Accurate measurement of absolute experimental inelastic mean free paths and EELS differential cross-sections

Craven, A. J., Bobynko, J., Sala, B. and MacLaren, I. (2016) Accurate measurement of absolute experimental inelastic mean free paths and EELS differential cross-sections. Ultramicroscopy, 170, pp. 113-127. (doi: 10.1016/j.ultramic.2016.08.012) (PMID:27569850)

Abstract

Methods are described for measuring accurate absolute experimental inelastic mean free paths and differential cross-sections using DualEELS. The methods remove the effects of surface layers and give the results for the bulk materials. The materials used are VC0.83,TiC0.98,VN0.97and TiN0.88but the method should be applicable to a wide range of materials. The data were taken at 200 keVusing a probe half angle of 29mradand a collection angle of 36mrad. The background can be subtracted from under the ionisation edges, which can then be separated from each other. This is achieved by scaling Hartree-Slater calculated cross-sections to the edges in the atomic regions well above the threshold. The average scaling factors required are 1.00 for the non-metal K-edges and 1.01 for the metal L-edges (with uncertainties of a few per cent). If preliminary measurements of the chromatic effects in the post-specimen lenses are correct, both drop to 0.99. The inelastic mean free path for TiC0.98 was measured as 103.6±0.5 nm compared to the prediction of 126.9 nm based on the widely used Iakoubovskii parameterisation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Sala, Miss Bianca and MacLaren, Dr Ian and Craven, Professor Alan
• Authors: Craven, A. J., Bobynko, J., Sala, B., and MacLaren, I.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Ultramicroscopy
• Publisher: Elsevier
• ISSN: 0304-3991
• ISSN (Online): 1879-2723
• Published Online: 20 August 2016
• Copyright Holders: Copyright © 2016 Elsevier
• First Published: First published in Ultramicroscopy 170:113-127
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher