Effect of electronic transitions on near edge optical properties of off-stoichiometric boron carbide thin films

In the present study, soft x-ray optical properties of off-stoichiometric boron carbide thin films are investigated, and the structure and chemical composition of the film is analyzed using angle dependent x-ray reflectivity and x-ray photoelectron spectroscopy techniques. Energy dependent soft x-ray reflectivity measured at a fixed grazing angle of 1.5(degrees) is used to determine the optical constants in the boron K edge region by applying the Kramers-Kronig technique. The measured optical constants show near edge fine features corresponding to sigma* and pi* resonances. The electronic transitions corresponding to sigma* resonance cause a 40%-75% increase in the delta value in the above boron K edge region. The pi* transitions corresponding to off-stoichiometric nature of the boron carbide are observed in the absorption spectra near similar to 192.7 eV. Details of the measured soft x-ray optical properties of the off-stoichiometric boron carbide thin film are discussed.