Reactive Monitoring with Synchrotron Radiation as a Unique Source of Accurate Benchmark Data for Gas-Phase Reactions

Abstract

The important role of experiments with vacuum ultraviolet (VUV) radiation from synchrotron sources for the determination of thermodynamic benchmarks for ions in the gas phase is briefly reviewed. Smoothly tunable VUV photons from a synchrotron are used to ionize neutral precursor molecules. Monitoring the ion yields as a function of the VUV photon wavelength permits an accurate determination of ionization energies and fragmentation thresholds. The ions formed on photoionization above the ionization threshold bear a precisely determined internal energy, which can be used for investigation of their reactivity in bimolecular collision processes as a function of their internal energy content. This technique is referred to as “reactive monitoring”, which, among others, allows the determination of energy barriers in chemical reactions.