Ionization of atoms in the tunnelling regime with experimental evidence using Hg atoms (original) (raw)

Tunneling criteria and a nonadiabatic term for strong-field ionization

Physical Review A, 2018

We investigate tunneling ionization of a model helium atom in a strong circularly polarized short laser pulse using the classical backpropagation method and compare ten different tunneling criteria on the same footing, aiming for a consistent classical picture of the tunneling dynamics. These tunneling criteria are categorized into velocity-based, position-based, and energy-based criteria according to different notions of a tunnel exit. We find that velocity-based criteria give consistent tunneling exit characteristics with nonadiabatic effects fully included. Other criteria are either inconsistent or only able to include nonadiabatic effects partially. Furthermore, we construct a simple tunneling rate formula, identify a term in the rate responsible for the nonadiabatic effects, and demonstrate the importance of this term.

Above-threshold ionization in the tunneling regime

Physical Review A, 1997

A compact generalization of the Keldysh ionization amplitude is derived that includes rescattering. It is used for calculations of above-threshold ionization spectra with respect to energy for various emission angles for tunneling ionization of helium at high intensity, for the simple case of a zero-range potential as the binding potential. Most of the essential features of recent measurements are reproduced, that is, the onset, the extent, and the relative height of the plateau, which makes up the major part of the observed spectrum.

Non-exponential tunneling ionization of atoms by an intense laser field

Laser Physics Letters, 2015

We discuss the possibility of non-exponential tunneling ionization of atoms irradiated by intense laser field. This effect can occur at times which are greater than the lifetime of a system under consideration. The mechanism for non-exponential depletion of an initial quasistationary state is the cutting of the energy spectrum of final continuous states at long times. We first consider the known examples of cold emission of electrons from metal, tunneling alpha-decay of atomic nuclei, spontaneous decay in two-level systems, and the single-photon atomic ionization by a weak electromagnetic field. The new physical situation discussed is tunneling ionization of atoms by a strong low-frequency electromagnetic field. In this case the decay obeys ~t 1/ power-law dependence on the (long) interaction times.

Signatures of tunneling and multiphoton ionization in the electron-momentum distributions of atoms by intense few-cycle laser pulses

Physical Review A, 2006

Electron-momentum distributions for above-threshold ionization of argon in a few-cycle, linearly polarized laser pulse are investigated. Spectral features characteristic of multiphoton as well as tunneling ionization coexist over a range of the Keldysh parameter ␥ in the transition regime ␥ ϳ 1. Surprisingly, the simple strong-field approximation ͑SFA͒ is capable of reproducing the key features of the two-dimensional momentum distributions found in the full solution of the time-dependent Schrödinger equation, despite the fact that SFA is known to severely underestimate the total ionization probability.

Theory of molecular tunneling ionization

Physical Review A, 2002

... From these two assumptions we ``derive'' the experimental 033402-9 XM TONG, ZX ZHAO, AND CD LIN PHYSICAL REVIEW A 66, 033402 2002 FIG. 11. ... Rev. Lett. 85, 2280 2000 . 9 X. Chu and SI Chu, Phys. Rev. A 63, 013414 2001 . 10 A. Saenz, J. Phys. B 33, 4365 2000 . ...

Multiphoton ionization and multiphoton resonances in the tunneling regime

Physical Review A - PHYS REV A, 2010

The rate of ionization of an atom of helium, argon, or hydrogen exposed to an intense monochromatic laser field and the quasienergy spectrum of their dressed states are studied for values of the Keldysh parameter between 1 and 0.6 and wavelengths between 390 and 1300 nm. The calculations are carried out within the non-Hermitian Floquet theory. Resonances with intermediate excited states significantly affect ionization from the dressed ground state at all the intensities and all the wavelengths considered. The dressed excited states responsible for these structures are large-alpha0 states akin to the Kramers-Henneberger states of the high-frequency Floquet theory. Within the single-active-electron approximation, these large-alpha0 states become species independent at sufficiently high intensity or sufficiently long wavelength. Apart for the resonance structures arising from multiphoton coupling with excited states, the ab initio Floquet ionization rate is in excellent agreement with ...

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

Physical Review Letters, 1993

Electron energy spectra from ionization of the noble gases by 617-nm, 100-fs intense laser pulses show that the periodical double structure of narrow Stark-induced resonances and above-threshold ionization disappears gradually from xenon to helium. This implies that shifts and widths become of the order of the atomic-orbital frequencies, as expected at the onset of the tunneling regime.

Behaviour of tunnelling transition rate of argon atom exposed to strong low-frequency elliptical laser field

Pramana, 2016

We considered the tunnelling ionization of an electron under the influence of a monochromatic laser beam with the elliptical polarization. Arbitrary values of ellipticity were observed. The influence of ponderomotive potential and Stark shift on the ionization rate was discussed. A brief description of the dependence of the ponderomotive potential and the Keldysh parameter on the field intensity and ellipticity is given.

Tunnel Ionization of Heavy Atoms in Parallel Electric and Magnetic Fields

2010

In the fTamework of , the раrахiаl Fock-Leontovich approximation the three.dimensional version of WKB method is elaborated fоr solving the Dirac equation vrith axially s;rrnmetrical potentiab, which do not permit the соmplete separation of variables. Ву mеапs of this аррrоасh thе relativistic wave functions for the H-like atom in the parallel constant rmiform electriс a,Trd magnetic fieids але constructed in the ЬеIотч-Ьаrriеr апd classically allowed rапgеý. Gепегаl analytical ехрrеssiоп for probability of ionization of the atom in the ехtеrпаl electric and magnetic fields is oЫained. The соmраrisоп of the found formulas чrith results known previously Ь саrriеd out.