ABSORPTION-SPECTROSCOPY OF AN EXPANDING LASER-PRODUCED LITHIUM PLASMAIN THE EXTREME-ULTRAVIOLET USING THE DUAL LASER-PLASMA TECHNIQUE

We describe the essential features of the Dual Laser Plasma (DLP) vacu um ultraviolet photoabsorption spectroscopy technique and the characte ristics of our DLP apparatus. We show that the time- and space-resolve d capabilities of this technique are suited to the monitoring of the d ynamics 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 present ed. A model based on a self-similar expansion for the plume is develop ed and used to analyse the shape of absorption lines. Measurements in the photoionisation continuum of Li+ are also presented. (C) 1998 Else vier Science B.V.