Vibrational Quantum-State-Controlled Reactivity in the O(2)(+) + C(3)H(4) Reaction.

Quantum-state-controlled reactivity is a long-standing goal in the field of physical chemistry. In this work, we explore the vibrational-state-dependent behavior of the ion-molecule reaction between O in distinct vibrational states and two isomers of CH, allene (HCH) and propyne (HCH). While most products are formed regardless of the vibrational state of O, the branching ratios are influenced by vibrational excitation, and a new product, CO, appears exclusively in the excited-state reactions. This selective formation of CO demonstrates that vibrational excitation can effectively activate a reaction pathway, providing direct evidence of quantum-state control in the reactivity. These results represent an important step toward the goal of quantum-state-controlled chemistry in molecular systems.