Mixed-Valency Signature in Vibrational Inelastic Electron Tunneling Spectroscopy

4 páginas, 3 figuras, 1 tabla.-- PACS numbers: 68.37.Ef, 72.10.-d, 72.25.-b, 79.20.Rf
Density functional theory simulations of the vibrational inelastic electron tunneling spectroscopy (IETS) of O2 on Ag(110) permits us to solve its unexplained IETS data [ Hahn et al. Phys. Rev. Lett. 85 1914 (2000)]. When semilocal density functional theory is corrected by including static intra-atomic correlations, the IETS simulations are in excellent agreement with the experiment. The unforeseen consequence of our calculations is that when adsorbed along the [001] direction, molecular O2 on Ag(110) is a mixed-valent system. This analysis of IETS unambiguously reveals the paramagnetic nature of O2 on Ag(110).
We acknowledge financial support from the Spanish MICINN (No. FIS2007-066711-CO2-00 and No. FIS2009-12721-C04-01), and the Basque Government—UPV/EHU (Grant No. IT-366-07).