Spectroscopic characterisation of the isomeric H2NCH+ and H2CNH+ radical cations

The vibrational transitions and the relative abundances of the two isomeric ions H 2 CNH + and H 2 NCH + generated through electron impact ionization have been investigated in a noble gas tagging experiment. It could be shown that both species were formed with an abundance of 70 and 30% for H 2 NCH + and H 2 CNH + , respectively. The obtained vibrational bands of the two species have been assigned to vibrational transitions through comparison with the results of ab initio calculations. These computations also predict both species to be moderately polar. The present investigations show that both isomers should be included in chemical model calculations of dark interstellar clouds, protoplanetary disks, star-forming regions as well as planetary atmospheres. • Overview: This paper presents a spectroscopic study of H 2 CNH + and its isomer, the aminomethylene cation, H 2 CNH + , using noble gas tagging IRPD spectroscopy employing the infrared free electron laser FELIX located at Radboud University in Nijmegen. Ab initio calculations were performed to assign the vibrational spectra. • Core findings: The vibrational transitions and the relative abundances of the two isomeric ions of H 2 CNH + and H 2 CNH + , generated through electron impact ionization have been investigated in a noble gas tagging experiment. It could be shown that both species were formed with an abundance of 70 and 30% for H 2 CNH + and H 2 CNH + , respectively. The obtained vibrational bands of the two species have been assigned to vibrational transitions through comparison with the. results of ab initio calculations. These computations also predict both species to be moderately polar. • Significance: The present investigations show that both isomers should be included in chemical model calculations of dark interstellar clouds, protoplanetary disks, star-forming regions as well as planetary atmospheres.