Infrared Spectra of Small Molecular Ions Trapped in Solid Neon
Marilyn E. Jacox
The infrared spectrum of a molecular ion provides a unique signature for that species, gives information on its structure, and is amenable to remote sensing. It also serves as a comparison standard for refining ab initio calculations. Experiments in this laboratory trap molecular ions in dilute solid solution in neon at 4.2 K in sufficient concentration for observation of their infrared spectra between 450 and 4000 cm-1. Discharge-excited neon atoms produce cations by photoionization and/or Penning ionization of the parent molecule. The resulting electrons are captured by other molecules, yielding anions which provide for overall charge neutrality of the deposit. Recent observations of ions produced from C2H4 and BF3 will be discussed. Because of their relatively large possibility of having low-lying excited electronic states, small, symmetric molecular cations are especially vulnerable to breakdown of the Born-Oppenheimer approximation. Some phenomena which can result from this breakdown will be discussed. Ion-molecule reaction rates are sufficiently high that in some systems absorptions of dimer cations and anions are also observed. When H2 is introduced into the system, the initially-formed ion may react with it. Among the species resulting from such ion-molecule reactions that have recently been studied are O4+, NH4+, HOCO+, and HCO2-.
AIP Conference Proceedings, Eighth International Conference on Computational Methods in Sciences and Engineering
October 3-6, 2010
Spectroscopy of Molecular Ions in the Laboratory and in Space
Infrared Spectra of Small Molecular Ions Trapped in Solid Neon, AIP Conference Proceedings, Eighth International Conference on Computational Methods in Sciences and Engineering, Kos, -1, [online], https://doi.org/10.1063/1.4906704
(Accessed May 29, 2023)