Rovibrational Overtone and Combination Bands of the HCNH+ Ion

Abstract

Spectra of vibrational overtone and combination bands from vibrational ground state of HCNH+ were measured using an action spectroscopy technique with active background suppression in a cryogenic 22 pole radio frequency ion trap apparatus. Spectroscopic constants for the upper vibrational levels of the transitions were determined with vibrational band origins being 6846.77981(90) $\text{cm}^{-1}$ ($2\nu_1$ , NH stretch), 6640.47624(43) $\text{cm}^{-1}$ ($\nu_1 + \nu_2$), 6282.03578(63) $\text{cm}^{-1}$ ($2\nu_2$, CH stretch), and 6588.4894(20) $\text{cm}^{-1}$ ($\nu_2 + \nu_3 + 2\nu_5^0$). State of the art ab initio VCI calculations up to 10000 $\text{cm}^{-1}$ complement the experimental data.