Few-photon multiple ionization of ne and ar by strong free-electron-laser pulses.
Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I<6x10(12) W/cm2 and significant contributions of three-photon ionization as I increases. Ne2+ recoil-ion-momentum distributions suggest that two electrons absorbing "instantaneously" two photons are ejected most likely into opposite hemispheres with similar energies.
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
R
R
Moshammer
Y H
YH
Jiang
L
L
Foucar
A
A
Rudenko
Th
T
Ergler
C D
CD
Schröter
S
S
Lüdemann
K
K
Zrost
D
D
Fischer
J
J
Titze
T
T
Jahnke
M
M
Schöffler
T
T
Weber
R
R
Dörner
T J M
TJ
Zouros
A
A
Dorn
T
T
Ferger
K U
KU
Kühnel
S
S
Düsterer
R
R
Treusch
P
P
Radcliffe
E
E
Plönjes
J
J
Ullrich