Expansion of a multi-component laser-ablated plume

Institute of Fundamental Technological Research, Pawinskiego 5B, 02-106 Warsaw, Poland

^a e-mail: aslowick@ippt.gov.pl

Received: 10 February 2011
Revised: 16 May 2011
Accepted: 5 July 2011
Published online: 28 September 2011

Abstract

The expansion of a plume generated during laser ablation is studied with the Direct Simulation Monte Carlo method. The plume is a mixture of four disparate molecular mass components and expands in vacuum or into ambient gas. The time dependence of deposition rate is studied and the transition from an initial vacuum-like to a diffusion-like regime of expansion in ambient gas is shown. The lack of stoichiometry increases with the ratio of molecular masses of ablated particles and at disparate masses the stoichiometry is seriously affected. Ambient gas worsens the stoichiometry unless it supplies particles compensating the backward and sideward flows of plume constituents.