First vibrational overtone bandshape of HCl in fluid SF6: An experimental and theoretical study

A Simulation Study of the Far-Infrared Absorption Spectra of HCl Diluted in Liquid Ar

“…With this type of simulation, we solve the classical and quantum motion equations numerically without the need of truncating the cumulant expansions that lead to an unclear statistical hypothesis. On the other hand, MCQSS explain the presence of the Q-branch in the central part of the spectral density (5) [6], an effect largely unexplained with previous quantum spectral theories [14]. Perhaps the price to pay for all these improvements is a small discrepancy in the resolution of the rotational resonances.…”

“…MCQSS absorption coefficients calculated in the current work have been determined without using any ad hoc fitting parameters. Unlike previous works [12,14,15], we have used the statistical parameters of the anisotropic interactions (3) and (4) (see Table 1) obtained by means of MD, employing realistic models for the HCl-Ar interaction. In earlier works, the statistical parameters were obtained by using microscopic cell models [15], by fitting theoretical and experimental spectra [14], or by using an erroneous estimation of the correlation times (4) [12].…”

“…Unlike previous works [12,14,15], we have used the statistical parameters of the anisotropic interactions (3) and (4) (see Table 1) obtained by means of MD, employing realistic models for the HCl-Ar interaction. In earlier works, the statistical parameters were obtained by using microscopic cell models [15], by fitting theoretical and experimental spectra [14], or by using an erroneous estimation of the correlation times (4) [12]. Also, unlike previous theories, [12,14,15] based on the Kubo cumulant expansions, where it is not clear what specific statistical properties are assumed for the DIF tensor (2), in our work the kind of probabilistic properties assumed for the DIF is clear [6].…”

“…This spectral region is dominated by the dynamics of the high rotational states which are appreciably populated for the experimental temperatures of this work (see Table 1) ( = 6-10). These states have been traditionally modelled by means of quasifree rotation approach and successfully represented by the modified rotor model of Pérez et al [14], although they require the use of fitting parameters. In Figure 4, we have plotted the MCQSS absorption coefficient and the CSS pure rotational bands at the thermodynamic states = 108 K and = 120 K. We can observe again that both types of spectra show a clear similitude between them.…”

“…In earlier works, the statistical parameters were obtained by using microscopic cell models [15], by fitting theoretical and experimental spectra [14], or by using an erroneous estimation of the correlation times (4) [12]. Also, unlike previous theories, [12,14,15] based on the Kubo cumulant expansions, where it is not clear what specific statistical properties are assumed for the DIF tensor (2), in our work the kind of probabilistic properties assumed for the DIF is clear [6]. With this type of simulation, we solve the classical and quantum motion equations numerically without the need of truncating the cumulant expansions that lead to an unclear statistical hypothesis.…”