Research Papers in Physics and Astronomy


Date of this Version



Published in Science 361 (6 July 2018), pp 64–67.

doi 10.1126/science.aat0049


Copyright © 2018 by the Authors; published by the American Association for the Advancement of Science. Used by permission.


Conical intersections play a critical role in excited-state dynamics of polyatomic molecules because they govern the reaction pathways of many nonadiabatic processes. However, ultrafast probes have lacked sufficient spatial resolution to image wave-packet trajectories through these intersections directly. Here, we present the simultaneous experimental characterization of one-photon and two-photon excitation channels in isolated CF3I molecules using ultrafast gas-phase electron diffraction. In the two-photon channel, we have mapped out the real-space trajectories of a coherent nuclear wave packet, which bifurcates onto two potential energy surfaces when passing through a conical intersection. In the one-photon channel, we have resolved excitation of both the umbrella and the breathing vibrational modes in the CF3 fragment in multiple nuclear dimensions. These findings benchmark and validate ab initio nonadiabatic dynamics calculations.

Includes supplementary materials.

Movie S1 attached below.

Centurion SCIENCE 2018 ImagingCF3I SUPPL movie.mp4 (19377 kB)
Movie time = 1:08 min; file = 19 MB