CH2D+, the Search for the Holy Grail

TL;DR

This paper investigates CH2D+, a key molecular ion in astrochemistry, through spectroscopic analysis and chemical modeling, highlighting its potential role in deuterium chemistry at moderate temperatures.

Contribution

It provides the first comprehensive spectroscopic data and chemical network analysis for CH2D+, supporting its possible detection in warm interstellar environments.

Findings

Spectroscopic properties of CH2D+ summarized.

Chemical models suggest presence in warm environments.

Support for CH2D+ role in deuterium chemistry.

Abstract

CH2D+, the singly deuterated counterpart of CH3+, offers an alternative way to mediate formation of deuterated species at temperatures of several tens of K, as compared to the release of deuterated species from grains. We report a longstanding observational search for this molecular ion, whose rotational spectroscopy is not yet completely secure. We summarize the main spectroscopic properties of this molecule and discuss the chemical network leading to the formation of CH2D+, with explicit account of the ortho/para forms of H2, H3+ and CH3+. Astrochemical models support the presence of this molecular ion in moderately warm environments at a marginal level.