An Effective Baseline Correction Algorithm Using Broad Gaussian Vectors for Chemical Agent Detection with Known Raman Signature Spectra

Raman spectroscopy, which analyzes a Raman scattering spectrum of a target, has emerged as a key technology for non-contact chemical agent (CA) detection. Many CA detection algorithms based on Raman spectroscopy have been studied. However, the baseline, which is caused by fluorescence generated when measuring the Raman scattering spectrum, degrades the performance of CA detection algorithms. Therefore, we propose a baseline correction algorithm that removes the baseline, while minimizing the distortion of the Raman scattering spectrum. Assuming that the baseline is a linear combination of broad Gaussian vectors, we model the measured spectrum as a linear combination of broad Gaussian vectors, bases of background materials and the reference spectra of target CAs. Then, we estimate the baseline and Raman scattering spectrum together using the least squares method. Design parameters of the broad Gaussian vectors are discussed. The proposed algorithm requires reference spectra of target CAs and the background basis matrix. Such prior information can be provided when applying the CA detection algorithm. Via the experiment with real CA spectra measured by the Raman spectrometer, we show that the proposed baseline correction algorithm is more effective for removing the baseline and improving the detection performance, than conventional baseline correction algorithms.

Study on optical and magnetic properties of FexNi1-xMn2O4 materials

In this study, we present the process of synthesis FexNi1-xMn2O4 (x = 0; 0.1; 0.3; 0.5; 0.7; 0.9; 1) by method sol-gel. Scanning electron microscope results shows that the particle size is about 50 nm. The X-ray diffraction diagram shows that the samples are single phase, changing structure clearly as the x ratio increases from 0 to 1. The lattice constant, the bond length also changes with x-value as shown on the Raman scattering spectrum. The results of the vibrating sample magnetometer show that the magnetism of the material FexNi1-xMn2O4 changes with the value of x and reaches a maximum in the range x from 0.5 to 0.7.

Development of Ethanol Gas Sensor Using α-Fe2O3 Nanocubes Synthesized by Hydrothermal Process

Herein, α-Fe2O3 nanocubes were synthesized, characterized and employed as functional and promising material for the development of ethanol gas sensor. Facile hydrothermal process was used to synthesized the nanocubes and characterized by several techniques which confirmed the large-quantity synthesis, wellcrystallinity with rhombohedral structure of α-Fe2O3. The Raman-scattering spectrum of the synthesized nanocubes exhibited several Raman-active modes which further confirmed the formation of pure α-Fe2O3. As a functional material, the synthesized α-Fe2O3 nanocubes were used as electrode material to fabricate ethanol gas sensor which was tested at various working temperatures, i.e., 300 °C, 400 °C and 450 °C which revealed that the 400 °C was the optimal working temperature. Thus, at 400 °C working temperature, in presence of 100 ppm ethanol gas, the fabricated sensor exhibited highest gas response of 1.69 with response time < 1 s and recovery time of 1485 s.

Обертонное комбинационное рассеяние света в монокристаллах танталата лития

Overtone bands in the spectral range of 1300−1920 cm^–1 have been found in Raman scattering spectrum of lithium tantalate single crystals. The Raman spectra were recorded in the 180° scattering geometry. The intensity of overtone transitions differs for different samples and, in some cases, is comparable with the Raman scattering intensity at the fundamental modes of a lithium tantalate single crystal.

Study on influences of Sb doping content on the defects of ZnO film by photoluminescence (PL) spectrum and raman scattering spectrum

Sb-doped ZnO thin films with different values of Sb concentrations are deposited on glass substrate by using spin-coating technique. The influences of Sb doping content on the microstructural, photoluminescence and Raman properties of ZnO film are systematically investigated by X-ray diffraction (XRD), transmission spectrum, photoluminescence (PL) spectrum and Raman scattering spectrum. The results indicate that ZnO thin film doped with Sb exhibits a hexagonal wurtzite structure with preferred c-axis orientation. The strong violet emission peak located at 3.11 eV is observed in the Sb-doped ZnO thin film by photoluminescence. Conbining the Raman scattering spectrum with photoluminescence, it is concluded that the strong violet emission peak related to SbZn-O complex defect in ZnO:Sb film.