D. N. Kozlov

On the influence of electronically excited oxygen molecules on combustion of hydrogen–oxygen mixture

This communication reports on the experimental observation of the shortening of the induction zone length in a premixed mode of combustion in a subsonic H2–O2 low pressure flow due to the presence of oxygen molecules excited to the singlet a 1Δg electronic state. The low pressure electric glow discharge was used to produce singlet oxygen molecules. The analysis showed that even a small number of O2(a 1Δg) molecules (~1%) in the H2–O2 mixture allows one to noticeably reduce the ignition delay length and to ignite the mixture at a lower temperature. The results obtained exhibit the possibility to intensify the combustion of a hydrogen–oxygen mixture by means of excitation of O2 molecules by electrical discharge at low pressure (P = 10–20 Torr).

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.

Two wavelength-CARS thermometry of hydrogen

In this work, we present the results of two-wavelength (2λ)-CARS thermometry of hydrogen at temperatures from 300–1200 K. The choice of the pair of spectral lines for the 2λ-CARS thermometer with respect to optimal temperature sensitivity within a given temperature range was analysed. Software was developed to process the experimental data and calculate the temperature. In the experiments, temperature and density were measured in a heated cell using single-shot and averaged CARS intensities in the pure rotationalS branch. The accuracy achieved and its dependence on measured temperature values and on the number of averaged shots was analysed.

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.

High-Resolution CARS-IR Spectroscopy of Spherical Top Molecules

The report provides a detailed description of a high-resolution CARS-IR spectrometer for recording of Raman and infrared spectra. The obtained rotationally resolved structures of CARS spectra of the ν1 band Q-branch and IR spectra of the ν3 band QO-branch of 28SiH4 and 74GeH4, as well as the results of theoretical treatment of these spectra, are presented and discussed.