This grant is in the general area of analytical and surface chemistry and in the subfield of mass spectrometry. Professor McLafferty of Cornell University will continue his breakthrough work on neutralization reionization mass spectrometry (NRMS). Using NRMS unusual neutral species (biradicals, carbenes, ylides, hypervalent species and clusters) will be prepared and the energy surfaces of these molecules will be studied. Laser photodissociation and luminescence detection will also be used to study the spectroscopic states of these unusual species. Combining optical, mass spectrometric and energy release methods, ring opening and pyrolysis reactions of these small molecules of unusual electronic and molecular structure will be probed. Details of fragmentation mechanisms specific to isomeric species will be a particular focus of this work.