Physics Atomic Force Microscopy - 1429 Words

ATOMIC FORCE MICROSCOPY 1. Introduction to Atomic Force Microscopy An atomic force microscope (AFM) is a type of scanning probe microscope (SPM). An AFM uses a cantilever with a probe to scan over a sample’s surface. The probe is a sharp tip (3 to 6 ï  ­m pyramid; 15 to 40 nm end radius) such as the one shown in Fig. 1. As the tip of the AFM approaches the surface, at close range, attractive forces between the sample surface and the tip of the AFM causes the cantilever to deflect towards the surface. As the cantilever moves close to the surface, when the tip tends to make contact with it, increasingly repulsive forces take over and causes the cantilever to deflect away from the surface. A laser beam is used to detect cantilever movements towards or away from the surface. The laser beam is reflected back from the cantilever to a position-sensitive photo diode (PSPD). The deflections due to the interaction between the tip and the sample’s surface causes slight changes in the angle with which the laser beam reflects off the cantilever as shown in Fig. 2. This change in the angle of reflected beam is detected by the PSPD. Thus, if the tip passes over a depression on the sample, the resulting deflection of the cantilever causes a change in the angle and direction at which the laser beam reflects f rom the cantilever to the PSPD. AFM uses a feedback loop to continuously control the position of the tip (Fig. 3). By controlling the tip, an accurate surface imaging and topographicShow MoreRelatedThe Physics Of Atomic Force Microscopy1259 Words   |  6 Pages Abstract Atomic Force Microscopy was the method used to analyze samples inorder to identify their surface composition and determine their top structure. Compiled data was used to calculate the roughness of the sample. 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Developing graphene with specific structural properties depends upon controlling these defects, either by removing or deliberately engineering atomic structure to gain or tailoring specific properties. In the present article, a comprehensive review of defective graphene sheets with respect to its mechanical and thermal properties are presented and examined. Key Words: Graphene; point defects; lineRead MoreThe Theory Of Graphene On Science And Future Electronic Technology1905 Words   |  8 Pagesgraphene held together through weak Van der Waals forces.6 â€Å"Few-layer graphene† (very thin films of graphite, called FLG) was produced as early as 1948 by G. Ruess and F. Vogt7 but single-layer graphene, a single carbon atom thick, was not isolated successfully until 2004 at the University of Manchester by Andre Geim and Kostya Novoselov.1 Their work was published in the highly influential journal Science, and was subsequently awarded the Nobel Prize in Physics in 2010, for â€Å"ground-breaking experiments regardingRead MoreThe Effect Of Carbon Nanotubes On Other Fields Of Materials Science2155 Words   |  9 Pagesof sp2 bonds, like the ones seen in graphite. This bonding structure, stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into ropes hel d together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, thus acquiring great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking. 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