In this research, graphene obtained through synthesis with the Hummers method. Graphene synthesis was conducted by the Hummer using basic materials such as graphite powder, KMnO4, NaNO3 and H2SO4. A total of 5 grams of graphite powder mixed with 4 grams of NaNO3, 98 ml of 98% H2SO4 and rotated (stirring) for 4 hours on ice bath. After the stirring process runs for 1 hour, added 8 grams of KMnO4 little by little, then the stirring is continued. The solution will change color to greenish black. During the stirring process, the temperature is kept around 20 ° C. Stiring After 4 hours, the solution was removed from the ice bath, then Stiring was continued for 20 hours and the temperature is kept around 35 ° C. All material mixing process performed in a fume hood. The next step 200 ml of distilled water are added gradually and rotated (stirring) for 1 hour, the solution will change from light brown to dark brown. Next up is the addition of 20 ml 30% H2O2, the solution will change color from dark brown to yellow. To separate the sludge and liquid centrifuge process is carried out 6000 rpm and the addition of distilled water repeatedly until…show more content… The first do is input the data kappa and energy to be extrapolated . Determine the amount of extrapolation , the cut-off value of kappa and the cut off energy . Then make a new ( wave) for the extrapolation of the value of kappa and energy with the number of data extrapolation . Then , the next stage is the making of a computer program to program by entering the Kramers - Kronig input kappa value that has been extrapolated . If k is a function of frequency ( ), which is the imaginary part then to get the value of n can be done by using the Kramers - Kronig . First made discretization spaced frequency = 0.01 ( figure 1 ) . The n value can be calculated using the following equation