Direct UV absorption spectra of CO2+ in solid neon

The IR and UV absorption spectra of CO2+ isolated in solid neon were studied by using our newly built mass-selective matrix isolation system. The IR absorption spectrum revealed the formation of CO2 in both cationic and anionic forms in solid Ne, since neutral CO2 was also used to serve as an electron scavenger in this study. Subsequently, we recorded the UV absorption spectrum of the same matrix sample in the spectral region 270−400 nm, encompassing the electronic transitions of CO2+ from the ground state to the first two electronic excited states. Notably, the observation of the electronic transition A2Πu←X2Πg was dominated by the vibrational progression of the symmetric CO stretching mode, while a single sharp band was observed in the electronic transition B2Σu+←X2Πg. The presented spectra might be useful for future studies on terrestrial and astrochemical conjunctions.