Two-photon dissociation of diatomic molecules

Bunkin, F. V.; Tugov, I. I.

doi:10.1016/0375-9601(70)90079-4

Cited by 20 publications

(23 citation statements)

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“…Many previous theoretical studies of pair production [5,9,10,11,12] have been motivated by the seminal work of Keldysh [13] on atomic ionization in time-dependent electric fields; in particular the crossover between the two main mechanisms of pair creation due to strong constant electric fields and due to those with spatial or temporal variations has been of interest. It turns out that spatial variations tend to diminish the pair creation rate [10,12] whereas a time-dependence typically increases the effect [11,14].…”

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“…The basic idea is similar in spirit to ideas in the study of atomic physics in strong fields, where new experimental and theoretical results show that controlled engineering of special electric field pulse shapes can enhance certain interesting physical processes, such as high-harmonic generation and above threshold ionization (for reviews see [8]). Many previous theoretical studies of pair production [5,9,10,11,12] have been motivated by the seminal work of Keldysh [13] on atomic ionization in time-dependent electric fields; in particular the crossover between the two main mechanisms of pair creation due to strong constant electric fields and due to those with spatial or temporal variations has been of interest. It turns out that spatial variations tend to diminish the pair creation rate [10,12] whereas a time-dependence typically increases the effect [11,14].…”

mentioning

confidence: 99%

“…Consequently, we obtain (for γ ≥ π/2) (6), computed using the wordline instanton method, and plotted as a function of the combined Keldysh parameter γ defined in (9). The upper [red] dots correspond to ω = 100Ω and E = 100ε, while the lower [blue] dots correspond to ω = 10Ω and E = 10ε.…”

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Dynamically Assisted Schwinger Mechanism

2008

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We study electron-positron pair creation from the Dirac vacuum induced by a strong and slowly varying electric field (Schwinger effect) which is superimposed by a weak and rapidly changing electromagnetic field (dynamical pair creation). In the sub-critical regime where both mechanisms separately are strongly suppressed, their combined impact yields a pair creation rate which is dramatically enhanced. Intuitively speaking, the strong electric field lowers the threshold for dynamical particle creation -or, alternatively, the fast electromagnetic field generates additional seeds for the Schwinger mechanism. These findings could be relevant for planned ultra-high intensity lasers.PACS numbers: 12.20. Ds, 11.15.Tk, 11.27.+d. As first realized by Dirac [1], a consistent relativistic quantum description of electrons necessarily involves negative energy levels, which -in the Dirac-sea pictureare filled up in the vacuum state. This entails the striking possibility of pulling an electron out of the vacuum by means of some external influence, such as a (classical) electromagnetic field [2], where the remaining hole in the Dirac sea is then associated with a positron. Of course, to create such an electron-positron pair out of the vacuum, one has to overcome the energy gap of 2mc 2 between the filled and the empty levels. There are basically two main mechanisms for doing so: In a strong electric field E over a sufficiently long distance L, "virtual" electron-positron pair fluctuations may gain this energy when qEL ≥ 2mc2 . This pair creation process is called the Schwinger mechanism [3,4] and can be understood as tunneling through the classically forbidden region (energy gap). Thus it is suppressed exponentially O(exp{−πE S /E}) for weak fields E, where E S = m 2 c 3 /( q) is the Schwinger critical field. For E ≃ E S , the work done by separating the electron-positron pair over a Compton wavelength is of the order of the energy gap 2mc2 . Alternatively, a classical time-dependent electromagnetic field will also create electron-positron pairs in general (dynamical pair creation). However, if the frequency ω of the external field is not large enough, ω < 2mc 2 , these non-adiabatic corrections correspond to higher-order (i.e., multi-photon) processes and are also suppressed exponentially exp{− O(1/ω)} for small ω [5]. These pair-production processes are fundamental predictions of quantum electrodynamics (QED), but only the multi-photon production process has so far been observed experimentally: the positron data taken at the SLAC E-144 experiment have convincingly been explained by nphoton production with n ≃ 5 [6]. However, a verification of the Schwinger mechanism has still remained an experimental challenge [7]. Since the Schwinger mechanism is non-perturbative in the field, its discovery would help exploring the non-perturbative realm of quantum field theory in a controlled fashion. Here, we propose a new mechanism which can help to overcome the strong exponential suppression. The basic idea is similar in spirit to ide...

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Dynamically Assisted Schwinger Mechanism

2008

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“…indicating that the pair-production rate receives an enhancement (π|B|/|E|) coth(π|B|/|E|) to the prefactor, compared with the rate in the absence of magnetic fields [19,20] (see also [1,2]). It is worthwhile to study the phenomenon of plasma oscillations by numerically integrating Eqs.…”

Section: Plasma Oscillationmentioning

confidence: 99%

Electromagnetic and gravitational radiation from the coherent oscillation of electron-positron pairs and fields

Han¹,

Xue²

2014

Phys. Rev. D

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Integrating equations of particle-number and energy-momentum conservation and Maxwell field equations, we study the oscillation and drift of electron and positron pairs coherently with fields after these pairs are produced in external electromagnetic fields. From the electric current of oscillating pairs, we obtain the energy spectrum of electromagnetic dipole radiation. This narrow spectrum is so peculiar that the detection of such radiation can identify pair production and oscillation in strong laser fields. We also obtain the energy spectrum of gravitational quadrapole radiation from the energy-momentum tensor of oscillating pairs and fields. Thus, we discuss the generation of gravitational waves on the basis of rapid development of strong laser fields.

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“…and at the 2nd US-Japan Seminar on Laser Interaction with Matter, University of Rochester, N. Y., November 2-5, 1976; to be published in part in "Optical and Quantum Electronics"(London 1977). (6) for the linearly polarized case (7) and (8) in weakly relativistic electron movements"; hereby w is the plasma frequency as determined by:…”

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Kinetic Energy of Laser Accelerated Charged Particles in a Plasmaand the Possibility of Pair Production

Schwarz

Tabensky

1977

The Review of Laser Engineering

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An exact solution of the general equation of notion of charged particles in a medium of refractive index n subjected to irradiation of electromagnetic waves at any intensity and frequency is .given. No approximations are necessary even for the relativistic case. Linearly polarized as well as circularly poarized waves are considered. Self-induced fields due to the generated charged particle currents have very little influence on the solutions, especially at higher intensities, where electron-positron pair production can be expected.

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Two-photon dissociation of diatomic molecules

Cited by 20 publications

References 1 publication

Dynamically Assisted Schwinger Mechanism

Dynamically Assisted Schwinger Mechanism

Electromagnetic and gravitational radiation from the coherent oscillation of electron-positron pairs and fields

Kinetic Energy of Laser Accelerated Charged Particles in a Plasmaand the Possibility of Pair Production

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