Generalized oscillator strengths for forward electron scattering

Abstract

A simple analytical expression for calculating the generalized oscillator strengths for optically allowed atomic transitions in the forward direction is obtained. We found the correction to the first Born approximation by exploiting the analytical properties of the generalized oscillator strength function at small momentum transfers. A new procedure for experimental measurement of the differential cross sections for optically allowed transitions at small angles is proposed.

Electron impact excitation of the 6s 2S1/2 state of In atom at small scattering angles

“…1 we presented the absolute GOS values versus K 2 on a log-log graph together with the FSF for the resonant transition 5 2 P 1/2 -6 2 S 1/2 in indium atom. The all impact energies satisfy the necessary condition that the FSF method is applicable for the values E 0 P 2.5x [21].…”

“…We used the theoretical procedure suggested in [13,21] in order to put our experimental relative DCSs on an absolute scale. The formula:…”

“…The theoretical results obtained from the 1s-2p transition of the hydrogen can be used to obtain the forward scattering function (FSF) /ðxÞ for resonant or any other known transition of any element [21]. In our case, we have obtained /ðxÞ curve from the knowledge of the OOS values for both, the 1s-2p transition in hydrogen atom …”

Electron-impact excitation of the 3s3p 1P1 state of magnesium: Electron scattering at small angles

“…In the present work we have used the forward scattering function (FSF) method introduced by Avdonina et al [16] for determination of the absolute DCS values. The FSF curve was obtained using the experimental optical oscillator strength (OOS) of 1.83 ± 0.08 by Liljeby et al [17].…”

The 1S–1P electron excitations of Zn at small scattering angles

“…Instead, a theoretical approach of Msezane's group [14] has been adopted in order to normalize relative DCS to absolute scale. Their method of forward scattering function (FSF) [15], which uses only the optical oscillator strength (OOS) as input and describes the loci of the 0 • generalized oscillator strengths (GOS) and determines the normalization constant. Absolute GOSs and DCSs have been obtained in intermediate electron energy range from 15 to 100 eV.…”