State-correlated reaction dynamics unveiled in full from a single product-image measurement

Electron- or photoionization mass spectrometry coupled with product time-of-flight measurement is a universal detection scheme, which has been playing pivotal role in advancing our fundamental understanding of chemical reactions. This powerful detection scheme, however, usually does not provide the product state-specific information. Here, we propose a variant of universal detection with state-resolving capability by leveraging a three-dimensional velocity-map imaging detector with vacuum-ultraviolet photoionization probe. As demonstrated by a crossed-beam reaction of F + CH₄ → CH₃(vi) + HF(v), both product vibrational branching and state-resolved angular distributions are simultaneously unveiled in a (vi, v) pair-correlated manner from a single product-image measurement, which enables us to gain previously inaccessible insights. Comparisons with a six-dimensionality quantum dynamics calculation show excellent agreements, validating the approach. The proposed method is general and should open a new opportunity to gain deeper insights into many important complex chemical processes that are otherwise difficult to study.