IMPROVED DETERMINATION OF THE 1 0 -0 0 ROTATIONAL FREQUENCY OF NH 3 D + FROM THE HIGH-RESOLUTION SPECTRUM OF THE ν 4 INFRARED BAND

Abstract

The high resolution spectrum of the v4 band of NH3D+ has been measured by difference frequency IR laser spectroscopy in a multipass hollow cathode discharge cell. From the set of molecular constants obtained from the analysis of the spectrum, a value of 262817(6) MHz (3sigma) has been derived for the frequency of the 1(0)-0(0) rotational transition. This value supports the assignment to NH3D+ of lines at 262816.7 MHz recorded in radio astronomy observations in Orion-IRc2 and the cold prestellar core B1-bS.