A SPECTROSCOPIC STUDY OF CAOCH3 USING THE PUMP PROBE MICROWAVE AND THE MOLECULAR-BEAM OPTICAL STARK TECHNIQUES/

The Stark effect on the R-q(22)(0,0.5) (nu=17 682.9251 cm(-1)) and P-q (11)(0,1.5) (nu = 17 682.1966 cm(-1)) branch features of the (0,0) B ( 2)A(1)-X (2)A(1) band system of calcium methoxide, CaOCH3, was measure d and analyzed to give the magnitude of the permanent electronic dipol e moments, \mu\, of 1.58(8) D and 1.21(5) D for the X (2)A(1) and B (2 )A(1) states, respectively. The dipole moments are compared with other monovalent calcium compounds and those predicted from a simple electr ostatic model. Pure rotational transitions in the X (2)A(1) state were recorded using the pump/probe microwave-optical double resonance tech nique. The proton magnetic hyperfine splitting pattern confirms a C-3v symmetry of the ground electronic state. The determined Fermi contact and dipolar parameters are: a(F)=-0.421(27) MHz; T-aa=1.070(45) MHz, and \T-bb - T-cc\=0.292(47) MHz. The latter parameter is associated wi th the lifting of the K-degeneracy of this symmetric top molecule and mixing the I-0=1/2 and I-0=3/2 levels. (C) 1998 American Institute of Physics. [S0021-9606(98)01737-1].