OBSERVATION OF CD 4D(9)5S(2)5P J=3 AUTOIONIZING LEVELS IN (E,2E) ENERGY-SPECTRA

Cadmium (e,2e) energy spectra have been measured for kinematics corres ponding to a momentum transfer of 1 a.u. Two previously unknown cadmiu m autoinizing levels have been observed. Their energies are in excelle nt agreement with existing ab initio structure calculations of the 4d( 9)5s(2)5p J=3 levels. One level is easily seen at an ejected-electron direction along the momentum-transfer axis, but is absent for a direct ion 39 degrees away from this axis. The opposite is true for the other level; it is absent in the former, but present in the latter case. Th is behavior is in agreement with a calculation that takes into account that the J=3 levels can autoionize into both singlet and triplet 5sEf continua. The intensity of the new levels, relative to the well-known 4d(9)5s(2)5p J=1 levels, agrees well with a plane-wave Born approxima tion calculation for the J=3 levels. The third 4d(9)5s(2)5p J=3 level is calculated to lie within the broad 4d(9)5s(2)5p P-1(1) level and ca nnot be seen in the present experiments.