NUCLEAR-QUADRUPOLE INTERACTION AT W-187(BETA(-))RE-187 IN TUNGSTEN COMPOUNDS

The nuclear quadrupole interaction at W-187(beta(-))Re-187 was determi ned by time differential perturbed angular correlation in WC, WS2, WSe 2, WSi2, and CaWO4 to be (at 300 K): nu(Q) = 335.9(2), 1094.9(1), 1031 .6(1), 1131.5(1), and 1085.9(1) MHz, respectively. The asymmetry param eter eta was zero in all cases. For WSe2 and CaWO4 the temperature dep endence of the nuclear quadrupole interaction was determined between 3 00 K and about 900 K. Ab initio calculations of electric field gradien ts, using the WIEN95-code, were carried out for WC, WS2, WSe2, and WSi 2 at W-sites and Re-impurities, and for CaWO4 at W-sites. Good agreeme nt with experimental data was found.