ELECTRIC-DIPOLE-QUADRUPOLE INTERFERENCE OF OVERLAPPING AUTOIONIZING LEVELS IN PHOTOELECTRON ENERGY-SPECTRA

We have measured the photon energy dependence of electric-dipole-quadr upole interference in cadmium between the odd parity 4d(9)5s(2)5p J = 1 and even parity 5p6p P-3(2) autoionizing levels. The resonant interf erence structure is isolated by taking the difference between constant ionic state spectra at 45 degrees with respect to the photon beam in the forward and backward directions. We find interference effects that are approximately 0.5% of the dipole cross section for photon energie s of 13 eV, in good agreement with theory. We compare the results with those from (e,2e) experiments. [S0031-9007(98)06548-X].