QUANTUM INTERFERENCE IN 2D ATOMIC-SCALE STRUCTURES

Electrons occupying surface states on the close-packed faces of the no ble metals form a two-dimensional (2D) electron gas that is accessible to the scanning tunneling microscope (STM), Using a cryogenic STM, we have observed quantum mechanical interference patterns arising from 2 D electrons on the surface of Cu. These interference patterns can be a rtificially controlled by arranging individual Fe atoms into ''quantum corrals'' on the Cu surface, Quantum corrals behave qualitatively lik e 2D hard-wall boxes, but a quantitative understanding is obtained wit hin a multiple scattering formalism. The scattering here is characteri zed by a complex phase shift which can be extracted from the electroni c density pattern near a quantum corral.