A joint theoretical and experimental study on diiodomethane: Ions and neutrals in the gas phase

作者：Satta Mauro; Bolognesi Paola; Cartoni Antonella^*; Casavola Anna Rita; Catone Daniele; Markus Pal; Avaldi Lorenzo

来源：Journal of Chemical Physics, 2015, 143(24): 244312.

DOI：10.1063/1.4937425

The chemical physics of halomethanes is an important and challenging topic in several areas of chemistry in particular in the chemistry of the atmosphere. Among the class of halomethanes, the diiodomethane molecule has attracted some interest in the last years, but despite this, the information on its radical cation [CH2I2](center dot+) is still limited. In this work, we measured and calculated the appearance energy (AE) of the ionic fragments I-2(center dot+) and CH2 center dot+ and correlated the different fragmentation channels to the electronic states of the cation via photoelectron-photoion coincidence (PEPICO) experiments. In the case of the CH2/I-2(center dot+) channel, the experimentally determined AE is in excellent agreement with the adiabatic theoretical value while a discrepancy is observed for the CH2 center dot+/I-2 channel. This discrepancy can be understood accounting for a fragmentation involving the formation of two I atoms (CH2 center dot+/2I channel), which, as explained by time dependent density functional theory (TD-DFT) calculations, occurs when [CH2I2](center dot+) excited states are involved.

• 出版日期2015-12-28