Threshold Photoelectron−Photoion Coincidence Spectroscopy of Perfluorocarbons. 2. Unsaturated and Cyclic Perfluorocarbons C2F4, C3F6, 2-C4F8, and c-C4F8

Abstract

Threshold photoelectron−photoion coincidence (TPEPICO) spectroscopy of three unsaturated (C2F4, C3F6, 2-C4F8) and one cyclic (c-C4F8) perfluorocarbons has been performed using vacuum-ultraviolet radiation from a synchrotron source in the energy range 10−27 eV. Electrons and ions are detected by threshold electron analysis and time-of-flight mass spectrometry, respectively, allowing breakdown diagrams that show the formation probability of fragment/parent ions as a function of the internal energy of the parent ion to be obtained. Fixed-energy TPEPICO spectra with improved time resolution were performed on some of the fragment ions observed, from which the mean kinetic energy released in fragmentation was determined. High-resolution (ca. 0.01 eV at 10 eV) threshold photoelectron spectra of the three unsaturated species have been recorded, and assignments have been made of the type of electron removed by photoionization to the observed states of the parent ion. Unlike the saturated perfluorocarbons studied i...