Multivariate Calibration of Concentrations of C,Mn, Si,Cr, Ni,and Cu in Low-Alloy Steels from Raw Low-Resolution Spectra Obtained By Laser-Induced Breakdown Spectroscopy

Journal of Applied Spectroscopy - Multivariate models were developed on the basis of raw low-resolution LIBS spectra of reference samples of lowalloy steels for calibration of the concentrations of...     

Comparison of two laser-induced breakdown spectroscopy techniques for total carbon measurement in soils

The potentials of two advanced laser-induced breakdown spectroscopy (LIBS) techniques which are used to determine the total carbon content in soils have been examined. The first one is the combination of a single-pulse laser ablation with spark excitation of plasma plume triggering the gap between electrodes close to the target surface. The second one is a more conventional double-pulse LIBS. In both modes the calibration graphs have a nonlinear trend in the actual range of carbon contents and present a good R² value (0.97). In the combined laser-spark approach, using low-cost and portable laser instrumentation is possible, as well as inducing a micro-damage on the target surface. Certain regularities in the spectral line intensities of soil nutritious elements have been detected and appear to be connected to the total carbon content and to the soil origin.     

Development of a laser-induced breakdown spectroscopy method for soil and ecological analysis (review)

The application of laser spectrochemical analysis to testing for basic compounds and nutritious/toxic elements in soil has been reviewed. A combined laser-spark approach has been applied for the rapid measurement of the carbon content in soil. Spectra have been excited both directly in a laser-ablation plume and by passing a pulsed electric discharge through the plume. The emission spectrum intensity in the combined plasma is considerably higher. The application of a complex of methods to carbon determination in soil has shown that in fact the data on the humus content usually obtained in agrochemical practice by a conventional method of carbon oxidation by potassium dichromate need to be corrected taking into account the possibility of incomplete oxidation of organic matter in soil. The efficiency of various double-pulse LIBS applications has been demonstrated in solving a number of environmental problems such as the determination of heavy and toxic metals in soil and the detection of sulfur in coal. The instrumentation and analytical procedures have been proposed and optimized for rapid control of the chlorine content in plant samples. The technique can be easily extended to ecological monitoring of toxic elements and heavy metals in any biogenic material.     

Effect of Temperature on Parameters of Fluorescence Spectra of Solvatochromic Indicator Solutions in Stationary Phases for Gas–Liquid Chromatography

Journal of Applied Spectroscopy - Luminescence spectra of several polarity indicators, including Coumarin 153 and coronene that were previously studied at room temperature and Nile Red and Pigment...     

Optical spectra analysis for breast cancer diagnostics

Minimally invasive probe and optical biopsy system based on optical spectra recording and analysis seem to be a promising tool for early diagnostics of breast cancer. Light scattering and absorption spectra are generated continuously as far as the needle-like probe with one emitting and several collecting optical fibers penetrates through the tissues toward to the suspicious area. That allows analyzing not only the state of local site, but also the structure of tissues along the needle trace. The suggested method has the advantages of automated on-line diagnosing and minimal tissue destruction and in parallel with the conventional diagnostic procedures provides the ground for decision-making.     

Intramolecular interactions of N-(3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-2-hydroxyphenyl)acetamide derivatives

IR-Fourier spectroscopy methods are adopted to the study of intramolecular interactions occurring in CCl₄ solutions of antivirally active derivatives of N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide. Analysis of IR spectra has shown that intramolecular H-bonds O–H···O=C and N–H···O=C are formed in solutions of these compounds. The O–H···O=C and N–H···O=C bond strengths and the direction of the equilibrium shift between the two types of conformers depend on the type of carbonyl group substituent. An intramolecular O–H···O=C H-bond is characteristic of highly active derivatives of N-(3,5-di-tert-butyl-2-hydroxyphenyl)acetamide.     

Spectral-luminescence properties of a norbornene-substituted tetraazachlorin and its metal complexes

The spectral-luminescence properties of a tetraazachlorin derivative with a norbornene fragment annelated to a reduced pyrrole ring and its complexes with zinc and palladium have been studied at 293 and 77 K. For the norbornene-substituted free base, differences in fluorescence from unsubstituted tetraazachlroin and its dibenzobarrelene-substituted analog are found. The fluorescence lifetime is observed to rise by ∼7 times for the free base and by ∼1.6 ties for the Zn complex on going from 293 to 77 K. An essential dependence of the photophysical parameters on the nature of the solvent is noted. The fluorescence polarization spectrum of the norbornene-substituted tetraazachlorin reveals in the Soret band region at least four electronic transitions. For the Pd complex, weak phosphorescence in the near IR region has been detected; the 0–0 band maximum is at 990 nm and the singlet–triplet interval amounts to 5800 cm^–1, which is larger by 400 cm^–1 than for Pd tetraazaporphine. The quantum yields of the photosensitized formation of singlet oxygen have been determined using a relative luminescence method.