Multilayer thermal expansion of determined from surface core level shifts

¹ Sincrotrone Trieste S.C.p.A. - S.S. 14 km 163.5, 34012 Trieste, Italy
² Dipartimento di Fisica, Università di Trieste - Via Valerio 2, 34127 Trieste, Italy
³ Laboratorio TASC-INFM - S.S. 14 km 163.5, 34012 Trieste, Italy
⁴ Department of Physics, University of New Hampshire - Durham, NH 03824, USA
⁵ Institute for Storage Ring Facilities, University of Aarhus DK-8000 Aarhus C, Denmark
⁶ Scuola Internazionale Superiore di Studi Avanzati (SISSA) and INFM Via Beirut 2-4, I-34014, Trieste, Italy

Received: 27 May 2003
Accepted: 25 August 2003

Abstract

We have determined the thermal expansion of the first three interlayer spacings of by comparing measured temperature-dependent surface core level shifts and surface state positions to values calculated with Density Functional Theory for different surface geometries. Our results reveal that, in the temperature range from 300 to 700, the 1st-to-2nd, 2nd-to-3rd and 3rd-to-4th interlayer coefficient of thermal expansion are , and , respectively. We have now set as a challenge for further theoretical improvements, since a complete theoretical understanding of surface thermal expansion does not exist.