Two-photon ionization spectra of calcium above the 4s(1/2) threshold (Journal article)

Cohen, S./ Liontos, I./ Bolovinos, A./ Lyras, A./ Benech, S./ Bachau, H.

Two-photon ionization of ground state calcium is investigated both experimentally and theoretically in the 374 - 323 nm spectral range. The spectra are dominated by the presence of the 4p(2) S-1(0) perturber and by members of even parity 3dnd J = 0, 2 (4 <= n <= 10) and 3dns J = 2 (6 <= n <= 12) autoionizing Rydberg series, the latter appearing as window resonances. No single-photon resonances are observed. The majority of recorded lines are identified using older stepwise spectroscopic data while there is a number of newly discovered low-lying members. The two previously unobserved 3dns, n <= 12, series members are treated using a semi-empirical multichannel quantum defect theory (MQDT) model. Moreover, the low-lying part of the observed predominantly singlet spectrum is fairly well reproduced by theoretical calculations, combining a configuration interaction approach with B-splines basis functions and neglecting relativistic effects. The agreement between theory and experiment becomes less satisfactory as we move towards higher lying resonances dominated by singlet-triplet mixing effects, which are evident in the experimental data while neglected in the calculations.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών
Keywords: quantum-defect theory,laser optogalvanic spectroscopy,eigenchannel r-matrix,autoionizing states,theoretical-analysis,3-photon ionization,single-photon,energy-levels,neutral ca,excitation
ISSN: 0953-4075
Link: <Go to ISI>://000239306700009
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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