MatQ: René de Cotret et Schiff-Kearn

Laurent René de Cotret (in english):

Title: Ultrafast energyflow across the Brillouin zone in two-dimensional materials

Abstract: In this talk I willshow you how to extend ultrafast electron diffraction measurements to directlyaccess ultrafast phonon dynamics in two-dimensional materials. Ultrafastelectron scattering will be introduced, with special emphasis on the keyadvancement of RF-compression of electron bunches. Then, three experiments willbe presented. First, time- and momentum-dependent phonon population dynamics inphotoexcited graphite will be used to extract electron- and phonon-phononcoupling values across the Brillouin zone. Second, the source of anharmonicityin a high-efficiency thermoelectric material will be discussed via observationsof ultrafast phonon renormalization. Finally, if time permits, the phonondynamics of photoexcited 1T-TiSe2 will be used to infer some properties of thecharge-density wave phase.

 Aidan Schiff-Kearn (in english):

Title: To slip stream terahertz pulses

Abstract: The ability to uselight moves in lockstep with the ability to control it. In this talk, I willpresent our latest efforts in tailoring terahertz pulses using our parallelplate waveguide platform. Through interactions with a moving relativistic frontcreated by photoexcitation, we demonstrate two exotic photonic operations inthe terahertz range: temporal stretching and time-reversal of a terahertzpulse.