Hydrogen detection near surfaces and shallow interfaces with resonant nuclear reaction analysis

This review introduces hydrogen depth profiling by nuclear reaction analysis (NRA) via the resonant H-1(N-15,alpha gamma)C-12 reaction as a versatile method for the highly depth-resolved observation of hydrogen (H) at solid surfaces and interfaces. The technique is quantitative, non-destructive, and readily applied to a large variety of materials. Its fundamentals, instrumental requirements, advantages and limitations are described in detail, and its main performance benchmarks in terms of depth resolution and sensitivity are compared to those of elastic recoil detection (ERD) as a competing method. The wide range of H-1(N-15,alpha gamma)C-12 NRA applications in research of hydrogen-related phenomena at surfaces and interfaces is reviewed. Special emphasis is placed on the powerfiil combination of H-1(N-15,alpha gamma)C-12 NRA with surface science techniques of in-suit target preparation and characterization, as the NRA technique is ideally suited to investigate hydrogen interactions with atomically controlled surfaces and intact interfaces. In conjunction with thermal desorption spectroscopy, N-15 NRA can assess the thermal stability of absorbed hydrogen species in different depth locations against diffusion and desorption. Hydrogen diffusion dymimics in the near-surface region, including transitions of hydrogen between the surface and the bulk, and between shallow interfaces of nanostructured thin layer stacks can directly be visualized. As a unique feature of N-15 NRA, the analysis of Doppler-broadened resonance excitation curves allows for the direct measurement of the zero-point vibrational energy of hydrogen atoms adsorbed on single crystal surfaces, (C) 2014 Elsevier B.V. All rights reserved.