Two-photon double ionization of H<sub>2</sub>at 30 eV using exterior complex scaling

Morales, Felipe; Martı́n, Fernando; Horner, D. A.; Rescigno, T. N.; McCurdy, C. William

doi:10.1088/0953-4075/42/13/134013

Cited by 39 publications

(69 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 clearly show that there is a strong backward-forward asymmetry. The bending of the left and right (symmetric) lobes has already been well documented in previous studies in He [5,11,13,[29][30][31], H − [25], and H 2 [26][27][28]32], and we will only comment briefly on this feature here. Assuming for the moment that the electrons absorb one photon each in the two-photon double ionization event, this would, to a zeroth-order approximation, give rise to a p-lobe structure (oriented along the laser polarization direction) in their respective angular distributions.…”

supporting

confidence: 55%

Two-photon double ionization of helium by attosecond laser pulses: Evidence of highly correlated electron motion

2012

View full text Add to dashboard Cite

We apply a recently developed ab initio numerical framework to investigate the angular distributions of the emitted electrons in the immediate proximity of the threshold for the two-photon double ionization of helium. Provided one of the electrons is emitted perpendicular to the laser polarization direction, it is found that the angular distribution of the other electron is characterized by three lobes. The results are similar to those recently reported for the corresponding process in the hydrogen negative ion [R. The problem of direct (nonsequential) two-photon double ionization of helium has been studied extensively in recent years, as exemplified by numerous theoretical [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and experimental [19][20][21][22][23][24] works. This breakup process is fundamental in the sense that it is one of the simplest processes in nature where electron correlations are exhibited, manifested by a rather complex interplay between the electrons. As such, a complete understanding of it will pave the way for further investigations of the role of correlations in few-photon and multiphoton multiple ionization processes in atoms and molecules.In the present Brief Report, we investigate the direct two-photon double ionization process of helium in the near vicinity of the lower threshold (i.e., for 40 eV photons), and with particular emphasis on the direction of ejection of the photo-electrons. In a recent work [25], it was found that the corresponding process in H − is characterized by a strong backward-forward asymmetry in the sense that if one electron is emitted perpendicular to the (linear) laser polarization direction then the other electron is emitted most preferably in the opposite direction, forming three characteristic lobes in the angular distribution. Similar features have also been observed theoretically in H 2 [26][27][28].Solving the time-dependent Schrödinger equation numerically for helium [14], the conditional angular distribution is obtained for both short (500 and 1000 as) and long (4 fs) linearly polarized laser pulses. We examine the case where one of the electrons is emitted perpendicular to the laser polarization direction, and integrate over the energy of both electrons. It is found that the direction of emission of the other electron is characterized by three lobes, concordant with the observations in H − [25]. Furthermore, with increasing pulse duration, the lobe pointing in the backward direction, representing electrons being emitted back-to-back, becomes relatively more important. The "backward" lobe is most distinct at lower photon energies, and already at a photon energy of 42 eV it loses its significance [11]. We therefore anticipate that the presence of the structure at lower photon energies is * sigurd.askeland@ift.uib.no † morten.forre@ift.uib.no a signature of a competing double ionization mechanism that becomes suppressed at higher photon energies.Figure 1 depicts our results for the angular distributions in the double ionization process. I...

show abstract

supporting

confidence: 55%

Two-photon double ionization of helium by attosecond laser pulses: Evidence of highly correlated electron motion

2012

View full text Add to dashboard Cite

show abstract

“…Even more recently, Guan et al [36,37] calculated the corresponding cross sections using a fully ab initio, nonperturbative approach, solving the time-dependent Schrödinger equation in prolate spheroidal coordinates for a 10 cycle laser pulse of peak intensity 10 14 W/cm 2 . The cross sections were obtained projecting the final continuum wave function onto a set of uncorrelated two-center Coulomb waves, and the results were found to differ from those reported by both Colgan et al [34] and Morales et al [35].…”

Section: Introductionmentioning

confidence: 63%

“…The study of fundamental breakup processes in nature is important and paves the way for further investigations of the role of correlations in few and multiphoton multiple ionization processes in atoms and molecules. More recently, the four-body breakup of H 2 by two-photon impact has received considerable attention, both in the direct [34][35][36][37] and sequential regime [38,39].…”

Section: Introductionmentioning

confidence: 99%

“…Total and triple-differential cross sections for the process were obtained for both parallel and perpendicular orientation of the molecule with respect to the linear laser polarization direction. In 2009, Morales et al [35] revisited the problem employing a time-independent approach and the method of exterior complex scaling. Clear discrepancies in the respective triple-differential cross sections were found.…”

Section: Introductionmentioning

confidence: 99%

“…The framework has here been further developed in order to take into account the two-center nature of the problem. Following [34][35][36][37] we * aleks.simonsen@gmail.com † morten.forre@ift.uib.no assume the fixed-nuclei approximation in the calculations, that is, the nuclei are considered being fixed at their equilibrium internuclear distance at R = 1.4 a.u. throughout the interaction with the laser pulse.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Direct two-photon double ionization of H2

et al. 2012

View full text Add to dashboard Cite

We have studied the process of direct (nonsequential) two-photon double ionization of molecular hydrogen (H2). Solving the time-dependent Schrödinger equation by an ab initio method, total (generalized) and singledifferential cross sections are obtained at photon energies from 26 to 33 eV. Both parallel and perpendicular orientation of the molecule with respect to the laser polarization direction are considered, and the results are compared with previously calculated cross sections at 30 eV, as well as the predictions of a simple model.

show abstract