Faculty of Engineering and Natural Sciences
Simultaneous AFM/STM Investigation of Surfaces at the Atomic Scale
H. Özgür Özer
SFI Trinity Nanoscience Lab., School of Physics., Trinity College Dublin, Dublin2, Ireland
Scanning Probe Microscopy has proven to be a powerful technique in surface science in investigating physical phenomena at molecular and atomic scale. Especially Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AFM) have helped a lot to the field of nanoscience, with their high spatial resolution and capabilities in manipulating structures even down to the atomic level. We investigated atomically clean Cu(100) and Si(111) surfaces using a combined AFM /STM system working in ultra high vacuum. The microscope employs a high resolution fibre interferometer with a very high sensitivity which allows direct quantitative measurements of force/force gradients between the probe and the sample surface. Simultaneous force gradient and STM topography images of the surfaces are obtained with atomic resolution. We also carried out force/tunnel current vs distance spectroscopy experiments allowing more insight into the inter-atomic potentials. Conservative and dissipative force interactions are extracted. Investigation of dissipative force interactions is the route to understanding the origins of friction and mechanisms of atomic manipulation. Furthermore, simultaneous use of AFM and STM with small lever oscillation amplitudes is crucial in identifying the adsorbed species on surfaces. The first results on Br adsorption on Si(111) and controversial surface of TiO2(110) will also be presented.
Dr. H. Özgür Özer, graduated from Bilkent University, Turkey with a BSc in Physics. He then went on to earn his MSc and PhD degrees from the same institution. During his PhD study he spent more than a year in the group of Prof. Pethica in the Department of Materials, Oxford University, where he was involved in the construction of a novel Atomic Force Microscope. He was a visiting researcher in the same group at Oxford University before he joined the group of Prof. Pethica in SFI Trinity Nanoscience Laboratory at Trinity College Dublin. His current interests include: understanding of physical phenomena on the nanometer scale including atomic manipulation, dissipative processes, quantized conductance, investigation of atomic and molecular forces, identification of adsorbates on surfaces, and design and construction of new AFM techniques to help simplify use of microscopes and interpretation of the data.
May 8, 2006, 15:40, FENS L056