NMR Observation of Mobile Protons in Proton-Implanted ZnO Nanorods

Abstract

The diffusion properties of H+ in ZnO nanorods are investigated before and after 20 MeV proton beam irradiation by using H-1 nuclear magnetic resonance (NMR) spectroscopy. Herein, we unambiguously observe that the implanted protons occupy thermally unstable site of ZnO, giving rise to a narrow NMR line at 4.1 ppm. The activation barrier of the implanted protons was found to be 0.46 eV by means of the rotating-frame spin-lattice relaxation measurements, apparently being interstitial hydrogens. High-energy beam irradiation also leads to correlated jump diffusion of the surface hydroxyl group of multiple lines at -1 ppm, implying the presence of structural disorder at the ZnO surface.