Multiphoton ionization of Ba atoms in two fields of laser radiation

І. І. Бондар

В.В. Лиханский

І. І. Бондар, В. В. Суран

The experimental investigation of the formation of doubly charged ions by the multiphoton ionization of Ba atoms by simultaneous irradiation with the fundamental radiation of a colour centres laser (ω = 8800–8880 cm −1 ) and its second harmonics was carried out. A two-electron mechanism was observed to be responsible for the formation of these ions; they are formed as a result of the excitation and subsequent ionization of strongly perturbed states of neutral Ba atoms.

Svetlana Kotochigova

A model of multiple resonances between groups of discrete and autoionizing levels is proposed for the description of the process of multiphoton ionization. The phenomena of the extremely rapid broadening and growth of amplitudes of the multiphoton resonances, observed experimentally in the yield of Sr+ and Ba+ ions [ J. Phys. B.14, 2253– 2359 ( 1981);Elementary Processes in Laser Radiation Field ( 1988), pp. 122– 153)] are explained on the basis of this model. The strong-coupling method was used in numerical calculations for Sr and Ba atoms in a strong laser field.

Vladimir V. Likhanskii

І. І. Бондар, В. В. Суран, M. I. Dudich

The new unknown resonances which occur in the case of multiphoton ionization of Ba atoms at simultaneous influence of two laser fields were discovered. The character of the display of these resonances depends on mutual orientation of polarization vectors of these fields.