Eur. Phys. J. D 32, 339-345 (2005)
https://doi.org/10.1140/epjd/e2004-00188-9

Obtaining colder ensembles of free clusters by using evaporation and recoil

¹ Chalmers University of Technology and Gothenburg University, School of Physics and Engineering Physics, 41296 Gothenburg, Sweden
² Department of Chemistry, University of California, Riverside, CA 92521, USA
³ Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA

Corresponding author: ^a kresin@usc.edu

Received: 26 August 2004
Revised: 28 October 2004
Published online: 21 December 2004

Abstract

We describe a theoretical model which treats the effects of evaporation-induced recoil on the mass and temperature distributions of a collimated beam of small neutral clusters emitted by a hot-nozzle source. The model incorporates two important consequences of in-flight cluster fragmentation processes. One is the well-known statistical evaporation of atoms and dimers accompanied by cluster size redistribution and cooling, and the other is the accompanying mechanical recoil of the fragments. We predict that the filtering effect introduced by cluster recoil can be used to an advantage by separating out the off-axis cluster population. This fraction will have a significantly narrower and colder distribution of internal temperatures than the on-axis ensemble.