This proposal has the goal of developing a microscopic understanding of the underlying physical processes for particle emission for semiconductor and insulator surfaces when surfaces are irradiated with a low flux pulsed UV laser beam. The emphasis will be focused on understanidng the role of surface defects in the particle emission process. New techniques for monitoring the possible surface structural changes of the topmost surface layer associated with the particle emission process will be developed. One such technique, ion scattering spectroscopy which has extreme surface sensitivity and can yield information not available by optical methods, will be explored. An attempt will be made to verify the correctness of two pending models (used for understanding silicon and germanium results) and to point to new directions that will enable the understanding of the underlying physical mechanisms. A possible application that might result is a means of quantifying the surface defect density by using defect- initiated particle emission. This work is complementary to the study of particle emission from metal surfaces.
