Optical-Optical Double Resonance Spectroscopy of the C2Π-A2Π and D2Σ+-A2Π Transitions of SrF

Optical-optical double resonance spectroscopy has been used to record rotationally resolved spectra of the C-2 Pi-A(2)Pi and D-2 Sigma(+)-A(2)Pi transitions of SrF. In the investigation, the spectrum of a previously unobserved (2)Sigma(+)-A(2)Pi transition was recorded. The new (2)Sigma(+) state was found to lie lower in energy than the previously labeled D-2 Sigma(+) (nu = 0) state by an amount equal to the vibrational spacing of the D-2 Sigma(+) state. Therefore, the new (2)Sigma(+) state was assigned as the nu = 0 level of the D-2 Sigma(+) state and the previous labeling of the vibrational quantum numbers of the D-2 Sigma(+) state should be increased by 1. Spectroscopic parameters were determined for the C-2 Pi, D-2 Sigma(+) (nu = 0), and D-2 Sigma(+) (nu = 1) states. The D-2 Sigma(+) (nu = 0) state was found to be perturbed, most likely by the spin-orbit components of the C-2 Pi (nu = 1) state. The spin-orbit constant of the C-2 Pi state was found to decrease significantly relative to the A(2)Pi state, similar to CaF and SrOH. Finally, the C-2 Pi and D-2 Sigma(+) states do not appear to form a unique perturber/pure precession pair of states.