biostudies-literatureVanuzzo GMinistero dell'Universit? e della Ricerca8278-8302https://www.ebi.ac.uk/biostudies/studies/S-EPMC12434676biostudies-literatureUnknown129(36)The reactions of ground state oxygen atoms, O(<sup>3</sup>P), with unsaturated hydrocarbons (UHs) are relevant in the oxidation in different environments. They are usually multichannel reactions that exhibit a variety of competing product channels, some of which occur adiabatically on the entrance triplet potential energy surface (PES), while others occur nonadiabatically on the singlet PES that can be accessed via <i>intersystem crossing</i> (ISC). ISC plays a key role on the mechanism of these reactions, impacting greatly the product yields. Identification of all primary reaction products, determination of their branching fractions (BFs), and assessment of the role of ISC is central for understanding the mechanism of these reactions. This goal can be best achieved combining crossed-molecThe journal of physical chemistry. ACrossed-Beams and Theoretical Studies of the Multichannel Reaction O(<sup>3</sup>P) + 1,2-Butadiene (Methylallene): Product Branching Fractions and Role of Intersystem Crossing.PMC124346762017PJ5XXXVanuzzo GBalucani NGiustini ACaracciolo ATanteri SCavallotti CDi Teodoro MElliott SNCasavecchia PStranges DRosi MfalseCrossed-Beams and Theoretical Studies of the Multichannel Reaction O(<sup>3</sup>P) + 1,2-Butadiene (Methylallene): Product Branching Fractions and Role of Intersystem Crossing.The reactions of ground state oxygen atoms, O(<sup>3</sup>P), with unsaturated hydrocarbons (UHs) are relevant in the oxidation in different environments. They are usually multichannel reactions that exhibit a variety of competing product channels, some of which occur adiabatically on the entrance triplet potential energy surface (PES), while others occur nonadiabatically on the singlet PES that can be accessed via <i>intersystem crossing</i> (ISC). ISC plays a key role on the mechanism of these reactions, impacting greatly the product yields. Identification of all primary reaction products, determination of their branching fractions (BFs), and assessment of the role of ISC is central for understanding the mechanism of these reactions. This goal can be best achieved combining crossed-molec2025-01-01T00:00:00Z2025 Sep2026-06-01T14:02:09.239Z2026-04-08T13:09:34.027ZS-EPMC124346764085672810.1021/acs.jpca.5c03937