LASER-RF DOUBLE-RESONANCE STUDY OF SIO+

We used the laser-rf double resonance method to measure 15 fine structure intervals for rotational quantum numbers ranging from N = 5 to 79 of the nu = 0 level of the X(2) Sigma(+) state of SiO+. We present a molecular model, including perturbations from the A(2)II state, which explains the observed strong variation of fine structure as a function of rotational quantum number. These data yield greatly improved predictions of the microwave spectrum of the ground state of SiO+. In particular we predicted the ground state rotational transition (N = 2, J = 5/2) --> (N = 1, J = 3/2) to be 86 063(1) MHz, confirming that this transition is not the source of the radio line known as U86.2 at 86 243.45(40) MHz.