Laboratoire de Météorologie Dynamique, IPSL, CNRS, Sorbonne Universités, UPMC University Paris 06, 75252 Paris, France.
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
J Chem Phys. 2017 May 21;146(19):194305. doi: 10.1063/1.4983397.
Using previously recorded spectra of HCl diluted in Ar gas at room temperature for several pressure conditions, we show that the absorptions in between successive P and R transitions are significantly different from those predicted using purely Lorentzian line shapes. Direct theoretical predictions of the spectra are also made using requantized classical molecular dynamics simulations and an input HCl-Ar interaction potential. They provide the time evolution of the dipole auto-correlation function (DAF) whose Fourier-Laplace transform yields the absorption spectrum. These calculations very well reproduce the observed super-Lorentzian behavior in the troughs between the intense lines in the central part of the band and the tendency of absorption to become sub-Lorentzian in the band wings between high J lines. The analysis shows that the former behavior is essentially due to incomplete collisions which govern the DAF at very short times. In addition, the increasing influence of line-mixing when going away from the band center explains the tendency of absorption to become more and more sub-Lorentzian in the wings.
使用之前在室温下记录的 HCl 在 Ar 气体中的稀释光谱，我们表明，在连续的 P 和 R 跃迁之间的吸收与仅使用纯洛伦兹线型预测的吸收有很大的不同。光谱的直接理论预测也使用重新量子化的经典分子动力学模拟和输入的 HCl-Ar 相互作用势能来进行。它们提供了偶极自相关函数（DAF）的时间演化，其傅里叶-拉普拉斯变换给出吸收光谱。这些计算很好地再现了在带中心部分强线之间的深谷中观察到的超洛伦兹行为，以及在高 J 线之间的带翼中吸收变得亚洛伦兹的趋势。分析表明，前者的行为主要是由于不完全碰撞，这些碰撞在非常短的时间内控制着 DAF。此外，当远离带中心时，线混合的影响增加，这解释了吸收在翼部变得越来越亚洛伦兹的趋势。
