UV absorption spectra of vibrationally excited O2 and its accumulation under KrF excimer laser irradiation in a low-temperature Ar crystal

Numerous lines were observed in the UV absorption spectra of O2 doped in a low-temperature Ar crystal excited by a KrF excimer laser. These lines were assigned to the transitions from vibrationally excited levels of the ground state O2 (ν″ = 4–11) to vibrational levels of the B state (ν′ = 0–8), where the B state vibrational numbering of Schnepp and Dressler was adopted. The steady-state concentration of the vibrationally excited O2 (ν″ = 4–8) was estimated to be 3.4 × 1016 molecules cm−3, corresponding to 0.07% of the total O2, under irradiation by the KrF laser at a fluence of 4.9 mJ cm−2 pulse−1 with a repetition rate of 10 Hz.