Dynamical interference in the vibronic bond breaking reaction of HCO

First-principles treatments of quantum molecular reaction dynamics have reached the level of quantitative accuracy even in cases with strong non–Born-Oppenheimer effects. This achievement permits the interpretation of puzzling experimental phenomena related to dynamics governed by multiple coupled potential energy surfaces. We present a combined experimental and theoretical study of the photodissociation of formyl radical (HCO). Oscillations observed in the distribution of product states are found to arise from the interference of matter waves—a manifestation analogous to Young’s double-slit experiment.