Infrared HCN Lineshapes as a Test of Galatry and Speed-Dependent Voigt Profiles

Dicke-narrowed spectral line shapes of CO in Ar: Experimental results and a revised interpretation

“…There is growing experimental evidence that the effective collision rate m does not agree with m diff [1,3,16,31,[40][41][42][43][44].…”

“…Only one study from that period concerns us here, however: the 1995 study of Duggan et al [2], which was the first to include speed dependence in an analysis of Dicke-narrowed line shapes. It has since been well established that a meaningful study of Dicke narrowing in CO-Ar, HF-Ar, and similar systems must account for speed dependence (see for example, [4,38,42,43,49,51,52]), and we therefore limit our discussion to speed-dependent analyses. To the best of our knowledge, [1][2][3][4][5][6][7]16,31,33,[36][37][38][39][40][41][42][43]49,[51][52][53][54][55][56][57][58][59][60][61][62] are the only studies that use a speed-dependent, Dicke-narrowed line shape model to analyze experimental data.…”

“…It is sometimes referred to as the (effective) velocity-changing collision rate. By convention, the narrowing parameter z is defined as m/x D , where x D = k(2k B T/m a ) 1/2 is the Doppler half width at e À1 intensity for wavevector k, Boltzmann constant k B , and temperature T. A common [2][3][4][5][36][37][38][39][40][41][42][43][44] approach to analyzing Dicke-narrowed line shapes is to fit for m and compare the result to the dynamic friction coefficient, m diff , which is obtained from the mass diffusion constant D by…”

Line-shapes and broadenings of rotational transitions of CH335Cl in collision with He, Ar and Kr

“…Since the Galatry profile (GP), assuming Β opt ¼Β Gal and based on a soft collision model [39], is well suited in case of a Fourier transform based code [32], it has been preferred to the Rautian one, based on a hard collision model [40]. Actually, both models are nearly equivalent from the viewpoint of numerical fits [41,42], namely for the present case of a nearly negligible influence of velocity-changing collisions (see Section 4). Clear insights in these features have been obtained from a detailed study of the J ¼31-32, K ¼3 line at 848.3 GHz, one of the most intense studied lines, which presents a small quadrupolar hyperfine structure (at least 10 times narrower than the Doppler width).…”

Absorption profiles of HCl for the J=1–0 rotational transition: Foreign-gas effects measured for N2, O2, and Ar

“…For the Galatry and Rautian-SobelÕman profiles, molecular-diffusion-process by velocity-changing collision is considered. It may be better to note that the speed-dependent Voigt profile with consideration of the speed dependence of molecular relaxation proposed by Berman [6], which is not included in their review, has been applied in some of the recent study, e.g., [7]. Ciurylo and Szudy [8] and Ciurylo et al [9] proposed two types of the speed-dependent Galatry profile, which take the speed-dependent collisional broadening and shift into account.…”