High-Resolution Near-Infrared Spectroscopy of CH2+ and Its Deuterated Isotopologues

Aiming to provide approximate rotational constants for millimeter wave spectroscopists to identify the corresponding species in space, we have recorded the near-infrared spectra of the methylene cation CH2+ and its deuterated isotopologues, CD2+ and CHD+, using a high resolution and high sensitivity spectrometer. Detection of CH2+ in space will shed light on interstellar chemistry as it is the intermediate between the abundant CH+ and yet to be observed CH3+, which is important in the formation of larger organic molecules. CH2+ and its deuterated isotopologues are also of special interest for theoretical studies because of their unique intramolecular dynamics, i.e., the Renner–Teller interaction and quasi-linearity. This paper will discuss several new bands of CH2+, the Ã(0,5[11],0)0 ← X̃(0,0[0],0)1 and Ã(0,4[11],0)2 ← X̃(0,0[0],0)1 bands of CD2+, which have been identified and analyzed, and the candidate lines for the Ã(0,4[10],0)1 ← X̃(0,0[1],0)0 band of CHD+, in comparison with the theoretical predictions by Bunker and colleagues.