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Optical and Judd-Ofelt spectroscopic study of Er3+/Pr3+-codoped Gd3Ga5O12 crystal
摘要： Optical and spectroscopic properties of Er3+/Pr3+-codoped Gd3Ga5O12 single-crystal grown by Czochralski method have been studied. Absorption spectrum of the crystal was measured at room temperature and Er3+ absorption cross-section spectral distributions were calibrated from it. The Er3+ spectroscopic properties were analyzed on the basis of the Judd-Ofelt theory. Fundamental spectroscopic parameters were obtained that include absorption coefficient, cross-section spectral distribution, electronic transition oscillator strength, Judd-Ofelt parameters, fluorescence branch ratio, transition probability, radiative and fluorescence lifetimes, and quantum efficiency as well. Study shows that Pr3+-codoping results in substantial change of Er3+ spectroscopic properties, in qualitative consistent with the previous fluorescence studying result. In addition, refractive index of the crystal was measured at different wavelengths using prism coupling method, and the Sellmeier equation reported previously for Er3+-only doped Gd3Ga5O12 crystal is corrected.
关键词： Sellmeier equation.,Er3+/Pr3+:Gd3Ga5O12 crystal,Judd-Ofelt spectroscopic analysis
更新于2025-09-23 15:23:52
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Controlled optoelectronic properties and abrupt change in photosensitivity by suppressing density of oxygen vacancies in SnO <sub/>2</sub> nanocrystalline thin films prepared at various spray-deposition temperatures
摘要： Nanostructured SnO2 thin films were synthesized at various substrate temperatures using a modified chemical spray pyrolysis (MCSP) technique. The x-ray diffraction (XRD) patterns confirmed the presence of a rutile SnO2 with tetragonal structure for all the resultant film samples. The XRD results ascertained increase in the grain growth rate and consequent enhancement in crystallinity with increasing the spray-deposition temperature. The optical spectroscopic analysis revealed a significant increase in the optical transmission within the visible region as well as a considerable increase in the optical bandgap by increasing the deposition temperature. However, the spectral distribution of the absorption coefficient ascertained the dominance of direct allowed transition for the SnO2 film samples. The analysis of the current-voltage characteristic curves revealed that the variation of the spray-deposition temperature strongly influences the photosensitivity of the film samples. Based on the electrical results, these film samples reveal a semiconductor behaviour of the transport property over the entire investigated range of the working temperature, with two different conduction mechanisms. The optical and electrical results were combined to evaluate the influence of varying the deposition temperature on the figure of merit (FOM) factor for the SnO2 film samples.
关键词： MCSP technique,optical spectroscopic analysis,electrical transport properties,figure of merit,structural properties,spray deposition temperature
更新于2025-09-23 15:19:57
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Super-resolution imaging of self-assembled nanocarriers using quantitative spectroscopic analysis for cluster extraction
摘要： Self-assembled nanocarriers have inspired a range of applications for bioimaging, diagnostics, and drug delivery. Non-invasive visualization and characterization of nanocarriers are important for understanding their structure to function relationship. However, quantitative visualization of nanocarriers in the sample’s native environment remains challenging using existing technologies. Single-molecule localization microscopy (SMLM) has the potential to provide both high-resolution visualization and quantitative analysis of nanocarriers in their native environment. However, non-specific binding of fluorescent probes used in SMLM can introduce artifacts, which impose challenges in quantitative analysis of SMLM images. We showed the feasibility of using spectroscopic point accumulation for imaging in nanoscale topography (sPAINT) to visualize self-assembled polymersomes (PS) with molecular specificity. Furthermore, we analyzed the unique spectral signatures of Nile Red (NR) molecules bound to the PS to reject artifacts from non-specific NR bindings. We further developed quantitative spectroscopic analysis for cluster extraction (qSPACE) to increase the localization density by 4-fold compared to sPAINT; thus, reducing variations in PS size measurements to less than 5%. Finally, using qSPACE we quantitatively imaged PS at various concentrations in aqueous solutions with ~20-nm localization precision and 97% reduction in sample misidentification relative to conventional SMLM.
关键词： nanocarriers,Nile Red,super-resolution imaging,single-molecule localization microscopy,spectroscopic analysis,polymersomes
更新于2025-09-23 15:19:57
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Preparation, Structural, Spectroscopic, Thermal, Linear and Nonlinear Optical Characteristics of Semi-Organic Material: Samarium Chloride-Thiourea-L-Tartaric acid
摘要： Samarium chloride-thiourea-l-tartaric acid (SCTuT): a semi-organic material was prepared in the form of a single crystal with an orthorhombic crystal structure and a space group Pnma. The crystallinity and purity of the single crystals were tested by powder X-ray diffraction. The scanning electron microscopy (SEM) analysis shows the rod-like microstructure. Energy dispersive X-ray analysis has confirmed the elemental composition. Fourier transform infrared and Raman spectroscopy analysis established the mode of coordination and functional groups. The thermal effects such as dehydration, melting and decomposition, etc. were observed by the thermogravimetric and differential thermoanalytical (TGA/DTA) analysis. Linear and non-linear characteristics of the compound were studied in detail. The optical band transitions due to C=O and C=S chromophores remain active in grown crystals and thus are recorded in the UV-Vis optical spectrum. The crystals possess finite values of non-linear absorption, non-linear refraction and third order nonlinearity as confirmed by Z-scan experiments.
关键词： Spectroscopic Analysis,Semi-organic Material,Non-Linear Optical Properties
更新于2025-09-19 17:15:36
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An eye on molecular interaction studies of non-aqueous binary liquid mixtures with reference to dielectric, refractive properties and spectral characteristics
摘要： This review article presents an overview of the various molecular interactions (inter/intra) that exist between different non aqueous binary mixtures. The content of this article briefly summarizes the scope of scrutinizing and analysing the various intermolecular interactions through dielectric studies, refractive measurements and spectroscopic investigations. The feasible associations between solute-solvent and solvent-solvent molecules demonstrate the advent of this novel phenomenon, which is completely absent in pure state. With the aid of excess values, the deviations from ideal behaviour are articulated by different parameters (dielectric constant and refractive index). Different literatures are cited that focus the aforementioned features. The theme of this article is illustrated in the sketch given above.
关键词： Refractive Index,Dielectric permittivity,Spectroscopic Analysis,Binary Mixture.
更新于2025-09-19 17:15:36
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Equidistant combination wavelength screening and step-by-step phase-out method for the near-infrared spectroscopic analysis of serum urea nitrogen
摘要： We applied near-infrared (NIR) spectroscopy with chemometrics for the rapid and reagent-free analysis of serum urea nitrogen (SUN). The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability. A multiparameter optimization platform with Norris derivative filter–partial least squares (Norris-PLS) was developed to select the most suitable mode (d = 2, s = 33, g = 15). Using equidistant combination PLS (EC-PLS) with four parameters (initial wavelength I, number of wavelengths N, number of wavelength gaps G and latent variables LV), we performed wavelength screening after eliminating high-absorption wavebands. The optimal EC-PLS parameters were I = 1228 nm, N = 26, G = 16 and LV = 12. The root-mean-square error (SEP), correlation coefficient (RP) for prediction and ratio of performance-to-deviation (RPD) for validation were 1.03 mmol L?1, 0.992 and 7.6, respectively. We proposed the wavelength step-by-step phase-out PLS (WSP-PLS) to remove redundant wavelengths in the top 100 EC-PLS models with improved prediction performance. The combination of 19 wavelengths was identified as the optimal model for SUN. The SEP, RP and RPD in validation were 1.01 mmol L?1, 0.992 and 7.7, respectively. The prediction effect and wavelength complexity were better than those of EC-PLS. Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis of SUN. WSP-PLS is a secondary optimization method that can further optimize any wavelength model obtained through other continuous or discrete strategies to establish a simple and better model.
关键词： wavelength step-by-step phase-out,near-infrared spectroscopic analysis,equidistant combination wavelength screening,Serum urea nitrogen,Norris derivative filter
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Do Infrared Molecular Fingerprints of Individuals Exist? Lessons from Spectroscopic Analysis of Human Blood
摘要： Genetic, lifestyle and environmental factors, along with development and aging impact molecular composition of human blood. Although many diseases leave their trace in blood, the question is whether this trace can be robustly and reproducibly measured and used for health monitoring of a given adult population. Infrared molecular spectra of blood serum can be obtained in a non-invasive, time- and cost-efficient manner, delivering molecular information from all molecular species within the highly complex samples. We demonstrate that broadband infrared spectroscopy can be used for reproducible molecular fingerprinting of human blood. To evaluate whether certain medium is sufficiently robust to facilitate detection of disease onset, the quantitative extent of variability of a person as well as a reference population needs to be evaluated. If within-person variability would exceed that of the between-personal variability in a reference population, the approach would not be suited for disease detection. To assess the extent of uniqueness of infrared molecular fingerprints as well as their biological variability, we performed a comprehensive prospective longitudinal study collecting blood samples of 27 healthy individuals donating blood at 8 consequent intervals. We apply broadband infrared molecular fingerprinting by Fourier transform infrared spectroscopy (FTIR) and analyse between-person and within-person variability based on all different molecular classes in the blood simultaneously. We report experimental evidence of the feasibility of identifying a person within a group of individuals based on her/his infrared molecular fingerprint, similarly to metabolic fingerprints [1]. In a first step, using standard methods for descriptive analysis we observe that the between-person variability is larger than the within-person variability by a factor of 3 (Fig.1 Left). This observation opens up the possibility for disease detection. In a second step, we combine standard dimensionality-reduction methods, such as principal component analysis (PCA), and several high-accuracy machine-learning algorithms [1] (random forests, extreme gradient boosting, k nearest neighbours) for deriving classification rules, which we then use for making predictions on test sets of unseen data. For a group of 7 donations that span a period of 6 weeks, we reach peak classification accuracy of above 95% (Fig.1 Right), while the accuracy of a classifier predicting in random would have been as low as 3.7%. In addition, we evaluate the underlying spectral features with respect to their importance on signalling separation and in this way identifying the human blood serum constituents associated with between-person variation. Observed robustness of infrared molecular fingerprints suggests their applicability for health and treatment monitoring.
关键词： infrared molecular fingerprints,FTIR,health monitoring,human blood,spectroscopic analysis
更新于2025-09-12 10:27:22
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[IEEE 2019 10th Workshop on Hyperspectral Imaging and Signal Processing: Evolution in Remote Sensing (WHISPERS) - Amsterdam, Netherlands (2019.9.24-2019.9.26)] 2019 10th Workshop on Hyperspectral Imaging and Signal Processing: Evolution in Remote Sensing (WHISPERS) - Closed-Loop Moving Windows Wavelength Selection Method With Application To Near-Infrared Spectroscopic Analysis
摘要： Wavelength selection plays a very important role in near-infrared (NIR) spectroscopy, which has always been an important research direction. Based on the reverse-deletion waveband idea, the closed-loop moving window-partial least squares (closed-loop MW-PLS) method was proposed, which can eliminate interference wavelengths and enable flexible multi-band wavelength selection. NIR analysis of soil organic matter was taken as an example to evaluate the performance of closed-loop MW-PLS. And the MW-PLS was also used for comparison. The proposed algorithm traversed all the sub-bands of the original range to perform forward and backward optimization. The forward optimization was just the original MW-PLS. Therefore, the closed-loop MW-PLS completely covered the MW-PLS. The results of soil organic matter indicated that the close-loop MW-PLS was strictly superior to original MW-PLS, and the method extension was meaningful and had no increase in operational complexity. We believe that the closed-loop MW-PLS method will have a wider application.
关键词： soil,organic matter,closed-loop moving window-partial least squares,wavelength model optimization,Near-infrared spectroscopic analysis
更新于2025-09-12 10:27:22
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Spectroscopic and Simulation Analysis of Facile PEDOT:PSS Layer Deposition-Silicon for Perovskite Solar Cell
摘要： In this research work, we have characterized and simulated a well-known hole transport material (HTM) for perovskite solar cell (PSC) and conductive polymer poly (3, 4- ethylenedioxy-thiophene) - poly (styrene sulfonate) (PEDOT: PSS). The PEDOT:PSS is a better contender in the field of photovoltaic with its excellent combination of characteristics like high hole conductivity, stability and transparency. The nanocomposite PEDOT:PSS is deposited on the silicon wafer which is N-type doped for the testing the structure characteristic variations. The thin film of PEDOT:PSS over Silicon wafer is prepared with the conventional coating technique and characterized with spectroscopic techniques. The structural behavior has been disclosed under the comprehensive study of Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), and X-Ray Diffractometer (XRD) mapping. On the other hand, the important optical properties were revealed by detailed analysis by spectroscopy characterization (FTIR, UV-vis, Raman spectra) covering the range of 200–2500 nm. The maximum absorbance range of PEDOT:PSS is 270–320 nm with maximum absorption at 280.5 nm. The photovoltaic cell is simulated by using Spiro-OMeTAD and PEDOT:PSS as Hole Transport Layer (HTL) for a better comparison in terms of power efficiency, quantum efficiency and fill factor. The PSC device shows exemplary power efficiency of 11.89% and 12.13% for PEDOT:PSS & Spiro-OMeTAD as HTL respectively.
关键词： FESEM,Perovskite,Hole transport layer,FTIR,Spectroscopic analysis,Raman spectra,PEDOT:PSS
更新于2025-09-11 14:15:04
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Silicon etching of difluoromethane atmospheric pressure plasma jet combined with its spectroscopic analysis
摘要： A capacitivly coupled radio-frequency double-pipe atmospheric-pressure plasma jet is used for etching. An argon carrier gas is supplied to the plasma discharge jet; and CH2F2 etch gas is inserted into the plasma discharge jet, near the silicon substrate. Silicon etchings rate can be e?ciently-controlled by adjusting the feeding etching gas composition and plasma jet operating parameters. The features of silicon etched by the plasma discharge jet are discussed in order to spatially spreading plasma species. Electronic excitation temperature and electron density are detected by increasing plasma power. The etched silicon pro?le exhibited an anisotropic shape and the etching rate was maximum at the total gas ?ow rate of 4500 sccm and CH2F2 concentration of 11.1%. An etching rate of 17 μm/min was obtained at a plasma power of 100 W.
关键词： spectroscopic analysis,atmospheric-pressure plasma jet,silicon etching,di?uoromethane
更新于2025-09-04 15:30:14