QUANTUM BEAT STUDY OF THE NUCLEAR HYPERFINE-STRUCTURE OF OD AND AR-CENTER-DOT-OD IN THEIR A-(2)SIGMA(+) ELECTRONIC STATES

The nuclear hyperfine structure of OD and Ar . OD in their A (2) Sigma (+) electronic states has been studied by quantum beat spectroscopy. T he very cold transient species were produced in a supersonic expansion using a pulsed discharge nozzle. Coherent excitation of hyperfine (hf ) states, arising from one fine structure (OD) or rotational (Ar . OD) level, created quantum beats on the fluorescence decay. The beat freq uencies, which correspond to energy separations between hf levels, cou ld be measured to +/-75 kHz. The splitting of the hf levels into their Zeeman components was investigated in a weak magnetic field. A fit of the zero field and Zeeman data yielded the relevant constants for the nuclear magnetic and electric quadrupole hyperfine interactions as we ll as the pertinent g-factors in each species. In the case of OD, the hf parameters agree well with those reported previously but are more a ccurately defined. For Ar . OD the previously unknown hyperfine and sp in-rotation parameters of the A (2) Sigma(+) State were determined. A comparison of the hf parameters in the two systems allowed assessment of the effect of van der Waals complex formation on the electron distr ibution. Thus complexation is found to reduce the unpaired electron de nsity on the deuteron by 7% which is indicative of significant chemica l bonding between the Ar atom and the OD moiety in the A (2) Sigma(+) state of Ar . OD. For both systems, the g-factors g(s) and g(l) obtain ed suggest an admixture of other, possibly quartet, electronic states into the A (2) Sigma(+) state. (C) 1996 American Institute of Physics.