ACCOUNTING FOR SECONDARY EXTINCTION IN A NOVEL X-RAY ABSORPTION METHOD USED FOR THICKNESS MEASUREMENTS OF THIN FOILS

摘要

A new approach accounting for secondary extinction (SE) is proposed for calculating the thickness of a foil mounted on textured substrate. To this end, the extinction-affected intensities of a strong substrate reflection are measured at different levels of interaction between X-radiation and crystal medium and, hence, these intensities suffer different extinction. Making use of such a series of measured intensities, the effect of extinction on the calculated foil thickness is eliminated by a proper definition of the zero-extinction condition. In this case, the definition is based on the incident-bean intensity independence of the empirical extinction coefficient k which is expressed by the measured intensities. The more precise interpretation of the experimental data leads to defining an extinction-free foil thickness, which results in improvement in the accuracy of the foil thickness determination.