Gas-Phase Infrared Action Spectroscopy of CHCl and CHClH: Likely Protagonists in Chlorine Astrochemistry.

Two fundamental halocarbon ions, CHCl and CHClH, were studied in the gas phase using the FELion 22-pole ion trap apparatus and the Free Electron Laser for Infrared eXperiments (FELIX) at Radboud University, Nijmegen (the Netherlands). The vibrational bands of a total of four isotopologs, CHCl and CHClH, were observed in selected wavenumber regions between 500 and 2900 cm and then spectroscopically assigned based on the results of anharmonic force field calculations performed at the CCSD(T) level of theory. As the infrared photodissociation spectroscopy scheme employed probes singly Ne-tagged weakly bound complexes, complementary quantum-chemical calculations of selected species were also performed. The impact of tagging on the vibrational spectra of CHCl and CHClH is found to be virtually negligible for most bands; for CHClH-Ne, the observations suggest a proton-bound structural arrangement. The experimental band positions as well as the best estimate rotational molecular parameters given in this work provide a solid basis for future spectroscopic studies at high spectral resolutions.