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O: Fachverband Oberflächenphysik

O 71: Scanning Probe Techniques and New Experimental Methods

O 71.17: Poster

Mittwoch, 9. März 2016, 18:15–20:30, Poster A

Source Development for Ultrafast Transmission Electron Microscopy — •Nora Bach, Armin Feist, Reiner Bormann, Sascha Schäfer, and Claus Ropers — IV. Physical Institute, University of Göttingen, Göttingen

Ultrafast transmission electron microscopy (UTEM) is a novel experimental technique that combines a nanoscale spatial with femtosecond temporal resolution [1]. The imaging and diffraction resolution in this technique is governed by the brightness of the laser-driven electron source used [2].

Here, we present the design and implementation of an advanced UTEM instrument based on the modification of a commercial Schottky Field emission TEM [3]. Single-photon photoemission from a tip-shaped ZrO/W(100) emitter is employed, yielding a spectral bandwidth of 0.6 eV, a low intrinsic emittance of about 5 nm·mrad, and an electron probe size down to 1.5 nm.

We characterize the temporal structure of the electron pulses by electron-photon cross-correlation and obtain a pulse width of 300 fs (full-width-at-half-maximum). The demonstrated high beam quality of the source will enable new applications in the study of nanoscale ultrafast dynamics, including ultrafast electron holography and phase-contrast imaging.

[1] A. H. Zewail, Science 328, 187 (2010).

[2] M. Gulde et al., Science 345, 200 (2014).

[3] A. Feist et al., Nature 521, 200 (2015).