title: Snell's law for surface electrons: refraction of an electron gas imaged in real space.
abstract: On NaCl(100)/Cu(111) an interface state band is observed that descends from the surface-state band of the clean copper surface. This band exhibits a Moiré-pattern-induced one-dimensional band gap, which is accompanied by strong standing-wave patterns, as revealed in low-temperature scanning tunneling microscopy images. At NaCl island step edges, one can directly see the refraction of these standing waves, which obey Snell's refraction law.
authors.affiliation: IBM Research, Zurich Research Laboratory, CH-8803 Rüschlikon, Switzerland.
authors.forename: Jascha
authors.initials: J
authors.lastname: Repp
authors.forename: Gerhard
authors.initials: G
authors.lastname: Meyer
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Rieder