Two-photon double-resonant excitation of the Xe*5p(5)nf ' (J=2) autoionization states using synchronized laser and synchrotron radiation pulses

The technique of synchronization between the pulses of a linear dye laser, synchronously pumped by a mode-locked Ar+ laser, and the synchrotron radiat ion pulses from the SuperACO storage ring in Orsay (France) has been applie d to study the photoionization of the Xe* 5p(5)5d [3/2](1) and Xe* 5p(5)6d [3/2](1) excited states in the energy region between the Xe+ 5p5(P-2(3/2)) and (P-2(1/2)) thresholds. The experimental spectra are dominated by strong transitions to the Xe* 5p(5)nf' [5/2](2) autoionization resonances, which are characterized by typical asymmetric Fano-type line profiles. The energy positions of the n = 4, 7-13 resonances have been measured. For the 4f' [5 /2](2) and nf' [5/2](2) (n = 7-9) resonances, the asymmetry parameter q and the linewidth Gamma could be determined upon photoexcitation from the inte rmediate state 5d [3/2](1) and 6d [3/2](1), respectively. As a general beha viour of the investigated excitations, the oscillator strengths for d --> f transitions were found to exceed by far those for the, also dipole-allowed , d --> p transitions.