Conformer-resolved ultrafast chemical dynamics observed at ambient temperature.
basic_science · Level V
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- Record sourced from PubMed, PMID 42066074.
- Also identified by DOI 10.1126/sciadv.aed8682 and PMC identifier 13134584.
- Licence recorded as CC BY-NC.
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Abstract
The nearly identical spectral features of conformers and their fast interconversion make tracking ultrafast chemical dynamics with conformational resolution at room temperature challenging. Here, we investigate the ionization-induced ultrafast dissociation dynamics of 1-iodopropane (1-C<sub>3</sub>H<sub>7</sub>I) conformers by high-resolution photoelectron-photoion coincidence spectroscopy, femtosecond extreme ultraviolet (XUV) transient absorption spectroscopy, and ab initio calculations. Vibrational wave packet dynamics obtained by monitoring the iodine 4d core-level transitions of 1-C<sub>3</sub>H<sub>7</sub>I<sup>+</sup> [Formula: see text] <sup>2</sup>E<sub>1/2</sub> suggest rapid depopulation of the gauche conformer. Global analysis of the time-resolved XUV transient absorption spectra reveals simultaneous decay of 1-C<sub>3</sub>H<sub>7</sub>I<sup>+</sup> [Formula: see text] <sup>2</sup>E<sub>1/2</sub> and growth of I (<sup>2</sup>P<sub>3/2</sub>), with time constants of 0.19 ± 0.03 and 1.4 ± 0.3 ps, attributed to C─I dissociation of the gauche and anti conformers, respectively. Extended multistate CASPT2 and relativistic state-averaged CASSCF calculations support this assignment. Our findings show that the conformational degree of freedom plays an important role in determining the outcome of chemical reactions even on ultrashort timescales.