Intrinsic and extrinsic bands in optical spectra of linear-chained carbon films on sodium and potassium chloride substrates

A practically important task of synthesizing isolated carbon nanostructures can be solved by removing soluble chloride substrates. However, a reliable express characterization method to control the synthesis results is needed. In this paper, the optical reflection and absorption spectra of the linear-chain carbon (LCC) films on sodium and potassium chlorides surfaces were studied numerically using DFT modeling. In the optical absorption and reflection spectra three peaks were found that are absent in the spectra of pure substrates. Two of them observed in red and UV regions of the difference absorption spectra have been mapped to transitions between carbon states seen in the electronic DOS. Chlorine and potassium/sodium energy states have been found to contribute to the high-energy VUV peak. The bands discovered would be useful for the rapid characterization of an LCC coating and determination of the crystalline substrate orientation.