2015 E.W. Guptill Memorial Lecture: "Forcing a Molecule to Take a Selfie"
Presented by: Dr. Paul Corkum
Director, Joint Attosecond Science Laboratory
University of Ottawa and National Research Council of Canada
Waves – whether water waves, light waves or electron waves -- share many features. Fitting for Halifax, this lecture is about waves. To prepare for the lecture, you could go to the ocean and watch waves crash on-shore.
Imagine an intense light wave shining on a molecule (or solid). During the talk you will see that a light-irradiated molecule creates an electron wave and that this electron wave is pulled by the light away from the molecule to just the right distance for a selfie.
To snap the selfie, the electron wave serves as a flash. When the electron “flash” illuminates the molecule, the electron scatters, converting back to light much like a water wave breaking over a rock creates foam and ripples. A digital camera records the new beam with the resulting image becoming one frame of a tomographic image of the molecule.
Just as medical tomography images your body, tomography determines the orbital wavefunction of the electron that bonds a nitrogen molecule. But even the image is not the most important result. Standard camera flashes last about 1/1000 of a second but the electron flash that takes the molecular selfie only lasts about 1/1,000,000,000,000,000 of a second. As the colliding electron converts back to light (in the X-ray region), it simultaneously converts into the world’s shortest flash: 60 attoseconds (60/1,000,000,000,000,000,000 seconds). These pulses are fast enough to freeze-frame an electron orbiting an atom and they even enable us to see the undulations of visible light.
Ondaatje Hall, McCain Building
6135 University Avenue, Halifax, NS
Reception to follow2015 E.W. Guptill Memorial Lecture: "Forcing a Molecule to Take a Selfie"