PROBING DOUBLE-MINIMA ION-MOLECULE REACTION COORDINATES BY PHOTOELECTRON-SPECTROSCOPY OF CLUSTERS - PHOH++NH3-]PHO+NH4+

Recently, we reported the direct detection of two distinct and stable reactive complexes confirming a double-minima barrier process for the reaction PhOH+ + NH3 --> PhO + NH4+ (Steadman, J.; Syage, J. A. J. Am. Chem. Soc. 1991, 113,6786). A model explaining the origin of the barrier and its generality to proton-transfer reactions involving delocalized charge was also presented. However, in that study, the barrier height could not be experimentally estimated because the ion-complex energy distribution was not known. In this report, we present photoelectron spectra to measure the energy distribution of the complex form PhOH+...(NH3)n produced by resonance two-photon ionization of the corresponding neutral clusters. The collective photoelectron and mass spectra results indicate that the barrier to proton transfer from the reactive complex is 1.0-1.5 eV.