This volume contains the full proceedings of the Fourth International Workshop on "Desorption Induced by Electronic Transitions" (DIET IV), held October 2-4, 1989, at the Burghotel Kranichberg, Gloggnitz, Austria. It
followed earlier workshops held in Williamsburg, USA (1982), SchloB Elmau, FRG (1984), and Shelter Island, USA (1987). The workshop was attended by 77 participants from 9 countries, and 66 papers (8 invited, 24 oral
contributions and 34 poster contributions) were pre­ sented. The proceedings contain 53 separate papers and focus on 8 main topics: (1) Basic Mechanisms and Theory, (2) Photophysics and Photochemistry, (3) Laser Induced
Desorption, (4) Adsorbed Layers, (5) Condensed Gases, (6) In­ sulators, (7) Gas Phase Processes and (8) Applications and Related Processes. The workshop was opened by N. Tolk, who initiated this series of meetings in 1982, and
by D. Menzel, who mentioned the 25th birthday of one of the basic processes in DIET, the so-called MGR model, which was first published in 1964. One of the goals of the meeting was to achieve a better understanding and further
improved theoretical descriptions of desorption by electronic transitions.