Formation of different isotopomers of chloronium in the interstellar
  medium
  Main focus of this paper is to explore the possibility of findings two
deuterated isotopomers of H2Cl+ (Chloronium) in and around the Interstellar
Medium (ISM). Presence of Chloronium ion has recently been confirmed by
Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared
(Neufeld et al., 2012). It observed para-chloronium towards six sources in the
Galaxy. Existence of its deuterated isotopomers (HDCl+ & D2Cl+) are till date
not discussed in the literature. We find that these deuterated gas phase ions
could be destroyed by various ion-molecular reactions, dissociative
recombination (DR) and by cosmic rays (CR). We compute all the Ion-molecular
(polar) reaction rates by using the parameterized trajectory theory and the
Ion-molecular (non-polar) reaction rates by using the Langevin theory. For DR
and CR induced reactions, we adopt two well behaved rate formulas. We also
include these rate coefficients into our large gas-grain chemical network to
study the chemical evolution of these species around the outer edge of the cold
dense cloud. In order to study spectral properties of chloronium ion and its
two deuterated isotopomers, we have carried out quantum chemical simulations.
We calculated ground state properties of these species by employing second
order Moller-Plesset perturbation theory (MP2) along with quadruple-zeta
correlation consistent (aug-cc-pVQZ) basis set. Infrared and electronic
absorption spectra of these species are calculated by using the same level of
theory. MP2/aug-cc-pVQZ level of theory is used to report the different
spectroscopic constants of these gas phase species. These spectroscopic
constants are essential to predict rotational transitions of these species. Our
predicted column densities of D2Cl^+, HDCl^+ along with the spectral
information may enable their future identification around outer edges of cold
dark clouds.
