Multiple ionization of Ar, Kr, and Xe in a superstrong laser field

Abstract

We report the numerical calculation of Ar 9+ · · · Ar 13+ , Kr 13+ · · · Kr 17+ , and Xe 19+ · · · Xe 23+ ion yield in the laser field with intensity exceeding 10 19 W/cm 2 . The results of the calculations agree with the experimental data [K. Yamakawa et al., Phys. Rev. A 68, 065403 (2003)] (for the Ar ions) or qualitatively (for the Kr ions). The theoretical results disagree with the experimental data for the Xe ions. We discuss the possible influence of the relativistic effects on this disagreement between theory and experiment. We obtained the approximation formula for the position of the maximum ionic population with the given ionization multiplicity Z depending on the radiation intensity. This position is described by the power function of Z; the exponent is determined by the dependence of sequential ionization potentials on Z value. We discuss the dependence of the approximation formula parameters on the value of the FWHM of the laser pulse.

Correlation effects in La, Ce, and lanthanide ions

“…This subject has been of active interest since the 1970s, when conflicting ideas emerged regarding the role of single-particle vs. collective excitations in photoabsorption by the atomic 4d shell of lanthanides and neighboring elements [23]. It has also arisen again in the interpretation of recent experiments on multiple ionization of Xe by intense extreme ultraviolet radiation produced at free-electron laser facilities [24][25][26][27][28].…”

Keldysh theory in a few-cycle laser pulse, inelastic tunneling and Stark shift: comparison withab initiocalculation

“…The stepwise structure of the curves corresponds to the predictions of (12). It should be noted that with increasing the pulse duration at fixed frequency ω and amplitude F ˜the number of cycles N grows, resulting in the violation of condition (13). In this case it is necessary to take into account the saturation.…”

“…index ′ f corresponds to all possible values of ν and m. The factor F F ˜a in (13) shows that in the range of amplitudes allowing the usage of (10) in the ac field will be wider compared to the range of the intensities of the static field F due to the oscillations. In figure 3 the results are given similar to those in figures 1 and 2 but with the lower values of the amplitude F ˜(the Stark effect is taken into account).…”

“…The most thorough calculations were carried out in [6], where the cases of ionization of Ne and Xe are considered when the ions can be created in two states, the ground and excited states. In the brief report [7], the numerical results obtained in [6] for Ne were perfectly reproduced by generalization of the Keldysh theory on a few-cycle laser pulse and combination of this theory with the inelastic tunneling model that was developed earlier [8][9][10][11][12][13][14]. We use the term 'inelastic tunneling' for the process of ionization of an atom or an ion when the resulting ion turns out in an excited state, not in the ground state.…”

Classical study of atomic bound state dynamics in circularly polarized ultrastrong fields

“…Typically this occurs at optical frequencies for fields of order 10 18 W cm −2 and greater. In ultraintense fields, non-dipole effects from B laser can affect the basic photoionization process [5,6]. The current understanding of this breakdown is limited to the propagation of the photoelectron in an ultra-intense continuum [7] where B laser has been calculated to deflect the electron by nanometers during the first optical cycle subsequent to ionization [8].…”