Linear and circular dichroism in two-step photoionization of barium atoms

ABSTRACT The line contour of the autoionizing resonance of 6p'Tp configuration in barium atoms was experimentally studied in the range of energies 48000 cm1 to 54000 cm1 with the help of a two-step ionization via intermediate states 6snp('Pi), n = 6,7, 8. Using various combinations of polarization of the first- and second-step laser, both linear and circular dichroism were measured in the process of ionization from an excited state. 1. INTRODUCTION The method of two-step photoionization of atoms, were the first laser excites a discrete atomic state, and thesecond laser is used to ionize the atom from the excited state, is very fruitful, because it allows one to use variouscombinations of pump laser polarizations {1—4]. We report here on the measurements of both linear and circulardichroism near the autoionizing resonance with the momentum J = 1 (the energy of excitation is 52,158 cm1). Based on these measurements, we were able to determine the values of two theoretical parameters, namely, the ratios