Direct tracking of H<sub>2</sub> roaming reaction in real time.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39107291.
- Also identified by DOI 10.1038/s41467-024-49671-6 and PMC identifier 11303762.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Roaming is an unconventional type of molecular reaction where fragments, instead of immediately dissociating, remain weakly bound due to long-range Coulombic interactions. Due to its prevalence and ability to form new molecular compounds, roaming is fundamental to photochemical reactions in small molecules. However, the neutral character of the roaming fragment and its indeterminate trajectory make it difficult to identify experimentally. Here, we introduce an approach to image roaming, utilizing intense, femtosecond IR radiation combined with Coulomb explosion imaging to directly reconstruct the momentum vector of the neutral roaming H<sub>2</sub>, a precursor to <math xmlns="http://www.w3.org/1998/Math/MathML"> <msup> <mrow> <msub><mrow><mi>H</mi></mrow> <mrow><mn>3</mn></mrow> </msub> </mrow> <mrow><mo>+</mo></mrow> </msup> </math> formation, in acetonitrile, CH<sub>3</sub>CN. This technique provides a kinematically complete picture of the underlying molecular dynamics and yields an unambiguous experimental signature of roaming. We corroborate these findings with quantum chemistry calculations, resolving this unique dissociative process.