A kiloelectron-volt ultrafast electron micro-diffraction apparatus using low emittance semiconductor photocathodes

W H Li; C J R Duncan; M B Andorf; A C Bartnik; E Bianco; L Cultrera; A Galdi; M Gordon; M Kaemingk; C A Pennington; L F Kourkoutis; I V Bazarov; J M Maxson

doi:10.1063/4.0000138

A kiloelectron-volt ultrafast electron micro-diffraction apparatus using low emittance semiconductor photocathodes

Struct Dyn. 2022 Mar 18;9(2):024302. doi: 10.1063/4.0000138. eCollection 2022 Mar.

Authors

W H Li¹, C J R Duncan¹, M B Andorf¹, A C Bartnik¹, E Bianco², L Cultrera¹, A Galdi¹, M Gordon³, M Kaemingk¹, C A Pennington¹, L F Kourkoutis, I V Bazarov¹, J M Maxson¹

Affiliations

¹ Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA.
² Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA.
³ University of Chicago, Chicago, Illinois 60637, USA.

Abstract

We report the design and performance of a time-resolved electron diffraction apparatus capable of producing intense bunches with simultaneously single digit micrometer probe size, long coherence length, and 200 fs rms time resolution. We measure the 5d (peak) beam brightness at the sample location in micro-diffraction mode to be $7 \times 10^{13} A / m^{2} {rad}^{2}$ . To generate high brightness electron bunches, the system employs high efficiency, low emittance semiconductor photocathodes driven with a wavelength near the photoemission threshold at a repetition rate up to 250 kHz. We characterize spatial, temporal, and reciprocal space resolution of the apparatus. We perform proof-of-principle measurements of ultrafast heating in single crystal Au samples and compare experimental results with simulations that account for the effects of multiple scattering.