Metal surfaces and surface alloys studied by electron spectroscopy and synchrotron radiation

Abstract

The atomic structure and the electronic structure of the surface of a solid can be very different from that of the interior of the material; however, it is this region that will dictate many of the important properties of materials. It is therefore surprising to discover that up to 1998 only about 1000 surfaces had been well characterized with respect to atomic and electronic structure; the situation is particularly difficult for metallic alloys in general and especially for surface alloys. With this project we intended to upgrade our experimental infrastructure at the Institute of Physics at Unicamp (IFGW) and at the Brazilian National Synchrotron Laboratory, LNLS, for the study of the surfaces of metals and alloys using different electron spectroscopies (XPS, LEED, PD and RHEED) and to use this infrastructure to study alloys based on noble metals and transition metals that have potentially interesting catalytic properties. We also intend to study the surfactant properties of some sp metals (In, Sn, and Sb) on the noble metals and some transition metals. Parallel to these studies we will also try to get insight into fundamental problems related with the emission of photoelectrons and Auger electrons from these materials mainly to understand phenomena such as screening and the relaxation of atoms with the creation of a core bole. Basically the project will involve: a) installing a new samples manipulator with two motorized axes of rotation and integrate their control into the electron analyzer control software for automated photo-electrons diffraction experiments; b) build an angular resolved photo-electron spectrometer system for angular resolved studies; c) install a data acquisition system for LEED and RHEED experiments; d) set up a system to study the growth of epitaxiallayers by RHEED. This will make it possible to get important parameters such as interatomic distances and growth modes in real time during the actual growth of our alloys; e) study metallic alloys grown on noble metal single crystal substrates and of metals with an almost full "d" band (Ni, Pd, and Pt) from the atomic structure and electronic structure viewpoints; f) study the effect of low coverings of "sp" metals such as In, Sn and Sb on the growth of the metals of the previous item to understand the surfactant -properties of these elements on those systems. (AU)