Terahertz spectroscopy and global analysis of the rotational spectrum of doubly deuterated Amidogen radical ND$_{2}$

TL;DR

This study measured and analyzed the rotational spectrum of the doubly deuterated Amidogen radical ND₂, providing precise spectroscopic data to aid its potential detection in space and improve understanding of interstellar deuteration processes.

Contribution

The paper presents new high-frequency rotational transition measurements of ND₂ and a comprehensive global analysis, enhancing the accuracy of spectroscopic parameters for astrophysical applications.

Findings

64 new transition frequencies measured between 588 and 1131 GHz

Global analysis yields precise spectroscopic parameters for ND₂

Accurate predictions of ND₂ rotational transitions up to several THz

Abstract

The deuteration mechanism of molecules in the interstellar medium (ISM) is still being debated. Observations of deuterium-bearing species in several astronomical sources represent a powerful tool to improve our understanding of the interstellar chemistry. The doubly deuterated form of the astrophysically interesting Amidogen radical could be a target of detection in space. In this work, the rotational spectrum of the ND$_{2}$ radical in its ground vibrational and electronic $X^{2}B_{1}$ states has been investigated between 588 and 1131 GHz using a frequency modulation millimeter/submillimeter-wave spectrometer. The ND$_{2}$ has been produced in a free-space glass absorption cell by discharging a mixture of ND$_{3}$ and Ar. Sixty-four new transition frequencies involving $J$ values from 2 to 5 and $K_{a}$ values from 0 to 4 have been measured. A global analysis including all the previous field-free pure rotational data has been performed, allowing for a more precise determination of a very large number of spectroscopic parameters. Accurate predictions of rotational transition frequencies of ND$_{2}$ are now available from a few GHz up to several THz.