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Structural Dynamics of Dimethyl Sulfoxide Aqueous Solutions Investigated by Ultrafast Infrared Spectroscopy: Using Thiocyanate Anion as a Local Vibrational Probe
摘要： The microscopic structure of dimethyl sulfoxide (DMSO) aqueous solutions was investigated by FTIR spectroscopy and ultrafast IR spectroscopy. The structural dynamics of the binary mixtures were reflected by using thiocyanate anion (SCN-) as a local vibrational probe. FTIR spectra of SCN- anion showed the hydrogen bond networks of water are affected by the presence of DMSO molecules, and the peak position and bandwidth of SCN- anions are red-shifted and narrowed accordingly due to the weak hydration in the binary mixture. The vibrational lifetime of the SCN- anion showed almost linear enhancement with the increase of DMSO, which can be explained by the weak interaction between SCN- and the hydrophobic groups in DMSO molecule. However, the rotational dynamics of SCN- are slowing down significantly and showed a maximum response at XDMSO (mole fraction) of 0.35, which is mainly caused by the confinement of SCN- anions positioned in the vicinity of the complex structure formed between DMSO and water molecules. The concentration dependent rotational dynamics of water molecules and SCN- anions are having similar behavior, indicated that the complex structure can be formed between water and DMSO molecules due to the strong interaction. The result also demonstrates that the structural inhomogeneity in aqueous solution can be unraveled by monitoring the vibrational relaxation dynamics of SCN- anion serving as the local vibrational probe.
关键词： structural dynamics,thiocyanate anion,FTIR spectroscopy,Dimethyl sulfoxide,ultrafast IR spectroscopy,aqueous solutions,vibrational probe
更新于2025-09-10 09:29:36
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Understanding Crystal Structure and Site Symmetry of Undoped, Eu3+:Ba2LaSbO6 & Eu3+:BaLaMSbO6 (M = Mg,Ca): Tuning Eu-site Occupancy to Develop Both Orange and Red Phosphor
摘要： Double perovskite antimonates of the type BaLaMSbO6 (M=Mg, Ca) were synthesized by standard solid state route. The compounds were characterized by X-ray diffraction and the crystal structure was refined using Rietveld method. BaLaMgSbO6 and BaLaCaSbO6 crystallized in monoclinic (I2/m) and (P21/n) space group respectively. In both the compounds, La occupied A-site of perovskite, which is 12-coordinated as compared to Ba2LaSbO6 where La ion shifts to B-site octahedral coordination due to larger size of Ba as compared to Mg and Ca. The samples were further characterized using FTIR and the frequency of the octahedral vibration is correlated to the electronegativity of the B-site ions. Photoluminescence study of the title compounds and Ba2LaSbO6 was also studied upon doping with 2 atom% Eu3+ ion, which confirmed that Eu3+ occupies distorted 12-coordinated A-site in BaLaMSbO6 (M=Mg, Ca) and symmetrical octahedral B-site in Ba2LaSbO6. Further, the emission spectrum due to each Eu3+ ion at different crystal site was successfully isolated by TRES study. This enables to understand the structural differences of these compounds. This site selective occupancy of Eu3+ ion also has a direct impact on the light emission, which was found to change from orange to red in a dark room in the order Ba2LaSbO6:Eu → BaLaCaSbO6:Eu → BaLaMgSbO6:Eu. Such study will have high impact in designing new commercial Eu3+ ion doped phosphor materials and tailoring of their optical properties.
关键词： Double perovskites,FTIR spectroscopy,Crystal structure,Phosphor material,Antimonates,Photoluminescence (PL)
更新于2025-09-10 09:29:36
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Insight into Rapid DNA-Specific Identification of Animal Origin Based on FTIR Analysis: A Case Study
摘要： In this study, a methodology has been proposed to identify the origin of animal DNA, employing high throughput extension accessory Fourier transform infrared (HT-FTIR) spectroscopy coupled with chemometrics. Important discriminatory characteristics were identified in the FTIR spectral peaks of 51 standard DNA samples (25 from bovine and 26 from fish origins), including 1710, 1659, 1608, 1531, 1404, 1375, 1248, 1091, 1060, and 966 cm?1. In particular, the bands at 1708 and 1668 cm?1 were higher in fish DNA than in bovine DNA, while the reverse was true for the band at 1530 cm?1 was shown the opposite result. It was also found that the PO2? Vas/Vs ratio (1238/1094 cm?1) was significantly higher (p < 0.05) in bovine DNA than in fish DNA. These discriminatory characteristics were further revealed to be closely related to the base content and base sequences of different samples. Multivariate analyses, such as principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were conducted, and both the sensitivity and specificity values of PLS-DA model were one. This methodology has been further validated by 20 meat tissue samples (4 from bovine, 5 from ovine, 5 from porcine, and 6 from fish origins), and these were successfully differentiated. This case study demonstrated that FTIR spectroscopy coupled with PLS-DA discriminant model could provide a rapid, sensitive, and reliable approach for the identification of DNA of animal origin. This methodology could be widely applied in food, feed, forensic science, and archaeology studies.
关键词： animal origin,PLS-DA,DNA,rapid identification,FTIR spectroscopy
更新于2025-09-09 09:28:46
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VO <i> <sub/>n</sub></i> Complexes in RTA Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy
摘要： Oxygen-vacancy complexes formed after rapid thermal annealing in silicon wafers were investigated by FTIR spectroscopy at 6 K. It was found that VO4 is the only detectable complex. The concentration of VO4 complexes increases with increasing temperature of RTA treatment in the temperature range between 1250?C and 1400?C. The concentration at maximal temperature is equal to 4.5 × 1013 cm?3. The experimental results were compared with concentrations of VOn complexes in silicon wafers obtained using ab-initio calculations combined with rate equation modelling. The simulated concentration of VO4 corresponds well to the measured concentration. The bulk microdefect density increases with increasing VO4 concentration. The vacancies stored in VOn complexes after RTA are slowly released during further annealing and enhance oxide precipitation.
关键词： VO4 complexes,silicon wafers,Rapid thermal annealing,FTIR spectroscopy,oxygen precipitation
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) 2ND INTERNATIONAL CONFERENCE ON CHEMISTRY, CHEMICAL PROCESS AND ENGINEERING (IC3PE) - Yogyakarta, Indonesia (14 August 2018)] - Rapid analysis of adulterated sildenafil citrate in marketed herbal aphrodisiacs using infrared spectroscopy
摘要： A simple, rapid, non-destructive and cost-effective FTIR spectroscopy in combination with multivariate calibration of Stepwise Multiple Linear Regression (SMLR) has been developed for quantification of sildenafil citrate in marketed herbal aphrodisiacs. Selecting the best wavenumbers capable of providing the high coefficient of determination (R2), low values of Root Mean Square Error of Calibration (RMSEC) and predictive residual error sum of squares (PRESS) was the main point in this study. Finally, wavenumbers 1791, 1692, 1691 and 971 cm-1 were selected for prediction of sildenafil citrate in the marketed herbal aphrodisiacs. The correlation between actual values of sildenafil citrate determined in marketed herbal aphrodisiacs using FTIR spectroscopy combined with SMLR at 1791, 1692, 1691 and 971 cm-1 revealed R2 values of 1.00. The RMSEC values obtained are 0.000310913. The PRESS value obtained as the results of cross-validation model selection for sildenafil citrate in marketed herbal aphrodisiacs is 0.0009191. The high value of R2 and low value of RMSEC and PRESS indicated this method has high accuracy and precision in validated condition for quantification of sildenafil citrate in marketed herbal aphrodisiacs. These results indicated that FTIR spectroscopy combined with SMLR can be an alternative method for determination of sildenafil citrate in marketed herbal aphrodisiacs.
关键词： SMLR,FTIR spectroscopy,herbal aphrodisiacs,sildenafil citrate
更新于2025-09-09 09:28:46
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Vibrational Microspectroscopy for Cancer Screening
摘要： Vibrational spectroscopy analyses vibrations within a molecule and can be used to characterise a molecular structure. Raman spectroscopy is one of the vibrational spectroscopic techniques, in which incident radiation is used to induce vibrations in the molecules of a sample, and the scattered radiation may be used to characterise the sample in a rapid and non-destructive manner. Infrared (IR) spectroscopy is a complementary vibrational spectroscopic technique based on the absorption of IR radiation by the sample. Molecules absorb specific frequencies of the incident light which are characteristic of their structure. IR and Raman spectroscopy are sensitive to subtle biochemical changes occurring at the molecular level allowing spectral variations corresponding to disease onset to be detected. Over the past 15 years, there have been numerous reports demonstrating the potential of IR and Raman spectroscopy together with multivariate statistical analysis techniques for the detection of a variety of cancers including, breast, lung, brain, colon, oral, oesophageal, prostate and cervical cancer. This paper discusses the recent advances and the future perspectives in relation to cancer screening applications, focussing on cervical and oral cancer.
关键词： cytology,oral cancer,Raman spectroscopy,FTIR spectroscopy,optical diagnosis,cervical cancer,lasers,screening
更新于2025-09-04 15:30:14
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Investigation of the Atomic Structure of Ge-Sb-Se Chalcogenide Glasses
摘要： Glasses with composition of GexSb40-xSe60 (x= 40, 35, 32, 27, 20, 15 at. %) have been synthesized. Neutron and X-ray diffraction techniques were used to study the atomic glassy structure, and Reverse Monte Carlo (RMC) simulations were applied to model the 3-dimensional atomic configurations and thorough mapping of the atomic parameters, such as first and second neighbour distances, coordination numbers, and bond-angle distributions. The results are explained with formation of GeSe4 and SbSe3 structural units, which correlate with the Ge/Sb ratio. For all the studied compositions, the Ge-Se, Sb-Se, Ge-Ge, and Se-Se bonds are significant. RMC simulations reveal the presence of Ge-Sb and Sb-Sb bonds, being dependent on Ge/Sb ratio. All atomic compositions satisfy formal valence requirements, i.e., Ge is fourfold coordinated, Sb is threefold coordinated, and Se is twofold coordinated. By increasing the Sb content, both the Se-Ge-Se bonds angle of 107±3° and Se-Sb-Se bonds angle of 118±3° decrease, respectively, indicating distortion of the structural units. Far infrared Fourier Transform spectroscopic measurements conducted in the range of 50-450 cm-1 of oblique (75°) incidence radiation have revealed clear dependences of the IR band’s shift and intensity on the glassy composition, showing features around x=27 at.% supporting the topological phase transition to a stable rigid network consisting mainly of SbSe3 pyramidal and GeSe4 tetrahedral clusters. These results are in agreement with the Reverse Monte Carlo models, which define the Ge and Sb environment.
关键词： X-ray diffraction,chalcogenide glasses,atomic structure,FTIR spectroscopy,Ge-Sb-Se,neutron diffraction,Reverse Monte Carlo
更新于2025-09-04 15:30:14
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Preparation, characterization and electrical behaviors of PEDOT:PSS-Au/Ag nanocomposite thin films: an ecofriendly approach
摘要： Structure, morphology and electrical behaviors of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) or PEDOT:PSS thin films are investigated in the presence of protein-mediated green chemically synthesized positively charged gold and silver nanoparticles. The pure and PEDOT:PSS nanocomposite thin films are prepared by spin coating method. The presence of both nanoparticle and polymer is confirmed from X-ray diffraction, whereas composite formation is confirmed from Raman and FTIR spectroscopy. Atomic force microscopy (AFM) images show the surface morphologies of both pure and composite films, whereas average film thicknesses are obtained from AFM and X-ray reflectivity analysis. The presence of electrostatic interaction between the positively charged metallic nanoparticles and negatively charged PSS chains leads to the electrostatic shielding between cationic PEDOT and anionic PSS, which favors better charge transfer through PEDOT–PEDOT conducting paths. The increase in electrical conductivity is visualized from the current–voltage (I–V) curves, which show that the conductivity is relatively higher in the presence of silver than gold nanoparticles in the composite thin films. The conductivity of nanocomposite films is approximately five to six times enhanced in comparison with the pristine PEDOT:PSS thin films.
关键词： FTIR spectroscopy,PEDOT:PSS-Au/Ag thin films,AFM,UV–Vis,Nanocomposites,Conductivity
更新于2025-09-04 15:30:14
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ATR FTIR Spectroscopic Study on Insect Body Surface Lipids Rich in Methylene-Interrupted Diene
摘要： To protect themselves, insects cover their bodies with what is called cuticular lipid. The cuticular lipid of American cockroach has a unique lipid content; the most abundant is a cis-alkadiene, cis, cis-6, 9-heptacosadiene amounting to about 70%, which is followed by a branched alkane 3-methylpentacosane. In order to clarify the structural features of the unique lipid composition below the critical temperature, the cuticular lipid was studied by Fourier Transform Infrared (FTIR) spectroscopy in combination with attenuated total reflection (ATR) sampling technique. The infrared spectra measured on an extracted lipid sample at 20°C suggested that the lipid keeps an appreciable level of conformational and lateral packing regularity, in spite of high cis-unsaturated lipid content and also a highly disordered condition around the methyl terminals and cis-olefin groups. The CH2 scissoring and the CH2 rocking regions showed the characteristics of the O⊥ subcell. The same characteristics were observed also by in-situ measurements on a forewing of American cockroach. Combining the spectral features of these bands and the physicochemical properties of each component, it can be inferred that saturated lipids form highly ordered domains within the liquid containing the cis, cis-diene as main component. For comparison, the cuticular lipid of male cricket, which consisted many different hydrocarbons including 15 percent of unsaturated hydrocarbons, showed a lower regularity both in the conformation and in the lateral packing of hydrocarbon chains. These results imply that not only the degree of cis-unsaturation but also the chemical structure diversity of hydrocarbons is the important factor to determine the physicochemical properties of cuticular lipid.
关键词： cuticular lipid,American cockroach,FTIR spectroscopy,lateral packing,methylene-interrupted diene,cis-unsaturated lipids,ATR sampling technique,hydrocarbon chains,conformational order
更新于2025-09-04 15:30:14