Rotational excitation and de-excitation of HF molecules by He atoms ^*

¹ Department of Chemical Engineering, Stanford University, 381 North-South Mall, Stanford, CA 94305, USA
² Laboratoire de Physico-Chimie Moléculaire, Université de Bordeaux 1, 351 cours de la Libération, 33405 Talence Cedex, France e-mail: t.stoecklin@lpcm.u-bordeaux1.fr

Received: 15 April 2004
Accepted: 17 September 2004

Abstract

We report Close Coupling calculations of the rotational transitions induced in collisions between HF molecules and He atoms. We consider transitions for levels up to and for temperatures up to 300 K. We use a new global 3D potential energy surface which we proposed recently and is the best available at the moment. This surface exhibits two minima associated both with linear geometries ( cm^-1 for He–HF and  cm^-1 for He-FH). Close Coupling calculations are performed in the collision energy 10^-6 to 2000 cm^-1 interval. Our results validate the estimate, by Neufeld et al., of the abundance of HF in the interstellar medium which was detected recently.