Ordering, Interaction, and Reactivity of the Low‐Lying nπ and ππ Excited Triplet States of Acetophenone Derivatives

Lay low for a while: The low‐lying nπ* and ππ* triplet states of substituted acetophenones have been directly observed by time‐resolved near‐infrared spectroscopy. The apparent reactivities of the ππ* T1 states of acetophenones have been shown to arise from the thermal population of the higher nπ* T2 states. Thermal equilibrium also occurs between the T1 and T2 states of the acetophenones.