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Seminário de Física da Matéria Condensada

23/11 - 5a feira - 11h00
Sala 429 - 4o andar da torre nova

Palestrante:  Fernando Stavale

Título: Probing the electronic structure of gold nanoparticles on polar ZnO (0001)



Resumo: The electronic properties of nanoparticles on oxide surfaces are strongly dependent on its size, symmetry and the interfacial interactions [1]. Particular combinations of particle dimensions and oxide electrical response usu- ally result on unique optical properties related to plasmonic excitations [2]. Likewise, the proper tuning of the metal/oxide interaction also promote its chemical reactivity, where one of the most prominent being the remark- able catalytic activity of gold clusters onto selected oxides [3]. In this contribution, angle-resolved photoemission spectroscopy (ARPES) has been employed to investigate the electronic structure of gold nanoparticles deposited on the ZnO (0001) surface. The energy position and curvature of the confined Shockley surface states on the top (111) facets of the nanogold are revealed from the Fermi-surface maps. The spectral features support the understandings that charge transfer occurs from the metal to the surface in order to electrostatically balance the oxide. Our findings reveal how metal nanoparticles are modified by the surrounding oxide, a topic of wide relevance in most applications of the nanotechnology.

[1] X. Lin, N. Nilius, H.-J. Freund, M. Walter, P. Frondelius, K. Honkala, H. H ?akkinen, Phys. Rev. Lett. 102, 206801 (2009). [2] U. Kreibig and W. Vollmer (Eds.), Optical Properties of Metal Clusters (Springer, Berlin, 1995). [3] N. Udawatte, M. Lee, J. Kim, D. Lee, Appl. Mater. Interfaces 3, 4531 (2011).