Relaxation Dynamics in Photoexcited Chiral Molecules Studied by Time-Resolved Photoelectron Circular Dichroism: Toward Chiral Femtochemistry

Antoine Comby (1) , Samuel Beaulieu (1, 2) , Martial Boggio-Pasqua (3) , Dominique Descamps (1) , Francois Légaré (2) , Laurent Nahon (4) , Stéphane Petit (1) , Bernard Pons (1) , Baptiste Fabre (1) , Yann Mairesse (1) , Valérie Blanchet (1)

1 CELIA - Centre d'Etudes Lasers Intenses et Applications
2 Advanced Laser Light Source-INRS-EMT
3 PTC - Photochimie théorique et computationnelle (LCPQ)
4 SSOLEIL - Synchrotron SOLEIL

Unravelling the main initial dynamics responsible for chiral recognition is a key step in the understanding of many biological processes. However this challenging task re- quires a sensitive enantiospecic probe to investigate molecular dynamics on their natu- ral femtosecond timescale. Here we show that, in the gas phase, the ultrafast relaxation dynamics of photoexcited chiral molecules can be tracked by recording Time-Resolved PhotoElectron Circular Dichroism (TR-PECD) resulting from the photoionisation by a circularly polarized probe pulse. A large forward/backward asymmetry along the probe propagation axis is observed in the photoelectron angular distribution. Its evo- lution with pump-probe delay reveals ultrafast dynamics that are inaccessible in the angle-integrated photoelectron spectrum nor via the usual electron emission anisotropy parameter (β). PECD, which originates from the electron scattering in the chiral molec- ular potential, appears as a new sensitive observable for ultrafast molecular dynamics in chiral systems.

Domaines: Chimie-Physique [physics.chem-ph]

Antoine Comby, Samuel Beaulieu, Martial Boggio-Pasqua, Dominique Descamps, Francois Légaré, et al.. Relaxation Dynamics in Photoexcited Chiral Molecules Studied by Time-Resolved Photoelectron Circular Dichroism: Toward Chiral Femtochemistry. Journal of Physical Chemistry Letters, 2016, 7 (21), pp.4514 - 4519. ⟨10.1021/acs.jpclett.6b02065⟩. ⟨hal-01395562v1⟩