Real-Time Observation of Adsorbate Atom Motion above a Metal Surface

• Published in: Science (American Association for the Advancement of Science) Vol. 288; no. 5470; pp. 1402 - 1404
• Main Authors: Petek, Hrvoje, Weida, Miles J., Nagano, Hisashi, Ogawa, Susumu
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 26.05.2000; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Adsorbed layers and thin films; Alkalies; Applied sciences; Atoms; Atoms & subatomic particles; Cesium; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Copper; Electron and ion emission by liquids and solids; impact phenomena; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electrons; Energy; Exact sciences and technology; Impurity and defect levels; energy states of adsorbed species; Lasers; Metal surfaces; Metals. Metallurgy; Motion; Observation; Orbitals; Photoelectric emission; Photoemission and photoelectron spectra; Photoexcitation; Physics; Real time; Spectroscopy; Surface and interface electron states; Wave packets; Chemisorption; Surface electron state; Cesium; Surface diffusion; Experimental study; Real time; Photoelectron spectroscopy; Time resolution; Adsorption; Transition elements; Chemical bonds; Two-photon spectra; Copper
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.288.5470.1402

The dynamics of cesium atom motion above the copper(111) surface following electronic excitation with light was studied with femtosecond (10-15seconds) time resolution. Unusual changes in the surface electronic structure within 160 femtoseconds after excitation, observed by time-resolved two-photon photo-emission spectroscopy, are attributed to atomic motion in a copper-cesium bond-breaking process. Describing the change in energy of the cesium antibonding state with a simple classical model provides information on the mechanical forces acting on cesium atoms that are "turned on" by photoexcitation. Within 160 femtoseconds, the copper-cesium bond extends by 0.35 angstrom from its equilibrium value.