Imaging Molecular Structures with Atomic Force Microscopy Tyler Flanagan, Unurbat Erdenemunkh Sponsor - (Professor Michael Boyer) Abstract As part of the LEEP project we repaired the Atomic Force Microscopy (AFM), and wrote a user manual on using AFM. Then we scanned Self Assembly of Copolymer Films collaboration with Prof. Sergio Granados – Focil and Copper Oxide Nanocubes with Professor Prof.Luis Smith. Atomic Force Microscopy Atomic Force Microscopy (AFM) is a high-resolution form of Scanning Probe Microscopy (SPM) which can produce object resolution on the order of less than meters. AFM imaging provides high-resolution three-dimensional information for both conductive and non-conductive materials in a variety of the environments including fluid and controlled temperature conditions. AFM works by having a sharp tip at the end of a cantilever brought into, or near contact with a sample surface. The tip interacts with the surface causing the cantilever to bend as it is moved along the surface. Modes A.AAC Mode In Alternating Current Atomic Force Microscopy (ACAFM) a piezoelectric transducer oscillates the cantilever at its resonant frequency. These oscillations are then reduced by interaction between the tip and sample and this reduction is then used as the feedback signal to maintain constant amplitude of the cantilever. The tip is then moved across the surface of the sample and using the feedback creates a topographic image. A.Constant Height Mode In constant height mode the tip is brought into contact with the surface, exerting a force of ~ to N. The tip is then dragged across the surface following the rises and falls of the sample surface. In constant height mode the height of the scanner is fixed and deflections/bending of the cantilever indicates topographical changes. B. Constant Force Mode Constant force mode utilizes the error signal as an input to a feedback circuit which is amplified and then used to control the height of the piezo actuator. This feedback circuit responds to the surface topography and aims to keep the deflection of the cantilever constant and in turn the force exerted by the tip on the sample constant as well. With this the feedback current can be used as an effective means of constructing the topography image. Facilitating Research Collaborations We facilitated two collaborated research with two chemistry professor on imaging molecular structures of Self Assembly of Copolymer films with Professor Sergio Granados-Focil and Copper Oxide Nanocubes with Professor Luis Smith. Self Assembly of Copolymer Films The first collaborative research was to image the Self Assembly of Copolymer Films. Copolymer Films are used for fuel cell. Therefore, Professor Sergio is interested in the ion transport within polymeric matrices. We used AFM to investigate the self assembly of copolymer films of different rations. Copper Oxide Nanocubes (Prof. Luis Smith) The second collaborative research we conducted was Imaging Copper Oxide Nano particles with Professor Luis Smith. Cu2O nanoparticles are catalytic important. We attempt to utilize the AFM to image the cube structures to give insight into what parts of the cube might be the important active sites for catalysis. We had little trouble of flattening the surface when we scanned because of the its powder form. Although, we produced decent topographic images like below, we still in process of finding best way to scan this cubes. Scanning The scan size, speed, orientation, resolution, and offset can all be adjusted within the window. A general rule is that slower cans will provide better resolution and that the maximum speed to have coarse resolution of features is about two ln/s The set point determines the amount the tip will push into the sample, a low set point might not resolve features while a high set point might push into the sample and damage the tip, for this reason it is recommended to begin with a low set point when scanning and increase gradually depending on the results. The integral and proportional gains determine how quickly the system can react to the feedback system which measures the changed in deflection of the tip. Low feedback may cause the tip to be unable to adjust to the feedback fast enough to have good image resolution while feedback that is too high may introduce unwanted noise and distort image features. Reference Agilent Technologies  5420 Scanning Probe Microscope User’s Guide. N.p.: © Agilent Technologies, 2010, n.d. Print. Kossek, Sebastian, and Mark Flowers. "Atomic Force Microscopy Overview." Atomic Force Microscopy Overview. © Nanoscience Instruments, Inc., n.d. Web. 15 Aug Figure 1: The first image is the MeOH, 2 nd image is ration MeOH and 3 rd is MEOH and 27-9 ration MEOH Figure 2:The following images show how the structure changes with the ratio.