Electronic Properties and Ionic Photodissociation of Thionitrite Compounds RSNO [R=(CH₃)₃C– and (CH₃)₂CH–]

Abstract

The gas phase electronic properties of thionitrites (RSNO) in both the outermost (valence) and the shallow-core regions (S 2p) are experimentally studied for the first time by using photoelectron spectroscopy and synchrotron radiation in the VUV range with time-of-flight mass spectrometry in the Photoelectron Photoion Coincidence (PEPICO) mode. The He(I) photoelectron spectrum of <i>tert</i>-butyl thionitrite, (CH₃)₃CSNO, has been recorded and analyzed with the assistance of quantum chemical calculations. Furthermore, the dissociative photoionization mechanisms for two close related secondary and tertiary species, namely <i>iso</i>-propyl thionitrite, (CH₃)₂HCSNO (I) and (CH₃)₃CSNO (II), have been determined irradiating gaseous beams with photons in the 155–185 eV range, i. e. exciting and ionizing S 2p electrons of the central –SNO group. The branching ratio of ions produced on this way is analyzed allowing for a clear description of the main fragmentation channels operating after the electronic decay.