Explosion of Atomic Clusters Heated by High Intensity, Femtosecond Laser Pulses

Abstract

Atomic clusters have long been studied by chemists and physicists because of the unique position that clusters hold as an intermediate state between molecules and solids [1]. Many studies have traced the properties of materials from their monatomic characteristics to their bulk state characteristics through an examination of the material as it forms larger and larger clusters. Recently, there has been much activity in extending these studies to very high intensity, ultrashort laser pulses with peak laser intensities >10¹⁵ Wcm ⁻² and pulse widths of 0.1 to 10 ps [2–11]. There has also been some preliminary theoretical work in this area as well [6,12]. In this parameter regime the physics governing the laser cluster interaction is fundamentally different than in previous studies. At these intensities the laser interaction is non-perturbative and very high order multiphoton ionization and strong electric field tunnel ionization are possible. Consequently, highly charged ions can be produced [2,5,8,10]. Furthermore, the short pulses used are comparable to or shorter than the disassembly times of a cluster in the laser field [6] and, so, the entire laser pulse interacts with an inertially confined body of atoms.