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

Pan, Huilin; Liu, Shu; Wang, Pengcheng; Yang, Xueming; Zhang, Dong H; Liu, Kopin · Nat Commun · 2025

basic_science · Level V

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Abstract

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 + CH<sub>4</sub> → CH<sub>3</sub>(v<sub>i</sub>) + HF(v), both product vibrational branching and state-resolved angular distributions are simultaneously unveiled in a (v<sub>i</sub>, 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.