Photon stimulated gas desorption from pure aluminum

Abstract

To investigate photon stimulated gas desorption from a sample inside, it is necessary to separate the gas desorption from the sample surface and the one from inside. When a sample has no inside gas content, does photon stimulated gas desorption soon become very small after surface gas is cleaned away? An experiment using a thin film carefully prepared at an ultrahigh vacuum can give this answer. The gas desorption experiments were carried out in a molecular-beam epitaxy apparatus made of aluminum alloys with special surface treatments. The apparatus is connected with the TRISTAN accumulation ring. Synchrotron light can be applied on samples in the apparatus. Pure aluminum films were prepared by vacuum evaporation (99.999% aluminum) on a silicon wafer in the pressure range from 10−9 to 10−8 Torr. Gas desorption measurements were made at a pressure around 10−10 Torr using ionization gauges and a quadrupole mass analyzer. Photon stimulated gas desorption of a pure aluminum sample was small compared to other materials. Now the experimental apparatus is being improved to measure the very low gas desorption yield more precisely. The final purpose is to make clear the relation between an internal gas content of material and photon stimulated gas desorption.