The excitation of the Rydberg states is used to study the nonpolar solvation dynamics in supercrit. fluids (SCFs). The system NO in supercrit. Ar serves as the model system. First, the steady-state, absorption and fluorescence spectra of the NO X 2P-A 2S+(3ss) Rydberg transition were recorded in the supercrit. domain of Ar. Then, mol.-dynamics simulations were carried out to explore the details of the structural rearrangements and solvation dynamics upon the excitation of the Rydberg state. The validity of the MD simulations was checked by reproducing the steady-state spectroscopical observables. Esp., the influence of the near crit., local d. fluctuations on the solvation dynamics was analyzed. The differences between the time-dependent Stokes shift (TDSS) and the equil. transition energy correlation function (ECF) are used for the anal. [on SciFinder (R)]