Rotationally resolved laser-excited fluorescence spectrum

Next, some of the Si-Sq vibronic bands have been studied by us with rotationally resolved laser-induced fluorescence experiments, with the goal of providing a more precise determination of the BDO Si-state equilibrium structure and its deformation in the first vibrational excited levels. In this study, based on analysis of the rotational structure of the different vibronic bands, some problems with the vibrational assignment of the vibronic spectrum became immediately clear [18]. In fact, on the basis of previous studies some of the bands under investigation should have a level in common, either in the So or in the 5i state, but the experimentally determined rotational constants for those states were not equal within the experimental error. 

The fluorescence of the IF product molecules originating from the 6 11(0)+ -> band system was observed in the wavelength range 470-675 nm. The relative product vibrational population densities were determined from the measured fluorescence intensities of the individual bands, the relative laser intensities and the transition probabilities, as described in Ref. 12. At slow scanning speed the resolved rotational structure in the IF excitation spectrum was obtained, except in the vicinity of the band heads. It was analysed according to the procedure described below. 

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