Resonant structure in doubly charged ion formation during multiphoton ionization of Sr and Ba atoms by infrared laser radiation

Abstract

Experimental investigations of resonant structure in doubly charged ion (A 2+ ) formation were carried out during Sr and Ba atom ionization by infrared laser radiation (ω = 8400-9100 cm −1 ). It has been shown that in this case the mechanism of ion formation is a two-electron process-the ions are produced immediately from the neutral atoms. It has been found for the first time that the resonant structure in A 2+ ion formation in such conditions is due to the excitation and ionization of neutral-atom mixed states. The atomic-state mixing in this case results from the Stark effect provided that the polarizability of these states is very high.

Multiphoton-double-ionization probability linearly depends on laser intensity: Experimental studies of barium

“…Figure 1 reveals a resonant structure in Ba + and Ba 2+ yields. This result qualitatively coincides with our previous results [23,24] in the same spectral region but with different intensities. An analysis shows that the resonant maximum in Ba + yield, displayed in Fig.…”

“…Figure 1 reveals a resonant structure in Ba + and Ba 2+ yields. This result qualitatively coincides with our previous results [23,24] in the same spectral region but with different intensities. An analysis shows that the resonant maximum in Ba + yield, displayed in Figure 1, is due to five-photon ionization of Ba atoms through the four-photon resonance with state 6p 2 1 D 2 substantially perturbed by the ac Stark effect.…”

THE MECHANISM OF DOUBLY CHARGED IONS FORMATION UPON MULTIPHOTON IONIZATION OF BARIUM ATOMS BY LASER RADIATION OF 16800-18700 сm_-1 SPECTRAL RANGE

“…Попередні наші дослідження показали, що в результаті нелінійної іонізації атомів стронцію [3][4][5][6][7] і барію [8][9][10][11] в інфрачервоній області спектра (ω≈8200-9500 см -1 ), реалізується двоелектронний механізм утворення двозарядних іонів, тобто відбувається одночасний відрив двох зовнішніх s-електронів від цих атомів.…”

Nonsequential double ionization below laser-intensity threshold: Anticorrelation of electrons without excitation of parent ion

“…Originally, NSDI has been discovered experimentally for alkaline-earth atoms [3] (regarding further experimental investigations of NSDI for alkaline-earth atoms, see, e.g., Refs. [4][5][6][7][8][9] and references therein). Later, NSDI has been found in nobel gas atoms [10,11].…”