Title

Phase diagram of hydrogen on Be(0001) from reconstruction-induced surface core-level shifts

Abstract

The surface core-level shifts (SCLS) on the (0001) surface of beryllium were used to study the phase diagram of the hydrogen-induced reconstructions on this surface. Two different top-layer reconstruction phases are formed upon atomic hydrogen adsorption below and above room temperature, respectively. We are able to assign a characteristic core-level spectrum to an individual reconstruction phase and trace its presence at various hydrogen coverages and sample temperatures. This technique makes it possible to survey the low-coverage regions that are lacking long-range ordering. Adsorption of atomic hydrogen in a temperature range of 100 to 270 K induces a (root3xroot3)R30degrees H-Be(0001) chemisorption structure, in which 1/3 of the Be top-layer atoms are removed to form a honeycomb structure of Be vacancies. Upon adsorption above 300 K a (1x3) superstructure forms, which has been proposed to exhibit a missing-row reconstruction of the Be top layer. Our hydrogen-induced SCLS measurements reveal that beryllium vacancies are forming already at small H coverages of 0.2 monolayers.

Department

Physics

Publication Date

12-29-2004

Journal Title

Physical Review B

Publisher

AMERICAN PHYSICAL SOC

Digital Object Identifier (DOI)

10.1103/PhysRevB.70.235424

Document Type

Article

Rights

© 2004 The American Physical Society

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