Opacity of dense C₉H₁₀ with 1 at.% fluorine (as a tracer element), normalised to that of cold material, at a photon energy of 9 keV as a function of pressure. The NIC effect on the partition functions of free electrons is included in our DLA method. Plasma conditions are determined at the shock front along the shock Hugoniot measured by Kritcher et al. (2020). Experimental and theoretical data from DCA (Kritcher et al. 2020) are shown for comparison. The upper and lower limits of the experimental data indicate the uncertainty contours of ±1σ in the measurement.