THICKNESS MEASUREMENTS OF MULTI-LAYER SAMPLES USING PHOTON-ATOM INTERACTIONS IN X-RAY ENERGY REGION

Abstract

The present work reports a method for thickness measurements of multi-layer samples using energy dispersive photon-atom interaction setup involving 59.5 keV -rays from 241Am radioactive source. The inelastic information has been used to measure thickness of polymer (mylar/polypropylene) films over a wide range 100 g/cm2 - 600 mg/cm2 (~700 - 4200,000 Å). The setup can be further improved for lower thickness ~few Å using in-vacuo measurements involving low-energy photons ~10 keV. The measurements were also extended to determine thickness of different layers of Cu and Pb-Sn alloy foils sandwiched between polymer films using the characteristic x-ray, elastic- and inelastic-scattering information. The experimental results recommend the use of reported methodology for thickness measurement of low-Z materials deposited on a thick substrate for material characterization. Various aspects of interaction of X-ray photons (below ~100 keV) with matter, i.e., about characteristic X-ray photons, elastic- and inelastic-scattered photons have been discussed for the sample elemental/thickness analysis applications.