Title

Study of UV absorption in Exfoliated Graphene

Document Type

Graduate Research

Publication Date

4-7-2016

Department

Physics

Abstract

Two-dimensional (2D) materials such as graphene exhibit very unique electronic, thermal conductivity and optical properties due to changes in the electronic band structure. Graphene is the most electrically and thermally conductive material known with a mechanical strength stronger than steel. Because of that, it is considered to be the future of computing power, next generation transistors, energy storage and bio sensing. It has already found application in electric car batteries. Graphene is formed from one or few layers thick, hexagonally connected carbon atoms. These carbon atoms are connected via covalent bonds. Multiple layers of graphene are held together by weak van der Waals forces. In our research we try to break the van der Waals forces using chemical solvents and sonication to isolate one or more layers of graphene. The samples are characterized with UV-Vis spectrometer and optical microscopy. In our presentation, we will discuss the absorption properties of graphene obtained from graphite powder, graphite rod and graphite sooth in acetonitrile. The results indicate the existence of strongly localized absorption doublet-peaks at about 223 nm and 273 nm in the UV region (4.78 eV and 4.44 eV photon energies respectively) with a line width range of 0.3-0.5 eV for graphite poweder in acetonitrile. The other two samples give only single peak at about 273 nm. We will present our data for different sonication times and try to explain the existence for the 223 nm peak, which was not observed in all samples.

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