An investigation of laser desorption of Au by PIXE and RBS techniques using a He beam

Abstract

Laser desorption has become an important tool for the production of atomic beams of refractory metals and has already been used successfully in laser-spectroscopic studies of Au and Pt isotopes. In the present experiment we have desorbed Au atoms implanted at 1 and 30 keV, to determine the optimum conditions for desorption and to follow the migration of the implanted atoms at selected laser fluences and in various substrates. The implanted Au surface densities ranged from 10¹³ to 10¹⁶ atoms/cm². A Nd-YAG laser operated with a frequency-doubled output at 532 nm and a pulse duration of 10 ns was used for the desorption. This laser beam was focussed to a 5 mm² spot, superimposed on the 2 mm² beam spot of 3 MeV alpha particles used for simultaneous PIXE-RBS analysis. The YAG fluence was varied step by step up to about 900 mJ/cm² and after each step the PIXE and RBS spectra were recorded. The quantity of material desorbed was found to be large for graphite, boron nitride and Macor, and much less for the other materials.