Surface-induced d-band anisotropy on Cu()

RDS investigation of adsorption and surface ordering processes on Cu(110)

“…L 1 from the Fermi-level to the s-electron like band at the L symmetry point [11]. This transition has been shown to be very sensitive to an externally applied strain [16].…”

“…Similar to what has been reported previously [2,9], the spectrum reveals a positive peak at 2.13 eV as well as a negative peak at 4.3 eV surrounded by some smaller features. The energies of these main features are shifted with respect to the room temperature data [10,11]. The second derivative of this spectrum is displayed in the lower part of Fig.…”

“…Two other important features showing up in Fig. 1 are the small peak at 4.2 eV involving a surface resonance at X [2] and a negative peak at 4.4 eV which corresponds to the d-band transition in the vicinity of the bulk symmetry point L [11]. Different kinds of adsorbates, from physisorbed rare gases to chemisorbed CO, lead to quite different changes of the optical anisotropy of Cu(110) as can be seen in electronic structure, the interaction of physisorbed Xe and N 2 with Cu(110) are relatively weak (Figs.…”

Optical anisotropy of nanostructured noble metal surfaces

“…The remaining spectral features of the Cu(110) spectrum have been explained by Sun et al [8] using the "derivative model". In this approach the dielectric properties of the surface are assumed to be essentially bulk-like apart from small modifications to critical point gap energies, E g , and broadenings, Γ. Rewriting the surface dielectric response in terms of perturbed bulk transitions we can write the RAS signal (round a single critical point) as…”

“…where the X(E) and Y(E) functions are determined by the bulk dielectric function and d. Sun et al [8] have shown that the Cu(110) RAS spectrum closely resembles the X function in the 4.3-5.5 eV region and surmised that the surface acts to alter anisotropically the L' 2 (ε f ) →L 1 and L' 2 →L 1 (p symmetry → s symmetry) bulk transitions which dominate this spectral region. The dominant ∆E g term was attributed to band narrowing caused by the reduced atomic co-ordination at the Cu(110) surface.…”