The infrared features and full rotational constant catalogue of the newly detected MgC2 astromolecule

Abstract

ABSTRACT The recent radioastronomical detection of magnesium dicarbide (MgC2) towards the carbon-rich star IRC+10216 leads to questions about whether this molecule can be observed in other wavelengths, especially with the wealth of IR data being produced by JWST. This present, theoretical spectral characterization, unfortunately, implies that mid-IR observations of MgC2 are unlikely due to small IR transition intensities, overlap with polycyclic aromatic hydrocarbon IR features, low frequencies/long wavelengths, or the relatively small column densities. In spite of this, the full set of fundamental anharmonic vibrational frequencies are provided for each of the 24Mg, 25Mg, and 26Mg isotopologues as are the complete rotational constants for the same set for additional laboratory characterization. Most notably and with regards to 24MgC2, the B0 and C0 (11452.7 and 9362.7 MHz) rotational constants are uniquely provided for the first time. The experimentally derived A0, (B + C)/2, and (B − C)/4 values are within 0.7 % of the presently computed anharmonic results implying similar accuracy for the remaining spectroscopic constants.