Colloque

Catching electrons with light

Paul Corkum

Membre a labase

Paul Corkum

Résumé de la communication

Many scientists would say that it is intrinsically impossible to measure molecular orbitals. A typical comment might be “Orbitals are but a mathematical construct -- a convenience for designing chemical reactions.” This lecture will show that orbitals (specifically Dyson orbitals) are measurable. In Ottawa, we exploit an intense light pulse to measure orbitals. In intense infrared light, an electron tunnels from a molecule. Even this first step towards orbital imaging is important. Just as we measure the surface structure of a solid by scanning an STM tip, we can also measure the square of the orbital wave function by measuring the ionization probability for every angle between the molecule and the laser field. But it is what happens next that is most exciting. After tunneling, the electron wave packet moves like a cork on a water wave. The electron is first carried away from the molecule by the light wave and then driven back to it, where it interferes with the unionized portion of the orbital from which it just separated. This electron interference creates attosecond XUV pulses – the shortest pulses ever generated. The generated XUV radiation also contains all the information needed to determine the amplitude and phase of the orbital. The lecture will conclude by describing how we might “film” orbital changes during a photochemical reaction – an upcoming molecular movie in 3-D: “The Fastest Molecular Movie on Earth!”

Résumé du colloque

2010 fut le 50 ième anniversaire de l'invention du laser et aussi le 25 ième anniversaire de l'invention par Gérard Mourou(École Polytechnique-Paris) du CPA (Chirped Pulse Amplification), une technique unique pour la génération d'impulsion laser intense. Ce colloque servira de "fêter" au Québec ces deux évènements importants en science laser et à la même fois de présenter les contributions importantes des chercheurs Québécois.