Absorption spectroscopy of an expanding laser produced lithium plasma in the extreme ultraviolet using the Dual Laser Plasma technique

Abstract

We describe the essential features of the Dual Laser Plasma (DLP) vacuum ultraviolet photoabsorption spectroscopy technique and the characteristics of our DLP apparatus. We show that the time- and space-resolved capabilities of this technique are suited to the monitoring of the dynamics of expanding plasma plumes in the regime used for pulsed laser deposition of materials. Examples of spectra showing the spatial and temporal evolution of a lithium plasma expanding in vacuum are presented. A model based on a self-similar expansion for the plume is developed and used to analyse the shape of absorption lines. Measurements in the photoionisation continuum of Li + are also presented.