Single and double ionization of strontium in the vicinity of four-photon excitation of the 5p(2) (1)S(0) doubly excited state
Φόρτωση...
Ημερομηνία
Συγγραφείς
Liontos, I.
Cohen, S.
Bolovinos, A.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Journal of Physics B-Atomic Molecular and Optical Physics
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Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
We report on the single and double multiphoton ionization of ground state Sr atoms observed in an atomic beam experiment with laser pulses of similar to 5 ns duration, maximum intensity similar to 4 x 10(11) W cm(-2) and within the 710-740 nm wavelength range. The Sr(+) spectrum consists of two strong lines originating from three-photon resonant four-photon ionization of bound states, a number of weak autoionizing resonances and a broad line due to four-photon excitation of the doubly excited 5p(2) (1)S(0) state. The latter, along with a strong, broad and structured spectral feature, is also evident in the wavelength dependence of the doubly charged Sr(2+) ion. A weakly evident but reproducible inflection point ('knee' structure) appears in the intensity dependence of the Sr(2+) yield at the location of the 5p2 1S0 resonance. A complementary fluorescence experiment revealed the accumulation of population in the 5p(1/2,3/2), 6s(1/2) and 5d(3/2,5/2) excited Sr(+) states during the laser pulse. All fluorescence signals depend on laser wavelength in a manner similar to the recorded Sr(+) spectrum. The population accumulation in the 5p(1/2,3/2) ionic states unambiguously proves the absorption of two photons above the first 5s(1/2) atomic threshold while that of the 5d(3/2),(5/2) and 6s(1/2) ones suggest the absorption of at least two more. Since under our laser pulse duration and intensity the absorption of such a number of photons in an unstructured continuum is highly improbable, it may be concluded that the process is mediated by dense manifolds of near-resonant doubly excited states, their role in the dynamics of laser - atom interaction under our conditions being far more crucial than in studies conducted using intense ultrashort pulses.
Περιγραφή
Λέξεις-κλειδιά
multiphoton double ionization, laser optogalvanic spectroscopy, above-threshold ionization, multi-photon ionization, autoionizing states, even-parity, theoretical-analysis, picosecond pulses, charged ions, ba atoms
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000253547600025
http://iopscience.iop.org/0953-4075/41/4/045601/pdf/0953-4075_41_4_045601.pdf
http://iopscience.iop.org/0953-4075/41/4/045601/pdf/0953-4075_41_4_045601.pdf
Γλώσσα
en
Εκδίδον τμήμα/τομέας
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Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών και Τεχνολογιών. Τμήμα Βιολογικών Εφαρμογών και Τεχνολογιών