Quantum-mechanical vs. semi-classical spectral-line widths and shifts from the line core in the non-impact region for the Ar-perturbed/K-radiator system

摘要

New quantum-mechanical (QM) and semi-classical (SC) shifts (d's) and widths (HWHM's, w's) were measured from the line core of computed full spectral-line shapes for the Ar-perturbed/K-radiator system (K/Ar). The initial state of our model was based on a 4p(2) P-3/2,P-1/2 pseudo-potential for the K/Ar system, and the final state on a zero potential. The Fourier transform of the line shape formed the basis for the computations. Excellent agreement was found between the QM and SC values of d and of w in a high-pressure (P) non-impact region, which was characterized by a root P dependence of w and a P dependence of d. These agreements were shown to be another example of a c orrespondence between classical (SC) quantities and QM quantities in the limit of large quantum numbers. Typically at P = 1 x 10(6) Torr and T = 400 K, w(QM) = 448 cm(-1) and w(SC) = 479 cm(-1) where the deviation from the mean is +/-3.3 %. Also, d(QM) = -3815 cm(-1) and d(SC) = -3716 cm(-1), where the deviation from the mean is +/-1.3%. A new general method was formulated which yielded a definite pressure P-0, which was defined as an upper limit to the low-pressure impact approximation and a lower limit to the non-impact region. (C) 2007 Elsevier Ltd. All rights reserved.