Optical properties of polystyrene from the near-infrared to the x-ray region and convergence of optical sum rules

Optical properties of polystyrene in the form of thin films were determined for photon energies between 0.6 and 82 eV from transmission measurements. The results for $k$, the extinction coefficient, were combined with previous experimental results in the soft and hard x-ray regions up to 8050 eV. Analyses were made on several sum rules for the optical properties in this unusually wide energy range, including a sum rule for the refractive index $n$ derived recently by Altarelli et al. Redistribution of the oscillator strength corresponding to 2.7% of the total electrons was found between the valence and core excitations of carbon. Using the complex dielectric function and the energy-loss function obtained, the average photoexcitation energy and the average energy loss for fast-charged particles over the entire oscillator strength distribution were evaluated to be 25.1 and 36.8 eV, respectively.