Titanium dioxide (TiO2) is an abundant, inexpensive and non-toxic material that is most commonly used as a white pigment in paints. Since the discovery by Fujishima and Honda in 1972 that water splits into hydrogen and oxygen gas at the surface of TiO2 on exposure to sunlight, there has been a massive research effort into understanding and improving the photoactivity of TiO2. One aspect of this is the characterisation of so-called ‘model’ surfaces, i.e. very large single crystal faces with low levels of contamination at ultra high vacuum (UHV) pressures, allowing the study of a single structure with a minimum of unknown variables effecting experimental results. Two techniques that are used to probe surface structure, amongst many, are Surface X-ray Diffraction (SXRD) and Photoelectron Spectroscopy (PES). SXRD allows quantitative determination of surface structure with high precision, and PES reveals surface chemical composition. In the context of this thesis both of these techniques were exploited at synchrotron radiation sources, which produce light of high brightness. In addition, the development of routines for extraction of SXRD data from 2D detectors to allow SXRD analysis is described. SXRD is employed to probe the structure of anatase-TiO2(101) both in UHV and following immersion in water vapour. The optimum UHV structure is largely in agreement with that previously predicted computationally, although there are some discrepancies in terms of atomic displacements. Water immersion leads to a H2O/OH terminated surface. The surface structure of a rutile-TiO2(110)(1x1) surface, that had been prepared under non-UHV conditions, using a wet chemical preparation technique, is also determined with SXRD. The studied surface, which was highly hydrophilic, has a similar substrate termination to UHV-prepared rutile-TiO2(110)(1x1) but with adsorbed surface H2O/OH species. Finally, PES is used to gain insight into the O1s signature of surface bridging oxygens on rutile-TiO2(110), as well as those (if any) of oxygen adatoms. Concerning bridging oxygens, it is demonstrated that there is no discernable shift in the O1s core level for these atoms away from the bulk oxide peak. Regarding oxygen adatoms, no conclusive evidence of a distinct emission signal in the O1s core level or valence band spectra can be discerned, due to interference from carbon contamination.

X-ray absorption is not only element specific, but atom specific: two atoms of the same element in different states or in different neighbourhoods will have slightly different absorption characteristics. These energy dependent atomic form factors are carried over to the diffraction intensities. The atomic form factors are sensitive not only to the the energy of the X-ray but also the diffraction criteria; providing individual local physical data at different ratios in various diffractions. This process is referred to as site selectivity, it is unique to Diffraction Spectroscopy, and is achieved only when the sample is in crystal form. Through this work, a technique has been devised to site-separate two atoms of iron from within a protein, that builds on prior small unit cell Diffraction Anomalous Fine Structure experiments and harnesses the collection and processing software commonly used in large unit cell crystallography. A technique (dev + PCA) has been developed to retrieve the small signals from individual atom-labels out of the large and noisy background of real diffraction taken across a spectrum. The intensity of the diffractions are calculated by integrating over multiple images, profiling spots, merging datasets, and scaling across the whole spectrum. This thesis explores how Diffraction Spectroscopy can be used effectively on large unit cells, namely those of proteins. Site-selective absorption experiments were conducted on large unit cell crystals at a 3rd generation beamline, exclusively using existing equipment. The spectra generated were limited in scope but are an adequate proof of concept.