Structure of Molecular Rydberg States in Supercritical Alkanes Gary L. Findley, Chemistry Department, University of Louisiana at Monroe Monroe, LA 71209 We have measured and successfully simulated the absorption spectra of CH3I in CH4 using a single set of intermolecular potential parameters. Example simulations of CH3I in CH4 are shown to the left as blue lines in comparison to experiment (black lines). The first moment of the simulated band is given below as a function of reduced number density ρr (ρr = ρ/ρc) and clearly illustrates the critical point effect (red points). Current studies focus on the structure of Xe and CH3I Rydberg states in CF4.