Measurement of complex refractive index of graphene in infrared bands by reflection spectra

Abstract

Graphene is a new type of infrared interference carbon Nano-material. The complex refractive index is an important parameter to study its extinction performance. The reflection spectra in 2.5 to 25 m wavebands of graphene pellets were measured by Fourier infrared spectrometer, and the complex refractive index was calculated by Kramers-Kronig ( K-K) relation, and calculation deviations were analyzed. The calculation results show that the real part of complex refractive index is 3.5 to 4.9 and the imaginary part is 0.3 to 2. The results of error analysis indicate that, the difference between the measured reflectivities of 22 degrees angle of incidence and the reflectivities of normal incidence is 10^-4 , the oblique incidence can be used to represent the normal incidence condition, and the different extrapolation of the reflectivities outside the test wavebands have little effect on the results. The data of complex refractive index has some reference value for the study of the infrared extinction characteristics of graphene.