STM and DFT studies of CO_2 adsorption on O-Cu(100) surface

摘要

We characterized CO2adsorption and diffusion on the missing row reconstructed (2√2 × √2) R45° O-Cu(100) surface using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations with dispersion. We deposited CO2moleculesin situat 5 K, which allowed us to unambiguously identify individual CO2molecules and their adsorption sites. Based on a comparison of experimental and DFT-generated STM images, we find that the CO2molecules sit in between the O atoms in the missing row reconstructed O-Cu(100) surface. The CO2molecules are easily perturbed by the STM tip under typical imaging conditions, suggesting that the molecules are weakly bound to the surface. The calculated adsorption energy, vibrational modes, and diffusion barriers of the CO2molecules also indicate weak adsorption, in qualitative agreement with the experiments. A comparison of tunneling spectroscopy and DFT-calculated density of states shows that the primary change near the Fermi level is associated with changes to the surface states with negligible contribution from the CO2molecular states.