The frontiers of surface structure analysis

Abstract Low‐energy electrons have been used predominantly to determine surface structure: low‐energy electron diffraction (LEED) surface crystallography to identify the location of surface atoms and molecules, their site symmetry, bond distances and bond angles; and high‐resolution electron energy‐loss spectroscopy (HREELS) to determine the vibrational spectra of atoms and molecules at surfaces. The key findings of research using LEED and HREELS will be discussed. The new directions of research using these two techniques for studies of disordered surface layers and more complex molecules will be reviewed. Scanning tunneling microscopy (STM) and atomic force microscopy are new techniques under rapid development for surface structure determination. The combination of STM and LEED crystallography permits the quantitative validation of STM findings. Atomic spatial resolution uncovered several unexpected surface structures. The use of STM during high‐pressure catalytic reactions is at the frontier of surface structure studies. Extended x‐ray adsorption fine structure (EXAFS) and photoelectron diffraction have been used to study the atomic structure and coordination of clusters. Laser sum frequency generation (SFG) is employed to obtain vibrational spectra of molecules at solid/liquid and solid/solid interfaces. These techniques expand the frontiers of surface structure analysis to new types of surface and interface systems.