Eur. Phys. J. D (2017) 71: 183
https://doi.org/10.1140/epjd/e2017-70812-8

Regular Article

Optical oscillator strengths of the valence-shell excitations of atoms and molecules determined by the dipole (γ,γ) method^*

¹ Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
² Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China
³ Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, P.R. China

^a e-mail: lfzhu@ustc.edu.cn

Received: 26 December 2016
Published online: 6 July 2017

Abstract

The dipole (γ,γ) method, which is the inelastic X-ray scattering operated at a negligibly small momentum transfer, has been developed to determine the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules. This new method is free from the line saturation effect, and its Bethe-Born conversion factor varies much more slowly with the excitation energy than that of the dipole (e, e) method. Thus the dipole (γ,γ) method provides a reliable approach to obtain the benchmark optical oscillator strengths of the valence-shell excitations for gaseous atoms and molecules. In this paper, we give a review of the dipole (γ,γ) method and some recent measurements of absolute optical oscillator strengths of gaseous atoms and molecules.