Experimental and theoretical analysis of the 5
pnpJ
=0
e
, 1
e
, 2
e
autoionizing spectrum of Sr |
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Authors: | S Cohen M Aymar A Bolovinos M Kompitsas E Luc-Koenig H Mereu P Tsekeris |
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Institution: | (1) Institute of Accelerating Systems and Applications, P.O. Box 17214, 10024 Athens, Greece, GR;(2) Laboratoire Aimé Cotton, CNRS II, batiment 505, 91405 Orsay Cedex, France, FR;(3) Atomic and Molecular Physics Laboratory, Physics Department, University of Ioannina, 45110 Ioannina, Greece, GR;(4) Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vasileos Constantinou avenue, 11635 Athens, Greece, GR |
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Abstract: | The even parity 5
pnpJ
= 0, 1 and 2 doubly excited autoionizing states of strontium were investigated both experimentally and theoretically. Sr atoms
in an atomic beam were excited through the two-step Isolated Core Excitation (ICE) scheme 5s2
1
S
0
-λ
1
→ 5
sn'p
1
P
1
(
n'
= 12-16)-λ
2
→ 5
p
3/2
np
]
J
. The final ICE transition probes the 5
p
3/2
np
]
J
resonances. However, the 5
p
1/2
np
]
J
series below the 5
p
1/2
threshold were excited also due to their mixing with the 5
p
3/2
np
]
J
perturbers. An extended energy region was covered below and above the 5
p
1/2
ionization limit by saturating the central ICE lobe and recording as many as possible “red” and “blue” secondary lobes. J identification was achieved by using mutually parallel and perpendicular linear polarizations of the laser beams. The ICE
spectra were compared to those obtained by employing a two-step excitation scheme using the bound 4
d
5
p
1
P
1
valence state as an intermediate one. Final identification for very complex structures was achieved after comparison with
theoretical energy level positions and excitation profiles produced by the R-matrix method combined with the multichannel quantum defect theory (MQDT) method. The agreement between theoretical and observed
structures is quite satisfactory.
Received 31 May 2000 |
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Keywords: | PACS 32 80 Rm Multiphoton ionization and excitation to highly excited states (e g Rydberg states) – 32 30 Jc Visible and ultraviolet spectra – 32 80 Dz Autoionization |
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