SURFACE-STATE AND DIRECT TRANSITIONS ON AL (111) INVESTIGATED WITH ANGLE-RESOLVED PHOTOELECTRON-SPECTROSCOPY

Al(111) has been studied with angle-resolved photoelectron spectroscopy. A previously not observed surface state band located around the K point in the surface Brillouin zone is reported. The measured dispersion of the surface state band falls in an absolute electron energy band gap when the three-dimensional band structure from a new LAPW (Linearized-Augmented-Plane-Wave) calculation is projected onto the surface Brillouin zone of the (111) crystal face. The existence of this surface state has been theoretically predicted by several authors. Direct transitions between bulk bands are found to give significant contributions to the photocurrent. Experimentally deduced initial-state energy dispersions of the bulk transitions are compared to the corresponding dispersions obtained from the LAPW band structure calculation.