Reemitted-Positron Energy-Loss Spectroscopy: A Novel Probe of Adsorbate Vibrational Levels

Abstract

Vibrational excitations of carbon monoxide on Ni(100) have been observed for the first time in the energy-loss spectrum of reemitted positrons. For $\mathrm{Ni}\mathrm{}\left(100\right)c(2\mathrm{}\times 2)\mathrm{CO}$ at room temperature, energy-loss peaks are found at ∼ 57 and ∼ 248 meV, corresponding to Ni-C and C-O stretching vibrations, respectively. These peak positions are in good agreement with previously reported results for electron energy-loss spectroscopy. Anticipated improvements in resolution promise to make reemitted-positron energy-loss spectroscopy competitive with high-resolution electron energy-loss spectroscopy.