Photoemission Photomicroscopy and Free-Electron Laser Spectroscopy of Solid-Surfaces and Interfaces

1993 has been full of landmarks for interface research: the new ultrabright soft X-ray synchrotron sources ALS-Berkeley, ELETTRA-Trieste and SRRC-Taiwan, and the user operation of the free electron laser (FEL) at Vanderbilt. They are particularly important for the increasing use of lateral resolution in photoemission, and for the first use of FEL spectroscopy. We review some recent results: the discovery of lateral band-bending changes of cleaved III-V's; [1] Gozzo et al.'s observation of spatially-varying barriers at Schottky [2] and heterojunction [3] interfaces; Cerrina et al.'s photoelectron micrographs of homojunctions; [4] Coluzza er al.'s evidence that many of the conventional photoemission spectra of insulators are heavily affected by local charging [5]. As to the FEL, we will present the two-photon absorption at the indirect Ge gap [6], and Coluzza er al.'s accurate and reliable measurements of energy barriers at ''buried'' interfaces with internal photoemission [7].