Reactivity of sub 1 nm supported clusters: (TiO2)(n) clusters supported on rutile TiO2 (110)

Metal oxide clusters of sub-nm dimensions dispersed on a metal oxide support are an important class of catalytic materials for a number of key chemical reactions, showing enhanced reactivity over the corresponding bulk oxide. In this paper we present the results of a density functional theory study of small sub-nm TiO2 clusters, Ti2O4, Ti3O6 and Ti4O8 supported on the rutile (110) surface. We find that all three clusters adsorb strongly with adsorption energies ranging from -3 eV to -4.5 eV. The more stable adsorption structures show a larger number of new Ti-O bonds formed between the cluster and the surface. These new bonds increase the coordination of cluster Ti and O as well as surface oxygen, so that each has more neighbours. The electronic structure shows that the top of the valence band is made up of cluster derived states, while the conduction band is made up of Ti 3d states from the surface, resulting in a reduction of the effective band gap and spatial separation of electrons and holes after photon absorption, which shows their potential utility in photocatalysis. To examine reactivity, we study the formation of oxygen vacancies in the cluster-support system. The most stable oxygen vacancy sites on the cluster show formation energies that are significantly lower than in bulk TiO2, demonstrating the usefulness of this composite system for redox catalysis.

The endless search for SA: spiritual ideology in Hindustāni music

This dissertation centres on philosophical attitudes presented by North Indian classical musicians in relation to the concept and experience of rāga improvisation. In Hindustāni music, there is a dynamic tension ideology and pragmatism, devotion and entertainment, fixity and improvisational freedom, and cognition and visceral experience. On one hand, rāga is an embodied methodological template for the creation of music. On the other hand, rāga improvisation is conceptualised as a path to metaphysical experience and as an evocation of an ineffable divine presence. A masterful rendition of rāga is both a re-enactment of a systematic prescribed formula and a spontaneous flow of consciousness. This study presents these apparent dichotomies to highlight ideological concerns, while simultaneously contextualising philosophical idealism in relation to pragmatic realities. A central paradigm is the manner in which pragmatic concerns are elevated in status and given spiritual significance. The dissertation begins with a view into historical and religious context. The discussion continues with a speculative investigation positing co-relations between Hindustāni music and central tenets of Indian philosophy, considering how rāga improvisation may manifest as a philosophy of sound. The study then explores the concept of rāga, a modal and conceptual construct that forms the heart of Indian classical music. The final three sections ground the subject of spiritual ideology within the life experience of Hindustāni musicians: ‘Transmission’ looks at the learning and enculturation process, which encapsulates values intrinsic to the ethos of Hindustāni music culture. ‘Practice’ explores the discipline, science and experience of musical practice, revealing core ideological concerns connecting spirituality to musical experience; and ‘Performance’ examines the live presentation of rāga improvisation, and the relationship between music as ‘entertainment’ and music as ‘devotion’. Both ethnographic and musicological, this research is the culmination of various fieldtrips to India, extensive interviews with Hindustāni musicians, fifteen year’s sitār training, and the study of relevant musicological and philosophical texts.