Channel coupling between perturbed autoionizing Rydberg series in the presence of an interloper by multichannel quantum defect theory in the systems involving one open and three closed channels

摘要

The Rydberg series perturbed by an interloper is one of the important systems showing complex autoionization spectra due to the overlapping resonance. A method restricted to a single lower-lying series, which separates the interloper's spectra from the autoionizing Rydberg series, was extended to a system involving two lower-lying autoionizing series. Using the extended formulation, the coupling between the two lower-lying autoionizing Rydberg series was found to be negligible in the spectrum obtained by Kalyar et al. The formulation, which can be called a merged one, was found when the channel coupling of the two lower-lying series with the remaining series was limited to equal strength. It allowed the spectrum of a four-channel system to be treated similar to that of a three-channel system. The direct coupling between two lower-lying autoionizing series, which is absent in the systems involving only a single lower-lying one, was limited to the topological role within the merged framework. However, a conspicuous phenomenon was observed at the avoided crossing point of two series. An analysis of an interesting phenomenon pertaining to the identical two lower-lying autoionizing series in the four-channel system in relation to the three-channel system was also possible using the merged formulation.