Conformer-resolved ultrafast chemical dynamics observed at ambient temperature
- Zhengrong Wei
- Jesús González Vázquez
- Pedro Recio
- Gustavo A. García
- Sonia Marggi Poullain
- Jialin Li
- Luis Bañares
- Zhi-Heng Loh
2026-05-01
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 3 H 7 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 3 H 7 I + X ~ 2 E 1/2 suggest rapid depopulation of the gauche conformer. Global analysis of the time-resolved XUV transient absorption spectra reveals simultaneous decay of 1-C 3 H 7 I + X ~ 2 E 1/2 and growth of I ( 2 P 3/2 ), 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.