Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 2014 | Supplemental Material
Journal Article Open

Characterization of fast photoelectron packets in weak and strong laser fields in ultrafast electron microscopy


The development of ultrafast electron microscopy (UEM) and variants thereof (e.g., photon-induced near-field electron microscopy, PINEM) has made it possible to image atomic-scale dynamics on the femtosecond timescale. Accessing the femtosecond regime with UEM currently relies on the generation of photoelectrons with an ultrafast laser pulse and operation in a stroboscopic pump-probe fashion. With this approach, temporal resolution is limited mainly by the durations of the pump laser pulse and probe electron packet. The ability to accurately determine the duration of the electron packets, and thus the instrument response function, is critically important for interpretation of dynamics occurring near the temporal resolution limit, in addition to quantifying the effects of the imaging mode. Here, we describe a technique for in situ characterization of ultrashort electron packets that makes use of coupling with photons in the evanescent near-field of the specimen. We show that within the weakly-interacting (i.e., low laser fluence) regime, the zero-loss peak temporal cross-section is precisely the convolution of electron packet and photon pulse profiles. Beyond this regime, we outline the effects of non-linear processes and show that temporal cross-sections of high-order peaks explicitly reveal the electron packet profile, while use of the zero-loss peak becomes increasingly unreliable.

Additional Information

© 2014 Elsevier B.V. Received 14 May 2014, Revised 29 July 2014, Accepted 3 August 2014, Available online 10 August 2014. DP and DJF acknowledge support from 3M in the form of a Nontenured Faculty Award (Grant #13673369) and from the Donors of the American Chemical Society Petroleum Research Fund in the form of a Doctoral New Investigator Grant PRF# 53116-DNI7. STP and AHZ acknowledge support from the National Science Foundation and the Air Force Office of Scientific Research in the Center for Physical Biology funded by the Gordon and Betty Moore Foundation.

Attached Files

Supplemental Material - mmc1.docx


Files (149.4 kB)
Name Size Download all
149.4 kB Download

Additional details

August 22, 2023
October 18, 2023