Experimental verification of quadrupole-dipole interference in spin-resolved photoionization.
We have measured the spin polarization of Xe (4p)(-1) photoelectrons after ionization with circularly polarized light at photon energies close to the ionization threshold where a resonant enhancement of quadrupole transitions has recently been predicted. At a reaction angle of 90 degrees a nonvanishing longitudinal spin polarization component of about 4% clearly indicates a quadrupole contribution to the photoexcitation. This is the first experimental evidence for the influence of nondipole transitions on the photoionization process at excitation energies much below 1 keV in an observable other than the intensity angular distribution.
Khalil
T
T
Universität Bielefeld, Fakultät für Physik, Universitätsstrasse 25, 33615 Bielefeld, Germany.
Schmidtke
B
B
Drescher
M
M
Müller
N
N
Heinzmann
U
U