Optical-Optical Double Resonance Spectroscopy of SrF: Analysis of the High-Lying F²Σ⁺ - and G²Π States

The F2Σ+−B2Σ+ and G2Π+−B2Σ+ systems of strontium monofluoride were investigated by optical-optical double resonance spectroscopy using two single-mode dye lasers in the rhodamine 6G region. The first laser populated a selected rotational level of the B2Σ+ state, which had been measured previously in our laboratory by Doppler-free polarization spectroscopy1). The second laser was scanned and the undispersed UV-fluorescence of the F2Σ+−X2Σ+ or G2Π+−X2Σ+ transition was detected. Energy transfer by collisions gives rise to additional lines. The intensity of these lines decreases rapidly with increasing |ΔJ| of rotational energy transfer. About 400 lines of the F2Σ+−B2Σ+(1,0),(2,0),(3,0), band and the G2Π−B2Σ+(0,0) band up to J=36.5 were measured and assigned. Molecular constants were derived by using a simultaneous fit of the X, B and F or G state including the known B2Σ+−X2Σ+ line positions for minimizing the correlation between these constatns.