Picosecond time-resolved laser mass spectroscopy

The extension of laser mass spectroscopy to the picosecond time domain and the application of this method to the study of fast surface processes is described. The technique is based on a pump-probe scheme in which a first pulse stimulates the desorption of surface material, and a second delayed pulse is used to photoionize the desorbed particles to allow detection with a mass spectrometer. Measurements on picosecond-laser-heated GaAs surfaces demonstrate the feasibility of the method. For example, it was possible to measure the thermal desorption of Ga and of Ga/sub 2/O with picosecond time resolution. >