Eur. Phys. J. D (2013) 67: 52
https://doi.org/10.1140/epjd/e2013-30523-x

Regular Article

Absorption spectra of Na atoms in dense He

¹ Observatoire de Paris, GEPI, UMR 8111, CNRS, 61 avenue de l’Observatoire, 75014 Paris, France
² Institut d’Astrophysique de Paris, UMR 7095, CNRS, Université Paris VI, 75014 Paris, France
³ Division of Chemistry, Graduate School of Science, Hokkaido University, 060-0810 Sapporo, Japan
⁴ Laboratoire de Chimie et Physique Quantique, Université de Toulouse (UPS) and CNRS, 118 route de Narbonne, 31400 Toulouse, France
⁵ Department of Physics and Astronomy, University of Louisville, Louisville, 40292 Kentucky, USA
⁶ Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 76104 Freiburg, Germany

^a e-mail: nicole.allard@obspm.fr

Received: 27 July 2012
Received in final form: 4 December 2012
Published online: 19 March 2013

Abstract

We present an analysis of Na-He collisional profiles at high density and very low temperature in a unified line shape semi-classical theory which contains the impact as well the quasistatic limits. Clearly understanding the variation of shape of the two fine-structure components of the 3s-3p line with increasing helium density allows us to understand experimental spectra of a Na atom attached to He nanodroplets. We compare our collisional approach to path integral Monte Carlo calculations using the same ab initio Na-He molecular potentials.