MILLIMETER-WAVE SPECTRA OF CASH AND CASD

The pure rotational spectra of CaSH and CaSD were observed using milli meter-wave absorption spectroscopy, The gas phase free radicals were p roduced in a high-temperature cell by the reaction of Ca vapor with H2 S or D2S in the presence of an electrical discharge. The spectra were analyzed using an S-reduced Hamiltonian. The molecular constants inclu ding the rotational constants, centrifugal distortion constants, and s pin-rotation constants were extracted from the spectra. The off-diagon al spin-rotation term, \epsilon(ab) + epsilon(ba)\/2, is 3.38(12) MHz and 4.59(4) MHz for CaSH and CaSD, respectively. The moment of inertia data of CaSH and CaSD yielded the r(0) structure, The three structura l parameters are Ca-S = 2.564(2) Angstrom, S-H = 1.357(17) Angstrom, a nd angle Ca-S-H = 91.0(18)degrees. (C) 1996 American Institute of Phys ics.