Two-dimensional Penning ionization electron spectroscopy of CH3I and CH2I2 by He*(23S) metastable atoms

Naoki Kishimoto, Andriy Borodin, Takuya Horio, Masakazu Yamazaki, Koichi Ohno

Research output: Contribution to journalConference articlepeer-review


Penning ionization of iodomethane (CH3I) and diiodomethane (CH2I2) upon collision with metastable He*(2 3S) atoms was studied by collision-energy/electron-energy resolved two-dimensional Penning ionization electron spectroscopy (2D-PIES) over a wide range of collision energies (20 - 350 meV). Collision energy dependence of partial ionization cross sections (CEDPICS) indicates that the interaction with He*(23S) atoms around the valence molecular orbitals is attractive at low collision energies except for the only σCH molecular orbital region of iodomethane which has a repulsive character in the normal collision energy range (70 - 350 meV). Large bands at lower electron energies (3.7 - 5.5 eV) in PIES spectra were ascribed to autoionization from a transient ion-pair. The related entrance ionization channel has an attractive character. The excitation transfer, which is responsible for the I** autoionization, takes place in regions close to carbon atoms and is repulsive towards He*(23S) in the normal collision energy range. The superexcited complex of (He-CH2I2)** autoionizes via the excitation transfer occurring close to the σCI regions of the targets.

Original languageEnglish
Article number012014
JournalJournal of Physics: Conference Series
Issue number1
Publication statusPublished - 2010
Externally publishedYes
EventInternational Workshop on Electronic Spectroscopy for Gas-phase Molecules and Solid Surfaces, IWES2009 - Matsushima, Japan
Duration: Oct 12 2009Oct 15 2009

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


Dive into the research topics of 'Two-dimensional Penning ionization electron spectroscopy of CH3I and CH2I2 by He*(23S) metastable atoms'. Together they form a unique fingerprint.

Cite this