Research Projects

Organizational Units

Journal Issue


\hspace{0.25in} Although molecular oxygen, O$_2$, has long been thought to be present in interstellar environments, it has only been tentatively detected toward one molecular cloud. The fractional abundance of O$_2$ determined from these observations is well below that predicted by astrochemical models. Given the difficulty of O$_2$ observations from ground-based telescopes, identification of a molecule that could be used as a tracer of O$_2$ in interstellar environments would be quite useful. \hspace{0.25in} To this end, we have begun a collaborative examination of HO$_2^+$ in an attempt to evaluate the feasibility of its detection in interstellar clouds. The formation reaction for HO$_2^+$ is nearly thermoneutral, and so a full thermochemical evaluation of its formation mechanism is required. In addition to this uncertainty, no laboratory spectroscopic information is available for HO$_2^+$, and previous {\it ab initio} calculations are not sufficiently accurate to guide observational searches. Here, we will present highly accurate spectral predictions based upon the new high-level {\it ab initio} calculations presented in the preceding talk. We will also report the HO$_2^+$ formation reaction enthalpy and equilibrium constant, which were obtained from an Active Thermochemical Tables (ATcT) analysis and are the most accurate values available to date. Additionally, we will discuss the potential formation and destruction pathways for HO$_2^+$ in interstellar environments. Based on this information, we will estimate the HO$_2^+$ column density in molecular clouds and discuss the feasibility of its detection. Progress on obtaining the high-resolution infrared laboratory spectroscopy on the $\nu_1$ band of HO$_2^+$ will also be reported.


current Address: Department Of; University, Emory; Atlanta, ; 30322
Author Institution: Departments of Chemistry and Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439; Departments of Chemistry and Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801