Capturing roaming molecular fragments in real time.

摘要: Since the discovery of roaming as an alternative molecular dissociation pathway in formaldehyde (H2CO), it has been indirectly observed numerous molecules. The phenomenon describes a frustrated with fragments at relatively large interatomic distances rather than following conventional transition-state dissociation; incipient radicals from parent molecule self-react to form products. Roaming identified spectroscopically through static product channel-resolved measurements, but not real-time observations fragment itself. Using time-resolved Coulomb explosion imaging (CEI), we directly imaged individual "roamers" on ultrafast time scales prototypical reaction. high-level first-principles simulations all critical experimental steps, distinctive signatures were identified. These rendered observable by extracting rare stochastic events out overwhelming background using highly sensitive CEI method.