Accurate measurement of hydrogen concentration in transition metal hydrides utilizing electronic excitations by MeV ions

Abstract

This study focuses on enhancing the accuracy of hydrogen content verification in hydrogen-rich ultrathin materials relevant for sustainable energy applications. Ion beams are used for distinctive real-space detection leveraging elastic and inelastic interactions with hydrogen atoms. However, the lack of experimental reference data on electronic interactions poses a challenge to the accuracy of analytical techniques. We investigate the effect of absorbed hydrogen on the electronic energy deposition of 15N-ions in amorphous transition metal compounds, specifically V and Zr, covering concentrations >1H/M. Employing resonant nuclear reactions and Rutherford backscattering, the energy loss is found to increase considerably with hydrogen content, in line with Bragg's additivity. The electronic energy loss cross section for 15N-ions at 6.5 MeV measured (64.55±3.38) eV cm2/1015 atoms. Results are compared to semi-empirical and theoretical models. The findings improve hydrogen profiling accuracy using 15N-nuclear reaction analysis and enable unprecedented methods for hydrogen quantification by other, commonly available ion beams.