Atoms in strong optical fields: Evolution from multiphoton to tunnel ionization

Mével, E.; Breger, P.; Trainham, R.; Petite, G.; Agostini, Pierre; Migus, A.; Chambaret, Jean-Paul; Antonetti, A.

doi:10.1103/physrevlett.70.406

Cited by 158 publications

(93 citation statements)

References 9 publications

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“…As the response of the system to the field is approaching the tunneling regime, ATI peaks broaden and eventually overlap with each other. 60 In the case of molecules, in addition to electronic motion, nuclear motion must be considered. In the MPI regime ( > 1) up to 10 10 W cm À2 , as the intensity becomes higher and the pulse duration becomes longer, the ionization process changes from soft ionization (where only parent ions appear) to hard fragmentation (small fragments are produced).…”

Section: Multiphoton Ionization and Tunnel Ionizationmentioning

confidence: 99%

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

Kono

Satô

Kanno

et al. 2006

Bulletin of the Chemical Society of Japan

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We have developed a method for describing the reaction dynamics of a polyatomic molecule in intense laser fields. First, the dynamical behavior of H 2 þ and H 2 in near-infrared, intense laser fields (I > 10 13 W cm À2 and ! > 700 nm) was examined; accurate evaluation of the electronic and nuclear wave packet was achieved by the dual transformation method that we developed. Using ''field-following'' time-dependent adiabatic states defined as eigenfunctions of the ''instantaneous'' electronic Hamiltonian, we have clarified the dynamics of bound electrons, ionization processes, Coulomb explosion processes, and molecular vibrations of H 2 þ and H 2 . The analyses indicate that the multielectron dynamics and nuclear dynamics of polyatomic molecules in intense fields can be described by using the potential surfaces of time-dependent adiabatic states and the nonadiabatic coupling elements between those states. To obtain time-dependent adiabatic states of a molecule, one can diagonalize the electronic Hamiltonian including the interaction with the instantaneous laser electric field by ab initio molecular orbital (MO) methods. The time-dependent adiabatic potentials obtained are used to evaluate the multichannel nuclear dynamics until the next ionization process. We have applied the time-dependent adiabatic state approach to reveal the characteristic features of the dynamics of structural deformations of CO 2 and its cations in a near-infrared intense laser field. The experimentally observed stretched and bent structure of CO 2 3þ just before Coulomb explosions originates from the structural deformation of CO 2 2þ . We also revealed the mechanism of the experimentally observed bond dissociation of C 2 H 5 OH; we found that the relative probability of C-O bond cleavage to that of C-C bond cleavage becomes smaller with decreases in the pulse length. This example clearly shows that field-induced nonadiabatic transitions play a decisive role in the reaction dynamics of molecules in an intense laser field.

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Section: Multiphoton Ionization and Tunnel Ionizationmentioning

confidence: 99%

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

Kono

Satô

Kanno

et al. 2006

Bulletin of the Chemical Society of Japan

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“…The current combination of ω las and E 0 spans the interval 0.55 ≤ γ ≤ 2.2, i.e., from multiphoton ionization for γ > 1 to tunneling ionization for γ < 1. This transition has been experimentally studied in PES of rare gases [44]. In the above expression, φ CEP is the carrier-envelope phase (CEP).…”

Section: Laser Fieldmentioning

confidence: 99%

Strong-field effects in the photoemission spectrum of theC60fullerene

et al. 2016

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Considering C60 as a model system for describing field emission from the extremity of a carbon nanotip, we explore electron emission from this fullerene excited by an intense, near-infrared, fewcycle laser pulse (10 13 -10 14 W/cm 2 , 912 nm, 8-cycle). To this end, we use time-dependent density functional theory augmented by a self-interaction correction. The ionic background of C60 is described by a soft jellium model. Particular attention is paid to the high energy electrons. Comparing the spectra at different emission angles, we find that, as a major result of this study, the photoelectrons are strongly peaked along the laser polarization axis forming a highly collimated electron beam in the forward direction, especially for the high energy electrons. Moreover, the high-energy plateau cut-off found in the simulations agrees well with estimates from the classical three-step model. We also investigate the build-up of the high-energy part of a photoelectron spectrum by a time-resolved analysis. In particular, the modulation on the plateau can be interpreted as contributions from intracycle and intercycle interferences.

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“…In the range of γ ≈ 1 both effects compete with each other [9,10]. In later papers the Keldysh parameter has been connected to the notion of adiabaticity of the ionization process [11,12]. Far into the tunneling regime, the atomic response is considered to be purely adiabatic.…”

Section: Introductionmentioning

confidence: 99%

Adiabaticity and diabaticity in strong-field ionization

2013

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If the photon energy is much less than the electron binding energy, ionization of an atom by a strong optical field is often described in terms of electron tunneling through the potential barrier resulting from the superposition of the atomic potential and the potential associated with the instantaneous electric component of the optical field. In the strict tunneling regime, the electron response to the optical field is said to be adiabatic, and nonadiabatic effects are assumed to be negligible. Here, we investigate to what degree this terminology is consistent with a language based on the so-called adiabatic representation. This representation is commonly used in various fields of physics. For electronically bound states, the adiabatic representation yields discrete potential energy curves that are connected by nonadiabatic transitions. When applying the adiabatic representation to optical strong-field ionization, a conceptual challenge is that the eigenstates of the instantaneous Hamiltonian form a continuum; i.e., there are no discrete adiabatic states. This difficulty can be overcome by applying an analytic-continuation technique. In this way, we obtain a rigorous classification of adiabatic states and a clear characterization of (non)adiabatic and (non)diabatic ionization dynamics. Moreover, we distinguish two different regimes within tunneling ionization and explain the dependence of the ionization probability on the pulse envelope.

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Atoms in strong optical fields: Evolution from multiphoton to tunnel ionization

Cited by 158 publications

References 9 publications

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

Theoretical Investigations of the Electronic and Nuclear Dynamics of Molecules in Intense Laser Fields: Quantum Mechanical Wave Packet Approaches

Strong-field effects in the photoemission spectrum of theC60fullerene

Adiabaticity and diabaticity in strong-field ionization

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