Three-photon excitation of autoionizing states between the ${}_{}{}^2{}_{}{}^{}$${\mathit{P}}_{3/2}$ and ${}_{}{}^2{}_{}{}^{}$${\mathit{P}}_{1/2}$ ionic limits of atomic argon, krypton, and xenon has been investigated using multiphoton ionization in combination with supersonic expansion techniques. As the result of the high signal-to-noise ratios and energy resolution achieved in these experiments, we have been able to study autoionizing states in argon with multiphoton excitation, and have considerably augmented the knowledge of the autoionizing states of krypton and xenon. All atoms show (in ${\mathit{j}}_{\mathit{c}}$l coupling notation) the odd ns’[1/2${]}_1$, nd’[3/2${]}_1$, and ng’[7/2${]}_3$ autoionizing series, while the nd’[5/2${]}_3$ series can only be observed in xenon. The analysis of the line profile of the autoionizing resonances has enabled a detailed comparison of the present results with those obtained with other experimental techniques and predictions by theoretical studies.

• Received 29 November 1993

DOI:https://doi.org/10.1103/PhysRevA.49.3322