Double photoionisation spectra of HI, CH3I and CF3I from TOF-PEPECO measurements

Double photoionisation spectra of HI, CH3I and CF3I have been measured by the TOF-PEPECO technique, providing complete information on electron energy distributions. The lowest energy states of HI2+ and CH3I2+ are identified and their vibrations are resolved. Possible reasons for the markedly different CF3I spectrum are discussed. There is evidence for atomic autoionisation of iodine as a pathway contributing to the double photoionisation.