Zhengming Luo

Measurements of L-shell x-ray production cross-sections of Au and Ag by low energy electron impact

Lα, Lβ x-ray production cross-sections for Gd (Z = 64) and W (Z = 74) by electron impact up to 40 keV have been measured. Thin films with thick carbon substrates were used as targets in the experiments. The effects of multiple scattering of electrons when penetrating the target film, of electrons reflected from the thick pure carbon substrate and of bremsstrahlung photons produced by the impact of incident electrons on the target were corrected by means of Monte Carlo simulation. For Gd L-shell x-ray characteristic peaks, the spectra were fitted by using spectrum-fitting program ALLFIT to extract more accurately the Lα and Lβ peak counts. The experimental data are compared with the DWBA theory and the PWBA–C–Ex theory and available experimental data from the literature.

Some recent progress on the measurement of K-shell ionization cross-sections of atoms by electron impact: Application to Ti and Cr elements

In this paper, we have taken some measures to improve the accuracy of our experimental data for K-shell ionization cross-sections by electron impact. These measures include (1) measurement of the thin target thickness with Rutherford backscattering spectroscopy and (2) detection efficiency calibration in the lower energy region using thick carbon target bremsstrahlung by electron impact and (3) electron reflection correction and electron mean track length correction based upon Monte Carlo method. These measures are applied to the measurement of K-shell ionization cross-sections of Ti and Cr elements from the threshold energies up to 26 keV. From the comparison with some theoretical models, empirical formulae and some previous experimental data, it is concluded that these measures taken in this paper are effective in the improvement of accuracy of experimental data. The present experimental data for Ti and Cr elements also clarify the discrepancies among some experimental data sets. In addition, these measures will also be very helpful in the measurement of K-shell ionization cross-sections for lower Z elements and in the measurement of L, M-shell ionization cross-sections for medium and higher Z elements.

Theoretical calculations of the self-reflection coefficients for some species of ions☆

Abstract The bipartition model of ion transport has been applied to study the self-reflection coefficients of some species of ion beams which are normally incident to a surface. The computational results has been compared with the results taken from Eckstein and Biersack and the compilation data given by Thomas, Janev and Smith. It was found that there are in reasonable agreement between the results given by the bipartition model and the results given by Monte Carlo method.