ASSIGNMENT AND FREQUENCY-MEASUREMENT OF ROTATIONAL TRANSITIONS OF (CD3OH)-C-13 BY INTRACAVITY LASER STARK SPECTROSCOPY

We present the results of an intracavity Stark spectroscopy experiment on the fundamental state of (CD3OH)-C-13. We use an optically pumped hybrid waveguide FIR laser, CH2F2 as active molecule, and (CD3OH)-C-13 as absorbent molecule. No Brewster window is needed to separate the l asing gas from the absorbing deuterated methanol. An absorption line i s assigned as E(l) symmetry (n, K, J): (1,4,18) --> (1,5,18) and its f requency is measured as 63.08631 cm(-1) with a precision of a few part s in 10(7); two more absorptions are reported and a tentative assignme nt for one of them.