CrO is an important intermediate in the high temperature oxidation chemistry of chromium containing species. This work reports the first detection of CrO in a flame. The B5π-X5π electronic transition was probed by cavity ringdown spectroscopy (CRDS) in a lean (φ = 0.38), low-pressure, flat, laminar hydrogen-oxygen-argon flame seeded with Cr(CO)6. The previous B5π - X5π CrO spectrum of Hocking et al. (605.0 nm-606.5 nm) is extended from the band head located at 605.6 nm to 614.4 nm. The temperature profiles of the doped and undoped flames were obtained from measurements of OH laser-induced fluorescence. Seeding the flame with Cr(CO)6 increased the flame temperature by approximately 150 K. The concentration profile of CrO was measured as a function of height above the burner. CrO absorption signals were converted to concentration using the measured temperature profile and absorption cross-section calculated from lifetimes by Hedgecock et al. A lower limit peak CrO concentration of 1.6 ppb was found in the flame. Some uncertainty in the cross-section remains. Comparisons to calculations using STANJAN indicate that CrO is present in flames at super equilibrium concentrations.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physics and Astronomy (miscellaneous)