Elliptical dichroism is known in atomic photoionization as the difference in the photoelectron angular distributions produced in nonlinear ionization of atoms by left- and right-handed elliptically polarized light. We theoretically demonstrate that the maximum dichroism |Δ_{ED}|=1 always appears in two-photon ionization of any atom if the photon energy is tuned in so that the electron emission is dominantly determined by two intermediate resonances. We propose the two-photon ionization of atomic helium in order to demonstrate this remarkable phenomenon. The maximum elliptical dichroism could be used as a sensitive tool for analyzing the polarization state of photon beams produced by free-electron lasers.Elliptical dichroism is known in atomic photoionization as the difference in the photoelectron angular distributions produced in nonlinear ionization of atoms by left- and right-handed elliptically polarized light. We theoretically demonstrate that the maximum dichroism |Δ_{ED}|=1 always appears in two-photon ionization of any atom if the photon energy is tuned in so that the electron emission is dominantly determined by two intermediate resonances. We propose the two-photon ionization of atomic helium in order to demonstrate this remarkable phenomenon. The maximum elliptical dichroism could be used as a sensitive tool for analyzing the polarization state of photon beams produced by free-electron lasers.

arXiv:1808.01860Physical Review LettersJul 30, 201830 citations

One- and two-photon ionization of model atoms

Giovanni P. Arrighini, Carla Guidotti, N. Durante

Il Nuovo Cimento DApr 1, 198610 citations

Integrated cross sections and polarization of photoelectrons in two-photon ionization of alkali metal atoms using two optical beams

R. Parzyński

General equations are proposed for the integrated cross section and degree of spin polarization of photoelectrons emitted by ground-state alkali metal atoms in two-photon ionization by two different optical beams. The equations, which are derived in the fine-structure approximation, are valid for polarized and unpolarized atoms, parallel experimental geometries, completely polarized (elliptically, circularly, and linearly polarized) and completely unpolarized optical beams, and also near resonance with an nP intermediate doublet level.General equations are proposed for the integrated cross section and degree of spin polarization of photoelectrons emitted by ground-state alkali metal atoms in two-photon ionization by two different optical beams. The equations, which are derived in the fine-structure approximation, are valid for polarized and unpolarized atoms, parallel experimental geometries, completely polarized (elliptically, circularly, and linearly polarized) and completely unpolarized optical beams, and also near resonance with an nP intermediate doublet level.

Soviet Journal of Quantum ElectronicsOct 31, 19800 citations

Two-photon above-threshold ionization of atoms

Nikolai L. Manakov, S. I. Marmo, S. A. Sviridov

Bulletin of the American Physical SocietyMay 19, 20060 citations

Wave-mixing interference in three-photon resonant atomic excitation with cross-polarized angled beams

Viktor E. Peet

Three-photon excitation and associated wave mixing near the $6s$ and $6{s}^{\ensuremath{'}}$ resonances of xenon have been studied utilizing resonance-enhanced multiphoton ionization in angled beams with different polarizations. It has been shown that a complete cancellation of three-photon resonant atomic excitation caused by the well-known destructive wave-mixing interference occurs in $s$ and $p$ polarization of angled beams but distinct resonance ionization enhancement is observed when pump beams have orthogonal polarization planes. Pressure-induced evolution of the resonance ionization peak in cross-polarized beams is identical to that observed with counterpropagating beams. The reason for such resonance ionization enhancement is unknown and cannot be explained within the frame work of existing theory. The effect may result from some peculiarities of wave-mixing interference in a multilevel atomic system, where different degenerate magnetic sublevels of the upper atomic state and multiple interfering excitation processes are involved. Another possibility is that the resonance ionization enhancement results from a process where weak counterpropagating light is generated within the excitation region of cross-polarized angled beams.Three-photon excitation and associated wave mixing near the $6s$ and $6{s}^{\ensuremath{'}}$ resonances of xenon have been studied utilizing resonance-enhanced multiphoton ionization in angled beams with different polarizations. It has been shown that a complete cancellation of three-photon resonant atomic excitation caused by the well-known destructive wave-mixing interference occurs in $s$ and $p$ polarization of angled beams but distinct resonance ionization enhancement is observed when pump beams have orthogonal polarization planes. Pressure-induced evolution of the resonance ionization peak in cross-polarized beams is identical to that observed with counterpropagating beams. The reason for such resonance ionization enhancement is unknown and cannot be explained within the frame work of existing theory. The effect may result from some peculiarities of wave-mixing interference in a multilevel atomic system, where different degenerate magnetic sublevels of the upper atomic state and multiple interfering excitation processes are involved. Another possibility is that the resonance ionization enhancement results from a process where weak counterpropagating light is generated within the excitation region of cross-polarized angled beams.

Physical Review ASep 15, 20064 citations

Three-photon excitation and associated wave mixing near the

6s

and $6{s}^{\ensuremath{'}}$ resonances of xenon have been studied utilizing resonance-enhanced multiphoton ionization in angled beams with different polarizations. It has been shown that a complete cancellation of three-photon resonant atomic excitation caused by the well-known destructive wave-mixing interference occurs in

s

and

p

polarization of angled beams but distinct resonance ionization enhancement is observed when pump beams have orthogonal polarization planes. Pressure-induced evolution of the resonance ionization peak in cross-polarized beams is identical to that observed with counterpropagating beams. The reason for such resonance ionization enhancement is unknown and cannot be explained within the frame work of existing theory. The effect may result from some peculiarities of wave-mixing interference in a multilevel atomic system, where different degenerate magnetic sublevels of the upper atomic state and multiple interfering excitation processes are involved. Another possibility is that the resonance ionization enhancement results from a process where weak counterpropagating light is generated within the excitation region of cross-polarized angled beams.