Vibrational spectra of the monolayer films of hexagonal boron nitride and graphite on faceted Ni(755)

Hexagonal boron nitride (h-BN) and graphite films on faceted Ni(755) have been investigated by means of vibrational spectroscopy, accompanied by low energy electron diffraction and Auger electron spectroscopy. A faceted surface consisting of the (111) face and high-Miller index face has been grown by the adsorption of monolayer films. Vibrational spectra of the monolayer h-BN have exhibited two peaks at 90 and 97 meV, which originate from the optical phonons with out-of-plane displacement (TO_⊥) of the films adsorbed on the faceted (111) and the other high-index faces, respectively. These peaks indicate that the bond strength between h-BN films and a Ni face depends on the Ni face orientation. On the contrary, only one peak of TO_⊥ mode has appeared in the monolayer graphite on the same faceted surface. The single peak means a similar strength of the interfacial bond on various surfaces.