Photofragmentation analysis from fluorescence-radiation angular-asymmetry parameter measurements of fine-structure resolved transitions on resonances

Abstract

The angular asymmetry parameter β fl of the photon-induced fluorescence radiation of Ar + (4p-4s) fine-structure resolved satellite lines was measured from threshold up to 38.4 eV. It is well known that the cross sections of these valence shell satellites are dominated by the decay of aligned doubly excited states leading to an extremely complicated energy dependence. In contrast, we observe that the β fl parameter becomes less structured with increasing total angular momentum J of the photoion. The β fl measurements can be interpreted by a partialwave analysis of the photofragmentation products. For the population of the 4p 2 F 7/2 ion state only d 5/2 photoelectrons are emitted on all resonances. For the population of the 4p 2 D 5/2 and the 4p 4 P 5/2 ion states the emission of the parity-unfavoured d 5/2 photoelectrons dominates.

Alignment following Au L3photoionization by synchrotron radiation

“…In photoionization the alignment was first observed in Cd by Caldwell and Zare [4]. Recent photoionization experiments have used synchrotron radiation for measurements of the alignment [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Most of the experimental results were basically in agreement with the theoretical calculations [20][21][22][23].…”

Use of partial-wave decomposition to identify resonant interference effects in the photoionization–excitation of argon

“…Interestingly, the relative intensities of the 8p and 9p d-wave intensities flip depending on the j of the residual D-state ions. The partial-wave intensities we observe are consistent with the fluorescence angular distribution measurements made by Mentzel et al [8] in the cases of reactions (2)-(5).…”

“…We consider next the quartet (3p 4 (6); figures 9 and 10 respectively). Reaction (5) has been investigated recently by Mentzel et al as well [8], and has been considered theoretically in separate calculations by van der Hart and Greene [24]. The formation of such states represents an unambiguous experimental signature of relativistic interactions because it requires a spin nonconserving interaction.…”

Giant spin-orbit interactions in argon photoionization

“…The singlet component decays to the doublet states of Ar + plus a free electron. Previous measurements of the formation of quartet states suggest that the resonant states of Ar* * are indeed dominated by the 1 P 1 o state [2,3]. In this Rapid Communication we report on measurements where quartet cross sections are larger than the doublet cross sections, an unexpected result within the context of the present theoretical development [1].…”

“…We note that the peak heights and areas of the quartet states are significantly greater than the doublets. For this particular ionizing photon energy our measurements show that the cross sections for the two quartet states, which are proportional to the area under each peak, are significantly larger than the integrated area of the dipole-allowed doublet states, 2 …”