Investigation of line profiles in the ν2 band of H2S

Experiments with a three-channel lead salt diode laser spectrometer concerning collisional effects for lines from the ν2 band of H2S were carried out in the laser spectroscopy group in Berlin. An improved experimental set-up in comparison to the system as described in Sumpf et al. (J. Quant. Spectrosc. Radiat. Transfer 59 (1998) 99), e.g. liquid nitrogen cooling system, improved laser stability, multipass cells in both channels, allows us now to detect the Dicke narrowing effect. To analyze the measured line profiles three types of contours, i.e. Voigt. Rautian-Sobel’man, and Galatry, were taken into account. As result of this study Dicke narrowing was clearly observed for several lines. The most significant narrowing coefficient (31±4) · 10 cm−1 atm−1 was found for the line 121.12←110.11 perturbed by Neon. Nevertheless, it was shown that for the lines under study the pressure broadening and shift coefficient’s deviation due to not taking into account Dicke narrowing, lies in the range of the uncertainties of the determination of the coefficients.