Structural investigation of the $\mathrm{Rh}\mathrm{}\left(110\right)-c(2\mathrm{}\times 2)-\mathrm{CN}$ phase

The $\mathrm{Rh}\mathrm{}\left(110\right)\mathrm{}-c(2\mathrm{}\times 2)-\mathrm{CN}$ phase has been examined by means of scanning tunneling microscopy (STM) and full dynamical low-energy electron diffraction (LEED). From STM large $c(2\mathrm{}\times 2)$ domains are observed. The detailed LEED-IV structural analysis indicates that CN is located in the grooves of the (110) surface, approximately atop second layer rhodium atoms. The CN molecules lie almost flat with their bond axes oriented perpendicular to the rhodium troughs. An outward relaxation of the first substrate interlayer distance and a strong buckling of the second Rh layer are induced by CN adsorption. Calculated and experimental intensity curves are in good agreement. An exhaustive set of other possible adsorption sites and configurations was tested and excluded on the basis of reliability-factor analysis.