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 requires a sensitive enantiospecic probe to investigate molecular dynamics on their natural 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 evolution 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 molecular 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-01395562v2⟩