Non-dipolar asymmetries of photoelectron angular distributions
- Argonne National Lab., IL (United States); and others
Current understanding of atomic photoionization phenomena is largely based on the dipole approximation of the photon/atom interaction. However, non-dipolar interactions have been predicted to strongly modify photoelectron angular distributions due to interference between dipolar and non-dipolar amplitudes. These effects have generally been ignored in experimental studies. The authors have measured the non-dipolar contributions to the Ar 1s, Kr 2s, and Kr 2p photoelectron angular distributions using 2-5 keV polarized x-rays. The non-dipolar interaction results in a forward/backward asymmetry with respect to the photon beam measured by rotating an electron spectrometer about the polarization vector with a fixed polar angle of 54.7{degrees}. This eliminates the angular dependence on the dipolar asymmetry parameter b. The non-dipolar asymmetries for different atomic subshells vary with energy in different ways; at certain energies the photoelectron intensity is enhanced in the backward direction, while at other energies the asymmetry vanishes or is enhanced in the forward direction. In all cases, the measured asymmetries are in good agreement with recent non-relativistic calculations which include interference between the electric-dipole and electric-quadrupole photoionization amplitudes.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 394290
- Report Number(s):
- CONF-9605105--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 3 Vol. 41; ISSN BAPSA6; ISSN 0003-0503
- Country of Publication:
- United States
- Language:
- English
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