Research Article

Attosecond-resolved photoionization of chiral molecules

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Science  08 Dec 2017:
Vol. 358, Issue 6368, pp. 1288-1294
DOI: 10.1126/science.aao5624

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Clocking departures from chiral origins

Just as the atoms in a molecule can be arranged in a left- or right-handed manner, the field in a beam of light can circulate like a left- or right-handed corkscrew. Matches or mismatches in this mutual handedness give rise to an asymmetric distribution of trajectories as electrons are ejected during photoionization. Beaulieu et al. used an interferometric approach to uncover the temporal dynamics associated with this asymmetry. They probed the mirror-image isomers of camphor with circularly polarized light, which revealed the angle-dependent delays between trajectories that spanned up to 24 attoseconds.

Science, this issue p. 1288

Abstract

Chiral light-matter interactions have been investigated for two centuries, leading to the discovery of many chiroptical processes used for discrimination of enantiomers. Whereas most chiroptical effects result from a response of bound electrons, photoionization can produce much stronger chiral signals that manifest as asymmetries in the angular distribution of the photoelectrons along the light-propagation axis. We implemented self-referenced attosecond photoelectron interferometry to measure the temporal profile of the forward and backward electron wave packets emitted upon photoionization of camphor by circularly polarized laser pulses. We measured a delay between electrons ejected forward and backward, which depends on the ejection angle and reaches 24 attoseconds. The asymmetric temporal shape of electron wave packets emitted through an autoionizing state further reveals the chiral character of strongly correlated electronic dynamics.

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