Time-resolved electron holography and its application to an ionic liquid specimen

Abstract

Time-resolved electron holography was implemented in a transmission electron microscope by means of e-beam gating with a parallel-plate electrostatic deflector. Stroboscopic observations were performed by accumulating gated electron interference images while applying a periodic modulation voltage to the specimen. Electric polarization in an ionic liquid specimen was observed under applied DC and AC fields. While the DC electric field in the specimen was reduced by the polarization of the material, an AC field of 10 kHz was not screened. This indicates that time-resolved electron holography is capable of determining the frequency limit of dynamic response of polarization in materials.

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“…The TIE approach is easy to implement but suffers from reduced spatial and phase resolution compared to other techniques that give higher resolution at the expense of additional experimental requirements 22,23 . For example, off-axis holography requires an electron biprism and the ability to obtain a reference electron wave, making it unsuitable for many samples [24][25][26] , and 4D-STEM requires long measurement times and pixelated detectors 27 . Recently, a machine-learning-based approach was developed to apply direct automatic differentiation (AD) to a forward model, which has been shown to reconstruct ϕ more accurately than the TIE method when using an input TFS 28 .…”