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Aggregation States of Organic Dye Molecules in Organic – Inorganic Hybrid Films Studied by Near-Field and Far-Field Fluorescence Spectroscopy
摘要： Near-field fluorescence spectroscopy in conjunction with far-field fluorescence and Raman spectroscopy has been applied to investigate the aggregation states of cyanine dye of 2-[5-(1,3-Dihydro-3,3-dimethyl-1-octadecyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3,3-dimethyl-1-octadecyl-3H-indolium perchlorate (NK3175) molecules in the depth direction, from the nanometer-scale top surface to the bulk, in the hybrid films consisted of NK3175 and a clay compound (SWN). The far-field Raman spectra reveal that these hybrid films contained both NK3175 molecules which did not take part in the adsorption and those adsorbed on SWN. The near-field photoluminescence (PL) spectra in the outermost surface within ca. 30 nm exhibit a significant blue shift for the hybrid films as compared to their respective PL spectra in the bulk, implying that the top surface of these hybrid films becomes more polar and/or rigid in terms of the microenvironment around NK3175 molecules compared to the bulk of them, in contrast to the case for the other hybrid film which was prepared by the alternative method. These results provide new information on the aggregation states of organic dye molecules not only in the bulk but in the nanometer-scale top surface of organic-inorganic hybrid systems.
关键词： far-field fluorescence,Raman spectroscopy,organic-inorganic hybrid films,aggregation states,Near-field fluorescence spectroscopy,cyanine dye
更新于2025-09-10 09:29:36
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Deciphering the Finger Prints of Brain Cancer Glioblastoma Multiforme from Four Different Patients by Using Near Infrared Raman Spectroscopy
摘要： To explore the effectiveness of Raman spectra to diagnose brain cancer glioblastoma multiforme (GBM), we investigated the Raman spectra of single cell from four different GBM cell lines developed from four different patients and analyzed the spectra. The Raman spectra of brain cancer (GBM) cells were similar in all these cell lines. The results indicate that Raman spectra can offer the experimental basis for the cancer diagnosis and treatment.
关键词： Raman spectroscopy,Optical tweezers,Cancer,Glioblastoma multiforme
更新于2025-09-10 09:29:36
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Species Selective Measurement of 10 B. anthracis-Sterne Spores within 10 Minutes by Surface-Enhanced Raman Spectroscopy
摘要： The use of biological warfare agents by terrorists remains a global concern. While there has been substantial effort since the 2001 distribution of Bacillus anthracis spores through the US Postal System to develop analyzers to detect this and other biological agents, the analyzers lack sensitivity, lack specificity (produce high false-positive rates), are too slow, or cannot be fielded. For the past decade we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to overcome these limitations. Recently, we developed an assay by functionalizing silver nanoparticles with various peptides to selectively bind B. anthracis, and then adding acetic acid and silver colloids to release and detect, respectively, dipicolinic acid as a biomarker by SERS. Here we describe the successful measurement of B. anthracis-Sterne spores with a 10- to 20-fold selectivity over other Bacillus species at 105 spores/mL, using the peptide functionalized SERS assay with a sensitivity capable of detecting 10 spores in a 103 spores/mL sample in 6.5 minutes. This measurement represents 6 orders-of-magnitude improvement over our previous peptide based SERS assay measurements.
关键词： Anthrax,Biological warfare agents,Bacillus anthracis,Surface-enhanced Raman spectroscopy
更新于2025-09-10 09:29:36
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Aging spectral markers of tequila observed by Raman spectroscopy
摘要： In this work, were studied the aging spectral markers of three types of tequila: Blanco, Reposado, and A?ejo (white, rested, and aged, respectively) by Raman spectroscopy with the aim of qualitatively assessing the aging state of tequilas. The samples were elaborated in the same distillery to increase the correctness of the analysis since the contribution of manufacturing process factors, e.g., the type of water used for the elaboration, the origin of raw materials like agaves, sugar, barrels, and others would be similar for all the kinds of tequila. It was demonstrated that complementary information can be obtained through the employment of two excitation wavelengths: 532 and 785 nm. Fluorescence intensity increases with the aging degree of the tequilas as observed with the 532 nm line providing qualitative information about the resting time within the barrels. Additionally, by employing the 785 nm line it was possible to discern through the νs-CCO νa-CCO bands, (C–O) and (C–H) stretching modes and CH2 wagging bonds, the aging spectral markers of tequila.
关键词： Tequila,Raman spectroscopy,Beverage maturation,Cask aging
更新于2025-09-10 09:29:36
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Efficient quantitative hyperspectral image unmixing method for large-scale Raman micro-spectroscopy data analysis
摘要： Vibrational micro-spectroscopy is a powerful optical tool, providing a non-invasive label-free chemically specific imaging for many chemical and biomedical applications. However, hyperspectral image produced by Raman micro-spectroscopy typically consists of thousands discrete pixel points, each having individual Raman spectrum at thousand wavenumbers, and therefore requires appropriate image unmixing computational methods to retrieve non-negative spatial concentration and corresponding non-negative spectra of the image biochemical constituents. Here, we present a new efficient Quantitative Hyperspectral Image Unmixing (Q-HIU) method for large-scale Raman micro-spectroscopy data analysis. This method enables to simultaneously analyse multi-set Raman hyperspectral images in three steps: (i) Singular Value Decomposition with innovative Automatic Divisive Correlation which autonomously filters spatially and spectrally uncorrelated noise from data; (ii) a robust subtraction of fluorescent background from the data using a newly developed algorithm called Bottom Gaussian Fitting; (iii) an efficient Quantitative Unsupervised/Partially Supervised Non-negative Matrix Factorization method, which rigorously retrieves non-negative spatial concentration maps and spectral profiles of the samples' biochemical constituents with no a priori information or when one or several samples’ constituents are known. As compared with state-of-the-art methods, our approach allows to achieve significantly more accurate results and efficient quantification with several orders of magnitude shorter computational time as verified on both artificial and real experimental data. We apply Q-HIU to the analysis of large-scale Raman hyperspectral images of human atherosclerotic aortic tissues and our results show a proof-of-principle for the proposed method to retrieve and quantify the biochemical composition of the tissues, consisting of both high and low concentrated compounds. Along with the established hallmarks of atherosclerosis including cholesterol/cholesterol ester, triglyceride and calcium hydroxyapatite crystals, our Q-HIU allowed to identify the significant accumulations of oxidatively modified lipids co-localizing with the atherosclerotic plaque lesions in the aortic tissues, possibly reflecting the persistent presence of inflammation and oxidative damage in these regions, which are in turn able to promote the disease pathology. For minor chemical components in the diseased tissues, our Q-HIU was able to detect the signatures of calcium hydroxyapatite and b-carotene with relative mean Raman concentrations as low as 0.09% and 0.04% from the original Raman intensity matrix with noise and fluorescent background contributions of 3% and 94%, respectively.
关键词： Baseline correction,Biochemical quantification,Hyperspectral image analysis,Multivariate curve resolution,Non-negative matrix factorization,Raman spectroscopy
更新于2025-09-10 09:29:36
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Synthesis of Ge1?xSnx Alloy Thin Films by Rapid Thermal Annealing of Sputtered Ge/Sn/Ge Layers on Si Substrates
摘要： In this work, nanocrystalline Ge1?xSnx alloy formation from a rapid thermal annealed Ge/Sn/Ge multilayer has been presented. The multilayer was magnetron sputtered onto the Silicon substrate. This was followed by annealing the layers by rapid thermal annealing, at temperatures of 300 ?C, 350 ?C, 400 ?C, and 450 ?C, for 10 s. Then, the effect of thermal annealing on the morphological, structural, and optical characteristics of the synthesized Ge1?xSnx alloys were investigated. The nanocrystalline Ge1?xSnx formation was revealed by high-resolution X-ray diffraction (HR-XRD) measurements, which showed the orientation of (111). Raman results showed that phonon intensities of the Ge-Ge vibrations were improved with an increase in the annealing temperature. The results evidently showed that raising the annealing temperature led to improvements in the crystalline quality of the layers. It was demonstrated that Ge-Sn solid-phase mixing had occurred at a low temperature of 400 ?C, which led to the creation of a Ge1?xSnx alloy. In addition, spectral photo-responsivity of a fabricated Ge1?xSnx metal-semiconductor-metal (MSM) photodetector exhibited its extending wavelength into the near-infrared region (820 nm).
关键词： Raman spectroscopy,Ge-Sn,thin films,sputtering,semiconductors,nanocrystalline,X-ray diffraction,scanning electron microscopy
更新于2025-09-10 09:29:36
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Quantitative Analysis of Multiple Components in Wine Fermentation using Raman Spectroscopy
摘要： Glucose and ethanol are critical quality control components in the wine fermentation process. In this study, we present a novel method in which Fourier Transform (FT)-Raman spectroscopy and chemometric techniques are used to quantitatively analyze ethanolic beverages produced by fermentation. Chromium (VI) Oxide (CrO3) was flame-sealed into a fused silica cuvette and used as external standard. Band ratios between the Raman bands of the target molecule and that of CrO3 were calculated and found to be proportional to the concentration of ethanol and glucose. This method can eliminate factors such as laser power or instrumental effects. After pre-processing the spectra, Principal Component Analysis (PCA) and Partial Least Squares (PLS) were selected as the multivariate calibration models. The prediction models proved to be robust resulting in a desirable mapping between the spectra and output attributes. This method could predict the ethanol and glucose concentrations simultaneously and produced a more linear calibration curve. As a result, there is a great potential to use Raman spectroscopy in wine fermentation process and on line fermentation control.
关键词： Raman spectroscopy,principal component analysis,Partial least squares,wine fermentation,quantitative analysis
更新于2025-09-10 09:29:36
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Pb phases on Si(111)
摘要： We present here a combined experimental Raman spectroscopy and ab initio theoretical study of the (√3×√3) reconstructed SIC phase of Pb on Si(111) and discuss their relation to the atomic surface structure. The Raman response of the surface localized vibrational modes, in particular, is identified in the low-frequency spectral range (down to 15 cm?1). We demonstrate that Raman spectroscopy is a very powerful approach to test atomic structures of surfaces and a valuable complement to standard surface analytics. While the calculated spectra of H3 and T4 are too similar to allow a discrimination of these phases, the good overall agreement to the measured Raman spectra enables a classification of the observed vibrational modes.
关键词： surface vibrations,Pb/Si(111),atomic structure,ab initio,Raman spectroscopy
更新于2025-09-10 09:29:36
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Infrared and Raman Spectroscopy in Diagnosis of Infectious Diseases
摘要： There are a few techniques which are widely utilized for identification of epidemiologic diseases, including ELISA, PCR, immune fluorescent test and Western blotting, which have been utilized for the diagnosis of epidemiologic diseases. However the reality of the situation is none of them is great regarding cost-viability, speed and precision. At this moment, the rate of flare-up of rising infections is expanding definitely and in this manner the improvement and foundation of explanatory techniques for such popular infections are turning out to be more essential. Near infrared spectroscopy is a quick, multivariate measure that empowers non-prominent, non-ruinous examination. As of late, the finding of viral diseases utilizing near infrared spectroscopy has been endeavoured.
关键词： Infectious diseases,Infrared and Raman spectroscopy,Diagnosis
更新于2025-09-10 09:29:36
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STRUCTURAL AND MECHANICAL CHARACTERIZATION OF DEFORMED POLYMER USING CONFOCAL RAMAN MICROSCOPY AND DSC
摘要： Polymers have various interesting properties, which depend largely on their inner structure. One way to in?uence the macroscopic behaviour is the deformation of the polymer chains, which e?ects the change in microstructure. For analyzing the microstructure of non-deformed and deformed polymer materials, Raman spectroscopy as well as di?erential scanning calorimetry (DSC) were used. In the present study we compare the results for crystallinity measurements of deformed polymers using both methods in order to characterize the di?erences in micro-structure due to deformation. The study is ongoing, and we present the results of the ?rst tests.
关键词： Raman spectroscopy,DSC,crystallinity,deformed polymers
更新于2025-09-10 09:29:36