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Abstract

In the pursuit of an understanding of complex surfaces, the problem of obtaining quantitative structural information about local adsorbate geometry is especially difficult. Conventional diffraction methods rely on long-range order of the adsorbed species, rarely present in complex coadsorption systems. Elementally specific local structural probes can help, but ultimately one also requires chemical-state specificity. This can be achieved in structural methods that involve detection of photoelectrons through the well-known ‘chemical shifts’ in core-level photoelectron binding energies; specific methods of this type are scanned-energy mode photoelectron diffraction (PhD) and normal-incidence X-ray standing waves (NISXW). Recent examples of chemical-shift PhD and NIXSW applications to complex coadsorption systems and to larger molecular adsorbates demonstrate this potential.