Valery V. Smirnov

Study of processes of translational, rotational, and vibrational relaxation based on CARS spectra line shapes

This paper reviews the various physico-chemical processes responsible for actual linewidths encountered in high-resolution coherent anti-Stokes Raman spectroscopy (CARS). Most of the experimental data are based on linewidth measurements using a pulseamplified CARS spectrometer with an emission bandwidth (FWHM) of 2×10−3 cm−1. Detailed rotational and vibrational relaxation constants have been obtained from the analysis of theQ-branch profiles of C2H2, N2, CH4, and SiH4.

Local nonintrusive diagnostics of electron components of plasma glow discharge in nitrogen by CARS spectroscopy

The possibility is considered of restoring the electron energy distribution function (EEDF) in the interval of electron energies 0 < e < 5 eV from measurements of translational and vibrational temperatures by the coherent anti-Stokes Raman scattering (CARS) method in a positive column of a glow discharge in molecular nitrogen at 20 <E/N < 80 Td and dissociation degree ? ? 10-3, when a considerable fraction of electron energy goes to excitation of vibrational degrees of freedom. The results of calculation of EEDF along with drift velocity, electron temperature and of the ratio of transverse diffusion coefficient to electron mobility have demonstrated that the model proposed to restore the EEDF is in good quantitative agreement with the experiment depending on the variation of the parameter E/N and vibrational temperature.

Concentration composition determination of a multicomponent mixture of gases with fluctuating parameters on the basis of CARS spectroscopy

Diagnostics of gas mixtures with fluctuating temperature, density and concentration composition requires simultaneous detection of spectra of all species of a mixture with subsequent its joint treatment. Strategy of processing of experimental data, obtained at diagnostics by methods of a spectroscopy of Coherent Anti-Stokes Raman Scattering, is considered. An experimental approach to a performance of density numbers measurements in three-component mixture of O2, H2, H2O in a flame of oxygen-hydrogen burner is presented.

Fluorescence examinations of patients with tumors of diferent localizations in the course of photodynamic therapy with photosensitizer photosens

In the course of the clinical trials of Photosens (Al-sulphonated phthalocyanine) as a drug for PDT of cancer fluorescence examinations of 45 patients with injected photosensitizer (0.5 - 2.0 mg/kg b.w.) were performed. The aim of these investigations was to study the drug accumulation in normal, inflammatory tissues and tumors of different localizations. The data concerning kinetics of photosensitizer accumulation and its removal from normal skin and lip mucosa are also presented.

CARS measurements of intra-mode V-V exchange rate constants of nitrogen

Abstract The intra-mode V-V exchange rate constant in nitrogen, which turned out to be equal to K1001= (1±0.4) × 10−13 cm3/s, has been measured using pulsed excitation in a discharge or biharmonic laser field followed by CARS probing of the excited gas.

Single shot CARS thermometry of hydrogen-contaning multicomponent gaseous mixtures at high pressure and high temperature

We demonstrate the feasibility of the proposed new approach to CARS thermometry of hydrogen-containing mixtures with simultaneous measurement of the intensities of a hydrogen spectrum Q-branch lines and their linewidths in a single laser shot by means of a spectrograph combined with an interferometer, that have orthogonal directions of dispersions. This provides correct temperature evaluation that takes into account the linewidths, measured directly. The experiments were carried out in a H2:N2 = 1:10 mixture in a heated cell at a temperature of 1050 K. The values of gas mixture temperature, that were defined in a pressure range of 2-9 MPa from DBB CARS spectra taking into account linewidth corrections, coincide with a thermocouple measurements within ~ 2 %. Without these corrections the discrepancies increase up to 5 %. The proposed approach can be applied to CARS thermometry in the course of investigations of H2 and hydrocarbon combustion without the necessity to measure species concentrations, and does not require the knowledge of the line-broadening coefficients.

Nanosecond-resolution optical diagnostics of nonstationary gas heating and carbon cluster formation induced by pulsed laser radiation

The results are presented of pulsed laser diagnostics of the process of pyrolysis of hydrocarbons in a gas, aimed to obtain carbon clusters and to deposit them in a solid phase. The pyrolysis is carried out in a gas flow reactor using homogeneous gas heating by pulsed laser radiation.

Dual-broadband CARS thermometry in a H2/O2 atmospheric pressure diffusion flame

Dual-broadband coherent anti-Stokes Raman spectroscopy (CARS) of the Q-branch of H2 has been employed for thermometry in a laboratory atmospheric pressure hydrogen-oxygen flame. The aim was to investigate the applicability of the technique for single-shot temperature evaluation, to estimate its sensitivity and to analyze the accuracy of the measurements. The results are presented of single-shot temperature mapping of the flame in the temperature range of 700 - 3200 K. The achieved accuracy of single-shot measurements was 3 - 5%.

2lambda-CARS thermometry of hydrogen

In this work we present the results of two-wavelength rotational CARS thermometry (2(lambda) -CARS thermometry) of hydrogen at temperatures from 300 K to 1100 K. Experimentally, temperature was measured in a heated cell using single-shot and averaged CARS intensities in the rotational S-branch. Relative standard deviation for single-shot temperature values was approximately 1.5% at 296 K and approximately 8% at 1000 K. The accuracy achieved, its dependence on measured temperature, and possibility of their improvement were analyzed.

Endoscopic fluorescent diagnostics and PDT of early malignancies of lung and esophagus

In this paper the results of fluorescence diagnostics and photodynamic therapy of early stage malignancies of lung (17 patients) and esophagus (8 patients) are presented. 13 patients had multiple primary tumors. As photosensitizers the new drugs Photoheme and Photosense were used. Complete remission was obtained in 92%. The patients are followed up without relapses to 2,5 years.