Abstract
鈮(001)的表面能帶同時受到自旋-軌道角動量偶合與表面緊縮的影響.其 表面緊縮有13%.表面核層能階位移為0.49 eV. Angle-resolved photoemission was carried out to determine thesurface electronic structure along three high symmetry axes ofthe Nb(001) surface using gas discharge lamp. Ten surface bandshave been identified. The experimental data were compared with the self-consistent pseudopotential calculations for the 11-layer Nb(001) slabs. assuming that the first interlayer spacing is either bulk-like or 12% contraction. As a result, the band calculations for the later give better agreement with the experimental findings, except the absence of a surfaceresonance near the Fermi level. Spin-orbit interaction andsurface contraction affect the charge density distribution andposition of surface states and resonance as well. The effect due to surface contraction was pursued by thephotoelectron diffraction technique. The experimental data werecompared with the multiple-scattering calculations usinganalysis. The best agreement was 13%. Using the synchrotron radiation at the Synchrotron RadiationResearch Center, we for the first time observe surface coreemission of Nb(001). It is shifted 0.49 towards higherenergy from bulk emission. The positive shift is inthe previous theoretical predictions, butst recent ab initio calculation results.