10.1021/jp805620q.s001 Chet Swalina Chet Swalina Sergei Arzhantsev Sergei Arzhantsev Hongping Li Hongping Li Mark Maroncelli Mark Maroncelli Solvation and Solvatochromism in CO<sub>2</sub>-Expanded Liquids. 3. The Dynamics of Nonspecific Preferential Solvation American Chemical Society 2008 measurement Molecular dynamics computer simulations CH 3CN molecules DCS measure solvation dynamics CO system CH 3CN cybotactic region CH 3CN component GXL solvatochromism S 0. Solvation dynamics 2008-11-27 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Solvation_and_Solvatochromism_in_CO_sub_2_sub_Expanded_Liquids_3_The_Dynamics_of_Nonspecific_Preferential_Solvation/2896897 Subpicosecond time-resolved fluorescence of trans-4-dimethylamino-4′-cyanostilbene (DCS) is used to measure solvation dynamics in the gas-expanded liquid (GXL) system CH<sub>3</sub>CN + CO<sub>2</sub> at 25 °C along the liquid−vapor coexistence curve. These measurements are supplemented by measurements of the steady-state solvatochromism of DCS and of its rotation and isomerization times. Molecular dynamics computer simulations and a semiempirical spectral model that reproduces the observed solvatochromism in this system are used to interpret the experimental results. Simulations indicate that at compositions of <i>x</i><sub>CO2</sub> > 0.5, the cybotactic region surrounding DCS is enriched in CH<sub>3</sub>CN molecules, and the extent of this enrichment is greater in S<sub>1</sub> than that in S<sub>0</sub>. Solvation dynamics are dominated by the CH<sub>3</sub>CN component. These dynamics are biphasic, consisting of a subpicosecond inertial component, followed by a slower picosecond component, related to the redistribution of CH<sub>3</sub>CN molecules between the cybotactic region and the bulk solvent.