The lab has had a unique program in Canada to use LEED crystallography to learn about the detailed reconstructions, relaxations, bond lengths and angles for chemisorption on well-defined single crystal surfaces, and to establish how incipiently formed surface compounds match in detail to an underlying substrate structure when regularly ordered growth occurs. An objective is to establish the principles of surface structural chemistry, and to relate them to the better-established principles for molecular and solid state structural chemistry. A new theme of interest is to study structure for chemisorption at stepped surfaces, particularly using surface x-ray diffraction (SXRD). This latter technique uses beams from synchrotron sources at very small glancing angles of incidence, and it has the potential to make much wider-ranging studies of interface and surface structure that can be done with laboratory-based methods. Surface x-ray scattering is expected to have applications to study surface structure in situ for catalytic and electrochemical systems, as well as to determine structure as a function of depth, as in buried interfaces in electronic devices, by controlling the glancing angle to vary the X-ray penetration depth.