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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Poster

KFM 14.13: Poster

Mittwoch, 19. März 2025, 17:00–18:30, P1

Surface and near-surface positron annihilation spectroscopy at very low positron energy — •Maximilian Suhr¹, Lucian Mathes^1,2, Vassily V. Burwitz², Danny R. Russell¹, and Christoph Hugenschmidt¹ — ¹Heinz Maier-Leibnitz Zentrum, TU München — ²School of Natural Sciences, Physics Department, TU München

Positron annihilation spectroscopy is a highly sensitive tool for defect characterization in solids. We present the Setup for Low-Energy Positron Experiments (SLOPE) at TUM. This monoenergetic positron beam is realized via a high-activity ²²Na source, a W moderator, a sophisticated electromagnetic beam guidance system and two high purity Ge detectors. Our instrument features a state-of-the-art range of implantation energy, namely 3 eV to 40 keV, enabling bulk measurements as well as investigations of surfaces. With three different measurements we showcase the versatile applications of SLOPE: a full range depth profile of a W monocrystal, coincidence ratio curves of H-loaded Ni, and a valley-to-peak (positronium formation) scan of Cu and Kapton at very low implantation energies.

Keywords: positrons; spectroscopy; defects; surface