Resonant widths, line intensities and lineshapes for MQDT models with two or more open channels |
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Authors: | S Cohen |
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Institution: | (1) Institute of Accelerating Systems and Applications, P.O. Box 17214, 10024 Athens, Greece, GR |
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Abstract: | Approximate analytical formulae describing the energy variation of line intensities, autoionization widths and lineshape asymmetries,
are derived for a Phase-Shifted Multichannel Quantum Defect Theory model composed of two closed interacting channels coupled
to two effective continua. This is accomplished by putting the two compatibility equation solutions, for the common phase
shifts of the two open channels, in such a form so the resonant behavior is attributed to one of them, the other accounting
for an energy dependent background. Then, the well-known procedures for the simpler case where only one continuum is considered
are applied, using only the resonant solution. The method is quite general and applicable to any MQDT model with two or more
open channels. The resulting analytical formulae are tested on experimental spectra of Sr, Ba and Cu and it is shown that
they are valid as long as: i) The resonances are non-overlapping, ii) The direct closed channel coupling is much stronger
than the indirect one through the continua and (when excitation matrix elements are involved) iii) The open channels excitation
strength is smaller or at least comparable to the closed channels one.
Received: 26 May 1998 / Accepted: 1st July 1998 |
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Keywords: | PACS 32 80 Dz Autoionization - 32 80 Rm Multiphoton ionization and excitation to highly excited states (e g Rydberg states) - 32 80 Fb Photoionization of atoms and ions |
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