Graphitic optical absorption properties

Optical absorption measurements indicate that the band gap of graphite oxide is within 2.4. 3 eV [64]. A detailed calculation has been performed to understand the effect of functional group, such as epoxide, hydroxyl, carbonyl, and their concentration to the optical properties of GO [65]. Their calculations predict a strong blue shift of the tt + <7 plasmon peak when the concentration of epoxides and hydroxyl groups in GO vary from 25 % to 75 %, while the n plasmon is less sensitive. Carbonyl groups present in the GO plane will create holes, which cause a red shift. Carbonyl holes significantly decreases the optical gap and opens the band gap, and they are useful for developing opto-electronic applications. 

The most particular among the optical properties of graphite and related materials is the approximation to an ideal black body microcrystalline forms of carbon have the highest absorptivity. Soot, for example, absorbs up to 99.5% of the incoming radiation. This value is much lower for other, better crystallized carbons, and very thin crystals of graphite are even transparent. The big absorptive capacity and black color of polycrystaUine carbons is caused by their low particle size. Within... 

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