Characterization of the oxide surfaces
Average techniques such as electron spectroscopy (i.e. XPS, UPS or AES) can be applied at the first stage to characterize the surface stoichiometry and chemical modification of several materials. These data may stand however in contrast to the local nature of specific cations or anions sites, whose intrinsic properties are strongly influenced by the local morphological and chemical environment. To account for the close correlation between these properties and the local surface morphology, a spatially resolved topographic and optical technique is highly desired.
Local Microscopy and Spectroscopy by SPM
The experimental approach envisaged on this project combines low temperature-cooled photon-scanning probe microscope (SPM) for local microscopy and spectroscopy. For this purpose, a single tube scanner-type SPM head is placed such as a spherical lens system out-side the vacuum chamber channels the light towards an optical fiber. The optical fiber guides the light to a liquid-nitrogen cooled CCD detector coupled with a grating spectrograph. The CCD detector, characterized by an extremely high sensitivity and a small dark signal, allows the accumulation of photons and therefore the detection and spectral analysis of photon yields as small as 100 photons per second. Whereas topographic STM imaging might help identifying the spatial distribution of the species on the surface, the optical mode provides information on their electronic structure with high sensitivity. In addition, photon can be also guided inside to the tip-sample surface junction in order to investigate light matter interaction for spectroscopy (TERS, tip-enhanced Raman) or to investigate how photons can drive chemical reactions locally, photo-chemical processes.
People and Collaborations
Jorge Meyrelles, jotaengpuc at gmail.com
Prof. Ado Jorio, Universidade Federal de Minas Gerais
FAPERJ, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
CNPq , Conselho Nacional de Desenvolvimento Científico e Tecnológico