Next‐Generation Time‐Resolved Electron Paramagnetic Resonance for Direct Visualizing Mechanisms in Radical Chemistry

Abstract Radical chemistry is an important research field that plays a vital role in life science, material science, and energy conversions. However, directly visualizing the transient open‐shell intermediates unambiguously in radical chemistry is a significant and long‐standing challenge. Recently, we have developed an innovative ultrawide single‐sideband phase‐sensitive detection (U‐PSD) time‐resolved electron paramagnetic resonance (TREPR) technique, which enables the characterization of diverse transient radical intermediates and mechanistic studies close to reaction conditions. In this brief review, we will offer an outline of the principles underlying our U‐PSD TREPR technique, and present examples highlighting the technique's ability to accurately characterize and track free radical intermediates in photocatalytic reactions.