Ya. Ya. Ponurovskii

Near IR TDLS study of HF first overtone line shape. I. Experimental results

The HF first overtone vibration-rotational absorption spectral line profile (the transition 0–2 R(0)) broadened by Ar (mixture HF: Ar = 1: 150, T = 295 K, P = 10−300 mm Hg) is studied by the method of near IR diode laser spectroscopy. A tunable distributed feedback fiber diode laser was used as a radiation source in a two-channel spectrometer (λ ∼ 1.284 μm, spectral tuning range Δν = 1.5−2.0 cm−1, the output radiation power is 15 mW, the spectral half-width of lasing lines is ∼ 5 MHz). The broadening and shifting coefficients of the considered HF line are determined, using traditional Voigt, Rautian, and Galatry spectral profiles.

Measurement of Non-Stationary Gas Flow Parameters Using Diode Laser Absorption Spectroscopy at High Temperatures and Pressures

The layout of an absorption spectrometer with diode lasers for contactless measurement of the temperature and water-vapor concentration in gas flows with mixture pressures of up to 3 atm and temperatures of 300–2000 K has been designed. The technique is based on the rapid tuning of the radiation wavelength of two lasers, the registration of the absorption lines of water molecules that are located in the tuning range, and the fitting of the experimental absorption spectra by theoretical ones that have been simulated using spectroscopic databases. The original components of the spectrometer and different algorithms of the processing of experimental spectra are described. The performance of the spectrometer and processing methods were tested in the laboratory with a cuvette at a pressure of 1 atm and temperatures of 300–1500 K. The different processing algorithms give a reasonable coincidence of data on hot zone parameters that were obtained by the method of diode laser absorption spectrometry, and the temperature that was measured using standard sensors. The designed layout of the spectrometer passed the first tests on the T-131 experimental stand at the TsAGI (Central Aerohydrodynamics Institute).

Near IR TDLS study of the HF first overtone line shape. II. Theoretical analysis

Results of a theoretical study of the HF first overtone rovibrational absorption spectral line profile (the transition 0–2 R(0)), broadened by Ar (mixture HF : Ar = 1 : 150, T = 295 K, P = 10−300 mm Hg) are presented. The generalized Ciurylo-Pine-Szudy line shape model was selected for the analysis of different factors influencing the spectral line shape. The shortcomings of this model are revealed via validation of its basic assumptions, using the classical trajectory method. Special consideration is given to the elucidation of the nature of the anomalous asymmetry of the HF spectral line shape.

Investigation of broadening and shift of vapour absorption lines of H{sub 2}{sup 16}O in the frequency range 7184 – 7186 cm{sup -1}

We present the results of investigation of water vapour absorption spectra in the 7184 – 7186 cm-1 range that is of particular interest from the viewpoint of possible application of the data obtained for monitoring water vapour in the Earths stratosphere. The doublet of H216O near ν = 7185.596 cm-1 is analysed. The coefficients of broadening and shift of water vapour lines are found in the selected range in mixtures with buffer gases and compared to those obtained by other authors.

Study of the HF overtone line profile broadened by Ar, Xe, Kr, N2 using near-IR region diode laser spectroscopy

The profile of the 0-2 R(0) overtone vibrational-rotational absorption line of HF molecules in mixtures with Ar, Xe, Kr, N2 is experimentally studied using near-IR-range diode laser spectroscopy. The coefficients of collisional broadening, shift, and collisional narrowing of the HF line in these buffer gases are determined using the Voigt, Rautian, and Galatry profiles.

Control of radiation parameters of pulse-periodic tunable diode lasers based on lead salts with double heterostructure

Spectral and power properties of the pulse-periodic tunable diode lasers based on lead salts with double heterostructure grown by MBE are considered. Procedure and criteria of preliminary selection of the laser samples are discussed. Typical characteristics of such lasers are presented. Methods for controlling the spectral and power properties in the pulse mode are considered. General mechanisms of laser wavelength tuning by current and temperature variations are demonstrated on the basis of experimental data. Methods for optimizing these parameters are considered.