Eur. Phys. J. D 13, 165-180 (2001)
https://doi.org/10.1007/s100530170263

Experimental and theoretical analysis of the 5pnpJ=0^e, 1^e, 2^e autoionizing spectrum of Sr

¹ Institute of Accelerating Systems and Applications, P.O. Box 17214, 10024 Athens, Greece
² Laboratoire Aimé Cotton, CNRS II, bâtiment 505, 91405 Orsay Cedex, France
³ Atomic and Molecular Physics Laboratory, Physics Department, University of Ioannina, 45110 Ioannina, Greece
⁴ Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vasileos Constantinou avenue, 11635 Athens, Greece

Corresponding author: ^a abolovin@cc.uoi.gr

Received: 31 May 2000
Published online: 15 February 2001

Abstract

The even parity 5 p n p J=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 . The final ICE transition probes the resonances. However, the series below the threshold were excited also due to their mixing with the perturbers. An extended energy region was covered below and above the 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 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.