DETECTION OF OH-INFRARED LASER MAGNETIC-RESONANCE( IN ITS A (1)DELTA STATE BY FAR)

The spectrum associated with the J = 3 <-- 2 transition of OH+ in the a (1) Delta(v = 0) state has been observed by far infrared laser magne tic resonance spectroscopy. A new microwave discharge source enabled t he detection of this spectrum, which is the first observation of the r otational spectrum of an ion in a metastable state. Assignment and lea st-squares fitting of the observed transitions have determined the fol lowing molecular constants: B-0 = 494.420 388 (22) GHz, the proton hyp erfine parameter a = 74.84 (32) MHz, g(L)' = 1.000 915 (15), and g(r) = -0.001 815 (18), with the 1 sigma uncertainties of the last digits i n parentheses. The relationship of these parameters to the geometric a nd electronic structure of OH+ is discussed.