High-resolution measurements and multichannel quantum defect analysis of the Kr(4p(5)(P-2(1/2))nd ', J=2, 3) autoionizing resonances

Using two-step laser excitation of metastable Kr(4p(5)5s P-3(2,0)) atoms vi a selected Kr(4p(5)5p J = 1, 2) levels, we have recorded the low-lying auto ionizing resonances Kr(P-2(1/2) nd', J = 2, 3) (n = 6, 7) at high resolutio n in two different experiments (atomic beam spectroscopy and optogalvanic s pectroscopy in a discharge). Accurate values for the resonance positions (q uantum defects) and the (reduced) widths have been determined and profile i ndices are reported. For comparison, multichannel quantum defect theory (MQ DT) analyses, using energy-dependent MQDT parameters, have been carried out for the odd Kr(J = 1, 2, 3) levels, yielding good agreement in the quantum defects and partial agreement in the predicted reduced widths for the nd' resonances with the experimental values. Moreover, simplified phase-shifted quantum defect theory analyses of the measured bound odd Kr(J = 2 and 3) R ydberg levels were carried out with the aim of providing improved insight i nto the dominant decay mechanism of the resonances. We also present a summa ry and comparative discussion of the reduced widths for the nd'[K](J) reson ances of all the rare-gas atoms Ne, Ar, Kr and Xe.