Scanning Probe Microscopy for fundamental studies in nanoscience

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The atomic force microscope (AFM) is an ideal tool for Nanoscience, as it allows imaging, manipulation and characterization of individual nanometer sized objects. The long-term aim of my research program is to continue to gain a fundamental understanding of the structure-property relation of nanoscale systems with respect to information storage or processing by building on recent NSERC DG funded experimental breakthroughs and instrumentation developments. This research program provides a rich, interdisciplinary and world-class environment for the training of HQP and many potential socio-economic technology spin-offs.****We are planning on understanding the conductance and the mechanical properties of single molecular devices that could form the basis of future nanoelectronics using our two unique UHV AFM systems. We want to understand THE issue in molecular electronics: the role of contacts. The comparison of currently available experimental data with theoretical modeling is very difficult, as the atomic structure of the contact leads is of utmost importance, but usually not experimentally controlled. ****A further project is to understand how order and defects in organic molecular systems determines conductivity and opto-electronic properties. By pumping the sample with ~100 fs optical pulses we will generate excitons and ultimately free charges. By detecting the resulting electrostatic forces on the AFM tip we will achieve nm scale spatial resolution. In collaboration with specialists in optical and THz spectroscopy we will thus gain a deep understanding of light-matter interactions, charge separation and conductivity in organic systems.****We plan to use our cryogenic AFM to characterize the charging of semi-conducting and metallic quantum dots (QD). Our detailed quantitative understanding of the mechanically detected single electron signals allows us to extract the energy levels, density of states as well as coupling strengths of individual and coupled QD. We will test an exciting theoretical prediction that the coherence time T1 can be directly extracted from our AFM dissipation measurement! We also aim to observe the charge transfer due to a single molecule coupled to a QD, resulting in a shift of the experimentally observable energy levels and energy level alignment. By changing the coupling chemistry this will lead to a detailed understanding of organic contacts. ***Finally, we will continue our efforts to fundamentally understand how biological systems process information. We are in particular interested in understanding what determines the signal processing capabilities in neurons. We recently demonstrated that we could construct new, functioning neuronal connections. We can thus now experimentally control all the relevant parameters to understand a simple biological neuronal network with a view of implementing the lessons learned in engineered nanoelectronics systems.**