EXTENDED IMPACT THEORY OF PRESSURE BROADENING OF SPECTRAL-LINES FOR VAN-DER-WAALS INTERACTION POTENTIALS

We study the extension of the impact theory of foreign gas line broade ning to the case of non-instantaneous collisions. As has been shown by previous authors; the effect of finite duration of collisions can be taken into account by adding to the usual Lorentzian profile a dispers ion type contribution which introduces an asymmetry into the profile. We rederive this result by a new rigorous method and discuss the resul ts in terms of the Weiss-kopf radius defined for one-term van der Waal s interaction potentials. In this way, precise criteria for the validi ty domain of the theory can be established. (C) 1998 Elsevier Science Ltd. All rights reserved.