This research project, supported in the Analytical and Surface Chemistry Program, addresses the development of an understanding of the processes which occur when molecular ions of tens of eV energy impact upon surfaces. Surface induced dissociation (SID) and ion/surface reactions occur upon collision. The overall goal of this work is to develop the understanding which is needed to use ion/surface collisions as a structural analysis tool in analytical mass spectrometry. Self-assembled monolayer surfaces, as well as molecular adsorbates on characterizable gold and silver substrates will be investigated as useful surfaces for these SID applications. The range of ion/surface collision phenomena to be explored will include low energy sputtering of ionized adsorbates, partial neutralization of doubly charged ions, and molecular beam collisions with surfaces. %%% The structural characterization of large molecules by mass spectrometry is facilitated by the use of ion collision methods which introduce significant internal energy into the analyte. A very promising approach for introducing this internal energy is the process of ion/surface collision. Ion/surface collisions result in surface induced dissociation and reactions with the surface which can be used to obtain structural information about the molecules involved. This research project addresses the fundamental ion/surface interaction chemistry which forms the basis for this analytical approach.