Solvent environment controls ultrafast bifurcation between dissociation and isomerization in iodoform
Year: 2026
Type: article
Abstract: Solvent environments can profoundly influence reaction dynamics, yet capturing ultrafast atomic motions during these events remains challenging. Here, we employ femtosecond time-resolved x-ray liquidography to track the atomic motions of iodoform (CHI3) in acetonitrile. We observe an ultrafast bifurcation (<200 fs) into two distinct pathways: complete dissociation to CHI2• + I• radicals and roaming-like isomerization to iso-CHI2–I. Along the dissociation branch, the I⋯I distance increases with time, accompanied by increasing spatial dispersion. In contrast, the isomerization branch exhibits a rapid contraction of the bonding I–I pair to ∼2.8 Å, while non-bonded pairs persist at 3.6–3.9 Å, indicative of reorientation rather than separation. This behavior differs sharply from dynamics in cyclohexane, where sub-picosecond isomer formation is absent. These findings provide an atomically resolved visualization of the bifurcation between dissociation and roaming-like isomerization in solution, demonstrating how solvent environments fundamentally alter the structural dynamics of ultrafast solution photochemistry.
Source: The Journal of Chemical Physics
DOI: 10.1063/5.0354806
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,500
OpenAlex ID: W7223180481