Difference-frequency laser spectroscopy of the ν1 and ν3 fundamental bands of H 2Cl +: Determination of the equilibrium molecular structure

Abstract

The gas-phase spectra of the ν 1 and ν 3 fundamental bands of H 2Cl + have been observed with a difference-frequency laser spectrometer between 2525 and 2755 cm −1. The ions were generated in a hollow cathode discharge through a gas mixture of HCl and H 2. A simultaneous least-squares analysis of the ν 1 and ν 3 bands with an effective vibration-rotation Hamiltonian including Coriolis interaction between the v 1 = 1 and v 3 = 1 states yielded the band origins (2643.2200 and 2630.1404 cm −1 for the ν 1 and ν 3 of H 2 35Cl +, and 2641.4931 and 2628.1065 cm −1 for the ν 1 and ν 3 of H 2 37Cl +, respectively), the rotational constants, and the centrifugal distortion constants for the ground and excited states. The equilibrium molecular structure has been determined to be r e ( HCl) = 1.30412(17) A ̊ and θ e(HClH) = 94.243(27)° for H 2 35Cl + and r e ( HCl) = 1.30411(17) A ̊ and θ e(HClH) = 94.244(26)° for H 2 35Cl +.