Photodouble ionization differential cross sections for D₂with various electron energy sharing conditions

Abstract

The mutual angular distributions of the two ejected electrons following direct photodouble ionization have been measured for D 2 at an excess energy (E) of 25 eV using linearly polarized light. These (γ , 2e) 'triple' differential cross sections (TDCSs) were obtained for asymmetric electron energy conditions with energy sharing ratios (R = E 2 /E 1) of R = 24, 11.5, 4 and 2.57. In all cases the 'reference' electron (energy = E 1) was oriented along the direction of the electric field vector (ε) and detected in coincidence with a second electron (energy = E 2) coplanar with ε and the photon beam direction (k γ). For comparison, helium TDCSs were obtained for the same E and R values under nearly identical spectrometer conditions. These show very good agreement with the results of hyperspherical-matrix with semi-classical outgoing waves calculations, thus providing even more confidence in the D 2 TDCSs where there is as yet no accurate ab initio theory. The similarities and differences between the experimental results associated with the two targets are qualitatively discussed in terms of Feagin's model (

Complete photo-fragmentation of the deuterium molecule

“…5 An atomic photo-ionization cross section can be described by a dipole distribution with its symmetry axis in the direction of the polarization of the incoming photon. In contrast, figure 2 A key result of our experiment is shown in figure 3.…”

Hydrogen and fluorine migration in photo-double-ionization of 1,1-difluoroethylene (1,1-C2H2F2Gaire1, Bocharova2, Sturm3 et al. 2014Phys. Rev. A41130View full textAdd to dashboardCite

“…As mentioned in Sec. III C, this is due to the repulsion between the two electrons, a phenomenon observed in the PDI of atomic and diatomic targets [24,25].…”

“…The relative angle of the two electrons in the NDI channel is guided by the electron-electron repulsion and it is decreasing with increasing sum of the kinetic energy of the electrons (E sum ), as discussed later in Sec. III D. This is due to the repulsion between two identical charged particles, a phenomenon observed in the PDI of atomic targets [24] and diatomic molecules [25] where photoelectrons with small sum of their kinetic energy E sum repel each other more strongly, and thus emerge into opposite hemispheres. Among the DI channels the relative electron angular distributions follow a trend of increasing width with increasing threshold energy.…”

Nondipole Effects in Photo-Double-Ionization of He by a vuv Photon

“…(The only exceptions, to our knowledge, are the measurements in Ref. [11] and in more recent work [12], all of which deal with low excess energies, 25 eV.) In lowest order, retardation corrections stem from terms k r in the power series expansion of the vector potential.…”

“…In order to establish the dependence of the quadrupole amplitude A q on the photon parameters e and k and the mutual angle 12 between p 1 and p 2 , we employ the techniques developed for parametrization of the electricdipole TDCS [10]. First, we use the well-known multipole expansion of the final state jp 1 p 2 i in terms of bipolar harmonics C l 1 l 2 lm p p 1 ;p p 2 of the unit vectorsp p 1 andp p 2 ,…”