Analysis of the elastic peaks of hydrogen and oxygen from electron beams hitting liquid water

Abstract Elastic peak electron spectroscopy, also known as electron Compton scattering or electron Rutherford backscattering, is a powerful technique for analyzing the elastic peak line shape in reflection electron energy spectra. The elastic peak represents electrons that have undergone elastic scattering without inelastic collisions, but whose position and width are affected by the energy recoil. As a result, a shift of the peak and a broadening due to atomic motion can be observed, both of which provide information about the interactions between electrons and material. Due to its low atomic mass, hydrogen exhibits pronounced recoil effects, which makes elastic peak electron spectroscopy a promising method for the detection of hydrogen. Monte Carlo simulations have proven useful in modeling the experimental elastic peak. Water, a molecular system of critical importance in fields ranging from biology to cancer therapy, has been extensively studied for its dynamic properties. Recent advances include theoretical studies of nuclear quantum effects and direct measurements of the kinetic energy of the atoms that make up water using neutron scattering techniques. This study investigates the elastic reflection of electrons from liquid water at 276 K, analyzes the influence of elastic and inelastic scattering on the energy distribution of the reflected electrons, and reports the elastic reflection coefficient of water as a function of the energy and the angle of incidence of the electron beam. In contrast to previous studies that focused on Doppler broadening at higher energies, this work explores a more subtle region where the effects approach the limits of instrumental resolution, posing additional analytical challenges.