Observation of Cd [Formula Presented] [Formula Presented] autoionizing levels in [Formula Presented] energy spectra

Cadmium [Formula Presented] energy spectra have been measured for kinematics corresponding to a momentum transfer of 1 a.u. Two previously unknown cadmium autoinizing levels have been observed. Their energies are in excellent agreement with existing ab initio structure calculations of the [Formula Presented] [Formula Presented] levels. One level is easily seen at an ejected-electron direction along the momentum-transfer axis, but is absent for a direction 39° away from this axis. The opposite is true for the other level; it is absent in the former, but present in the latter case. This behavior is in agreement with a calculation that takes into account that the [Formula Presented] levels can autoionize into both singlet and triplet [Formula Presented] continua. The intensity of the new levels, relative to the well-known [Formula Presented] [Formula Presented] levels, agrees well with a plane-wave Born approximation calculation for the [Formula Presented] levels. The third [Formula Presented] [Formula Presented] level is calculated to lie within the broad [Formula Presented] level and cannot be seen in the present experiments.