Single, double and triple ionization of tetraphenyl iron(III) porphyrin chloride

Abstract

Tetraphenyl iron(III) porphyrin chloride (FeTPPCl) cations are generated in the gas phase by electron impact ionization. The ionization is accompanied by extensive fragmentation as well as formation of doubly and triply charged ions. The most prominent fragments are analyzed and identified by fitting with calculated natural isotope patterns. Appearance energies of the most abundant singly and doubly charged product ions are determined. For the singly charged parent ions FeTPPCl +, CuTPP + and the fragment ion FeTPP + we obtain a value of 9.7 ± 0.5 eV which is about 3 eV higher than the value published for photo ionization of FeTPPCl. The appearance energy of the doubly charged ion FeTPP 2+ is obtained to be 18 eV. The additional loss of one or two phenyl groups requires between 10 and 14 eV more for singly and doubly charged ions. Also, the metastable decay of singly and doubly charged ions is investigated with the mass analyzed ion kinetic energy (MIKE) scan technique, performed on a three sector field mass spectrometer (BEE-geometry). In the mass spectrum and the MIKE scans a strongly reduced stability of the porphyrin ions is observed with increasing charge state.