Eur. Phys. J. B 70, 507-512 (2009)
https://doi.org/10.1140/epjb/e2009-00277-1

Theory of the optical spectrum of Na₂ on ⁴He droplets: effects of the zero-point energy of the nearest atoms

¹ Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
² Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, via R. Cozzi 53, 20125 Milano, Italy

Corresponding author: ^a giorgio.benedek@mater.unimib.it

Received: 29 May 2009
Published online: 11 August 2009

Abstract

An analytical theory of the optical transitions of a molecule bound at the surface of a ⁴He droplet is developed for the case of a strong softening of the excited-state nearest neighbor dynamics. The optical bandwidth is found to be determined by the zero-point kinetic energy released at the transition. The theory is applied to the triplet-triplet optical transition in Na₂ molecule, for which an asymmetric vibronic band with no pronounced zero-phonon line is predicted, in good agreement with the experiment.