Overtone Transition 2ν1 of HCO+ and HOC+: Origin, Radiative Lifetime, Collisional Quenching

• Published in: Chemphyschem 2024-11, Vol.25 (21), p.e202400106-n/a
• Main Authors: Jiménez‐Redondo, Miguel, Uvarova, Liliia, Dohnal, Petr, Kassayová, Miroslava, Caselli, Paola, Jusko, Pavol
• Format: Article
• Language: English
• Subjects: astrophysics; cryogenic ion trap; Cryogenic quenching; ion-molecule interactions; isomers; Radiative lifetime; Spectra; vibrational spectroscopy
• ISSN: 1439-4235; 1439-7641; 1439-7641
• DOI: 10.1002/cphc.202400106

We present spectra of the first overtone vibration transition of C−H/ O−H stretch (2ν1) in HCO+ and HOC+, recorded using a laser induced reaction action scheme inside a cryogenic 22 pole radio frequency trap. Band origins have been located at 6078.68411(19) and 6360.17630(26) cm−1, respectively. We introduce a technique based on mass selective ejection from the ion trap for recording background free action spectra. Varying the number density of the neutral action scheme reactant (CO2 and Ar, respectively) and collisional partner reactant inside the ion trap, permitted us to estimate the radiative lifetime of the state to be 1.53(34) and 1.22(34) ms, respectively, and the collisional quenching rates of HCO+(2ν1) with He, H2, and N2. The C−H/O−H stretch vibration overtone of one of the simplest molecular ion isomeric systems HCO+/HOC+ is studied in a cryogenic ion trap experiment. Moreover, our comprehensive “zero background” method enables the determination of radiative lifetimes and select quenching reaction rates at the same time.