ELECTRONICALLY STIMULATED DESORPTION.

In the valence region, desorption of neutrals predominates; nevertheless most research has been on ions up to recently. New methods have made the investigation of neutrals easier, and angle as well as energy distributions have been reported; on this basis the salient mechanisms can be deduced both for chemisorbed and physisorbed layers. Desorption of ions and, in particular, of fragment ions, is strongly enhanced following higher excitations. These can most easily be reached via Auger decay of adsorbate core holes. Considerable detail of understanding is obtainable through polarization-dependent measurements with synchrotron radiation.