threshold photoelectron-photoion coincidence spectroscopy

The valence threshold photoelectron spectrum of NF is reported for the first time in the literature, and threshold 3 . photoelectron-photoion coincidence TPEPICO spectroscopy has measured, state-selectively, the decay dynamics of the valence states of NF q in the range 13-23 eV. Vacuum-UV radiation from the Daresbury synchrotron source dispersed by a 3 1 m Seya-Namioka monochromator photoionises the parent molecules. Electrons and ions are detected by threshold electron analysis and time-of-flight mass spectrometry, respectively. TPEPICO spectra are recorded continuously as a function of photon energy, allowing coincidence ion yields of the fragment ions and the breakdown diagram to be obtained. A comparison of the integrated threshold photoelectron and the total ion signals as a function of energy suggests that, in the range 16-19 eV, autoionisation via Rydberg states of NF makes a significant contribution to the production of threshold