Recoil-ion momentum distributions for two-photon double ionization of He and Ne by 44 eV free-electron laser radiation

Rudenko, A; Foucar, L; Kurka, M; Ergler, Th; Kuhnel, K.U; Jiang (Yiang), Y.H; Voitkiv, A; Najjari, B; Kheifets, Anatoli; Ludemann, S; Havermeier, T; Smolarski, M; Schossler, S; Cole, K; Schoffler, M S; Dorner, R; Dusterer, S; Li, W; Keitel, B; Treusch, R; Gensch, M; Schroter, C D; Moshammer, R; Ullrich, Joachim

Recoil-ion momentum distributions for two-photon double ionization of He and Ne by 44 eV free-electron laser radiation

Date

2008-08-15

Authors

Rudenko, A

Foucar, L

Kurka, M

Ergler, Th

Kuhnel, K.U

Jiang (Yiang), Y.H

Voitkiv, A

Najjari, B

Kheifets, Anatoli

Ludemann, S

Publisher

American Physical Society

Abstract

Recoil-ion momentum distributions for two-photon double ionization of He and Ne (ℏω=44 eV) have been recorded with a reaction microscope at FLASH (the free-electron laser at Hamburg) at an intensity of ∼1×1014 W/cm2 exploring the dynamics of the two fundamental two-photon–two-electron reaction pathways, namely, sequential and direct (or nonsequential) absorption of the photons. We find strong differences in the recoil-ion momentum patterns for the two mechanisms pointing to the significantly different two-electron emission dynamics and thus provide serious constraints for theoretical models.