| 1. |
- Lindgren, S.Å., et al.
(författare)
-
Low-energy electron diffraction from close-packed Na
- 1982
-
Ingår i: Journal of Physics. C, Solid State Physics. - : IOP Publishing. - 0022-3719. ; 15:30, s. 6285-6291
-
Tidskriftsartikel (refereegranskat)abstract
- The authors obtain a homogeneously thick film of close-packed Na with close-packed planes parallel to the surface by evaporating Na onto Cu(111) held at LN2 temperature. Comparison between measured LEED intensity spectra, recorded at LN2 temperature, and theoretical ones, calculated under the assumption that the crystal structure of Na is FCC or HCP, favours the HCP structure. The authors UPS results indicate that if Na is evaporated onto Cu(111) held at RT, it will form three-dimensional clusters on top of a Na film only few atomic layers thick.
|
|
| 2. |
- Lindgren, S.Å., et al.
(författare)
-
Surface state energy shifts by molecular adsorption : CO on clean and Na covered Cu(111)
- 1982
-
Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 117:1-3, s. 426-433
-
Tidskriftsartikel (refereegranskat)abstract
- Angle resolved photoelectron energy spectra recorded in the near UV show that the surface state 0.4 eV below EF of Cu(111) shifts to higher energy upon CO adsorption. The surface band related emission intensity is reduced by the adsorption at a rate suggesting that each adsorbed molecule wipes out the surface state over an area corresponding to seven surface layer Cu atoms. The surface state energy shift is not as closely related to the adsorbate induced workfunction change as found theoretically and experimentally for alkali adsorbates. The influence on the shift of the workfunction and initial energy of the surface state is studied by preadsorbing Na on the Cu(111) surface.
|
|
| 3. |
|
|
| 4. |
- Paul, Jan, et al.
(författare)
-
Electronic structure of CO adsorbed on a Cu(111) surface analyzed with molecular cluster models
- 1982
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 26:8, s. 4073-4077
-
Tidskriftsartikel (refereegranskat)abstract
- Using the self-consistent Hartree-Fock-Slater model we have calculated the electronic structure for various Cux(CO)y clusters symbolizing not only CO bound to "on-top" and "bridge" sites but also some lateral CO-CO interaction on a Cu(111) surface. By comparison with experimental photoemission data we are able to reproduce the observed energies of the occupied CO 4σ, 1π, and 5σ orbitals as well as the partly occupied 2π orbital. In our model we assume CO to be adsorbed on "top" sites for coverages less than ⊖=0.33 [(sqrt[3]×sqrt[3])R30°] and on both top and bridge sites for ⊖>0.33. The experimentally observed peak of intensity at the Fermi edge which increases with coverage above 0.33 is in our model explained by the occupation of CO orbitals of the b1 and b2 symmetry types, i.e., "π" orbitals, degenerate for top positions (C3v), split by the change to bridge positions (C2v). Our results further indicate that the broadened 5σ-1π intensity peak at high coverages is a result of CO bound to top and bridge sites.
|
|
