[Phys-seminars] 2011-03-24 Condensed Matter & Lasers Seminar

hbaruch at bgu.ac.il hbaruch at bgu.ac.il
Thu Mar 17 19:45:22 IST 2011

Condensed Matter & Lasers Seminar

  DATE: 24-03-2011

  TIME: 12:15pm (Thursday)  Note special time

  PLACE: Physics building (#54) room 207

High harmonic generation with aligned and oriented molecules.

Dr. Eugene Frumker, Joint Attosecond Science Laboratory
National Research Council of Canada and University of Ottawa

Asymmetric molecules look different when viewed from one side or the other. This difference influences the electronic structure of the valence electrons thereby giving stereo sensitivity to chemistry and biology.  We show that attosecond and re-collision science provides a detailed and sensitive probe of electronic asymmetry. On each 1/2 cycle of an intense light pulse, laser-induced tunneling extracts an electron wave packet from the molecule. When the electron wave packet recombines, alternately from one side of the molecule or the other, its amplitude and phase asymmetry determines the even and odd harmonics radiation that it generates. This harmonic spectrum encodes three manifestations of asymmetry; an amplitude and phase asymmetry in electron tunneling; an asymmetry in the phase that the electron wave packet accumulates relative to the ion between the moment of ionization and recombination; and an asymmetry in the amplitude and phase of the transition moment. We report the first measurement of high harmonics from oriented samples.  We determine the phase asymmetry of the attosecond XUV pulses emitted, when electron recollides from opposite sides of the CO molecule, and the phase asymmetry of the re-collision electron just before recombination. We discuss how the various contributions to asymmetry can be isolated in future experiments.

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