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Electric-octupole and pure-electric-quadrupole effects in soft-x-ray photoemission

A. Derevianko·O. Hemmers·S. Oblad·P. Glans·H. Wang·S. B. Whitfield·R. Wehlitz·I. A. Sellin·W. R. Johnson·D. W. Lindle
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Abstract

Second-order [O(k^2), k=omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and theoretical study of angular distributions of neon valence photoelectrons in the 100--1200 eV photon-energy range. A newly derived theoretical expression for nondipolar angular distributions characterizes the second-order effects using four new parameters with primary contributions from pure-quadrupole and octupole-dipole interference terms. Independent-particle calculations of these parameters account for a significant portion of the existing discrepancy between experiment and theory for Ne 2p first-order nondipole parameters.

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A. Derevianko, O. Hemmers, S. Oblad, P. Glans, H. Wang, S. B. Whitfield, R. Wehlitz, I. A. Sellin, W. R. Johnson, D. W. Lindle. 1999-08-18. Electric-octupole and pure-electric-quadrupole effects in soft-x-ray photoemission. https://doi.org/10.1103/physrevlett.84.2116

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