Application of highresolution electron energy loss spectroscopy to the adsorption and the photoreaction of CH2I2 and CD3OD on a MoO x thin film ZnCH 3 and CdCH 3 radicals have been prepared in a coLd super.sonic free jet expansion and their laser-induced-fluorescence spectrum recorded for the A 2E<-X 2AI electronic transition. These spectra show well resolved rotational and spin structure, which has been completely analyzed. This !lnalysi~yields the rotational constants and the components of the spin-rotation tensors in the A and X states of both radicals. The observed constants are discussed in terms of the electronic structure of the radicals. It is demonstrated that the upper F2 spin-orbit component of the A 2E state of CdCH 3 is stronglY'perturbed by another, dissociative electronic state. This leads to some predissociation of the A 2E3/2 component and a broadening of its lines. The rotational and fine structure in this state is also quite perturbed leading to an unusual, but still interpretable spectrum.9376

High-resolution electronic excitation spectra of the 0 : and the 9; bands of the near-UV electronic transition of the ethoxy radical have been recorded. The ethoxy radical was produced in a free-jet expansion by photodissociation of ethyl nitrite (CzHsONO). Both spectra have a linewidth of about 400 MHz. A complete rotational analysis of the spectrum indicates that the electronic transition of ethoxy is C-type (perpendicular) and the ground-state spin-rotation splittings are fully resolved, while the excited state spin-rotation splittings are not resolved. The spin-rotational parameters are compared to the corresponding spin-rotational parameters of the closely related radicals, methoxy and vinoxy.

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Magnetic hyperfine interactions in the ground and first excited states of CdH and CdCH3 were studied using high resolution electronic spectroscopy. Hyperfine splittings associated with the H nucleus were observed in the X state of CdH; hyperfine splittings associated with 111Cd and 113Cd were observed in both the ground and first excited states of CdH and CdCH3. The hyperfine parameters of CdH were found to be similar to the corresponding parameters of CdCH3. Comparison of the ground state molecular hyperfine constants with values determined in an Ar matrix electron paramagnetic resonance (EPR) study [L. B. Knight, Jr. and W. Weltner, Jr., J. Chem. Phys. 55, 2061 (1971)] indicates clearly a shift of unpaired electron spin density towards Cd, in the matrix. The excited state molecular hyperfine constants indicate that the unpaired electron essentially resides in a Cd 5pπ orbital.