Internal energy effects in proton transfer reactions

The Utah tandem Dempster-Ion Cyclotron Resonance (ICR) mass spectrometer has been used to study internal energy effects in a number of simple proton transfer reactions. The ICR second stage serves the functions of an energy filter, collision chamber and mass analyzer. A recently added capability allows the investigation of the unimolecular decompositions of proton transfer products. In these studies the proton transfer products are formed in the Dempster source, are mass-selected, and injected into the ICR section where unimolecular reactions (metastables) are observed, occurring over the time interval of 10-6 to 10-2 s. The use of appropriately labelled (deuterated) reactants in each of these operating modes provides further insight into the effect of internal energy on the rate constants, branching ratios and isotope effects in proton transfer reactions. (U.K.)