US-Sweden Cooperative Research: Ion Beam Desorption of Molecular Solids

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This award will support cooperative research in solid state physics, involving Drs. R.E. Johnson and J.W. Boring, University of Virginia and Dr. B.U. Sundquist, Tandem Accelerator Laboratory, University of Uppsala, Sweden. The objective of the project is to describe the common mechanisms for electrical-induced desorption and modification of a variety of organic materials and molecular insulators. The US investigators have been carrying out a theoretical program on modeling the electronic and chemical processes which are initiated when an ion penetrates insulating materials, as well as an experimental program for electron and keV ion modification of such materials. A primary effort has been the study of low- temperature, molecular condensed gases. Dr. Sundquist's research group at Uppsala, using the tandem accelerator and recently acquired lasers, has been studying MeV ion and laser-induced desorption of large biological molecules from samples of condensed molecules as a unique means of mass determination. They have also been studying modification of certain electronic insulators with the tandem accelerator. In the next few years they will have the ability to irradiate with very high energy particles using the new accelerator which was built at Uppsala. The US and Swedish efforts have concentrated on describing the principal energy ejection processes which occur in the bulk; however, they have begun to describe the common energy transfer processes occuring in molecular solids. In the proposed collaboration the two groups will study organic solids; the experiments performed by the two groups will be coordinated in order to expose the common aspects of the physical and chemical mechanisms. The project will benefit from the recently-added capabilities of the Uppsala group to study neutral biomolecule ejection and laser desorption and of the ability of Virginia group to make complementary measurements on chemically similar samples. Results of this research will be of interest in a number of scientific areas, such as biophysics, astrophysics, electronics and pharmaceuticals.