Fig. 1: Light-induced chiral dynamics of methyl lactate.

a, A few-femtosecond linearly polarized UV pulse excites an ensemble of randomly oriented chiral molecules, creating an electronic wave packet of Rydberg states by means of two-photon absorption. The dynamics is probed by means of one-photon ionization by a time-delayed circularly polarized NIR pulse. The probing step leads to the ejection of photoelectrons along the light-propagation axis defined along the z direction and the resulting angular distribution is recorded by a VMIS. b, The red and blue structures show the temporal evolution of the coherent electron density in the excited neutral molecule: the chiral evolution of the photoexcited Rydberg wave packet leads to a reversal of the 3D photoelectron angular distribution at two distinct time delays, t and t + Δt, captured by the measurements. c, For each time delay, an image is recorded for both left and right circular polarization of the probe pulse. The differential image PECD(ε, θ, t), defined in the main text, is shown for time delays of 5, 11,17 and 26 fs for photoelectrons with kinetic energies from 25 to 300 meV along the radial coordinate. The white dashed circles identify the photoelectrons below 100 meV that experience an ultrafast reversal of their emission direction in the laboratory frame.