Resonant capture reactions are a versatile tool to measure concentration profiles of light elements in near‐surface layers. They allow us to monitor, with nanometer depth resolution, atomic transport processes caused by thermal diffusion, ion irradiation, nucleation and chemical forces. We have investigated properties of ion‐implanted super saturated Na solutions in metals by using the 309 keV23Na(p,&ggr;) resonance. Results on Na‐nucleation, outdiffusion and hydrogen decoration are presented; theH‐profiles were measured with the resonant1H(15N,a&ggr;) reaction. The second example refers to 30–300 nm magnetron sputtered TiN and Cr2N hard coatings irradiated with 100‐900 keV Ar, Kr and Xe ions. The resonant15N(p,a&ggr;) reaction served to monitor the composition of the coatings and ion‐induced surface sputtering and interface mixing effects.