The a1Δg−X3Σg− band of 16O17O, 17O18O and 17O2 by high sensitivity CRDS near 1.27 μm

The very weak a1Δg−X3Σg− system of the three 17O isotopologues of oxygen - 16O17O, 17O18O and 17O2 - was studied by high sensitivity CW-Cavity Ring Down Spectroscopy. The spectra of a 17O highly enriched sample were recorded at room temperature between 7640 and 7917 cm−1 and at liquid nitrogen temperature in the 7876-7893 cm−1 region. The magnetic dipole (0-0) band was observed for all three 17O isotopologues. At liquid nitrogen temperature, some of the transitions were observed with partially resolved hyperfine splitting due to the 17O nuclear spin. The electric quadrupole (0-0) band and the (1-1) hot band were also observed for the 16O17O and 17O2 species. The rotational and hyperfine spectroscopic parameters of the X3Σg− and a1Δg states of the three studied isotopologues were derived from a global fit of the measured line positions and microwave and Raman measurements available in the literature. The spectroscopic constants of the a1Δg (v=0, 1) states of 17O2 are reported for the first time.

Research highlights► The very weak a1Δg−X3Σg− bands of 16O17O, 17O18O and 17O2 were studied by CRDS. ► Spectra were recorded at room temperature and 80 K. ► The hyperfine structure due to the 17O nuclear spin was partly resolved. ► The first detection of the a1Δg−X3Σg− (1-1) hot band of 16O17O and 17O2 is reported. ► The best set of constants of the a1Δg state of 16O17O, 17O18O and 17O2 was derived.