neurotoxicity through fluorescence, UV-vis spectra, and molecular docking.

PubMed

Wang, Shutao; Wu, Chuan; Liu, Zhisheng; You, Hong

2018-05-01

The neurotoxicity of polybrominated diphenyl ethers (PBDEs) has been of concern. Acetylcholinesterase (AChE) is a critical enzyme in the central and peripheral nervous system related to neurotoxicity. The interaction between BDE-47, BDE-209, and AChE was investigated through fluorescence and UV-vis spectra combined with molecular docking. Both BDE-47 and BDE-209 bound with AChE and changed the microenvironment of some amino acid residues, resulting in a change of AChE conformation. Hydrophobic interaction is the main binding force between BDE-47, BDE-209, and AChE, and electrostatic interaction exists according to the thermodynamic parameters of the interaction between them. A hydrophobic interaction of BDE-47-AChE and BDE-209-AChE has been confirmed through molecular docking to dominate the binding force. The binding constants of BDE-47-AChE and BDE-209-AChE were 4.2 × 10 4 and 4.1 × 10 4  L/mol, respectively, and the lowest binding energies of BDE-47-AChE and BDE-209-AChE were -7.8 and -5.9 kJ/mol, respectively. BDE-47 is more likely to bind with AChE than BED-209. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

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

Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in; Baby, C.; Gopalakrishnan, R.

2016-09-15

Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra establishedmore » the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.« less

White light generation by carbonyl based indole derivatives due to proton transfer: an efficient fluorescence sensor.

PubMed

Singla, Nidhi; Bhadram, Venkata Srinu; Narayana, Chandrabhas; Chowdhury, Papia

2013-04-04

The motivation of the present work is to understand the optical, chemical, and electrical aspects of the proton transfer mechanism of indole (I) and some carbonyl based indole derivatives: indole-3-carboxaldehyde (I3C) and indole-7-carboxaldehyde (I7C) for both powder form and their liquid solution. Structural information for indole derivatives (isolated molecule and in solution) is obtained with density functional theory (DFT) and time dependent DFT (TD-DFT) methods. Calculated transition energies are used to generate UV-vis, FTIR, Raman, and NMR spectra which are later verified with the experimental spectra. The occurrence of different conformers [cis (N(c)), trans (N(t)), and zwitterion (Z*)] have been interpreted by Mulliken charge, natural bond orbital (NBO) analysis, and polarization versus electric field (P-E loop) studies. (1)H and (13)C NMR and molecular vibrational frequencies of the fundamental modes established the stability of Nc due to the presence of intramolecular hydrogen bonding (IHB) in the ground state (S0). Computed/experimental UV-vis absorption/emission studies reveal the creation of new species: zwitterion (Z*) and anion (A*) in the excited state (S1) due to excited state intramolecular and intermolecular proton transfer (ESI(ra)PT and ESI(er)PT). Increased electrical conductivity (σ(ac)) with temperature and increased ferroelectric polarization at higher field verifies proton conduction in I7C.

Kr photoionized plasma induced by intense extreme ultraviolet pulses

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

Bartnik, A., E-mail: andrzej.bartnik@wat.edu.pl; Wachulak, P.; Fiedorowicz, H.

Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Krmore » plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.« less

Effect of side-chain structure of rigid polyimide dispersant on mechanical properties of single-walled carbon nanotube/cyanate ester composite.

PubMed

Yuan, Wei; Li, Weifeng; Mu, Yuguang; Chan-Park, Mary B

2011-05-01

Three kinds of polymer, polyimide without side-chain (PI), polyimide-graft-glyceryl 4-nonylphenyl ether (PI-GNE), and polyimide-graft-bisphenol A diglyceryl acrylate (PI-BDA), have been synthesized and used to disperse single-walled carbon nanotubes (SWNTs) and to improve the interfacial bonding between SWNTs and cyanate ester (CE) matrix. Visual observation, UV-vis-near-IR (UV-vis-NIR) spectra, and atomic force microscopy (AFM) images show that both PI-GNE and PI-BDA are highly effective at dispersing and debundling SWNTs in DMF, whereas PI is less effective. Interaction between SWNTs and PI, PI-GNE or PI-BDA was confirmed by computer simulation and Raman spectra. A series of CE-based composite films reinforced with different loadings of SWNTs, SWNTs/PI, SWNTs/PI-GNE and SWNTs/PI-BDA were prepared by solution casting. It was found that, because of the unique side-chain structure of PI-BDA, SWNTs/PI-BDA disperse better in CE matrix than do SWNTs/PI-GNE, SWNTs/PI, and SWNTs. As a result, SWNTs/PI-BDA/CE composites have the greatest improvement in mechanical properties of the materials tested. These results imply that the choice of side-chain on a dispersant is very important to the dispersion of SWNTs in matrix and the filler/matrix interfacial adhesion, which are two key requirements for achieving effective reinforcement.

Synthesis, crystal structure and interaction of L-valine Schiff base divanadium(V) complex containing a V2O3 core with DNA and BSA.

PubMed

Guo, Qiong; Li, Lianzhi; Dong, Jianfang; Liu, Hongyan; Xu, Tao; Li, Jinghong

2013-04-01

A divanadium(V) complex, [V2O3(o-van-val)2] (o-van-val=Schiff base derived from o-vanillin and L-valine), has been synthesized and structurally characterized. The crystal structure shows that both of the vanadium centers in the complex have a distorted octahedral coordination environment composed of tridentate Schiff base ligand. A V2O3 core in molecular structure adopts intermediate between cis and trans configuration with the O1V1⋯V1AO1A torsion angle 115.22 (28)° and the V1⋯V1A distance 3.455Å. The binding properties of the complex with calf thymus DNA (CT-DNA) have been investigated by UV-vis absorption, fluorescence, CD spectra and viscosity measurement. The results indicate that the complex binds to CT-DNA in non-classical intercalative mode. Meanwhile, the interaction of the complex with bovine serum albumin (BSA) has been studied by UV-vis absorption, fluorescence and CD spectra. Results indicated that the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process, and cause its conformational change. The calculated apparent binding constant Kb was 1.05×10(6)M(-1) and the binding site number n was 1.18. Copyright © 2013 Elsevier B.V. All rights reserved.

Water-soluble phosphine-protected Au9 clusters: Electronic structures and nuclearity conversion via phase transfer

NASA Astrophysics Data System (ADS)

Yao, Hiroshi; Tsubota, Shuhei

2017-08-01

In this article, isolation, exploration of electronic structures, and nuclearity conversion of water-soluble triphenylphosphine monosulfonate (TPPS)-protected nonagold (Au9) clusters are outlined. The Au9 clusters are obtained by the reduction of solutions containing TPPS and HAuCl4 and subsequent electrophoretic fractionation. Mass spectrometry and elemental analysis reveal the formation of [Au9(TPPS)8]5- nonagold cluster. UV-vis absorption and magnetic circular dichroism (MCD) spectra of aqueous [Au9(TPPS)8]5- are quite similar to those of [Au9(PPh3)8]3+ in organic solvent, so the solution-phase structures are likely similar for both systems. Simultaneous deconvolution analysis of absorption and MCD spectra demonstrates the presence of some weak electronic transitions that are essentially unresolved in the UV-vis absorption. Quantum chemical calculations for a model compound [Au9(pH3)8]3+ show that the possible (solution-phase) skeletal structure of the nonagold cluster has D2h core symmetry rather than C4-symmetrical centered crown conformation, which is known as the crystal form of the Au9 compound. Moreover, we find a new nuclearity conversion route from Au9 to Au8; that is, phase transfer of aqueous [Au9(TPPS)8]5- into chloroform using tetraoctylammonium bromide yields [Au8(TPPS)8]6- clusters in the absence of excess phosphine.

Kr photoionized plasma induced by intense extreme ultraviolet pulses

NASA Astrophysics Data System (ADS)

Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.

2016-04-01

Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Kr plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.

Substituent and solvent effects on the UV-vis absorption spectrum of the photoactive yellow protein chromophore.

PubMed

García-Prieto, F Fernández; Aguilar, M A; Galván, I Fdez; Muñoz-Losa, A; Olivares del Valle, F J; Sánchez, M L; Martín, M E

2015-05-28

Solvent effects on the UV-vis absorption spectra and molecular properties of four models of the photoactive yellow protein (PYP) chromophore have been studied with ASEP/MD, a sequential quantum mechanics/molecular mechanics method. The anionic trans-p-coumaric acid (pCA(-)), thioacid (pCTA(-)), methyl ester (pCMe(-)), and methyl thioester (pCTMe(-)) derivatives have been studied in gas phase and in water solution. We analyze the modifications introduced by the substitution of sulfur by oxygen atoms and hydrogen by methyl in the coumaryl tail. We have found some differences in the absorption spectra of oxy and thio derivatives that could shed light on the different photoisomerization paths followed by these compounds. In solution, the spectrum substantially changes with respect to that obtained in the gas phase. The n → π1* state is destabilized by a polar solvent like water, and it becomes the third excited state in solution displaying an important blue shift. Now, the π → π1* and π → π2* states mix, and we find contributions from both transitions in S1 and S2. The presence of the sulfur atom modulates the solvent effect and the first two excited states become practically degenerate for pCA(-) and pCMe(-) but moderately well-separated for pCTA(-) and pCTMe(-).

In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

PubMed

Alin, Jonas; Rubino, Maria; Auras, Rafael

2015-10-15

UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

UV absorbers for cellulosic apparels: A computational and experimental study

NASA Astrophysics Data System (ADS)

Sahar, Anum; Ali, Shaukat; Hussain, Tanveer; Irfan, Muhammad; Eliasson, Bertil; Iqbal, Javed

2018-01-01

Two triazine based Ultra Violet (UV) absorbers Sulfuric acid mono-(2-{4-[4-chloro-6-(4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino-phenylamino)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl}-ethyl) ester (1a) and 4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino}-2-[4-chloro-6-(2-sulfooxy-ethanesulfonyl)-[1,3,5]triazin-2-ylamino]-benzenesulfonic acid (2a) with different substituents were designed computationally. The influence of different substituents on the electrochemical properties and UV spectra of the absorbers was investigated. The presence of electron deficient unit in 1a to the molecular core significantly reduces the LUMO levels and energy gap. The designed absorbers were synthesized via condensation reaction and characterized by UV-Vis, FT-IR, MS studies. The performance of synthesized compounds as UV absorbers and their fastness properties were assessed by finishing the cotton fabric through exhaust method at different concentration and results appeared in good range.

Heparin Assisted Photochemical Synthesis of Gold Nanoparticles and Their Performance as SERS Substrates

PubMed Central

Rodríguez-Torres, Maria del Pilar; Díaz-Torres, Luis Armando; Romero-Servin, Sergio

2014-01-01

Reactive and pharmaceutical-grade heparins were used as biologically compatible reducing and stabilizing agents to photochemically synthesize colloidal gold nanoparticles. Aggregates and anisotropic shapes were obtained photochemically under UV black-light lamp irradiation (λ = 366 nm). Heparin-functionalized gold nanoparticles were characterized by Scanning Electron Microscopy and UV-Vis spectroscopy. The negatively charged colloids were used for the Surface Enhanced Raman Spectroscopy (SERS) analysis of differently charged analytes (dyes). Measurements of pH were taken to inspect how the acidity of the medium affects the colloid-analyte interaction. SERS spectra were taken by mixing the dyes and the colloidal solutions without further functionalization or addition of any aggregating agent. PMID:25342319

Optical study of plasma sprayed hydroxyapatite coatings deposited at different spray distance

NASA Astrophysics Data System (ADS)

Belka, R.; Kowalski, S.; Żórawski, W.

2017-08-01

Series of hydroxyapatite (HA) coatings deposited on titanium substrate at different spray (plasma gun to workpiece) distance were investigated. The optical methods as dark field confocal microscopy, Raman/PL and UV-VIS spectroscopy were used for study the influence of deposition process on structural degradation of HA precursor. The hydroxyl group concentration was investigated by study the OH mode intensity in the Raman spectra. Optical absorption coefficients at near UV region were analyzed by Diffuse Reflectance Spectroscopy. PL intensity observed during Raman measurement was also considered as relation to defects concentration and degradation level. It was confirmed the different gunsubstrate distance has a great impact on structure of deposited HA ceramics.

Modeling Optical Spectra of Large Organic Systems Using Real-Time Propagation of Semiempirical Effective Hamiltonians.

PubMed

Ghosh, Soumen; Andersen, Amity; Gagliardi, Laura; Cramer, Christopher J; Govind, Niranjan

2017-09-12

We present an implementation of a time-dependent semiempirical method (INDO/S) in NWChem using real-time (RT) propagation to address, in principle, the entire spectrum of valence electronic excitations. Adopting this model, we study the UV/vis spectra of medium-sized systems such as P3B2 and f-coronene, and in addition much larger systems such as ubiquitin in the gas phase and the betanin chromophore in the presence of two explicit solvents (water and methanol). RT-INDO/S provides qualitatively and often quantitatively accurate results when compared with RT- TDDFT or experimental spectra. Even though we only consider the INDO/S Hamiltonian in this work, our implementation provides a framework for performing electron dynamics in large systems using semiempirical Hartree-Fock Hamiltonians in general.

Substituent and solvent effects on the UV/Vis absorption spectra of 5-(4-substituted arylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridones

NASA Astrophysics Data System (ADS)

Ušćumlić, Gordana S.; Mijin, Dusanˇ Z. ˇ; Valentić, Nataša V.; Vajs, Vlatka V.; Sušić, Biljana M.

2004-10-01

Absorption spectra of ten 5-(4-substituted arylazo)-6-hydroxy-4-methyl-3-cyano-2-pyridones have been recorded in fifteen solvents in the range 200-600 nm. The substituents at the phenyl nucleus are as follows: OH, OCH 3, CH 3, C 2H 5, H, Cl, Br, I, COOH and NO 2. The effects of substituents on the absorption spectra of investigated compounds are interpreted by correlation of absorption frequencies with simple Hammett equation. The effects of solvent polarity and solvent/solute hydrogen bonding interactions are analyzed by means of linear solvation energy relationships concept proposed by Kamlet and Taft. The azo-hydrazone tuatomeric equilibration is found to depend upon substituents as well as on solvents.

Spectroscopic identification of rare earth elements in phosphate glass

NASA Astrophysics Data System (ADS)

Devangad, Praveen; Tamboli, Maktum; Muhammed Shameem, K. M.; Nayak, Rajesh; Patil, Ajeetkumar; Unnikrishnan, V. K.; Santhosh, C.; Kumar, G. A.

2018-01-01

In this work, rare earth-doped phosphate glasses were synthesized and characterized using three different spectroscopic techniques. The absorption spectra of the prepared praseodymium (Pr) and samarium (Sm) doped glasses, recorded by a UV-VIS-NIR spectrophotometer, show the characteristic absorption bands of these elements. To confirm this inference, laser-induced fluorescence spectra of Pr and Sm were obtained at a laser excitation of 442 nm. Their emission bands are reported here. The elemental analysis of these samples was carried out using a laser-induced breakdown spectroscopy (LIBS) system. Characteristic emission lines of Pr and Sm have been identified and reported by the recorded LIBS spectra of glass samples. Results prove that using these three complimentary spectroscopic techniques (absorption, fluorescence and LIBS), we can meaningfully characterize rare earth-doped glass samples.

Using DNA to Design Plasmonic Metamaterials with Tunable Optical Properties

DTIC Science & Technology

2014-01-01

using both UV –vis spectroscopy for ensemble measurements and optical micro- spectrophotometry for individual superlattice electric fi elds at...lated data). The red-shift seen between the micro-spectropho- tometer measurements (Figure 3 b) and the UV –vis ensemble measurements (Figure 3 a...the measurements. Using UV –vis spectroscopy ( Figure 3 a), red- shifting of the superlattices’ bulk LSPR with decreased nano- particle spacing is

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

Wang, Peigong; Fan, Caimei, E-mail: fancm@163.com; Wang, Yawen

Graphical abstract: The cubic phase BaTiO{sub 3} nanoparticles can be obtained at 600 °C and changed into tetragonal phase at 900 °C by a dual chelating sol–gel method, and the photocatalytic activities of the photocatalysts calcined at different temperatures were investigated by the removal of humic acid (HA) from water under UV light irradiation. Highlights: ► The humic acid in water was firstly degradated by BaTiO{sub 3} photocatalyst. ► The cubic BaTiO{sub 3} was obtained and changed into tetragonal phase at lower temperature. ► The chelating agents had an important influence on the phase formation of BaTiO{sub 3}. ► Themore » tetragonal phase BaTiO{sub 3} calcined at 900 °C exhibited higher photocatalytic activity under UV irradiation. -- Abstract: In this paper, a dual chelating sol–gel method was used to synthesize BaTiO{sub 3} nanoparticles by using acetylacetone and citric acid as chelating agents. The samples calcined at different temperatures were analyzed by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectra (UV–vis). The results indicated that cubic phase BaTiO{sub 3} nanoparticles about 19.6 nm can be obtained at 600 °C and changed into tetragonal phase at 900 °C about 97.1 nm. All the BaTiO{sub 3} nanoparticles showed effective photocatalytic activities on the removal of humic acid (HA) under UV light irradiation. A comparison of single (acetylacetone or citric acid) and dual chelating (acetylacetone and citric acid) synthetic processes was also studied and the results demonstrated that the dual chelating agents indeed reduced phase transformation temperature from cubic to tetragonal BaTiO{sub 3}.« less

The Use of UV-Visible Reflectance Spectroscopy as an Objective Tool to Evaluate Pearl Quality

PubMed Central

Agatonovic-Kustrin, Snezana; Morton, David W.

2012-01-01

Assessing the quality of pearls involves the use of various tools and methods, which are mainly visual and often quite subjective. Pearls are normally classified by origin and are then graded by luster, nacre thickness, surface quality, size, color and shape. The aim of this study was to investigate the capacity of Artificial Neural Networks (ANNs) to classify and estimate the quality of 27 different pearls from their UV-Visible spectra. Due to the opaque nature of pearls, spectroscopy measurements were performed using the Diffuse Reflectance UV-Visible spectroscopy technique. The spectra were acquired at two different locations on each pearl sample in order to assess surface homogeneity. The spectral data (inputs) were smoothed to reduce the noise, fed into ANNs and correlated to the pearl’s quality/grading criteria (outputs). The developed ANNs were successful in predicting pearl type, mollusk growing species, possible luster and color enhancing, donor condition/type, recipient/host color, donor color, pearl luster, pearl color, origin. The results of this study shows that the developed UV-Vis spectroscopy-ANN method could be used as a more objective method of assessing pearl quality (grading) and may become a valuable tool for the pearl grading industry. PMID:22851919

Obtaining titanium dioxide nanoparticles with spherical shape and antimicrobial properties using M. citrifolia leaves extract by hydrothermal method.

PubMed

M, Sundrarajan; K, Bama; M, Bhavani; S, Jegatheeswaran; S, Ambika; A, Sangili; P, Nithya; R, Sumathi

2017-06-01

In this work, we synthesized titanium dioxide (TiO 2 ) nanoparticles using leaf extract of Morinda citrifolia (M. citrifolia) by the advanced hydrothermal method. The synthesized TiO 2 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transmission infrared (FT-IR), Ultraviolet-visible diffuse reflectance (UV-Vis DRS), Ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM with EDX) techniques. The XRD major peak at 27.3° corresponds to the (110) lattice plane of tetragonal rutile TiO 2 phase and average crystalline size of nanoparticles is 10nm. The FT-IR result confirmed that TiO 2 nanoparticles and the presences of very few amount of anthraquinone and phenolic compounds of the leaf extract. The obtained nanoparticles were also characterized by UV-Vis DRS absorption spectroscopy and an intense band at 423nm clearly reveals the formation of nanoparticles. SEM images with EDX spectra clearly reveal the size of the nanoparticles, between 15 and 19nm in excellent quasi-spherical shape, by virtue of stabilization (capping) agent. The presence of elements-titanium and oxygen was verified with EDX spectrum. Furthermore, the inhibitory activity of green synthesized TiO 2 nanoparticles was tested against human pathogens like Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger by the agar well-diffusion method. The TiO 2 nanoparticles exhibited superior antimicrobial activity against Gram-positive bacteria, demonstrating their antimicrobial value against pathogenic diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Post-discharge gas composition of a large-gap DBD in humid air by UV-Vis absorption spectroscopy

NASA Astrophysics Data System (ADS)

Moiseev, T.; Misra, N. N.; Patil, S.; Cullen, P. J.; Bourke, P.; Keener, K. M.; Mosnier, J. P.

2014-12-01

Large gap dielectric barrier discharges (DBD) provide non-thermal, non-equilibrium plasmas that can generate specific gas chemistry with enhanced bactericidal effects when working in humid air. The present study investigates the post-discharge gas composition of such plasmas operated in humid air using UV-Vis (200-800 nm) absorption spectroscopy. Absorbance spectra have been de-convoluted using direct deconvolution and iterative methods and results are correlated to the DBD electrical parameters. The high-voltage (56 and 70 kV rms) DBD plasma generated at 50 Hz frequency in a closed container over a 20 mm gap in air with relative humidity (RH) of 5-70% has been characterized by I-V and capacitive methods. The post-discharge gas composition at each RH is assessed by UV-Vis absorption spectroscopy for plasma exposure times of 15-120 s. The concentration of ozone and nitrogen oxides (O3, NO2, NO3, N2O4) increases with plasma exposure time but a strong decrease in [O3] levels is obtained with increase in RH. The decrease in [O3] and an abundance of nitrogen oxides is ascribed to high specific power densities in the closed container and to increasing RH levels. The absorbance residual following deconvolution shows a strong band at 230-270 nm consistent with the presence of pernitric acid (HNO4) and other HNOx (x = 1, 3) species. Humid air large gap DBD plasmas in closed containers generate along with O3, high levels of nitrogen oxides and HNOx (x = 1, 4) acids leading to increased bactericidal rates.

Surface-enhanced Raman scattering studies of the reduction of p-nitroaniline catalyzed by a nanonized Ag porous-glass hybrid composite.

PubMed

Huang, Genin Gary; Sou, Nga-Lai; Hung, Mei-Jou

2016-09-05

Nanonized noble metal composites have been known for their excellent catalytic properties. However, the mechanism and intermediates formed on the surfaces of nanocatalysts during catalysis are speculated with mostly insufficient evidence. In this study, to obtain further understanding of the roles of noble metal nanocatalysts in a catalytic reaction, surface-enhanced Raman scattering (SERS) was used to monitor the surfaces of silver (Ag) nanocatalysts. Furthermore, UV-Vis spectrometry was used to trace the concentration variations of reactants and products in bulk solutions, thereby correlating the variations of the Ag nanocatalyst surfaces with those in the bulk solutions. Nanonized Ag porous-glass hybrid composites were prepared by reducing naked Ag nanoparticles on porous-glass filter plates and were used as catalysts for nitroanilines reduction. The complete process was monitored using SERS and UV-Vis spectrometry simultaneously. The results indicated that the reactant and product molecules adsorbed on the Ag nanocatalysts can reach equilibrium, and the equilibrium is affected by the reaction conditions, including reducing agent concentration, pH of the reaction system, and temperature. In addition, the reduction of reactants in the bulk solutions is also related to the behavior of Ag nanocatalyst surfaces. Furthermore, Ag nanocatalysts can act as electron relays even if their surfaces are occupied by reactants and products. Analyzing the collected SERS and UV-Vis spectra can provide a new insight into Ag nanoparticle catalysis, and the role of Ag nanocatalysts can be further comprehended. Copyright © 2016 Elsevier B.V. All rights reserved.

X-ray structure determination, Hirshfeld surface analysis, spectroscopic (FT-IR, NMR, UV-Vis, fluorescence), non-linear optical properties, Fukui function and chemical activity of 4‧-(2,4-dimethoxyphenyl)-2,2‧:6‧,2″-terpyridine

NASA Astrophysics Data System (ADS)

Demircioğlu, Zeynep; Yeşil, Ahmet Emin; Altun, Mehmet; Bal-Demirci, Tülay; Özdemir, Namık

2018-06-01

The compound 4‧-(2,4-dimethoxyphenyl)-2,2‧:6‧,2″-terpyridine (Mtpyr) was synthesized and investigated using X-ray single crystal structure determination, combined with Hirshfeld topology analysis of the molecular packing. In addition, Mtpyr was characterized by experimental and theoretical FT-IR, UV-Vis, 1H NMR, 13C NMR and fluorescence emission spectra. The optimized molecular geometry (bond length, bond angle, torsion angle), the complete vibrational frequency and all other theoretical computations were calculated by using density functional theory (DFT) B3LYP method with the help of 6-311++G(d,p) basis set. From the recorded UV-Vis spectrum, the electronic properties such as excitation energies, wavelength and oscillator strength are evaluated by TD-DFT in chloroform solution. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge-independent atomic orbital (GIAO) method and compared with experimental results. The calculated HOMO-LUMO band gap energies confirmed that charge transfer and chemical stability within the molecule. The hyperconjugative interaction energy E(2) and electron densities of donor (i) and acceptor (j) bonds were calculated using natural bond orbital (NBO) analysis. Besides Mulliken and natural population charges (NPA), non-linear optic properties (NLO), Fukui Function analysis, molecular electrostatic potential (MEP) were also computed which helps to identifying the electrophilic/nucleophilic nature.

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes

NASA Astrophysics Data System (ADS)

Was-Gubala, Jolanta; Starczak, Roza

2015-05-01

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800 nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye.

Nondestructive identification of dye mixtures in polyester and cotton fibers using raman spectroscopy and ultraviolet-visible (UV-Vis) microspectrophotometry.

PubMed

Was-Gubala, Jolanta; Starczak, Roza

2015-01-01

Presented in this paper is an assessment of the applicability of Raman spectroscopy and microspectrophotometry (MSP) in visible and ultraviolet light (UV-Vis) in the examination of textile fibers dyed with mixtures of synthetic dyes. Fragments of single polyester fibers, stained with ternary mixtures of disperse dyes in small mass concentrations, and fragments of single cotton fibers, dyed with binary or ternary mixtures of reactive dyes, were subjected to the study. Three types of excitation sources, 514, 633, and 785 nm, were used during Raman examinations, while the MSP study was conducted in the 200 to 800 nm range. The results indicate that the capabilities for discernment of dye mixtures are similar in the spectroscopic methods that were employed. Both methods have a limited capacity to distinguish slightly dyed polyester fiber; additionally, it was found that Raman spectroscopy enables identification of primarily the major components in dye mixtures. The best results, in terms of the quality of Raman spectra, were obtained using an excitation source from the near infrared. MSP studies led to the conclusion that polyester testing should be carried out in the range above 310 nm, while for cotton fibers there is no limitation or restriction of the applied range. Also, MSP UV-Vis showed limited possibilities for discriminatory analysis of cotton fibers dyed with a mixture of reactive dyes, where the ratio of the concentration of the main dye used in the dyeing process to minor dye was higher than four. The results presented have practical applications in forensic studies, inter alia.

Monitoring Time-Dependent Formation of Oligomers and Brown Carbon in Reactions of Glycolaldehyde, Methylglyoxal, and Amines

NASA Astrophysics Data System (ADS)

Espelien, B.; Galloway, M. M.; De Haan, D. O.

2012-12-01

Authors: Brenna Espelien, Melissa Galloway, and David De Haan The brown carbon components of atmospheric aerosol exhibit strong UV absorbance with a featureless 'tail' that extends into the visible range. Recent work has shown that brown carbon (or HULIS) is formed at least in part by aqueous-phase chemical reactions in the atmosphere. Reactions between aldehydes (such as glycolaldehyde and methylglyoxal) and amines create brown products that have similar light-absorbing spectra as HULIS extracted from atmospheric aerosol. However, the structures of these products have not been well-characterized. Bulk-phase reactions were monitored using LCMS and UV-Vis spectroscopy over a period of 2-3 weeks to see what products formed, whether oligomerization is occurring, and how this correlates with the development of absorbance peaks in the visible range. UV-Vis data shows that these reactions generally take several days to reach maximum absorbance in the visible range. For the glycolaldehyde/glycine reaction, the appearance of a strong absorber at about 400 nm correlated with the appearance of high-mass products at m/z 227, 363, 393, and 431. Additional reactions between aldehydes and amines that quickly produce brown products are being studied. We suggest that imine oligomers are major products of these reactions.

Combined micro-Raman/UV-visible/fluorescence spectrometer for high-throughput analysis of microsamples.

PubMed

Noh, Jermim; Suh, Yung Doug; Park, Yong Ki; Jin, Seung Min; Kim, Soo Ho; Woo, Seong Ihl

2007-07-01

Combined micro-Raman/UV-visible (vis)/fluorescence spectroscopy system, which can evaluate an integrated array of more than 10,000 microsamples with a minimuma size of 5 microm within a few hours, has been developed for the first time. The array of microsamples is positioned on a computer-controlled XY translation microstage with a spatial resolution of 1 mum so that the spectra can be mapped with micron precision. Micro-Raman spectrometers have a high spectral resolution of about 2 cm(-1) over the wave number range of 150-3900 cm(-1), while UV-vis and fluorescence spectrometers have high spectral resolutions of 0.4 and 0.1 nm over the wavelength range of 190-900 nm, respectively. In particular, the signal-to-noise ratio of the micro-Raman spectroscopy has been improved by using a holographic Raman grating and a liquid-nitrogen-cooled charge-coupled device detector. The performance of the combined spectroscopy system has been demonstrated by the high-throughput screening of a combinatorial ferroelectric (i.e., BaTi(x)Zr(1-x)O(3)) library. This system makes possible the structure analysis of various materials including ferroelectrics, catalysts, phosphors, polymers, alloys, and so on for the development of novel materials and the ultrasensitive detection of trace amounts of pharmaceuticals and diagnostic agents.

Generation and characterization of highly strained dibenzotetrakisdehydro[12]- and dibenzopentakisdehydro[14]annulenes.

PubMed

Hisaki, Ichiro; Eda, Takeshi; Sonoda, Motohiro; Niino, Hiroyuki; Sato, Tadatake; Wakabayashi, Tomonari; Tobe, Yoshito

2005-03-04

To generate dibenzotetrakisdehydro[12]- and dibenzopentakisdehydro[14]annulenes ([12]- and [14]DBAs) having a highly deformed triyne moiety, [4.3.2]propellatriene-anneleted dehydro[12]- and dehydro[14]annulenes were prepared as their precursors. UV irradiation of the precursors resulted in the photochemical [2 + 2] cycloreversion to generate the strained [12]- and [14]DBAs, respectively. The [12]DBA was not detected by 1H NMR spectroscopy, but it was intercepted as Diels-Alder adducts in solution, suggesting its intermediacy. Its spectroscopic characterization was successfully carried out by UV-vis spectroscopy in a 2-methyltetrahydrofuran (MTHF) glass matrix at 77 K and by FT-IR spectroscopy in an argon matrix at 20 K. On the other hand, the [14]DBA was stable enough for observation by 1H and 13C NMR spectra in solution, though it was not isolated because of the low efficiency of the cycloreversion. The [14]DBA was also characterized by interception as Diels-Alder adducts in solution and by UV-vis spectroscopy in a MTHF glass matrix at 77 K. The kinetic stabilities of the DBAs are compared with the related dehydrobenzoannulenes with respect to the topology of the pi-systems. In addition, the tropicity of the [14]DBA is discussed based on its experimental and theoretical 1H NMR chemical shifts.

Pseudo-enantiomeric chiral components and formation of the helical micro- and nanostructures in charge-transfer complexes

NASA Astrophysics Data System (ADS)

Langer, Jerzy J.; Hreczycho, Grzegorz

2018-03-01

Helical organic micro- and nanostructures are formed by a charge-transfer complex, cinchonidine-TCNQ. These unusual forms result from the chirality, the steric structure and specific interactions of cinchonidine molecules. These materials are semiconductors (10-4 S cm-1), with the typical absorption spectra in IR and UV-vis, but also have a characteristic of CD spectrum. Surprisingly, conductive micro and nano helices are not formed in pseudo-enantiomeric cinchonine, i.e. the complex of cinchonine and TCNQ.

Curcumin based chemosensor for selective detection of fluoride and cyanide anions in aqueous media.

PubMed

Ponnuvel, Kandasamy; Santhiya, Kuppusamy; Padmini, Vediappen

2016-11-30

The conjugate N,N-dimethyl curcumin analogue fluorophore dye 1 has been synthesized and its performance as a sensor was demonstrated. As a fluoride and cyanide sensor it enabled visual detection, and showed changes in UV-vis and fluorescence spectra in the presence of fluoride and cyanide ions in aqueous medium. The Job's plot indicated that the formation of a complex between dye-1 fluoride ions has a 1 : 1 stoichiometric ratio.

Electron beam irradiation for biological decontamination of Spirulina platensis

NASA Astrophysics Data System (ADS)

Brasoveanu, Mirela; Nemtanu, Monica; Minea, R.; Grecu, Maria Nicoleta; Mazilu, Elena; Radulescu, Nora

2005-10-01

The Cyanobacterium Spirulina is commercialized for its use in health foods and for therapeutic purposes due to its valuable constituents particularly proteins and vitamins. The aim of the paper is to study the Spirulina platensis behaviour when it is electron beam irradiated for biological decontamination. Microbial load, antioxidant activity, enzymatic inhibition, electron spin resonance (ESR) and UV-Vis spectra were measured for doses up to 80 kGy. The results were correlated with doses in order to find where decontamination is efficient, keeping the Spirulina qualities.

Preparation and characterization of the nanoporous ultrathin multilayer films based on molybdenum polyoxometalate (Mo 38) n

NASA Astrophysics Data System (ADS)

Wang, L.; Jiang, M.; Wang, E. B.; Duan, L. Y.; Hao, N.; Lan, Y.; Xu, L.; Li, Z.

2003-11-01

Ultrathin multilayer films of the wheel-shaped molybdenum polyoxometalate cluster (Mo 38) n and poly(allylamine hydrochloride)(PAH) have been prepared by the layer-by-layer (LbL) self-assembly method. The ((Mo 38) n/PAH) m multilayer films have been characterized by X-ray photoelectron spectra (XPS) and atomic force microscopy (AFM). UV-VIS measurements reveal regular film growth with each (Mo 38) n adsorption. The electrochemistry behavior of the film at room temperature was investigated.

Light-triggered self-assembly of triarylamine-based nanospheres

NASA Astrophysics Data System (ADS)

Moulin, Emilie; Niess, Frédéric; Fuks, Gad; Jouault, Nicolas; Buhler, Eric; Giuseppone, Nicolas

2012-10-01

Tailored triarylamine units modified with terpyridine ligands were coordinated to Zn2+ ions and characterized as discrete dimeric entities. Interestingly, when these complexes were subsequently irradiated with simple visible light in chloroform, they readily self-assembled into monodisperse spheres with a mean diameter of 160 nm.Tailored triarylamine units modified with terpyridine ligands were coordinated to Zn2+ ions and characterized as discrete dimeric entities. Interestingly, when these complexes were subsequently irradiated with simple visible light in chloroform, they readily self-assembled into monodisperse spheres with a mean diameter of 160 nm. Electronic supplementary information (ESI) available: Synthetic procedures and products' characterization (2-4 and 6-9). 1H NMR titration of compound 6 by Zn(OTf)2 to form complex 7. Kinetic measurements by UV-Vis-NIR spectroscopy. Transmission electron microscopy imaging for complexes 8 and 9. UV-Vis-NIR for an Fe2+ analogue of complex 7. Dynamic light scattering and time autocorrelation function for self-assembly of complexes 7-9. Copies of 1H and 13C NMR spectra for compounds 2-4 and 6. See DOI: 10.1039/c2nr32168h

Evaluation of Biologically Active Compounds from Calendula officinalis Flowers using Spectrophotometry

PubMed Central

2012-01-01

Background This study aimed to quantify the active biological compounds in C. officinalis flowers. Based on the active principles and biological properties of marigolds flowers reported in the literature, we sought to obtain and characterize the molecular composition of extracts prepared using different solvents. The antioxidant capacities of extracts were assessed by using spectrophotometry to measure both absorbance of the colorimetric free radical scavenger 2,2-diphenyl-1-picrylhydrazyl (DPPH) as well as the total antioxidant potential, using the ferric reducing power (FRAP) assay. Results Spectrophotometric assays in the ultraviolet-visible (UV-VIS) region enabled identification and characterization of the full range of phenolic and flavonoids acids, and high-performance liquid chromatography (HPLC) was used to identify and quantify phenolic compounds (depending on the method of extraction). Methanol ensured more efficient extraction of flavonoids than the other solvents tested. Antioxidant activity in methanolic extracts was correlated with the polyphenol content. Conclusions The UV-VIS spectra of assimilator pigments (e.g. chlorophylls), polyphenols and flavonoids extracted from the C. officinalis flowers consisted in quantitative evaluation of compounds which absorb to wavelengths broader than 360 nm. PMID:22540963

TiO2-PANI/Cork composite: A new floating photocatalyst for the treatment of organic pollutants under sunlight irradiation.

PubMed

Sboui, Mouheb; Nsib, Mohamed Faouzi; Rayes, Ali; Swaminathan, Meenakshisundaram; Houas, Ammar

2017-10-01

A novel photocatalyst based on TiO 2 -PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline (PANI)-modified TiO 2 on cork. The TiO 2 -PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (UV-vis DRS) and the Brunauer-Emmett-Teller (BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO 2 -PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency. Copyright © 2017. Published by Elsevier B.V.

Preparation of narrow dispersity gold nanorods by asymmetrical flow field-flow fractionation and investigation of surface plasmon resonance.

PubMed

Runyon, J Ray; Goering, Adam; Yong, Ken-Tye; Williams, S Kim Ratanathanawongs

2013-01-15

The development of an asymmetrical field-flow fractionation (AsFlFFF) method for separating gold nanorods (GNR) is reported. Collected fractions containing GNR subpopulations with aspect ratios, sizes, and shapes which are more narrowly dispersed than the original population were further characterized by UV-vis spectroscopy and transmission electron microscopy. This ability to obtain different sizes and shapes of nanoparticles enabled the evaluation of a new approach to estimating the retention time and hydrodynamic size of nanorods and the investigation of GNR optical properties at a previously unattainable level of detail. Experimental results demonstrate that the longitudinal surface plasmon absorption maximum of GNRs is correlated with the effective particle radius in addition to the aspect ratio. This may account for some of the variabilities reported in published empirical data from different research groups and supports reports of simulated absorption spectra of GNRs of different physical dimensions. The use of AsFlFFF with dual UV-vis detection to rapidly assess relative changes in GNR subpopulations was demonstrated for irregularly shaped gold nanoparticles formed at different synthesis temperatures.

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

NASA Astrophysics Data System (ADS)

Xing, Weinan; Ni, Liang; Huo, Pengwei; Lu, Ziyang; Liu, Xinlin; Luo, Yingying; Yan, Yongsheng

2012-10-01

A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

[Effects of annealing temperature on the structure and optical properties of ZnMgO films prepared by atom layer deposition].

PubMed

Sun, Dong-Xiao; Li, Jin-Hua; Fang, Xuan; Chen, Xin-Ying; Fang, Fang; Chu, Xue-Ying; Wei, Zhi-Peng; Wang, Xiao-Hua

2014-07-01

In the present paper, we report the research on the effects of annealing temperature on the crystal quality and optical properties of ZnMgO films deposited by atom layer deposition(ALD). ZnMgO films were prepared on quartz substrates by ALD and then some of the samples were treated in air ambient at different annealing temperature. The effects of annealing temperature on the crystal quality and optical properties of ZnMgO films were characterized by X-ray diffraction (XRD), photoluminescence (PL) and ultraviolet-visible (UV-Vis) absorption spectra. The XRD results showed that the crystal quality of ZnMgO films was significantly improved when the annealing temperature was 600 degrees C, meanwhile the intensity of(100) diffraction peak was the strongest. Combination of PL and UV-Vis absorption measurements showed that it can strongly promote the Mg content increasing in ZnMgO films and increase the band gap of films. So the results illustrate that suitable annealing temperature can effectively improve the crystal quality and optical properties of ZnMgO films.

The Effect of Titanium Tetrahedral Coordination of Silica-Titania Catalyst on the Physical Properties of Biodiesel

NASA Astrophysics Data System (ADS)

Nizar, U. K.; Hidayatul, J.; Sundari, R.; Bahrizal, B.; Amran, A.; Putra, A.; Latisma DJ, L.; Dewata, I.

2018-04-01

This study investigates the correlation of the number of titanium tetrahedral coordination and biodiesel production. The solid-state method has been used to synthesis of silica-titania catalyst for biodiesel production, which the precursors, i.e. silica and titania commercials were heated in the temperature range of 450 - 550°C. The characterization of the prepared silica-titania has been studied by FTIR and DR UV-Vis in order to identify and calculate the presence of titanium tetrahedral coordination in silica-titania catalyst. A very small peak at around 950 cm-1 indicated the presence of titanium tetrahedral coordination through Si–O–Ti bonds. Deconvolution of DR UV-Vis spectra showed the coordination of titanium in silica-titania is more octahedral. However, the number of titanium tetrahedral coordination of the prepared silica-titania is found higher than that of TiO2 commercial. The increasing of titanium tetrahedral fraction in silica-titania affects the physical properties of biodiesel in terms of boiling point, viscosity and density, which is produced by the reaction of methanol and palm oil.

Structural and optical properties of chromium doped zinc oxide nanoparticles synthesized by sol-gel method

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

Naqvi, Syed Mohd. Adnan, E-mail: adiaks2004@yahoo.co.in; Irshad, Kashif, E-mail: alig.kashif@gmail.com; Soleimani, Hassan, E-mail: hassan.soleimani@petronas.com.my, E-mail: noorhana-yahya@petronas.com.my

2014-10-24

Nanosized Cr-doped ZnO nano particles were synthesized by facile sol-gel auto combustion method. The structural and optical properties of Cr-doped ZnO nanoparticles have been investigated by XRD and UV-Vis spectroscopy at room temperature for 0% to 8% concentration. X-ray diffraction analysis reveals that the Cr-doped ZnO crystallizes in a single phase polycrystalline nature with wurtzite lattice. With every % of doping, the peaks are shifting scarcely and doping of Cr is possible up to 7%. After that, the last peak vanishes, that signifies its structure is transmuted from 8% doping. The average crystallite size decreases with increase in Cr concentrationmore » (i.e. 28.9 nm for 0% to 25.8 nm for 8%). The UV-Vis spectra of the nanoparticles betoken an incrementation in the band gap energy from 3.401, 3.415, 3.431, 3.437,3.453, 3.514,3.521, 3.530 and 3.538 eV respectively, for 0,1, 2, 3, 4, 5, 6, 7 and 8 % doping concentration.« less

Multi-technique approach for qualitative and quantitative characterization of furazidin degradation kinetics under alkaline conditions.

PubMed

Bērziņš, Kārlis; Kons, Artis; Grante, Ilze; Dzabijeva, Diana; Nakurte, Ilva; Actiņš, Andris

2016-09-10

Degradation of drug furazidin was studied under different conditions of environmental pH (11-13) and temperature (30-60°C). The novel approach of hybrid hard- and soft-multivariate curve resolution-alternating least squares (HS-MCR-ALS) method was applied to UV-vis spectral data to determine a valid kinetic model and kinetic parameters of the degradation process. The system was found to be comprised of three main species and best characterized by two consecutive first-order reactions. Furazidin degradation rate was found to be highly dependent on the applied environmental conditions, showing more prominent differences between both degradation steps towards higher pH and temperature. Complimentary qualitative analysis of the degradation process was carried out using HPLC-DAD-TOF-MS. Based on the obtained chromatographic and mass spectrometric results, as well as additional computational analysis of the species (theoretical UV-vis spectra calculations utilizing TD-DFT methodology), the operating degradation mechanism was proposed to include formation of a 5-hydroxyfuran derivative, followed by complete hydrolysis of furazidin hydantoin ring. Copyright © 2016 Elsevier B.V. All rights reserved.

Ion beam radiation effects on natural halite crystals

NASA Astrophysics Data System (ADS)

Arun, T.; Ram, S. S.; Karthikeyan, B.; Ranjith, P.; Ray, D. K.; Rout, B.; Krishna, J. B. M.; Sengupta, Pranesh; Parlapalli, Venkata Satyam

2017-10-01

Halites are one of the interesting material due to its color variations. Natural halites whose color ranges from transparent to dark blue were studied by UV-VIS and Raman spectroscopy. The halite crystals were irradiated with 3 MeV proton micro-beam (∼20 μm beam width with ∼80 PA beam current) for 10 and 90 min to study the radiation damage. After 10 mins of irradiation, small spot developed on the surface of transparent halite crystal whereas after 90 mins of irradiation the spot spread inside the bulk leading to a brown coloration (20 μm initial size to ∼2.0 mm final size). The irradiated portion and the un-irradiated portion of the halites was characterized by Raman spectroscopic technique. The variation in the population density was observed from the UV-Vis spectra. The change in the Raman band intensities was observed for transparent, blue colored and proton beam irradiation halites. Such variation of spectroscopic characteristics due to proton irradiation suggests that the halite can be used for the radiation monitoring.

Morphological and optoelectronic characteristics of nanocomposites comprising graphene nanosheets and poly(3-hexylthiophene).

PubMed

Chang, Yo-Wei; Yu, Shiau-Wei; Liu, Cheng-Hao; Tsiang, Raymond Chien-Chao

2010-10-01

P3HT/graphene nanocomposite was prepared via in-situ reduction of exfoliated graphite oxide in the P3HT polymer matrix, where the exfoliated graphite oxide was formed beforehand via the oxidation of graphite via the Hummers method. The oxidation reaction not only imparts functional groups, such as C=O, C-OH, and C-O-C, to graphite but also causes exfoliation of the resulting graphite oxide. The functional groups render graphite oxide an additional, lower thermal degradation temperature (T(d)) and the exfoliation shifts the XRD pattern towards a much smaller angle. The oxidation of graphite into graphite oxide creates a pleated flaking morphology for graphite oxide as opposed to that of graphite. UV/Vis and photoluminescence (PL) spectra of P3HT/graphene nanocomposite indicate that the existence of graphene does not alter the UV/Vis and PL excitation characteristics of P3HT, and the P3HT/graphene composite has higher electron mobility, a smaller band gap and higher conductivity than the pristine P3HT.

Synthesis and characterization of silver nanoparticles: effect on phytopathogen Colletotrichum gloesporioides

NASA Astrophysics Data System (ADS)

Aguilar-Méndez, Miguel A.; San Martín-Martínez, Eduardo; Ortega-Arroyo, Lesli; Cobián-Portillo, Georgina; Sánchez-Espíndola, Esther

2011-06-01

Colloidal silver nanoparticles were synthesized by reducing silver nitrate solutions with glucose, in the presence of gelatin as capping agent. The obtained nanoparticles were characterized by means of UV-Vis spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The response surface methodology (RSM) was also used to determine the influence of the variables on the size of the nanoparticles. The antifungal activity of the silver nanoparticles was evaluated on the phytopathogen Colletotrichum gloesporioides, which causes anthracnose in a wide range of fruits. The UV-Vis spectra indicated the formation of silver nanoparticles preferably spherical and of relatively small size (<20 nm). The above-mentioned was confirmed by TEM, observing a size distribution of 5-24 nm. According to RSM the synthesis variables influenced on the size of the silver nanoparticles. By means of FTIR spectroscopy it was determined that gelatin, through their amide and hydroxyl groups, interacts with nanoparticles preventing their agglomeration. The growth of C. gloesporioides in the presence of silver nanoparticles was significantly delayed in a dose dependent manner.

A spectroscopic study on the interaction between gold nanoparticles and hemoglobin

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

Garabagiu, Sorina, E-mail: sgarabagiu@itim-cj.ro

2011-12-15

Highlights: Black-Right-Pointing-Pointer The interaction was studied using UV-vis and fluorescence spectroscopy. Black-Right-Pointing-Pointer Gold nanoparticles quench the fluorescence emission of hemoglobin solution. Black-Right-Pointing-Pointer The binding and thermodynamic constants were calculated. Black-Right-Pointing-Pointer Major impact: electrochemical applications of the complex onto a substrate. -- Abstract: The interaction between horse hemoglobin and gold nanoparticles was studied using optical spectroscopy. UV-vis and fluorescence spectra show that a spontaneous binding process occurred between hemoglobin and gold nanoparticles. The Soret band of hemoglobin in the presence of gold nanoparticles does not show significant changes, which proves that the protein retained its biological function. A shift to longermore » wavelengths appears in the plasmonic band of gold nanoparticles upon the attachment of hemoglobin molecules. Gold nanoparticles quench the fluorescence emission of tryptophan residues in the structure of hemoglobin. The Stern-Volmer quenching constant, the binding constant and the number of binding sites were also calculated. Thermodynamic parameters indicate that the binding was mainly due to hydrophobic interactions.« less

Synthesis and optoelectronic properties of new polyarylates with 2-naphthyldiphenylamine units

NASA Astrophysics Data System (ADS)

Cai, Wanan; Wu, Xiaotong; Xiao, Tiandi; Niu, Haijun; Bai, Xuduo; Wang, Cheng; Wang, Wen; Zhang, Yanhong

2018-02-01

Herein, five kinds of soluble electrochromic polyarylates were synthesized from the reaction of N,N'-bis(4-carboxyphenyl)-N,N'-di-2-naphthyl-1,4-phenylenediamine with five bisphenols via direct polycondensation process, respectively. These new materials showed no significant decomposition below 400 °C in nitrogen atmosphere. The maximum UV-vis absorption bands of these polyarylates located at 328-348 nm and 327-353 nm for solid films and DMSO solution, respectively. The polyarylate 6a, as an example, exhibited not only aggregation-induced emission (AIE) effect in different fraction tetrahydrofuran/water solution, but also solvatochromism in various polar solvents, markedly. Two reversible pairs of distinct redox peaks were associated with noticeable color changed from original colorless to yellowish orange and green for polymeric film could be observed in the cyclic voltammetry (CV) test. New absorption peaks emerged in near-infrared (NIR) region with increasing voltage in the UV-vis spectra, which indicates these polyarylates can be used as NIR electrochromic materials. These polyarylates performed high contrast of optical transmittance change around 42-53% with the highest coloration efficiency up to 236 cm2C-1.

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine.

PubMed

Deborah, M; Jawahar, A; Mathavan, T; Dhas, M Kumara; Benial, A Milton Franklin

2015-03-15

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

Vertical growth of ZnO nanorods on ZnO seeded FTO substrate for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Marimuthu, T.; Anandhan, N.

2018-04-01

Zinc oxide (ZnO) nanorods (NRs) were electrochemically grown on fluorine doped tin oxide (FTO) and ZnO seeded FTO substrates. X-ray diffraction (XRD) patterns, Raman spectra and photoluminescence (PL) spectra reveal that the hexagonal wurtzite structured ZnO grown on a seeded FTO substrate has a high crystallinity, crystal quality and less atomic defects. Felid emission scanning electron microscope (FE-SEM) images display a high growth density of NRs grown on seeded FTO substrate compared to NRs grown on FTO substrate. The efficiency of the DSSCs based on NRs grown on FTO and seeded FTO substrates is 0.85 and 1.52 %, respectively. UV-Vis absorption spectra and electrochemical impedance spectra depict that the NRs grown on seeded FTO photoanode have higher dye absorption and charge recombination resistance than that of the NRs grown on FTO substrate.

Photocatalytic oxidation of propylene on La and N codoped TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Liu, Jinfeng; Li, Haiyan; Zong, Lanlan; Li, Qiuye; Wang, Xiaodong; Zhang, Min; Yang, Jianjun

2015-02-01

Lanthanum- and nitrogen-codoped TiO2 photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO2 were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra. The La-/N-codoped TiO2 showed excellent photoactivity of propylene oxidation compared with the single-doped TiO2 and La-/N-codoped P25 TiO2 nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

Optical properties of cerium oxide (CeO2) nanoparticles synthesized by hydroxide mediated method

NASA Astrophysics Data System (ADS)

Ali, Mawlood Maajal; Mahdi, Hadeel Salih; Parveen, Azra; Azam, Ameer

2018-05-01

The nanoparticles of cerium oxide have been successfully synthesized by hydroxide mediated method, using cerium nitrate and sodium hydroxide as precursors. The microstructural properties were analyzed by X-ray diffraction technique (XRD). The X-ray diffraction results show that the cerium oxide nanoparticles were in cubic structure. The optical absorption spectra of cerium oxide were recorded by UV-VIS spectrophotometer in the range of 320 to 600 nm and photoluminescence spectra in the range of 400-540 nm and have been presented. The energy band gap was determined by Tauc relationship. The crystallite size was determined from Debye-Scherer equation and came out to be 6.4 nm.

An efficient and environment-friendly method of removing graphene oxide in wastewater and its degradation mechanisms.

PubMed

Zhang, Chao-Zhi; Li, Ting; Yuan, Yang; Xu, Jianqiang

2016-06-01

Graphene and graphene oxide (GO) have already existed in air, water and soil due to their popular application in functional materials. However, degradation of graphene and GO in wastewater has not been reported. Degradation of GO plays a key role in the elimination of graphene and GO in wastewater due to graphene being easily oxidized to GO. In this paper, GO was completely degraded to give CO2 by Photo-Fenton. The degradation intermediates were determined by UV-vis absorption spectra, elemental analysis (EA), fourier transform infrared (FT-IR) and liquid chromatography-mass spectrometry (LC-MS). Experimental results showed that graphene oxide was completely degraded to give CO2 after 28 days. Based on UV, FT-IR, LC-MS spectra and EA data of these degradation intermediates, the degradation mechanisms of GO were supposed. This paper suggests an efficient and environment-friendly method to degrade GO and graphene. Copyright © 2016 Elsevier Ltd. All rights reserved.

UV Raman detection of 2,4-DNT in contact with sand particles

NASA Astrophysics Data System (ADS)

Blanco, Alejandro; Pacheco-Londoño, Leonardo C.; Peña-Quevedo, Alvaro J.; Hernández-Rivera, Samuel P.

2006-05-01

Deep Ultra Violet Raman Spectroscopy (DUV-RS) is an emerging tool for vibrational spectroscopy analysis and can be used in Point Detection mode to detect explosive components of landmines and Improvised Explosive Devices (IED). Interactions of explosives with different substrates can be measured by using quantitative vibrational signal shift information of scattered Raman light associated with these interactions. In this research, grounds were laid for detection of explosives using UV-Raman Spectroscopy equipped with 244 nm laser excitation line from a 488 nm frequency doubled Coherent FreD laser. In other experiments, samples of 2,4-DNT were allowed to interact with Ottawa Sand and were studied using DUV-RS. Characteristic vibrational signals of energetic compounds were analyzed in the ranges: 400-1200 cm -1, 1200-1800 cm -1, and 2800-3500 cm -1. In addition these Raman spectra were compared with dispersive spectra that were acquired using Raman Microscopy equipped with 514.5 nm (VIS) 785 nm (NIR) and 1064 nm (NIR) excitation lasers.

Adsorption Properties of p -Methyl Red Monomeric-to-Pentameric Dye Aggregates on Anatase (101) Titania Surfaces: First-Principles Calculations of Dye/TiO 2 Photoanode Interfaces for Dye-Sensitized Solar Cells

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

Zhang, Lei; Cole, Jacqueline M.

2014-08-29

The optical and electronic properties of dye aggregates of p-methyl red on a TiO2 anatase (101) surface were modeled as a function of aggregation order (monomer to pentameric dye) via first principles calculations. A progressive red-shifting and intensity increase toward the visible region in UV/vis absorption spectra is observed from monomeric-to-tetrameric dyes, with each molecule in a given aggregate binding to one of the four possible TiO2 (101) adsorption sites. The pentamer exhibits a blue-shifted peak wave- length in the UV/vis absorption spectra and less absorption intensity in the visible region in comparison; a corresponding manifestation of H-aggregation occurs sincemore » one of these five molecules cannot occupy an adsorption site. This finding is consistent with experiment. Calculated density of states (DOS) and partial DOS spectra reveal similar dye…TiO2 nanocomposite conduction band characteristics but different valence band features. Associated molecular orbital distributions reveal dye-to-TiO2 interfacial charge transfer in all five differing aggregate orders; meanwhile, the level of intramolecular charge transfer in the dye becomes progressively localized around its azo- and electron-donating groups, up to the tetrameric dye/TiO2 species. Dye adsorption energies and dye coverage levels are calculated and compared with experiment. Overall, the findings of this case study serve to aid the molecular design of azo dyes towards better performing DSSC devices wherein they are incorporated. In addition, they provide a helpful example reference for understanding the effects of dye aggregation on the adsorbate…TiO2 interfacial optical and electronic properties.« less

Enhanced photo-stability and photocatalytic activity of Ag3PO4 via modification with BiPO4 and polypyrrole

NASA Astrophysics Data System (ADS)

Cai, Li; Jiang, Hui; Wang, Luxi

2017-10-01

Ag3PO4 photocatalysts modified with BiPO4 and polypyrrole (PPy) were successfully synthesized via a combination of co-precipitation hydrothermal technique and oxidative polymerization method. Their morphologies, structures and optical and electronic properties were characterized by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface areas, X-ray diffraction (XRD), fourier transform infrared spectra (FT-IR), X-ray photo-electron spectroscopy (XPS), UV-vis diffuse reflection spectra (UV-vis DRS), photocurrent technique and electrochemical impedance spectra (EIS). The typical triphenylmethane dye (malachite green) was chosen as a target organic contaminants to estimate the photocatalytic activities and photo-stabilities of Ag3PO4-BiPO4-PPy heterostructures under visible light irradiation. The results indicated that the existence of BiPO4 and PPy not only showed great influences on the photocatalytic activity, but also significantly enhanced photo-stability of Ag3PO4 in repeated and long-term applications. The degradation conversion of Ag3PO4-BiPO4-PPy heterostructures (ABP-3) was 1.58 times of that of pure Ag3PO4. The photo-corrosion phenomenon of Ag3PO4 was effectively avoided. The photocatalytic activity of up to 87% in the Ag3PO4-BiPO4-PPy heterostructures (ABP-3) can be remained after five repeated cycles, while only about 33% of the degradation efficiency can be reserved in pure Ag3PO4. The possible mechanism of enhanced photo-stability and photocatalytic activity of Ag3PO4-BiPO4-PPy heterostructures was also discussed in this work.

Novel Na(+) doped Alq3 hybrid materials for organic light-emitting diode (OLED) devices and flat panel displays.

PubMed

Bhagat, S A; Borghate, S V; Kalyani, N Thejo; Dhoble, S J

2015-05-01

Pure and Na(+) -doped Alq3 complexes were synthesized by a simple precipitation method at room temperature, maintaining a stoichiometric ratio. These complexes were characterized by X-ray diffraction, Fourier transform infrared (FTIR), UV/Vis absorption and photoluminescence (PL) spectra. The X-ray diffractogram exhibits well-resolved peaks, revealing the crystalline nature of the synthesized complexes, FTIR confirms the molecular structure and the completion of quinoline ring formation in the metal complex. UV/Vis absorption and PL spectra of sodium-doped Alq3 complexes exhibit high emission intensity in comparison with Alq3 phosphor, proving that when doped in Alq3 , Na(+) enhances PL emission intensity. The excitation spectra of the synthesized complexes lie in the range 242-457 nm when weak shoulders are also considered. Because the sharp excitation peak falls in the blue region of visible radiation, the complexes can be employed for blue chip excitation. The emission wavelength of all the synthesized complexes lies in the bluish green/green region ranging between 485 and 531 nm. The intensity of the emission wavelength was found to be elevated when Na(+) is doped into Alq3 . Because both the excitation and emission wavelengths fall in the visible region of electromagnetic radiation, these phosphors can also be employed to improve the power conversion efficiency of photovoltaic cells by using the solar spectral conversion principle. Thus, the synthesized phosphors can be used as bluish green/green light-emitting phosphors for organic light-emitting diodes, flat panel displays, solid-state lighting technology - a step towards the desire to reduce energy consumption and generate pollution free light. Copyright © 2014 John Wiley & Sons, Ltd.

Influence of annealing temperature on physical properties and photocatalytic ability of g-C3N4 nanosheets synthesized through urea polymerization in Ar atmosphere

NASA Astrophysics Data System (ADS)

Mai Oanh, Le Thi; Hang, Lam Thi; Lai, Ngoc Diep; Phuong, Nguyen Thi; Thang, Dao Viet; Hung, Nguyen Manh; Danh Bich, Do; Minh, Nguyen Van

2018-03-01

The influences of annealing temperature on structure, morphology, vibration, optical properties and photocatalytic ability of g-C3N4 nanosheets synthesized from urea in Ar atmosphere were investigated in detail by using x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption, and photoluminescence (PL). It was found that the preparation temperature had a great effect on structure and physical properties of g-C3N4. As the processing temperature increased from 450 °C to 650 °C, the interlayer stacking distance of g-C3N4 decreased from 3.281 Å to 3.217 Å and the lattice parameter a decreased from 5.010 Å to 4.934 Å. This indicated a denser packing fashion of g-C3N4 at high annealing temperature. Moreover, the FTIR spectra and SEM images revealed a large fraction of small polymer segments containing only a few heptazine units as annealing temperature increased. BET result indicated an increasing specific surface area as preparation temperature increased. UV-vis absorption spectra showed a decrease of the band gap energy with increasing calcination temperature which agrees well with the measured PL spectra. It was demonstrated that samples annealed at 550 °C exhibited the strongest photocatalytic activity. A decomposition of 80% and 100% of rhodamine B was obtained within respectively 1 h and 2 h under Xenon lamp irradiation. Photocatalytic result could be adequately explained based on evidences of specific surface area, average pore volume and pore size, and recombination rate of photoinduced electron-hole pairs.

Efficient Förster resonance energy transfer in 1,2,3-triazole linked BODIPY-Zn(II) meso-tetraphenylporphyrin donor-acceptor arrays.

PubMed

Leonardi, Matthew J; Topka, Michael R; Dinolfo, Peter H

2012-12-17

Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reactivity was successfully employed to synthesize three donor-acceptor energy transfer (EnT) arrays that contain one (Dyad), three (Tetrad) and four (Pentad) 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) donors connected to a Zn-tetraphenylporphyrin acceptor via 1,2,3-triazole linkages. The photophysical properties of the three arrays, along with individual donor and acceptor chromophores, were investigated by UV-vis absorption and emission spectroscopy, fluorescence lifetimes, and density functional theory (DFT) electronic structure modeling. Comparison of the UV-vis absorption spectra and frontier molecular orbitals from DFT calculations of the three arrays with ZnTPP, ZnTTrzlP, and Trzl-BODIPY shows that the electronic structure of the chromophores is essentially unperturbed by the 1,2,3-triazole linkage. Time-dependent DFT (TDDFT) calculations on the Dyad reproduce the absorption spectra in THF and show no evidence of excited state mixing of the donor and acceptor. The BODIPY singlet excited state emission is significantly quenched in all three arrays, consistent with EnT to the porphyrin core, with efficiencies of 95.8, 97.5, and 97.2% for the Dyad, Tetrad, and Pentad, respectively. Fluorescence excitation spectra of the three arrays, measured at the porphyrin emission, mirror the absorption profile of both the porphyrin and BODIPY chromophores and are consistent with the Förster resonance energy transfer (FRET) mechanism. Applying Förster theory to the spectroscopic data of the chromophores gives EnT efficiency estimates that are in close agreement with experimental values, suggesting that the through-space mechanism plays a dominant role in the three arrays.

Compositional analyses of small lunar pyroclastic deposits using Clementine multispectral data

USGS Publications Warehouse

Gaddis, L.R.; Hawke, B.R.; Robinson, M.S.; Coombs, C.

2000-01-01

Clementine ultraviolet-visible (UVVIS) data are used to examine the compositions of 18 pyroclastic deposits (15 small, three large) at 13 sites on the Moon. Compositional variations among pyroclastic deposits largely result from differing amounts of new basaltic (or juvenile) material and reworked local material entrained in their ejecta upon eruption. Characterization of pyroclastic deposit compositions allows us to understand the mechanisms of lunar explosive volcanism. Evidence for compositional differences between small pyroclastic deposits at a single site is observed at Atlas crater. At all sites, compositional variation among the small pyroclastic deposits is consistent with earlier classification based on Earth-based spectra: three compositional groups can be observed, and the trend of increasing mafic absorption band strength from Group 1 to Group 2 to Group 3 is noted. As redefined here, Group 1 deposits include those of Alphonsus West, Alphonsus Southeast, Alphonsus Northeast 2, Atlas South, Crüger, Franklin, Grimaldi, Lavoisier, Oppenheimer, Orientale, and Riccioli. Group 1 deposits resemble lunar highlands, with weak mafic bands and relatively high UV/VIS ratios. Group 2 deposits include those of Alphonsus Northeast 1, Atlas North, Eastern Frigoris East and West, and Aristarchus Plateau; Group 2 deposits are similar to mature lunar maria, with moderate mafic band depths and intermediate UV/VIS ratios. The single Group 3 deposit, J. Herschel, has a relatively strong mafic band and a low UV/VIS ratio, and olivine is a likely juvenile component. Two of the deposits in these groups, Orientale and Aristarchus, are large pyroclastic deposits. The third large pyroclastic deposit, Apollo 17/Taurus Littrow, has a very weak mafic band and a high UV/VIS ratio and it does not belong to any of the compositional groups for small pyroclastic deposits. The observed compositional variations indicate that highland and mare materials are also present in many large and small pyroclastic deposits, and they suggest that volcanic glasses or spheres may not be dominant juvenile components in all large pyroclastic deposits. Copyright 2000 by the American Geophysical Union.

Study on molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM, HOMO-LUMO energies and docking studies of 5-fluorouracil, a substance used to treat cancer.

PubMed

Almeida, Michell O; Barros, Daiane A S; Araujo, Sheila C; Faria, Sergio H D M; Maltarollo, Vinicius G; Honorio, Kathia M

2017-09-05

Cancer cells can expand to other parts of body through blood system and nodes from a mechanism known as metastasis. Due to the large annual growth of cancer cases, various biological targets have been studied and related to this disorder. A very interesting target related to cancer is human epidermal growth factor receptor 2 (HER2). In this study, we analyzed the main intermolecular interactions between a drug used in the cancer treatment (5-fluorouracil) and HER2. Molecular modeling methods were also employed to assess the molecular structure, spectroscopic properties (FTIR and UV-Vis), NBO, QTAIM and HOMO-LUMO energies of 5-FU. From the docking simulations it was possible to analyze the interactions that occur between some residues in the binding site of HER2 and 5-FU. To validate the choice of basis set that was used in the NBO and QTAIM analyses, theoretical calculations were performed to obtain FT-IR and UV/Vis spectra, and the theoretical results are consistent with the experimental data, showing that the basis set chosen is suitable. For the maximum λ from the theoretical calculation (254.89nm) of UV/Vis, the electronic transition from HOMO to LUMO occurs at 4.89eV. From NBO analyses, we observed interactions between Asp863 and 5-FU, i.e. the orbitals with high transfer of electrons are LP O 15 (donor NBO) and BD* (π) N 1 -H 10 (acceptor NBO), being that the value of this interaction is 7.72kcal/mol. Results from QTAIM indicate one main intermolecular H bond, which is necessary to stabilize the complex formed between the ligands and the biological target. Therefore, this study allowed a careful evaluation on the main structural, spectroscopic and electronic properties involved in the interaction between 5-FU and HER2, an important biological complex related to the cancer treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

DFT studies for three Cu(II) coordination polymers: Geometrical and electronic structures, g factors and UV-visible spectra

NASA Astrophysics Data System (ADS)

Ding, Chang-Chun; Wu, Shao-Yi; Xu, Yong-Qiang; Wu, Li-Na; Zhang, Li-Juan

2018-05-01

This work presents a systematic density functional theory (DFT) study for geometrical and electronic structures, g factors and UV-vis spectra of three Cu(II) coordination polymers (CPs) [Cu(XL)(NO3)2]n (1), {[Cu(XL)(4,4‧-bpy)(NO3)2]•CH3CN}n (2) and {[Cu(XL)3](NO3)2·3.5H2O}n (3) based on the ligand N,N‧-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxdiimide bi(1,2,4-triazole) (XL) with the linker triazole coordinated with copper to construct the CPs. For three CPs with distinct ligands, the optimized molecular structures with PBE0 hybrid functional and the 6-311g basis set agree well with the corresponding XRD data. Meanwhile, the electronic properties are also analyzed for all the systems. The calculated g factors are found sensitive to the (Hartree-Fock) HF character due to the significant hybridization between copper and ligand orbitals. The calculated UV-visible spectra reveal that the main electronic transitions for CP 1 contain d-d and CT transitions, while those for CPs 2 and 3 largely belong to CT ones. The present CPs seem difficult to adsorb small molecules, e.g., CP 1 with H2O and NO2 exhibit unfavorable adsorption and deformation structures near the Cu2+ site.

The SOA formation model combined with semiempirical quantum chemistry for predicting UV-Vis absorption of secondary organic aerosols.

PubMed

Zhong, Min; Jang, Myoseon; Oliferenko, Alexander; Pillai, Girinath G; Katritzky, Alan R

2012-07-07

A new model for predicting the UV-visible absorption spectra of secondary organic aerosols (SOA) has been developed. The model consists of two primary parts: a SOA formation model and a semiempirical quantum chemistry method. The mass of SOA is predicted using the PHRCSOA (Partitioning Heterogeneous Reaction Consortium Secondary Organic Aerosol) model developed by Cao and Jang [Environ. Sci. Technol., 2010, 44, 727]. The chemical composition is estimated using a combination of the kinetic model (MCM) and the PHRCSOA model. The absorption spectrum is obtained by taking the sum of the spectrum of each SOA product calculated using a semiempirical NDDO (Neglect of Diatomic Differential Overlap)-based method. SOA was generated from the photochemical reaction of toluene or α-pinene at different NO(x) levels (low NO(x): 24-26 ppm, middle NO(x): 49 ppb, high NO(x): 104-105 ppb) using a 2 m(3) indoor Teflon film chamber. The model simulation reasonably agrees with the measured absorption spectra of α-pinene SOA but underestimates toluene SOA under high and middle NO(x) conditions. The absorption spectrum of toluene SOA is moderately enhanced with increasing NO(x) concentrations, while that of α-pinene SOA is not affected. Both measured and calculated UV-visible spectra show that the light absorption of toluene SOA is much stronger than that of α-pinene SOA.

Rotationally resolved state-to-state photoionization and photoelectron study of titanium carbide and its cation (TiC/TiC⁺).

PubMed

Luo, Zhihong; Huang, Huang; Chang, Yih-Chung; Zhang, Zheng; Yin, Qing-Zhu; Ng, C Y

2014-10-14

Titanium carbide and its cation (TiC/TiC(+)) have been investigated by the two-color visible (VIS)-ultraviolet (UV) resonance-enhanced photoionization and pulsed field ionization-photoelectron (PFI-PE) methods. Two visible excitation bands for neutral TiC are observed at 16,446 and 16,930 cm(-1). Based on rotational analyses, these bands are assigned as the respective TiC((3)Π1) ← TiC(X(3)Σ(+)) and TiC((3)Σ(+)) ← TiC(X(3)Σ(+)) transition bands. This assignment supports that the electronic configuration and term symmetry for the neutral TiC ground state are …7σ(2)8σ(1)9σ(1)3π(4) (X(3)Σ(+)). The rotational constant and the corresponding bond distance of TiC(X(3)Σ(+); v″ = 0) are determined to be B0″ = 0.6112(10) cm(-1) and r0″ = 1.695(2) Å, respectively. The rotational analyses of the VIS-UV-PFI-PE spectra for the TiC(+)(X; v(+) = 0 and 1) vibrational bands show that the electronic configuration and term symmetry for the ionic TiC(+) ground state are …7σ(2)8σ(1)3π(4) (X(2)Σ(+)) with the v(+) = 0 → 1 vibrational spacing of 870.0(8) cm(-1) and the rotational constants of B(e)(+) = 0.6322(28) cm(-1), and α(e)(+) = 0.0085(28) cm(-1). The latter rotational constants yield the equilibrium bond distance of r(e)(+) = 1.667(4) Å for TiC(+)(X(2)Σ(+)). The cleanly rotationally resolved VIS-UV-PFI-PE spectra have also provided a highly precise value of 53 200.2(8) cm(-1) [6.5960(1) eV] for the adiabatic ionization energy (IE) of TiC. This IE(TiC) value along with the known IE(Ti) has made possible the determination of the difference between the 0 K bond dissociation energy (D0) of TiC(+)(X(2)Σ(+)) and that of TiC(X(3)Σ(+)) to be D0(Ti(+)-C) - D0(Ti-C) = 0.2322(2) eV. Similar to previous experimental observations, the present state-to-state PFI-PE study of the photoionization transitions, TiC(+)(X(2)Σ(+); v(+) = 0 and 1, N(+)) ← TiC((3)Π1; v', J'), reveals a strong decreasing trend for the photoionization cross section as |ΔN(+)| = |N(+) - J'| is increased. The maximum |ΔN(+)| change of 7 observed here is also consistent with the previous experimental results for the 3d transition-metal carbides, oxides, and nitrides. However, the VIS-UV-PFI-PE spectra for TiC(+)(X(2)Σ(+); v(+) = 0 and 1, N(+)) are found to display only the negative ΔN(+) (N(+)-J'≤ 0) transitions, indicating that the cross sections for the formation of positive ΔN(+) (N(+)-J' > 0) transitions by both the channel coupling mechanism and direct photoionization are negligibly small.

Photocatalytic antibacterial effects on TiO2-anatase upon UV-A and UV-A/VIS threshold irradiation.

PubMed

Wu, Yanyun; Geis-Gerstorfer, Jürgen; Scheideler, Lutz; Rupp, Frank

2016-01-01

Photocatalysis mediated by the anatase modification of titanium dioxide (TiO2) has shown antibacterial effects in medical applications. The aim of this study was to investigate the possibility of expanding the excitation wavelengths for photocatalytic antibacterial effects from ultraviolet (UV) into the visible light range. After deposition of salivary pellicle and adhesion of Streptococcus gordonii on anatase, different irradiation protocols were applied to induce photocatalysis: ultraviolet A (UV-A) > 320 nm; ultraviolet/visible (UV-A/VIS) light > 380 nm and > 390 nm; and VIS light 400-410 nm. A quartz crystal microbalance with dissipation (QCM-D) tests and microscopic examination were used to observe the photoinduced antibacterial effects. Salivary pellicle could be photocatalytically decomposed under all irradiation protocols. In contrast, effective photocatalytic attack of bacteria could be observed by UV-A as well as by UV-A/VIS at 380 nm < λ < 390 nm only. Wavelengths above 380 nm show promise for in situ therapeutic antifouling applications.

Effect of Co doping, capping agent and optical-structural studies of ZnO:Co2+ nanoparticles

NASA Astrophysics Data System (ADS)

Taheri Otaqsara, S. M.

2011-08-01

Co2+ doped ZnO nanoparticles (NPs) using PEG as a capping agent were prepared by colloidal wet-chemical method. The structure, morphology and characteristics of as-prepared samples were investigated. X-ray diffraction patterns studies revealed wurtzite crystal phase. STM-TEM micrographs show a spherical shape and nearly well distribution with an average particle size of ~15-20 nm. UV-VIS spectra show the presence of exciton peak at 349 nm which can be effectively tuned versus cobalt doping and PEG concentration. PL studies were done under the excitation of 347 nm, which exhibited a UV (~386 nm) and visible (blue-orange) emission peak because of free-exciton recombination and oxygen vacancy.

Effect of 50 MeV Li+3 and 80 MeV C+5 ions' beam irradiation on the optical, structural, chemical and surface topographic properties of PMMA films

NASA Astrophysics Data System (ADS)

Bharti, Madhu Lata; Dutt, Sanjay; Joshi, Veena

2017-10-01

The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50 MeV lithium (Li3+) and 80 MeV carbon (C5+) ions to the fluences of 3 × 1014, 1 × 1015, 1 × 1016 and 1 × 1017 ions µm-2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet-visible (UV-Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV-Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. Eg and Ea decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (Eg) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.

The UV-VIS optical environment of the shuttle

NASA Technical Reports Server (NTRS)

Torr, M. R.

1985-01-01

During the Spacelab 1 shuttle mission, spectroscopic measurements were made of the atmospheric emissions over a broad wavelength range extending from the extreme ultraviolet to the near infrared. Those measurements were made under a variety of vehicle attitude and sunlight conditions. Superimposed on such spectra would be any features associated with the induced vehicle environment and its interaction with solar photons and the ambient neutral atmosphere and plasma. Various anomalies and unexpected features in the spectra from the perspective of possible shuttle-induced origins are discussed. The data indicate a dramatic cleanup of the vehicle environment over the course of the 10-day mission, a strong non-atmospheric red continuum underlying the spectra at night and at large angles to the velocity vector, and a variety of molecular band distributions which are not explained by the present understanding of the atmosphere.

Synthesis of Cu/CuO nanoparticles in mesoporous material by solid state reaction

NASA Astrophysics Data System (ADS)

Sohrabnezhad, Sh.; Valipour, A.

2013-10-01

The Mobil Composition of Matter No. 41 (MCM-41) containing 1.0 and 5.0 wt.% of Cu was synthesized under solid state reaction. The calcinations of samples were done at two different temperatures, 500 and 300 °C. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used for samples characterization. Powder X-ray diffraction showed that when Cu(CH3COO)2 content is about 1.0 wt.% in Cu/MCM-41, the guest CuO-NPs and copper ions is formed on the silica channel wall, and more exists in the crystalline state. When Cu(CH3COO)2 content exceeds this value (5.0 wt.%), CuO nanoparticles and Cu2+ ions can be observed in low crystalline state. From the diffuse reflectance spectra it was confirmed that 5 wt.% Cu/MCM-41 sample calcined at 500 °C show plasmon resonance band due to Cu nanoparticles in the range between 500 and 600 nm and small copper clusters Cun in 450 nm. It also shows that some of the Cu2+ ions are present octahedrally in extraframework position in all samples. Both fourier transform infrared and diffuse reflectance spectra indicate that some of Cu2+ ions are tetrahedrally within the framework position in 1 wt.% Cu/MCM-41 samples. TEM images indicated that nanoparticles size of CuO is in range of 30-40 nm.

Synthesis, characterization, crystal structure and quantum chemical investigations of three novel coumarin-benzenesulfonohydrazide derivatives

NASA Astrophysics Data System (ADS)

Chethan Prathap, K. N.; Lokanath, N. K.

2018-04-01

Coumarin derivatives are an important class of heterocyclic compounds due to their physical and biological properties. Coumarin derivatives have been identified with many significant electro-optical properties and biological activities. Three novel coumarin derivatives containing benzene sulfonohydrazide group were synthesized by condensation reaction. The synthesized compounds were characterized by various spectroscopic techniques (Mass, 1H/13C NMR and FTIR). Thermal and optical properties were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and UV-Vis spectroscopic studies. Finally their structures were confirmed by single crystal X-ray diffraction (XRD) studies. The three compounds exhibit diverse intermolecular interactions, as observed by the crystal packing and Hirshfeld surface analysis. Further, their structures were optimized by density functional theory (DFT) calculations using B3LYP hybrid functionals with 6-311G+(d,p) level basis set. The Mulliken charge, molecular electrostatic potential (MEP), frontier molecular orbitals (HOMO-LUMO) were investigated. The experimentally determined parameters were compared with those calculated theoretically and they complement each other with a very good correlation. The transitions among the molecular orbitals were investigated using time-dependent density functional theory (TD-DFT) and the electronic absorption spectra obtained showed very good agreement with the experimentally measured UV-Vis spectra. Furthermore, non-linear optical (NLO) properties were investigated by calculating polarizabilities and hyperpolarizabilities. All three compounds exhibit significantly high hyperpolarizabilities compared to the reference material urea, which makes them potential candidates for NLO applications.

Photocatalytic Activity of Vanadium-Substituted ETS-10

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

Nash,M.; Rykov, S.; Lobo, R.

2007-01-01

Various amounts of vanadium have been isomorphously substituted for titanium in ETS-10, creating samples with V/(V+Ti) ratios of 0.13, 0.33, 0.43, and 1.00 and characterized experimentally using Raman, near-edge X-ray absorption fine structure (NEXAFS), X-ray powder diffraction, N{sub 2} adsorption, scanning electron microscopy (SEM), UV/vis spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Raman spectra reveal a disordered chain structure that contains different V-O bonds along with the presence of a V-O-Ti peak. The UV/vis spectra of the vanadium samples have three new absorption features in the visible region at 450, 594, and 850 nm, suggesting both V{sup 4+}more » and V{sup 5+} are present in the samples. NEXAFS results confirm the presence of both V{sup 5+} and V{sup 4+} in the vanadium samples, with a fraction of V{sup 4+} within the range of 0.2-0.4. The addition of vanadium lowers the band gap energy of ETS-10 from 4.32 eV to a minimum of 3.58 eV for the 0.43ETVS-10 sample. Studies of the photocatalytic polymerization of ethylene show that the 594 nm transition has no photocatalytic activity. The visible transition around 450 nm in the vanadium-incorporated samples is photocatalytically active, and the lower-concentration vanadium samples have higher photocatalytic activity than that of ETS-10 and AM-6, the all-vanadium analogue of ETS-10.« less

Facile fabrication of mesoporous Fe-Ti-SBA15 silica with enhanced visible-light-driven simultaneous photocatalytic degradation and reduction reactions

NASA Astrophysics Data System (ADS)

Chang, Fei; Jiao, Mingzhi; Xu, Quan; Deng, Baoqing; Hu, Xuefeng

2018-03-01

A series of mesoporous iron-titanium-containing silica Fe-TiO2-SBA15 (FTS) were constructed via a facile one-pot hydrothermal route and subsequently characterized by X-ray diffraction patterns, UV-vis diffuse reflection spectroscopy, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, and X-ray energy dispersion spectroscopy. By analyses, these samples possessed ordered two-dimensional hexagonal mesoporous structures, mainly involving mixed dual-phases of anatase and rutile TiO2, like commercial titania P25. The UV-vis diffuse reflection spectra demonstrated the presence of Fe species that was further confirmed by the X-ray photoelectron spectra and X-ray energy dispersion spectrum. The existence of Fe species in form of Fe3+ cations played an important role on the phase composition and electronic structure of these samples. With structural and morphological merits, these samples exhibited relatively high photocatalytic efficiency toward the degradation of dye methylene blue (MB) and reduction of Cr(VI) under visible-light irradiation, comparing with P25. In addition, among all candidates, the sample with a Fe/Si molar ratio of 0.03 showed the highest catalytic performance under optimal conditions, especially in the coexistence of both MB and Cr(VI), revealing an obviously synergistic effect when the consumption of both contaminants occurred. Finally, a primary catalytic mechanism was speculated on basis of active species capture experiments.

Study of DNA-emodin interaction by FTIR and UV-vis spectroscopy.

PubMed

Saito, Samuel T; Silva, Givaldo; Pungartnik, Cristina; Brendel, Martin

2012-06-04

Emodin, a plant- and fungus-derived anthraquinone, exerts genotoxic and antioxidative effects and shows promise in antitumor and antibacterial therapies. The aim of this study was to examine the molecular interactions of emodin with DNA in aqueous solution at physiological pH using spectroscopic methods. Fourier Transform Infrared (FTIR) Spectroscopy and UV absorption spectra were used to determine the structural features, the binding mode and the association constants. Our UV-spectroscopic results indicate that emodin interacts with DNA by intercalation and by external binding. FTIR results suggest that emodin interaction occurs preferably via adenine and thymine base pairs and also weakly with the phosphate backbone of the DNA double helix. The binding constant for emodin-DNA complex formation is estimated to be K=5.59×10(3)M(-1). No significant changes of DNA conformation were observed upon emodin-DNA complexation. Copyright © 2012 Elsevier B.V. All rights reserved.

FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: vigabatrin.

PubMed

Edwin, Bismi; Joe, I Hubert

2013-10-01

Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the C-C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system. Copyright © 2013 Elsevier B.V. All rights reserved.

Molecular structure, vibrational spectra, NBO, UV and first order hyperpolarizability, analysis of 4-Chloro-dl-phenylalanine by density functional theory.

PubMed

Govindarasu, K; Kavitha, E

2014-12-10

The Fourier transform infrared (4000-400cm(-1)) and Fourier transform Raman (3500-50cm(-1)) spectra of 4-Chloro-dl-phenylalanine (4CLPA) were recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational wavenumbers were investigated with the help of density functional theory (DFT) method using B3LYP/6-31G(d,p) as basis set. The observed vibrational wavenumbers were compared with the calculated results. Natural bond orbital analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction. Predicted electronic absorption spectra from TD-DFT calculation have been analyzed comparing with the UV-Vis (200-800nm) spectrum. The effects of chlorine and ethylene group substituent in benzene ring in the vibrational wavenumbers have been analyzed. The HOMO-LUMO energy gap explains the charge interaction taking place within the molecule. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of 4CLPA were calculated. The Chemical reactivity and chemical potential of 4CLPA is calculated. In addition, molecular electrostatic potential (MEP), frontier molecular orbital (FMO) analysis were investigated using theoretical calculations. Published by Elsevier B.V.

Optical characteristics of butyl rubber loaded with general purpose furnace (GPF) carbon black

NASA Astrophysics Data System (ADS)

Alfaramawi, K.

2018-06-01

Optical characteristics of butyl rubber/GPF carbon black (BR/GPFCB) composites with carbon black (CB) concentrations 40, 60, 80 and 100 phr (part per hundred part of rubber) were investigated. The structure of the BR/GPFCB composites was analyzed by x-ray diffraction (XRD). All samples with various CB showed diffraction peaks around 2θ = 14°, 25° and 44° which correspond to interlayer spacing of 6.23 Å, 3.62 Å and 2.10 Å respectively. The peaks were shifted toward larger 2θ angles with increasing CB concentration, indicating a decrease in layer spacing. Ultraviolet and visible (UV–vis) absorbance spectra in the range from 200 nm to 800 nm of the BR/GPFCB composites were studied. In the UV range of the spectra, an absorption edge was recorded. Direct and indirect optical band gaps for the composites were evaluated. The direct band gap values were found-as shown to be slightly greater than that of the indirect ones. The reflectance spectra in the UV optical range were demonstrated. Most of the incident UV light was absorbed inside the composites while a very small fraction was reflected and transmitted. This was attributed to the high UV absorption property of the CB filler. The refractive index of the composite was calculated from the reflectance data. The dependence of the real and imaginary parts of the complex dielectric constant on the incident light energy was characterized. The dielectric loss factor was found to decrease with increasing incident photon energy until approximately 5.5 eV (around the absorption edge) and then it increased rapidly.

Experimental, computational and chemometrics studies of BSA-vitamin B6 interaction by UV-Vis, FT-IR, fluorescence spectroscopy, molecular dynamics simulation and hard-soft modeling methods.

PubMed

Manouchehri, Firouzeh; Izadmanesh, Yahya; Aghaee, Elham; Ghasemi, Jahan B

2016-10-01

The interaction of pyridoxine (Vitamin B6) with bovine serum albumin (BSA) is investigated under pseudo-physiological conditions by UV-Vis, fluorescence and FTIR spectroscopy. The intrinsic fluorescence of BSA was quenched by VB6, which was rationalized in terms of the static quenching mechanism. According to fluorescence quenching calculations, the bimolecular quenching constant (kq), dynamic quenching (KSV) and static quenching (KLB) at 310K were obtained. The efficiency of energy transfer and the distance between the donor (BSA) and the acceptor (VB6) were calculated by Foster's non-radiative energy transfer theory and were equal to 41.1% and 2.11nm. The collected UV-Vis and fluorescence spectra were combined into a row-and column-wise augmented matrix and resolved by multivariate curve resolution-alternating least squares (MCR-ALS). MCR-ALS helped to estimate the stoichiometry of interactions, concentration profiles and pure spectra for three species (BSA, VB6 and VB6-BSA complex) existed in the interaction procedure. Based on the MCR-ALS results, using mass balance equations, a model was developed and binding constant of complex was calculated using non-linear least squares curve fitting. FT-IR spectra showed that the conformation of proteins was altered in presence of VB6. Finally, the combined docking and molecular dynamics (MD) simulations were used to estimate the binding affinity of VB6 to BSA. Five-nanosecond MD simulations were performed on bovine serum albumin (BSA) to study the conformational features of its ligand binding site. From MD results, eleven BSA snapshots were extracted, at every 0.5ns, to explore the binding affinity (GOLD score) of VB6 using a docking procedure. MD simulations indicated that there is a considerable flexibility in the structure of protein that affected ligand recognition. Structural analyses and docking simulations indicated that VB6 binds to site I and GOLD score values depend on the conformations of both BSA and ligand. Molecular modeling results showed that VB6-BSA complex formed not only on the basis of electrostatic forces, but also on the basis of π-π staking and hydrogen bond. There was an excellent agreement between the experimental and computational results. The results presented in this paper, will offer a reference for detailed and systematic studies on the biological effects and action mechanism of small molecules with proteins. Copyright © 2016 Elsevier Inc. All rights reserved.

NIR-Vis-UV Light-Responsive Actuator Films of Polymer-Dispersed Liquid Crystal/Graphene Oxide Nanocomposites.

PubMed

Cheng, Zhangxiang; Wang, Tianjie; Li, Xiao; Zhang, Yihe; Yu, Haifeng

2015-12-16

To take full advantage of sunlight for photomechanical materials, NIR-vis-UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR-vis-UV light. The homodispersed GO flakes act as photoabsorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well-controlled by adjusting the elongation ratio upon mechanical treatment. The NIR-vis-UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low-cost, and good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.

Effect of core twisting on self-assembly and optical properties of perylene bisimide dyes in solution and columnar liquid crystalline phases.

PubMed

Chen, Zhijian; Baumeister, Ute; Tschierske, Carsten; Würthner, Frank

2007-01-01

A series of highly soluble and fluorescent core-twisted perylene bisimide dyes (PBIs) 3 a-f with different substituents at the bay area (1,6,7,12 positions of the perylene core) were synthesized and fully characterized by (1)H NMR, UV/Vis spectroscopy, MS spectrometry, and elemental analysis. The pi-pi aggregation properties of these new functional dyes were investigated in detail both in solution and in condensed phase by UV/Vis and fluorescence spectroscopy, vapor pressure osmometry (VPO), differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. Concentration-dependent UV/Vis measurements and VPO analysis revealed that these core-twisted pi-conjugated systems show distinct self-dimerization equilibria in apolar solvent methylcyclohexane (MCH) with dimerization constants between 1.3x10(4) and 30 M(-1). The photoluminescence spectra of the dimers of PBIs 3 a-f exhibit bathochromic shifts of quite different magnitude which could be attributed to different longitudinal or rotational offsets between the dyes as well as differences in the respective pi-pi stacking distance. In condensed state, quite a few of these PBIs form luminescent rectangular or hexagonal columnar liquid crystalline phases with low isotropization temperatures. The effects of the distortion of the pi systems on their pi-pi stacking and the optical properties of the resultant stacks in solution and in LC phases have been explored in detail. In one case (3 a) a particularly interesting phase change from crystalline into liquid crystalline could be observed upon annealing that was accompanied by a transformation from non-fluorescent H-type into strongly fluorescent J-type packing of the dyes.

UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes.

PubMed

Was-Gubala, Jolanta; Starczak, Roza

2015-05-05

The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of variable pathlength UV-vis spectroscopy combined with partial-least-squares regression for wastewater chemical oxygen demand (COD) monitoring.

PubMed

Chen, Baisheng; Wu, Huanan; Li, Sam Fong Yau

2014-03-01

To overcome the challenging task to select an appropriate pathlength for wastewater chemical oxygen demand (COD) monitoring with high accuracy by UV-vis spectroscopy in wastewater treatment process, a variable pathlength approach combined with partial-least squares regression (PLSR) was developed in this study. Two new strategies were proposed to extract relevant information of UV-vis spectral data from variable pathlength measurements. The first strategy was by data fusion with two data fusion levels: low-level data fusion (LLDF) and mid-level data fusion (MLDF). Predictive accuracy was found to improve, indicated by the lower root-mean-square errors of prediction (RMSEP) compared with those obtained for single pathlength measurements. Both fusion levels were found to deliver very robust PLSR models with residual predictive deviations (RPD) greater than 3 (i.e. 3.22 and 3.29, respectively). The second strategy involved calculating the slopes of absorbance against pathlength at each wavelength to generate slope-derived spectra. Without the requirement to select the optimal pathlength, the predictive accuracy (RMSEP) was improved by 20-43% as compared to single pathlength spectroscopy. Comparing to nine-factor models from fusion strategy, the PLSR model from slope-derived spectroscopy was found to be more parsimonious with only five factors and more robust with residual predictive deviation (RPD) of 3.72. It also offered excellent correlation of predicted and measured COD values with R(2) of 0.936. In sum, variable pathlength spectroscopy with the two proposed data analysis strategies proved to be successful in enhancing prediction performance of COD in wastewater and showed high potential to be applied in on-line water quality monitoring. Copyright © 2013 Elsevier B.V. All rights reserved.

Unveiling the Aggregation of Lycopene in Vitro and in Vivo: UV-Vis, Resonance Raman, and Raman Imaging Studies.

PubMed

Ishigaki, Mika; Meksiarun, Phiranuphon; Kitahama, Yasutaka; Zhang, Leilei; Hashimoto, Hideki; Genkawa, Takuma; Ozaki, Yukihiro

2017-08-31

The present study investigates the structure of lycopene aggregates both in vitro and in vivo using ultraviolet-visible (UV-vis) and Raman spectroscopies. The electronic absorption bands of the J- and H-aggregates in vitro shift to lower and higher energies, respectively, compared to that of the lycopene monomer. Along with these results, the frequencies of the ν 1 Raman bands were shifted to lower and higher frequencies, respectively. By plotting the frequencies of the ν 1 Raman band against the S 0 → S 2 transition energy, a linear relationship between the data set with different aggregation conformations can be obtained. Therefore, the band positions depending on the different conformations can be explained based on the idea that the effective conjugated C═C chain lengths within lycopene molecules are different due to the environmental effect (site-shift effect) caused by the aggregation conformation. Applying this knowledge to the in vivo measurement of a tomato fruit sample, the relationship between the aggregation conformation of lycopene and the spectral patterns observed in the UV-vis as well as Raman spectra in different parts of tomato fruits was discussed in detail. The results showed that the concentration of lycopene (particularly that of the J-aggregate) specifically increased, whereas that of chlorophyll decreased, with ripening. Furthermore, Raman imaging indicated that lycopene with different aggregate conformations was distributed inhomogeneously, even within one sample. The layer formation in tomato tissues with high concentrations of J- and H-aggregates was successfully visualized. In this manner, the presence of lycopene distributions with different aggregate conformations was unveiled in vivo.

Profiling Polyphenols in Five Brassica species Microgreens by UHPLC-PDA-ESI/HRMSn

PubMed Central

Sun, Jianghao; Xiao, Zhenlei; Lin, Long-ze; Lester, Gene E.; Wang, Qin; Harnly, James M.; Chen, Pei

2014-01-01

Brassica vegetables are known to contain relatively high concentrations of bioactive compounds associated with human health. A comprehensive profiling of polyphenols from five Brassica species microgreens was conducted using ultra high-performance liquid chromatography photo diode array high-resolution multi-stage mass spectrometry (UHPLC-PDA-ESI/HRMSn). A total of 164 polyphenols including 30 anthocyanins, 105 flavonol glycosides, and 29 hydroxycinnamic acid and hydroxybenzoic acid derivatives were putatively identified.The putative identifications were based on UHPLC-HRMSn analysis using retention times, elution orders, UV/Vis spectra and high resolution mass spectra, in-house polyphenol database, and as well as literature comparisons. This study showed that these five Brassica species microgreens could be considered as good sources of food polyphenols. PMID:24144328

Optical spectra, electronic structure and aromaticity of benzannulated N-heterocyclic carbene and its analogues of the type C6H4(NR)2E: (E = Si, Ge, Sn, Pb).

PubMed

Aysin, Rinat R; Bukalov, Sergey S; Leites, Larissa A; Zabula, Alexander V

2017-07-11

A series of benzannulated N-heterocyclic compounds containing divalent 14 group atoms, C 6 H 4 (NR) 2 E II , E = C, Si, Ge, Sn, Pb, have been studied by various experimental (vibrational and UV-vis spectroscopy) and theoretical (NICS, ISE, ACID) techniques. The methods used confirm 10 π-electron delocalization (aromaticity) in these heterocycles, however, the aromaticity sequences estimated by the criteria based on different physical properties do not coincide.

Hydrothermal synthesis of tungsten doped tin dioxide nanocrystals

NASA Astrophysics Data System (ADS)

Zhou, Cailong; Li, Yufeng; Chen, Yiwen; Lin, Jing

2018-01-01

Tungsten doped tin dioxide (WTO) nanocrystals were synthesized through a one-step hydrothermal method. The structure, composition and morphology of WTO nanocrystals were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, UV-vis diffuse reflectance spectra, zeta potential analysis and high-resolution transmission electron microscopy. Results show that the as-prepared WTO nanocrystals were rutile-type structure with the size near 13 nm. Compared with the undoped tin dioxide nanocrystals, the WTO nanocrystals possessed better dispersity in ethanol phase and formed transparent sol.

Synthesis and Characterization of Rhodamine B-ethylenediamine-hyaluronan Acid as Potential Biological Functional Materials

NASA Astrophysics Data System (ADS)

Li, Y. L.; Wang, W. X.; Wang, Y.; Zhang, W. B.; Gong, H. M.; Liu, M. X.

2018-05-01

The purpose of this study is to synthesize and characterize fluorescent polymers, rhodamine B-ethylenediamine-hyaluronan acid (RhB-EA-HA). RhB-EA-HA was successfully synthesized by ester ammonolysis reaction and amidation reaction. Moreover, the structural properties of RhB-EA-HA were characterized by 1H-NMR spectra, UV-vis spectrometry and Fourier transform infrared spectroscopy (FT-IR). RhB-EA-HA can be grafted on the surface of silica nanomaterials, which may be potential biological functional materials for drug delivery system.

Synthesis and Electronic Properties of Length-Defined 9,10-Anthrylene-Butadiynylene Oligomers.

PubMed

Nagaoka, Maiko; Tsurumaki, Eiji; Nishiuchi, Mai; Iwanaga, Tetsuo; Toyota, Shinji

2018-05-18

Linear π-conjugated oligomers consisting of anthracene and diacetylene units were readily synthesized by a one-pot process that involved desilylation and oxidative coupling from appropriate building units. We were able to isolate length-defined oligomers ranging from 2-mer to 6-mer as stable and soluble solids. The bathochromic shifts in the UV-vis spectra suggested that the π-conjugation was extended with elongation of the linear chain. Cyclic voltammetric measurements showed characteristic reversible oxidation waves that were dependent on the number of anthracene units.

Preparation of silver nanoparticles/graphene nanosheets as a catalyst for electrochemical oxidation of methanol

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

Han, Kun; Miao, Peng; Tang, Yuguo, E-mail: tangyg@sibet.ac.cn

2014-02-03

In this report, silver nanoparticles (AgNPs) decorated graphene nanosheets have been prepared based on the reduction of Ag ions by hydroquinone, and their catalytic performance towards the electrochemical oxidation of methanol is investigated. The synthesis of the nano-composite is confirmed by transmission electron microscope measurements and UV-vis absorption spectra. Excellent electrocatalytic performance of the material is demonstrated by cyclic voltammograms. This material also contributes to the low peak potential of methanol oxidation compared with most of the other materials.

Label-free detection of specific DNA sequence-telomere using unmodified gold nanoparticles as colorimetric probes

NASA Astrophysics Data System (ADS)

Qi, Yingying; Li, Li; Li, Baoxin

2009-09-01

A simple and sensitive label-free colorimetric detection of telomere DNA has been developed. It was based on the color change of gold nanoparticles (AuNPs) due to DNA hybridization. UV-vis spectra and transmission electron microscopy (TEM) were used to investigate the change of AuNPs. Under the optimized conditions, the linear range for determination of telomere DNA was 5.7 × 10 -13 to 4.5 × 10 -6 mol/L. The detection limit (3 σ) of this method has decreased to pico-molar level.

Green Synthesis of Silver Nanoparticles Decorated by Fe₃O₄/GO with Enhanced Catalytic Activity.

PubMed

Guo, Jian; Wang, Yu; Liu, Dan-Dan; Wan, Rong; Han, Guo-Zhi

2018-05-01

We report a simple and green approach to synthesize stable water-dispersible silver nanoparticles decorated by magnetic Fe3O4 and graphene oxide (GO). These results of UV-Vis spectra, along with TEM and SEM indicated that the water-dispersible silver nanoparticles had cluster flat structure and retained the optical properties of the original silver particle. Combining the advantages of Fe3O4 and GO, the composite nanoparticles showed enhanced catalytic activity with good recycling utilization rate by magnetic separation.

Thickness-dependent photocatalytic performance of graphite oxide for degrading organic pollutants under visible light.

PubMed

Oh, Junghoon; Chang, Yun Hee; Kim, Yong-Hyun; Park, Sungjin

2016-04-28

Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication. All GO samples exhibit photocatalytic activity for degrading an organic pollutant, rhodamine B under visible light, and the thickest sample shows the best catalytic performance. UV-vis-NIR diffuse reflectance absorption spectra indicate that thicker GO samples absorb more vis-NIR light than thinner ones. Density-functional theory calculations show that GO has a much smaller band gap than that of single-layer graphene oxide, and thus suggest that the largely-reduced band gap is responsible for this trend of light absorption.

Identification of different species of Bacillus isolated from Nisargruna Biogas Plant by FTIR, UV-Vis and NIR spectroscopy

NASA Astrophysics Data System (ADS)

Ghosh, S. B.; Bhattacharya, K.; Nayak, S.; Mukherjee, P.; Salaskar, D.; Kale, S. P.

2015-09-01

Definitive identification of microorganisms, including pathogenic and non-pathogenic bacteria, is extremely important for a wide variety of applications including food safety, environmental studies, bio-terrorism threats, microbial forensics, criminal investigations and above all disease diagnosis. Although extremely powerful techniques such as those based on PCR and microarrays exist, they require sophisticated laboratory facilities along with elaborate sample preparation by trained researchers. Among different spectroscopic techniques, FTIR was used in the 1980s and 90s for bacterial identification. In the present study five species of Bacillus were isolated from the aerobic predigester chamber of Nisargruna Biogas Plant (NBP) and were identified to the species level by biochemical and molecular biological (16S ribosomal DNA sequence) methods. Those organisms were further checked by solid state spectroscopic absorbance measurements using a wide range of electromagnetic radiation (wavelength 200 nm to 25,000 nm) encompassing UV, visible, near Infrared and Infrared regions. UV-Vis and NIR spectroscopy was performed on dried bacterial cell suspension on silicon wafer in specular mode while FTIR was performed on KBr pellets containing the bacterial cells. Consistent and reproducible species specific spectra were obtained and sensitivity up to a level of 1000 cells was observed in FTIR with a DTGS detector. This clearly shows the potential of solid state spectroscopic techniques for simple, easy to implement, reliable and sensitive detection of bacteria from environmental samples.

Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes

PubMed Central

Raza, Muhammad Akram; Kanwal, Zakia; Rauf, Anum; Sabri, Anjum Nasim; Riaz, Saira; Naseem, Shahzad

2016-01-01

Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby–Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs. PMID:28335201

Multiwavelength UV/visible spectroscopy for the quantitative investigation of platelet quality

NASA Astrophysics Data System (ADS)

Mattley, Yvette D.; Leparc, German F.; Potter, Robert L.; Garcia-Rubio, Luis H.

1998-04-01

The quality of platelets transfused is vital to the effectiveness of the transfusion. Freshly prepared, discoid platelets are the most effective treatment for preventing spontaneous hemorrhage or for stopping an abnormal bleeding event. Current methodology for the routine testing of platelet quality involves random pH testing of platelet rich plasma and visual inspection of platelet rich plasma for a swirling pattern indicative of the discoid shape of the cells. The drawback to these methods is that they do not provide a quantitative and objective assay for platelet functionality that can be used on each platelet unit prior to transfusion. As part of a larger project aimed at characterizing whole blood and blood components with multiwavelength UV/vis spectroscopy, isolated platelets and platelet in platelet rich plasma have been investigated. Models based on Mie theory have been developed which allow for the extraction of quantitative information on platelet size, number and quality from multi-wavelength UV/vis spectra. These models have been used to quantify changes in platelet rich plasma during storage. The overall goal of this work is to develop a simple, rapid quantitative assay for platelet quality that can be used prior to platelet transfusion to ensure the effectiveness of the treatment. As a result of this work, the optical properties for isolated platelets, platelet rich plasma and leukodepleted platelet rich plasma have been determined.

NIR absorbing diferrocene-containing meso-cyano-BODIPY with a UV-Vis-NIR spectrum remarkably close to that of magnesium tetracyanotetraferrocenyltetraazaporphyrin.

PubMed

Didukh, Natalia O; Zatsikha, Yuriy V; Rohde, Gregory T; Blesener, Tanner S; Yakubovskyi, Viktor P; Kovtun, Yuriy P; Nemykin, Victor N

2016-10-04

Diferrocene-containing meso-cyano-BODIPY (4) was prepared by the direct cyanation/oxidation reaction of symmetric BODIPY 1 followed by Knoevenagel condensation with ferrocenealdehyde. Ferrocene-containing BODIPY 4 was characterized by a variety of spectroscopic, electrochemical, and theoretical methods and its UV-Vis-NIR spectrum has a striking similarity with a UV-Vis-NIR spectrum of the previously reported magnesium 2(3),7(8),12(13),17(18)-tetracyano-3(2),8(7),13(12),18(17)-tetraferrocenyl-5,10,15,20-tetraazaporphyrin.

Coupling Reagent for UV/vis Absorbing Azobenzene-Based Quantitative Analysis of the Extent of Functional Group Immobilization on Silica.

PubMed

Choi, Ra-Young; Lee, Chang-Hee; Jun, Chul-Ho

2018-05-18

A methallylsilane coupling reagent, containing both a N-hydroxysuccinimidyl(NHS)-ester group and a UV/vis absorbing azobenzene linker undergoes acid-catalyzed immobilization on silica. Analysis of the UV/vis absorption band associated with the azobenzene group in the adduct enables facile quantitative determination of the extent of loading of the NHS groups. Reaction of NHS-groups on the silica surface with amine groups of GOx and rhodamine can be employed to generate enzyme or dye-immobilized silica for quantitative analysis.

Synthesis and photocatalytic properties of TiO{sub 2} nanostructures

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

Xia, X.H.; Liang, Y.; Wang, Z.

2008-08-04

TiO{sub 2} particles, rods, flowers and sheets were prepared by hydrothermal method via adjusting the temperature, the pressure and the concentration of TiCl{sub 4}. The as-prepared TiO{sub 2} powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra and N{sub 2} adsorption-desorption measurements. It was found that pressure is the most important factor influencing the morphology of TiO{sub 2}. The photocatalytic activity of the products was evaluated by the photodegradation of aqueous brilliant red X-3B solution under UV light. Among the as-prepared nanostructures, the flower-like TiO{sub 2}more » exhibited the highest photocatalytic activity.« less

The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

[Effects of dynamic high-pressure microfluidization on the structure of waxy rice starch].

PubMed

Tu, Zong-Cai; Zhu, Xiu-Mei; Chen, Gang; Wang, Hui; Zhang, Bo; Huang, Xiao-Qin; Li, Zhi

2010-03-01

The effects of dynamic ultra high-pressure microfluidization on the structure of waxy rice starch solutions (6%) were analyzed using SEM, UV-Vis spectra, polarized light microscopy, and X-ray diffraction spectra. The results showed that: SEM graphs demonstrated that the crystal structure of waxy rice starch under different pressure treatment was destroyed with different degrees and impacted into flake up to 160 MPa; from the ultraviolet-visible spectrum we know the reduction in the blue iodine value and the decrease in the amylopectin content, which illustrated that the structure of waxy rice starch was fractured; polarized microscopic images showed that the polarization crosses of starch molecules became misty with the pressure increasing, and most of starch molecules lost polarization cross when the pressure reached 160 MPa; X-ray diffraction spectra indicated that relative crystallinity began to decline at 120 MPa with pressure treatment, and the decreased amplitude was slightly lower.

Post-chemiluminescence determination of chloramphenicol based on luminol-potassium periodate system.

PubMed

Yang, Xiao Feng; Li, Nian Bing; Luo, Hong Qun

2012-01-01

A post-chemiluminescence (PCL) phenomenon was observed when chloramphenicol was injected into a mixture of luminol and potassium periodate after the chemiluminescence (CL) reaction of luminol-potassium periodate had finished. The possible reaction mechanism was proposed based on studies of the CL kinetic characteristics, the CL spectra, the fluorescence spectra and the UV-vis absorption spectra of the related substances. Based on the PCL reaction, a rapid and sensitive method for the determination of chloramphenicol was established. The linear response range was 6.0 × 10(-7) -1.0 × 10(-5) mol/L, with a correlation coefficient of 0.9986. The relative standard deviation (RSD) for 5.0 × 10(-6) mol/L chloramphenicol was 2.3% (n = 11). The detection limit was 1.6 × 10(-7) mol/L. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.

Synthesis of a ternary Ag/RGO/ZnO nanocomposite via microwave irradiation and its application for the degradation of Rhodamine B under visible light.

PubMed

Surendran, Divya Kollikkara; Xavier, Marilyn Mary; Viswanathan, Vandana Parakkal; Mathew, Suresh

2017-06-01

Reduced graphene oxide supporting plasmonic photocatalyst (Ag) on ZnO has been synthesized via a facile two-step microwave synthesis using RGO/ZnO and AgNO 3 . First step involves fabrication of RGO/ZnO via microwave irradiation. The nanocomposites were characterized by X-ray diffraction analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Ag/RGO/ZnO shows enhanced photoactivity under visible light for the degradation of Rhodamine B. Enhanced charge separation and migration have been assigned using UV-vis diffuse reflectance spectra, photoluminescence spectra, electrochemical impedance spectra, and TCSPC analysis. The improved photoactivity of Ag/RGO/ZnO can be ascribed to the prolonged lifetime of photogenerated electron-hole pairs and effective interfacial hybridization between RGO and Ag with ZnO nanoparticles. Ag nanoparticles can absorb visible light via surface plasmon resonance to enhance photocatalytic activity.

Syntheses and characterization of Ru(III) with chelating containing ONNO donor quadridentate Schiff bases.

PubMed

Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

2008-09-01

Complexes of ruthenium(III) with N,N'-disalicylidene-l,2-phenylenediamine (H2dsp), N,N'-disalicylidene-3,4-diaminotoluene (H2dst), 4-nitro-N,N'-disalicylidene-1,2-phenylenediamine (H2ndsp) and N,N'-disalicylidene ethylenediamine (H2salen) have been prepared and characterized by elemental analysis, molar conductivity, spectral methods (mid-infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that all these complexes are non-electrolytes. The electronic spectra measurements were used to infer the structures. The IR spectra of the ligands and their complexes are used to identify the type of bonding. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The four ligands and their complexes have been studied for their possible biological antifungal activity.

Catalyzed formation of α,β-unsaturated ketones or aldehydes from propargylic acetates by a recoverable and recyclable nanocluster catalyst

NASA Astrophysics Data System (ADS)

Li, Man-Bo; Tian, Shi-Kai; Wu, Zhikun

2014-05-01

An active, recoverable, and recyclable nanocluster catalyst, Au25(SR)18-, has been developed to catalyze the formation of α,β-unsaturated ketones or aldehydes from propargylic acetates. The catalytic process has been proposed to be initialized by an SN2' addition of OH-. Moreover, a dramatic solvent effect was observed, for which a rational explanation was provided.An active, recoverable, and recyclable nanocluster catalyst, Au25(SR)18-, has been developed to catalyze the formation of α,β-unsaturated ketones or aldehydes from propargylic acetates. The catalytic process has been proposed to be initialized by an SN2' addition of OH-. Moreover, a dramatic solvent effect was observed, for which a rational explanation was provided. Electronic supplementary information (ESI) available: Experimental procedures, UV-Vis spectra and fluorescence spectra of catalysts, characterization data, and copies of MS spectra. See DOI: 10.1039/c4nr00658e

The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest

NASA Astrophysics Data System (ADS)

Sander, Rolf; Keller-Rudek, Hannelore; Moortgat, Geert; Sörensen, Rüdiger

2014-05-01

Measurements from satellites can be used to obtain global concentration maps of atmospheric trace constituents. Critical parameters needed in the analysis of the satellite data are the absorption cross sections of the observed molecules. Here, we present the MPI-Mainz UV/VIS Spectral Atlas, which is a large collection of more than 5000 absorption cross section and quantum yield data files in the ultraviolet and visible (UV/VIS) wavelength region for gaseous molecules and radicals primarily of atmospheric interest. The data files contain results of individual measurements, covering research of almost a whole century. To compare and visualize the data sets, multicoloured graphical representations have been created. The Spectral Atlas is available on the internet at http://www.uv-vis-spectral-atlas-mainz.org. It has been completely overhauled and now appears with improved browse and search options, based on PostgreSQL, Django and Python database software. The web pages are continuously updated.

Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

PubMed

Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

2014-02-01

The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. © 2013.

Anti-inflammatory drugs interacting with Zn (II) metal ion based on thiocyanate and azide ligands: synthesis, spectroscopic studies, DFT calculations and antibacterial assays.

PubMed

Chiniforoshan, Hossein; Tabrizi, Leila; Hadizade, Morteza; Sabzalian, Mohammad R; Chermahini, Alireza Najafi; Rezapour, Mehdi

2014-07-15

Zinc (II) complexes with non-steroidal anti-inflammatory drugs (NSAIDs) naproxen (nap) and ibuprofen (ibu) were synthesized in the presence of nitrogen donor ligands (thiocyanate or azide). The complexes were characterized by elemental analysis, FT-IR, (1)H NMR and UV-Vis spectroscopes. The binding modes of the ligands in complexes were established by means of molecular modeling of the complexes, and calculation of their IR, NMR and absorption spectra at DFT (TDDFT)/B3LYP level were studied. The experimental and calculated data verified monodentate binding through the carboxylic oxygen atoms of anti-inflammatory drugs in the zinc complexes. The calculated (1)H, FT-IR and UV-Vis data are in better agreement with the experimental results, and confirm the predicted tetrahedral structures for the Zn (II) complexes. In addition to DFT calculations of complexes, natural bond orbital (NBO) was performed at B3LYP/6-31+G(d,p) level of theory. Biological studies showed the antibacterial activity of zinc complexes against Gram-positive and Gram-negative bacterial strains. Copyright © 2014 Elsevier B.V. All rights reserved.

N, S co-doped-TiO2/fly ash beads composite material and visible light photocatalytic activity

NASA Astrophysics Data System (ADS)

Lv, Jun; Sheng, Tong; Su, Lili; Xu, Guangqing; Wang, Dongmei; Zheng, Zhixiang; Wu, Yucheng

2013-11-01

Using TiCl4 as the titanium source, urea as the precipitating agent, nano-TiO2/fly ash beads composite materials were prepared by hydrolysis-precipitation method. Using (NH2)2CO and (NH2)2SC as the N and S source respectively, N and S co-doped TiO2/fly ash beads composite materials were prepared by grinding them together according to a certain proportion and calcined at 500 °C for 2 h. The composite materials were characterized by SEM, EDS, XPS, and UV-vis spectrophotometer methods. The UV-vis absorption spectra results show that the absorption edge of un-doped composites is 390 nm while that of doped composites red-shifts to 500 nm. The photocatalytic activity of composite materials was evaluated by degradation of methyl orange under visible light irradiation (halogen lamp, 250 W). The results showed that after irradiation for 1 h, degradation rate of N, S co-doped-TiO2/fly ash beads composite material can reach 65%, while the degradation rate of un-doped sample and P25 were just 10% and 6%, respectively. The composite material also showed excellent recycling properties.

Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

PubMed

Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

2018-04-05

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

A new approach for white organic light-emitting diodes of single emitting layer using large stokes shift.

PubMed

Kim, Beomjin; Park, Youngil; Kim, Seungho; Lee, Younggu; Park, Jongwook

2014-08-01

DPPZ showed UV-Vis. and PL maximum values of 412 and 638 nm, meaning the large stokes shift. Blue host compound, TAT was synthesized and used for co-mixed white emission. TAT exhibited UV-Vis. and PL maximum values of 403 nm and 445 nm in film state. Thus, when two compounds are used as co-mixed emitter in OLED device, there is no energy transfer from blue emission of TAT to DPPZ due to large stokes shift of DPPZ. Based on the PL result, it is available to realize two-colored white in PL and EL spectra. As a result of this, two-mixed compounds showed vivid their own PL emission peaks of 449 and 631 nm in film state. Also, white OLED device using two-mixed compounds system was fabricated. EL spectrum shows 457 and 634 nm peaks and two separate EL peaks, respectively. As the operation voltage is increased from 7 to 11 V, EL spectrum does not change the peak shape and maximum wavelength values. EL performance of white device showed 0.29 cd/A, 0.14 lm/W, and CIE (0.325, 0.195) at 7 V.

Synthesis and characterization of Ag embedded graphitic carbon nitride

NASA Astrophysics Data System (ADS)

Patra, P. C.; Mohapatra, Y. N.

2018-05-01

Silver embedded graphitic carbon nitride (g-C3N4:Ag) was prepared by a simple wet chemical pathway using dimethylformamide (DMF) as a common solvent which facilitate homogenous distribution of Ag nanoparticles under ambient conditions. The phase, chemical structure and thermal stability of the as prepared g-C3N4:Ag composite was characterized by X-ray diffraction (XRD), Fourier transmission infrared (FTIR) spectroscopy and Thermo gravimetric analysis (TGA). The optical properties of g-C3N4:Ag were investigated by diffuse reflectance UV/vis spectroscopy and steady state photoluminescence (PL) spectroscopy. The bandgap of g-C3N4:Ag is determined to be 2.72 eV compared to 2.85 eV for that of pure g-C3N4 using Kubelka-Monk function. Comparing the UV/vis spectra, there is a broad spectrum in the region 2.3 to 2.6 eV in the case of g-C3N4:Ag, which is attributed to the presence of Ag nanoparticles. The emission peak of g-C3N4:Ag is slightly broadened and quenched in intensity to that of pure g-C3N4.

Polarization, excited states, trans-cis properties and anisotropy of thermal and electrical conductivity of the 4-(phenyldiazenyl)aniline in PVA matrix

NASA Astrophysics Data System (ADS)

Shahab, Siyamak; Filippovich, Liudmila; Sheikhi, Masoome; Kumar, Rakesh; Dikusar, Evgenij; Yahyaei, Hooriye; Muravsky, Alexander

2017-08-01

In the present work, Polarization, Excited States, Trans-Cis (E → Z) Isomerization Properties and Anisotropy of Thermal and Electrical Conductivity of the 4-(phenyldiazenyl)aniline in the presence of polyvinyl alcohol (PVA) matrix were studied. DFT, UV/Vis, IR-Spectroscopies and Indicator Method were used for Determination of Thermal Conductivity of polymer films. The absorption spectra of the 4-(phenyldiazenyl)aniline in dimethylformamide (DMF) solvent and in aqueous medium were calculated. The nature of absorption peaks of the 4-(phenyldiazenyl)aniline in the UV/Vis spectral regions were interpreted. The solvent effect on the absorption spectrum of the 4-(phenyldiazenyl)aniline has established. The molecular HOMO-LUMO, excitation energies and oscillator strengths for E and Z isomers of the 4-(phenyldiazenyl)aniline have also been calculated and presented. Optical Properties of the PVA-films containing 4-(phenyldiazenyl)aniline have been also investigated. Polarizing Efficiency (PE) of obtained PVA-film is 98-99% at Stretching Degree (Rs) 3.5. Anisotropy of thermal and electrical conductivity of PVA-films containing E and Z isomers of the 4-(phenyldiazenyl)aniline was also measured and discussed.

Study on the interaction of antiviral drug 'Tenofovir' with human serum albumin by spectral and molecular modeling methods

NASA Astrophysics Data System (ADS)

Shahabadi, Nahid; Hadidi, Saba; Feizi, Foroozan

2015-03-01

This study was designed to examine the interaction of Tenofovir (Ten) with human serum albumin (HSA) under physiological conditions. The binding of drugs with human serum albumin is a crucial factor influencing the distribution and bioactivity of drugs in the body. To understand the action mechanisms between Ten and HSA, the binding of Ten with HSA was investigated by a combined experimental and computational approach. UV-vis results confirmed that Ten interacted with HSA to form a ground-state complex and values of the Stern-Volmer quenching constant indicate the presence of a static component in the quenching mechanism. As indicated by the thermodynamic parameters (positive ΔH and ΔS values), hydrophobic interaction plays a major role in the Ten-HSA complex. Through the site marker competitive experiment, Ten was confirmed to be located in site I of HSA. Furthermore, UV-vis absorption spectra, synchronous fluorescence spectrum and CD data were used to investigate the structural change of HSA molecules with addition of Ten, the results indicate that the secondary structure of HSA molecules was changed in the presence of Ten. The experimental results were in agreement with the results obtained via molecular docking study.

Piper nigrum leaf and stem assisted green synthesis of silver nanoparticles and evaluation of its antibacterial activity against agricultural plant pathogens.

PubMed

Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Pandian, Kannaiyan; Annadurai, Gurusamy

2014-01-01

Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The observation of the peak at 460 nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7-50 nm and 9-30 nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology.

Spectroscopic properties of halite from Kłodawa salt mine, central Poland

NASA Astrophysics Data System (ADS)

Zelek, Sylwia M.; Wesełucha-Birczyńska, Aleksandra; Szklarzewicz, Janusz; Stadnicka, Katarzyna M.

2015-02-01

The dynamics of colour centre transformation was investigated in blue halite single crystals from Kłodawa Salt Mine, Central Poland, using UV-vis spectroscopy. The following colour centres were considered: F, R1, R2, as well as plasmons and M centres. The R2 centres predominated in navy blue (A) and pale blue (B) halites. Other relatively large populations were plasmons found in all examined samples. In purple (C) halite samples the plasmon population is the highest one among others and R1 centres appeared to be equally significant, whereas M centres were almost absent. For A and C samples unidentified bands were observed at 26,500 to 26,200 cm-1, respectively. The bleaching process of the blue halites was investigated using temperature dependent UV-vis and micro-Raman spectroscopies. In micro-Raman 300-100 cm-1 region three very intense sharp bands were attributed to the colour centres and colloidal Na precipitation in A and B halites. The one broad band in the range 3,500 to 500 cm-1, which was characteristic even for the colourless sample D but absent in the spectra of colourless NaCl obtained after recrystallization of sample A, requires further study.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-01

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic)2·H2O]·H2O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis.

Decomposition of 2-((2-methoxyphenyl)diazenyl)benzene-1,3,5-triol molecule by an argon plasma jet

NASA Astrophysics Data System (ADS)

Tanışlı, Murat; Taşal, Erol

2018-05-01

In this study, we have presented the effects of the argon plasma on a 2-((2-methoxyphenyl)diazenyl)benzene-1,3,5-triol molecule—AZO compound (abbreviated as 2MDB)—under atmospheric pressure. In order to do this, the validated molecule has been considered and plasma has been used to modify it. The atmospheric pressure plasma jet system was specially designed for performing decomposing processes of the 2MDB molecule. The characterizations before and after the application of plasma—which takes only 3 minutes under atmospheric pressure conditions, to dissolve the 2MDB molecule in ethanol and methanol solutions—were examined using the Fourier transform infrared and Ultraviolet-Visible (UV-Vis) spectroscopies. After the plasma treatment, the molecule was broken at -C-N=N-C-C bond. Accurate and important changes are seen clearly from the results. In addition, according to UV-Vis spectra, π-π* electronic transitions related to -N=N- AZO bridge for the 2MDB molecule in polar-aprotic solvents such as ethanol and methanol were recorded as strong transitions. The new photoproducts such as -C-N-N=C and C=O were obtained from the 2MDB molecule.

Structure and spectroscopic study of aqueous Fe(III)-As(V) complexes using UV-Vis, XAS and DFT-TDDFT.

PubMed

Chai, Liyuan; Yang, Jinqin; Zhang, Ning; Wu, Pin-Jiun; Li, Qingzhu; Wang, Qingwei; Liu, Hui; Yi, Haibo

2017-09-01

Aqueous complexes between ferric (Fe(III)) and arsenate (As(V)) are indispensable for understanding the mobility of arsenic (As) in Fe(III)-As(V)-rich systems. In this study, aqueous Fe(III)-As(V) complexes, FeH 2 AsO 4 2+ and FeHAsO 4 + , were postulated based on the qualitative analysis of UV-Vis spectra in both Fe(III)-As(V)-HClO 4 and Fe(III)-As(V)-H 2 SO 4 systems. Subsequently, monodentate structures were evidenced by Fe K-edge EXAFS and modeled as [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + by DFT. The feature band at ∼280 nm was verified as electron excitation chiefly from Fe-As-bridged O atoms to d-orbital of Fe in [FeH 2 AsO 4 (H 2 O) 5 ] 2+ and [FeHAsO 4 (H 2 O) 5 ] + . The structural and spectral information of Fe(III)-As(V) complexes will enable future speciation analysis in Fe(III)-As(V)-rich system. Copyright © 2017. Published by Elsevier Ltd.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters.

PubMed

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-05

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic) 2 ·H 2 O]·H 2 O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparative study of the reduction of silver and gold salts in water by a cathodic microplasma electrode

NASA Astrophysics Data System (ADS)

De Vos, Caroline; Baneton, Joffrey; Witzke, Megan; Dille, Jean; Godet, Stéphane; Gordon, Michael J.; Mohan Sankaran, R.; Reniers, François

2017-03-01

A comparative study of the reduction of aqueous silver (Ag) and gold (Au) salts to colloidal Ag and Au nanoparticles, respectively, by a gaseous, cathodic, atmospheric-pressure microplasma electrode is presented. The resulting nanoparticles (NPs) were characterized by ultraviolet-visible (UV-vis) absorption spectroscopy and transmission electron microscopy (TEM), and the aqueous solution composition before and after experiments was determined by ionic conductivity, electrochemical potential, and/or UV-vis absorption measurements. TEM showed that Ag and Au NPs were spherical and non-agglomerated when synthesized in the presence of a stabilizer, polyvinyl alcohol. The charge injected by the plasma was correlated to the maximum intensity in the absorbance spectra which in turn depends on the nanoparticle concentration. Separately, the charge injected was correlated to the metal cation concentration. Ag and Au reduction rates were found to be directly proportional to the charge injected, independent of plasma current and process time. Differences in the mechanism for Ag and Au reduction were also observed, and solution species generated by the plasma and their role in the reduction process (e.g. H2O2, electrons) is discussed.

Aromatic hydrazones derived from nicotinic acid hydrazide as fluorimetric pH sensing molecules: Structural analysis by computational and spectroscopic methods in solid phase and in solution

NASA Astrophysics Data System (ADS)

Benković, T.; Kenđel, A.; Parlov-Vuković, J.; Kontrec, D.; Chiş, V.; Miljanić, S.; Galić, N.

2018-02-01

Structural analyses of aroylhydrazones were performed by computational and spectroscopic methods (solid state NMR, 1 and 2D NMR spectroscopy, FT-IR (ATR) spectroscopy, Raman spectroscopy, UV-Vis spectrometry and spectrofluorimetry) in solid state and in solution. The studied compounds were N‧-(2,3-dihydroxyphenylmethylidene)-3-pyridinecarbohydrazide (1), N‧-(2,5-dihydroxyphenylmethylidene)-3-pyridinecarbohydrazide (2), N‧-(3-chloro-2-hydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (3), and N‧-(2-hydroxy-4-methoxyphenyl-methylidene)-3-pyridinecarbohydrazide (4). Both in solid state and in solution, all compounds were in ketoamine form (form I, sbnd COsbnd NHsbnd Ndbnd Csbnd), stabilized by intramolecular H-bond between hydroxyl proton and nitrogen atom of the Cdbnd N group. In solid state, the Cdbnd O group of 1-4 were involved in additional intermolecular H-bond between closely packed molecules. Among hydrazones studied, the chloro- and methoxy-derivatives have shown pH dependent and reversible fluorescence emission connected to deprotonation/protonation of salicylidene part of the molecules. All findings acquired by experimental methods (NMR, IR, Raman, and UV-Vis spectra) were in excellent agreement with those obtained by computational methods.

Synthesis Structural and Optical Properties Of (Co, Al) co-doped ZnO Nano Particles

NASA Astrophysics Data System (ADS)

Swapna, P.; Venkatramana Reddy, S.

2018-02-01

We prepared (Co, Al) co-doped ZnO nanostructures using the method chemical co-precipitation successfully, at room temperature using PEG (Poly ethylene glycol) as stabilizing agent. Samples are prepared with different concentrations by keeping aluminium at 5 mol percent constant and varying the concentration of cobalt from 1 to 5 mol percent. After the preparation all the samples are carefully subjected to characterizations such as XRD, SEM with EDS, TEM, PL and UV-VIS-NIR. XRD pattern shows that all the samples possess hexagonal wurtzite crystal structure having no secondary phases pertaining to Al or cobalt, which shows successful dissolution of the dopents. TEM results shows the accurate size of particles and is confirmed the XRD data. SEM images of all the samples shows that particles are in nearly spherical shape, EDS spectrum reveals that incorporation of cobalt and aluminum in host lattice. PL spectrum shows that all the samples containing two prominent peaks centered at 420 nm and 446 nm. UV-VIS-NIR spectra has shown three absorptions peaks in the range of wavelength 550 nm to 700 nm, which are ascribed as typical d-d transitions of cobalt ions.

UV-Vis spectroscopic study and DFT calculation on the solvent effect of trimethoprim in neat solvents and aqueous mixtures.

PubMed

Almandoz, M C; Sancho, M I; Duchowicz, P R; Blanco, S E

2014-08-14

The solvatochromic behavior of trimethoprim (TMP) was analyzed using UV-Vis spectroscopy and DFT methods in neat and binary aqueous solvent mixtures. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra of TMP and TMP:(solvent)n complexes in ACN and H2O using TD-DFT methods were in agreement with the experimental ones. Binary aqueous mixtures containing as co-solvents DMSO, ACN and EtOH were studied. Preferential solvation was detected as a nonideal behavior of the wavenumber curve respective to the analytical mole fraction of co-solvent in all binary systems. TMP molecules were preferentially solvated by the organic solvent over the whole composition range. Index of preferential solvation, as well as the influence of solvent parameters were calculated as a function of solvent composition. Copyright © 2014 Elsevier B.V. All rights reserved.

Shedding light on the photostability of two intermolecular charge-transfer complexes between highly fluorescent bis-1,8-naphthalimide dyes and some π-acceptors: A spectroscopic study in solution and solid states

NASA Astrophysics Data System (ADS)

Refat, Moamen S.; Ismail, Lamia A.; Adam, Abdel Majid A.

2015-01-01

Given the great importance of the various uses of 1,8-naphthalimides in the trends of biology, medicine and industry, the current study focused on extending the scope of these dyes by introducing some of their charge-transfer (CT) complexes. For this purpose, two highly fluorescent bis-1,8-naphthalimide dyes and their complexes with some π-acceptors have been synthesized and characterized spectroscopically. The π-acceptors include picric acid (PA), chloranilic acid (CLA), tetracyanoquinodimethane (TCNQ) and dichlorodicyanobenzoquinone (DDQ). The molecular structure, spectroscopic and fluorescence properties as well as the binding modes were deduced from IR, UV-vis and 1H NMR spectral studies. The binding ratio of complexation was determined to be 1:1 according to the elemental analyses and photometric titrations. It has been found that the order of acceptance ability for the different acceptors is TCNQ > DDQ > CLA > PA. The photostability of 1,8-naphthalimide dye as a donor and its charge-transfer complex doped in polymethyl methacrylate/PMMA were exposed to UV-Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.

Optical and structural properties of protein/gold hybrid bio-nanofilms prepared by layer-by-layer method.

PubMed

Pál, Edit; Hornok, Viktória; Sebok, Dániel; Majzik, Andrea; Dékány, Imre

2010-08-01

Lysozyme/gold thin layers were prepared by layer-by-layer (LbL) self-assembly method. The build-up of the films was followed by UV-vis-absorbance spectra, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. The structural property of films was examined by X-ray diffraction (XRD) measurements, while their morphology was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was found that gold nanoparticles (NPs) had cubic crystalline structure, the primary particles form aggregates in the thin layer due to the presence of lysozyme molecules. The UV-vis measurements prove change in particle size while the colour of the film changes from wine-red to blue. The layer thickness of films was determined using the above methods and the loose, porous structure of the films explains the difference in the results. The vapour adsorption property of hybrid layers was also studied by QCM using different saturated vapours and ammonia gas. The lysozyme/Au films were most sensitive for ammonia gas among the tested gases/vapours due to the strongest interaction between the functional groups of the protein. Copyright 2010 Elsevier B.V. All rights reserved.

Spectroscopic study of honey from Apis mellifera from different regions in Mexico

NASA Astrophysics Data System (ADS)

Frausto-Reyes, C.; Casillas-Peñuelas, R.; Quintanar-Stephano, JL; Macías-López, E.; Bujdud-Pérez, JM; Medina-Ramírez, I.

2017-05-01

The objective of this study was to analyze by Raman and UV-Vis-NIR Spectroscopic techniques, Mexican honey from Apis Mellífera, using representative samples with different botanic origins (unifloral and multifloral) and diverse climates. Using Raman spectroscopy together with principal components analysis, the results obtained represent the possibility to use them for determination of floral origin of honey, independently of the region of sampling. For this, the effect of heat up the honey was analyzed in relation that it was possible to greatly reduce the fluorescence background in Raman spectra, which allowed the visualization of fructose and glucose peaks. Using UV-Vis-NIR, spectroscopy, a characteristic spectrum profile of transmittance was obtained for each honey type. In addition, to have an objective characterization of color, a CIE Yxy and CIE L*a*b* colorimetric register was realized for each honey type. Applying the principal component analysis and their correlation with chromaticity coordinates allowed classifying the honey samples in one plot as: cutoff wavelength, maximum transmittance, tones and lightness. The results show that it is possible to obtain a spectroscopic record of honeys with specific characteristics by reducing the effects of fluorescence.

Synthesis, characterization and antimicrobial activity of dextran sulphate stabilized silver nanoparticles

NASA Astrophysics Data System (ADS)

Cakić, Milorad; Glišić, Slobodan; Nikolić, Goran; Nikolić, Goran M.; Cakić, Katarina; Cvetinov, Miroslav

2016-04-01

Dextran sulphate stabilized silver nanoparticles (AgNPs - DS) were synthesized from aqueous solution of silver nitrate (AgNO3) and dextran sulphate sodium salt (DS). The characterization of AgNPs - DS was performed by ultraviolet-visible spectroscopy (UV-VIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and antimicrobial activity. The formation of AgNPs - DS was monitored by colour changes of the reaction mixture from yellowish to brown and by measuring the surface plasmon resonance absorption peak in UV-VIS spectra at 420 nm. The SEM analysis was used for size and shape determination of AgNPs - DS. The presence of elemental silver and its crystalline structure in AgNPs - DS were confirmed by EDX and XRD analyses. The possible functional groups of DS responsible for the reduction and stabilization of AgNPs were determinated by FTIR spectroscopy. The AgNPs - DS showed strong antibacterial activity against Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 11778, Bacillus luteus in haus strain, Bacillus subtilis ATTC 6633, Listeria monocytogenes ATCC 15313, Escherichia coli ATTC 25922, Pseudomonas aeruginosa ATTC 27853, Klebsiella pneumoniae ATTC 700603, Proteus vulgaris ATTC 8427, and antifungal activity against Candida albicans ATTC 2091.

The green hydrothermal synthesis of nanostructured Cu2ZnSnSe4 as solar cell material and study of their structural, optical and morphological properties

NASA Astrophysics Data System (ADS)

Vanalakar, S. A.; Agawane, G. L.; Kamble, A. S.; Patil, P. S.; Kim, J. H.

2017-12-01

Cu2ZnSnSe4 (CZTSe) has attracted intensive attention as an absorber material for the thin-film solar cells due to its high absorption coefficient, direct band gap, low toxicity, and abundance of its constituent elements. In this study nanostructured CZTSe nanoparticles are prepared via green hydrothermal synthesis without using toxic solvents, organic amines, catalysts or noxious chemicals. The structural, optical, and morphological properties of CZTSe nanostructured powder were studied using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy, and transmission electron microscope (TEM) techniques. Raman peaks at 170, 195, and 232 cm-1 confirm the formation of pure phase CZTSe nanostructured particles. In addition, the EDS and XPS results confirm the appropriate chemical purity of the annealed CZTSe nanoparticles. Meanwhile, the TEM analysis showed the presence of phase pure oval like CZTSe particle with size of about 80-140 nm. The UV-Vis-NIR absorption spectra analysis showed that the optical band gap of CZTSe nanostructured particles is about 1.14 eV. This band gap energy is close to the optimum value of a photovoltaic solar cell absorber material.

Structural, optical and dielectric properties of pure and chromium (Cr) doped nickel oxide nanoparticles

NASA Astrophysics Data System (ADS)

Gupta, Jhalak; Ahmed, Arham S.

2018-05-01

The pure and Cr doped nickel oxide (NiO) nanoparticles have been synthesized by cost effective co-precipitation method having nickel nitrate as initial precursor. The synthesized samples were characterized by X-Ray diffraction (XRD), UV-Visible Spectroscopy(UV-Vis) and LCR meter for structural, optical and dielectric properties respectively. The crystallite size of pure nickel oxide nanoparticles characterized by XRD using Debye Scherer's formula was found to be 21.7nm and the same decreases on increasing Cr concentration whereas optical and dielectric properties were analyzed by UV-Vis and LCR meter respectively. The energy band gaps were determined by UV-Vis using Tauc relation.

FT-IR, FT-Raman, UV, NMR spectra and molecular structure investigation of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine: A combined experimental and theoretical study

NASA Astrophysics Data System (ADS)

Therasa Alphonsa, A.; Loganathan, C.; Athavan Alias Anand, S.; Kabilan, S.

2015-11-01

This work presents the characterization of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine (HDE) by quantum chemical calculations and spectral techniques. The structure was investigated by FT-IR, FT-Raman, UV-vis and NMR techniques. The geometrical parameters and energies have been obtained from Density functional theory (DFT) B3LYP (6-31G (d, p)) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital method (GIAO). The electronic properties such as excitation energies, wavelength, HOMO, LUMO energies performed by Time dependent density functional theory (TD-DFT) results complements with the experimental findings. NBO analysis has been performed for analyzing charge delocalization throughout the molecule. The calculation results were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. To provide information about the interactions between human cytochrome protein and the novel compound theoretically, docking studies were carried out using Schrödinger software.