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

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 [CH{sub 2}I{sub 2}]{sup ⋅+} is still limited. In this work, we measured and calculated the appearance energy (AE) of the ionic fragments I{sub 2}{sup ⋅+} and CH{sub 2}{sup ⋅+} and correlated the different fragmentation channels to the electronic states of the cation via photoelectron-photoion coincidence (PEPICO) experiments. In the case of the CH{sub 2}/I{sub 2}{sup ⋅+} channel, the experimentally determined AE is in excellent agreement with the adiabatic theoretical value while a discrepancy is observed for the CH{sub 2}{sup ⋅+}/I{sub 2} channel. This discrepancy can be understood accounting for a fragmentation involving the formation of two I atoms (CH{sub 2}{sup ⋅+}/2I channel), which, as explained by time dependent density functional theory (TD-DFT) calculations, occurs when [CH{sub 2}I{sub 2}]{sup ⋅+} excited states are involved.
Authors:
 [1] ; ; ; ;  [2] ;  [3] ;  [4]
  1. Dipartimento di Chimica, CNR-ISMN, Sapienza Università di Roma, Roma 00185 (Italy)
  2. CNR-ISM, Area della Ricerca di Roma 1, Monterotondo Scalo, RM 00015 (Italy)
  3. Dipartimento di Chimica, Sapienza Università di Roma, Roma 00185 (Italy)
  4. CNR-ISM, Area della Ricerca di Roma 2, Roma 00133 (Italy)
Publication Date:
OSTI Identifier:
22493411
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMS; CATIONS; CHEMICAL PHYSICS; CHEMISTRY; COINCIDENCE SPECTROMETRY; DENSITY FUNCTIONAL METHOD; EXCITED STATES; FRAGMENTATION; IODINE; METHANE; MOLECULAR IONS; MOLECULES; PHOTOELECTRON SPECTROSCOPY; RADICALS; TIME DEPENDENCE