In the framework of an international collaboration between NRC (Ottawa, Canada), the CELIA laboratory from Bordeaux, and the LCAR laboratory from Toulouse, the intricate ultrafast dynamics of the NO2 molecule have been elucidated.
Indeed, conical intersections play a crucial role in the chemistry of most polyatomic molecules, ranging from the simplest bimolecular reactions to the photostability of DNA. The real-time study of the associated electronic dynamics poses a major challenge to the latest techniques of ultrafast measurement. We show that high-harmonic spectroscopy reveals oscillations in the electronic character that occur in nitrogen dioxide when a photoexcited wave packet crosses a conical intersection. At longer delays, we observe the onset of statistical dissociation dynamics. The present results demonstrate that high-harmonic spectroscopy could become a powerful tool to highlight electronic dynamics occurring along nonadiabatic chemical reaction pathways.
This research has been published in Science :
Conical Intersection Dynamics in NO2 Probed by Homodyne High-Harmonic Spectroscopy
H. J. Wörner, J. B. Bertrand, B. Fabre, J. Higuet, H. Ruf, A. Dubrouil, S. Patchkovskii, M. Spanner, Y. Mairesse, V. Blanchet, E. Mével, E. Constant, P. B. Corkum, and D. M. Villeneuve
Science 14 October 2011 : 334 (6053), 208-212. [DOI:10.1126/science.1208664]