Photodissociation detection of microwave transitions in highly excited vibrational states

This paper describes a new spectroscopic technique which uses photodissocia tion to detect pure rotational transitions in highly excited vibrational en ergy levels of the ground electronic state. This method has initially been applied to the (HOCl)-Cl-35 molecule in its second excited OH stretching vi bration, the (200) state. In addition to observing the microwave signal, th e Stark effect for this transition provides a dipole moment measurement in the (200) vibrational state. The (200) 18(0,18) --> 17(1,17) transition occ urs at 14 858.40(1) MHz and the b component of the dipole moment of this st ate is mu(b) = 1.515(5) D. The technique is quite general in that the rotat ional transition can involve energy levels up to, and exceeding, the dissoc iation threshold of the ground electronic state. (C) 1999 American Institut e of Physics. [S0021-9606(99)00632-7].