Role of the ponderomotive energy in two-color photodetachment of an ion

Bugacov, Alejandro; Piraux, Bernard; Shakeshaft, Robin

doi:10.1103/physreva.45.3041

Cited by 9 publications

(3 citation statements)

References 18 publications

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“…The only additional work needed for a specific system is to identify all the possible closed classical orbits. We note that an experiment has been done for the photodetachment of negative chlorine ions in a microwave field [28,29], and several theoretical studies have also been reported [29][30][31]. However, all of the previous time-dependent treatments assumed the applied field varied slowly enough that the electron was driven by a constant electric field during each detachment event, which approximately corresponds to the situation in the reported experiment [28,29].…”

Section: Introductionmentioning

confidence: 91%

Closed-orbit theory for photodetachment in a time-dependent electric field

Yang

Robicheaux

2016

Phys. Rev. A

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The standard closed-orbit theory is extended for the photodetachment of negative ions in a timedependent electric field. The time-dependent photodetachment rate is specifically studied in the presence of a single-cycle terahertz pulse, based on exact quantum simulations and semiclassical analysis. We find that the photodetachment rate is unaffected by a weak terahertz field, but oscillates complicatedly when the terahertz pulse gets strong enough. Three types of closed classical orbits are identified for the photoelectron motion in a strong single-cycle terahertz pulse, and their connections with the oscillatory photodetachment rate are established quantitatively by generalizing the standard closed-orbit theory to a time-dependent form. By comparing the negative hydrogen and fluorine ions, both the in-phase and antiphase oscillations can be observed, depending on a simple geometry of the contributed closed classical orbits. On account of its generality, the presented theory provides an intuitive understanding from a time-dependent viewpoint for the photodetachment dynamics driven by an external electric field oscillating at low frequency.

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Section: Introductionmentioning

confidence: 91%

Closed-orbit theory for photodetachment in a time-dependent electric field

Yang

Robicheaux

2016

Phys. Rev. A

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“…In the regime characterized by 6/cuL ))1 it was not possible to make any connection between the threshold shift and the measured cross section [1,2]. The ripples found in the curve showing the cross section as a function of AH were interpreted [1 -3] in terms of interference of the direct photoelectron wave and the wave that rejects from the repulsive barrier formed by the LF field whose characteristic height was evaluated [3] to be 2b" in analogy with the explanation given in Ref. [4], where the photodetachment in the presence of a static electric field was studied.…”

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confidence: 99%

“…are still dominated by the interference processes made evident by Eq. (3), which gives the transition amplitude. By further decreasing ET, a situation may be realized, see Fig.…”

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confidence: 99%

Electron energy distribution in the photodetachment ofH−by two radiation fields

1993

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We report on the energy distribution of the electrons emitted in two-color photodetachment of H in a highly nonlinear regime, and compare these results with the ones found by averaging the cross section obtained in the presence of a static field over the values taken by the low-frequency field in a cycle. Similarities and differences are discussed. PACS number{s): 32.80.RmOver the last few years, multiphoton detachment of negative ions has become a topic of both theoretical and experimenta. investigation. The main reason for carryi'ng out experiments with these systems arises from the short-range nature of the interaction between the atomic core and the outer electron that allows a clearer determination of the continuum threshold as compared to the one measured in analogous experiments where use is made of neutral atoms. This circumstance has stimulated experiments aimed at measuring the detachment threshold shift due to the presence of a strong radiation field. For this purpose experiments of detachment of negative chlorine ions by a weak field of frequency coH in the presence of a strong microwave or infrared field of frequency co'I have been carried out [1]. In these experiments the role of the intense low-frequency field (LF) of amplitude I'L was to provide the ponderomotive shift b =FL l4mcol (with m the electron mass), while the intensity of the higher-frequency field (HF) was so weak that only one HF photon was absorbed in the photodetachment process. Experimental results were obtained in two different physical regimes characterized by the ratio 6/coL, for co~in the region of uv frequencies and col in the range of infrared or microwave frequencies. In the regime characterized by 6/cuL ))1 it was not possible to make any connection between the threshold shift and the measured cross section [1,2]. The ripples found in the curve showing the cross section as a function of AH were interpreted [1 -3] in terms of interference of the direct photoelectron wave and the wave that rejects from the repulsive barrier formed by the LF field whose characteristic height was evaluated [3] to be 2b" in analogy with the explanation given in Ref. [4], where the photodetachment in the presence of a static electric field was studied. Moreover, the poor sensitivity of the photodetachment event to the variation of coL was considered as a manifestation of the quasistaticity of the process. The cross sections were in fact proved to have a behavior quite similar to the ones obtained by averaging the cross sections of photodetachment in a static electric field over the values taken by the LF field in a period [2]. The present paper is aimed at further comparing the photodetachment process of H occurring in the presence of a static field with the one in an oscillating intense field, taking the latter as linearly polarized along the direction of the HF field and where T"(q,XI )= f da f"(a)M(q, KI (a)), (2) f"(a) = exp in a+i A+i sin, a 2~L (3) (q, I g(a))=&e ' IF~rliip(r)) (4) FI q sino, FLcosu Aq =, ICL(a) = COL COL (5)q=qp+qT is the a...

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