Two-, three-, and four-photon ionization of Mg in the circularly and linearly polarized laser fields: Comparative study using the Hartree–Fock and model potentials

Buică, Gabriela; Nakajima, Takashi

doi:10.1016/j.jqsrt.2007.05.004

Cited by 11 publications

(7 citation statements)

References 29 publications

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“…The background (non-resonant) ionization increases at both ends of the examined range and forms a 'valley' in between these two ends. With the help of figure 1 and by a comparison with the perturbatively calculated partial and total four-photon ionization cross sections of [16] (see figures 4 and 6 therein) and [23] (figures 3 and 7 therein) we may safely conclude that the 'valley' is formed by the blue and red spectral tails of the three-photon excited 3s4p 1 P 1 and 3s5p 1 P 1 levels, respectively. Judging from the 1 G 4 partial four-photon ionization cross section, the red tail of the 3s4f 1 F 3 level could also contribute to the increasing signal at ∼565 nm.…”

Section: Wavelength Dependence Of the Mg + Yieldmentioning

confidence: 76%

“…Nevertheless, in an attempt to gain some insight into the behaviour of this resonance, we currently extended the calculation to higher excitation energy by using wavelengthindependent Rabi frequencies and ionization widths (the bluest values given in [8]). The wavelength variation of perturbatively computed partial four-photon cross sections [16,23] implies that our fixed values may be somewhat overestimated around the middle of the range of current interest. Therefore, the computation may merely lead to qualitative conclusions and its outcome is not shown here.…”

Section: Energy Level Diagram and Excitation Schemementioning

confidence: 93%

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Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium

Dimitriou

Cohen

Lyras

et al. 2012

J. Phys. B: At. Mol. Opt. Phys.

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We investigate the interaction of ground-state Mg atoms with tuneable laser radiation of ∼5 ns duration and moderate intensity ( 10 12 W cm −2 ), capable of exciting the 3p 2 1 S 0 autoionizing state by four photons. For the corresponding photon energy range, this level is strongly one-photon coupled both with bound (third photon) and, primarily, a multitude of other autoionizing states (fifth photon). The coupling is strong enough to induce the absorption of up to six photons before the atom is ionized, creating thus population into the first excited 3p j Mg + levels which subsequently decay radiatively to the 3s 1/2 ionic ground state. The earlier studies devoted to this excitation scheme were thorough but partial. Particularly, the issues concerning the five-photon excited levels were not addressed. In this work, the examined wavelength range is greatly extended to include these states. Moreover, the interaction is characterized in more detail by employing an array of experimental techniques, namely Mg + ion and photoelectron spectroscopy (including photoelectron angular distributions (PADs) from four-and five-photon ionization) as well as fluorescence spectroscopy where the 3p j →3s 1/2 decay is monitored. The experimental data show that most of these five-photon excited levels undergo blue ac Stark shifts which are occasionally nonlinear with respect to the laser intensity and comparable to or even larger in magnitude than the large redshift of the 3p 2 1 S 0 state itself. Finally, for the latter state, the wavelength dependence of four-photon PAD measurements is suggestive of a situation reminiscent of an ac Stark splitting picture.

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Section: Wavelength Dependence Of the Mg + Yieldmentioning

confidence: 76%

Section: Energy Level Diagram and Excitation Schemementioning

confidence: 93%

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium

Dimitriou

Cohen

Lyras

et al. 2012

J. Phys. B: At. Mol. Opt. Phys.

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“…Since the general computational procedure has already been presented in Refs. [5,16,[19][20][21] and the specific details about the atomic structure calculation of…”

Section: Atomic Basis Statesmentioning

confidence: 99%

“…The aim of this work is to extend our previous investigations for MPI of Mg [4,5,15,16] to the Ca atom: In this paper we study the MPI processes of Ca by the second (photon energy 3.1 eV) and third (photon energy 4.65 eV) harmonics of Ti:sapphire laser pulses.…”

Section: Introductionmentioning

confidence: 99%

Multiphoton ionization of the calcium atom by linearly and circularly polarized laser fields

Buică

Nakajima

2010

Phys. Rev. A

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We theoretically study multiphoton ionization of the Ca atom irradiated by the second (photon energy 3.1 eV) and third (photon energy 4.65 eV) harmonics of Ti:sapphire laser pulses (photon energy 1.55 eV). Because of the dense energy level structure the second and third harmonics of a Ti:sapphire laser are nearly single-photon resonant with the 4s4p 1 P o and 4s5p 1 P o states, respectively. Although two-photon ionization takes place through the near-resonant intermediate states with the same symmetry in both cases, it turns out that there are significant differences between them. The photoelectron energy spectra exhibit the absence/presence of substructures.More interestingly, the photoelectron angular distributions clearly show that the main contribution to the ionization processes by the third harmonic arises from the far off-resonant 4s4p 1 P o state rather than the near-resonant 4s5p 1 P o state. These findings can be attributed to the fact that the dipole moment for the 4s 2 1 S e -4s5p 1 P o transition is much smaller than that for the 4s 2 1 S e -4s4p 1 P o transition.

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“…In that work, they also argued that the ratio of total multiphoton ionization cross sections for circular versus linear polarization increases rapidly with the order of the process. However, later theoretical studies [2][3][4] showed that, the multi-photon ionization by linearly polarized light beams dominates in the higher order interaction regime. These theoretical findings were confirmed experimentally for both low [5,6] and high [7] order ionization processes.…”

mentioning

confidence: 99%

Polarization effects in the total rate of biharmonic $ω+ 3ω$ ionization of atoms

Hofbrucker,

Ramakrishna,

Volotka

et al. 2022

Preprint

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Total ionization rate of biharmonic (ω + 3ω) ionization are studied within the independent particle approximation and third order perturbation theory. Particular attention is payed to how the polarization affects the total rate. The ratio of the biharmonic ionization is analyzed for linearly and circularly polarized beams as well as for co-and counterrotating elliptically polarized beams are analyzed and their dependence on beam parameters, such as the photon frequency or the phase between the ω and 3ω light beams, is explained. We show that the interference of the biharmonic ionization amplitudes determines the dominance of a particular beam polarization over another and that it can be controlled by an appropriate choice of beam parameters. We demonstrate our findings for the ionization of neon L shell electrons.

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Two-, three-, and four-photon ionization of Mg in the circularly and linearly polarized laser fields: Comparative study using the Hartree–Fock and model potentials

Cited by 11 publications

References 29 publications

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium

Multiphoton ionization of the calcium atom by linearly and circularly polarized laser fields

Polarization effects in the total rate of biharmonic $ω+ 3ω$ ionization of atoms

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Two-, three-, and four-photon ionization of Mg in the circularly and linearly polarized laser fields: Comparative study using the Hartree–Fock and model potentials

Cited by 11 publications

References 29 publications

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p2 1S0state of magnesium

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p2 1S0state of magnesium

Multiphoton ionization of the calcium atom by linearly and circularly polarized laser fields

Polarization effects in the total rate of biharmonic $ω+ 3ω$ ionization of atoms

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Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium

Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p^{2 1}S₀state of magnesium