Mapping wave packet bifurcation at a conical intersection in CH3I by attosecond XUV transient absorption spectroscopy
Abstract
Extreme ultraviolet (XUV) transient absorption spectroscopy has emerged as a sensitive tool for mapping the real-time structural and electronic evolution of molecules. Here, attosecond XUV transient absorption is used to track dynamics in the A-band of methyl iodide (CH3I). Gaseous CH3I molecules are excited to the A-band by a UV pump (277 nm, ∼20 fs) and probed by attosecond XUV pulses targeting iodine I(4d) core-to-valence transitions. Owing to the excellent temporal resolution of the technique, passage through a conical intersection is mapped through spectral signatures of nonadiabatic wave packet bifurcation observed to occur at 15 ± 4 fs following UV photoexcitation. The observed XUV signatures and time dynamics are in agreement with previous simulations [H. Wang, M. Odelius, and D. Prendergast, J. Chem. Phys. 151, 124106 (2019)]. Due to the short duration of the UV pump pulse, coherent vibrational motion in the CH3I ground state along the C–I stretch mode (538 ± 7 cm−1) launched by resonant impulsive stimulated Raman scattering and dynamics in multiphoton excited states of CH3I are also detected.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 15, 2021
- Source ID
- 10.1063/5.0056299
Entities
People
- Daniel Neumark
- David Prendergast
- Han Wang
- Kristina F Chang
- Sonia Marggi Poullain
- Stephen R. Leone
Organizations
- Army Research Office
- Complutense University of Madrid
- Lawrence Berkeley National Laboratory
- National Science Foundation
- United States Department of Energy
- Yusuf Hamied Department of Chemistry