Eur. Phys. J. D 38, 121-127 (2006)
https://doi.org/10.1140/epjd/e2006-00012-8

Cooling and alignment of ethylene molecules in supersonic seeded expansions: diagnostic and application to gas phase and surface scattering experiments

Collisional alignment

¹ Dipartimento di Ingegneria Civile ed Ambientale, Università di Perugia, 06100 Perugia, Italy
² Dipartimento di Chimica, Università di Perugia, 06100 Perugia, Italy
³ Dipartimento di Fisica, Università di Trento, Povo (TN), Italy
⁴ CNR/IFN, Trento, Italy
⁵ Dipartimento di Fisica, Università di Genova, Genova, Italy
⁶ CNR/IMEM, Genova, Italy

Corresponding author: ^a david.cappelletti@unipg.it

Received: 29 July 2005
Revised: 21 November 2005
Published online: 17 January 2006

Abstract

Rotational cooling and collisional alignment of ethylene molecules is induced by seeding effects in supersonic expansions with lighter gas carriers such as He and Ne. The dependencies of the degree of alignment on the rotational state, on the final speed of the molecules and on the diffusion angular cone have been characterized by coupling two different experimental methodologies. An application to surface scattering is then demonstrated by measuring stereo-dynamical effect in the adsorption on metallic surfaces.