Tuesady, March 22nd, 2022
Seminar room, 1st Floor, U5 Building – via Roberto Cozzi 55, Milano
Lecturer: Dr. Cameron Duncan from Cornell University (Ithaca, NY, USA)
Title: Tracing the impact of one pulse from femtoseconds to milliseconds: ultrafast electron diffraction at multiple scales in time and space
Abstract. Ultrafast electron diffraction (UED) provides direct experimental access to the fundamental time-scales of atomic motion, and is thus an integral tool for studying matter out of equilibrium. I will present the first UED results obtained from a new machine built at Cornell. Our machine utilizes a novel, high-brightness electron source together with a direct-electron detector having high dynamic range, single electron sensitivity and kilohertz frame rate. This combination of source and detector allows us to resolve, simultaneously, diffraction features that span multiple orders of magnitude in intensity. I will demonstrate this capability by describing UED experiments we performed on a Moire material, WSe2/MoSe2. Our data show the evolving role of long-wavelength interlayer interactions in determining the response of the material to ultrafast excitation, from hundreds of femtoseconds to milliseconds after pumping.