[en] Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of primary radiation chemistry, charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of reactions and product distributions. We study these issues by characterization of primary radiolysis products and measurements of their yields and reactivity, quantification of electron solvation dynamics and scavenging of electrons in different states of solvation, using BNL's Laser-Electron Accelerator Facility (LEAF). The recently-developed Optical Fiber Single-Shot (OFSS) optical detection technique permits us to directly examine the competitive kinetics of pre-solvated electron scavenging and electron solvation in ionic liquids using a broad range of scavengers and liquids of widely different viscosities. Pre-solvated electron scavenging is especially significant in ionic liquids because their relatively high viscosities make their solvation dynamics 100-1000 x slower than in conventional solvents. Pre-solvated electrons are more mobile and show different reactivity patterns than solvated ones. Using OFSS, we can compare and contrast the different mechanisms of pre-solvated electron scavenging, as demonstrated below for roughly equal concentrations of duroquinone and nitrate anion. Results will be presented for a wide variety of scavengers. (authors)