Infrared laser velocity modulation detection of HCl+

Abstract
Using velocity modulation detection, infrared diode laser absorption spectra of seventeen transitions of the fundamental band of HCl+ have been measured covering both 2Π1/2 and 2Π3/2 states of H 35Cl+ and H 37Cl+. The transitions were assigned on the basis of their absolute positions and Λ doublet splittings predicted by earlier optical spectra. Some of the additional lines detected, but not yet accurately measured, are tentatively assigned to hot band transitions in HCl+.