Université de Strasbourg

USIAS Fellows seminar - Small and fast

February 13, 2019
From 12:30 until 14:00
Salle Amériques, MISHA, Strasbourg

By Florian Banhart & Thomas LaGrange (2017 Fellows)

Small and fast: how we can observe rapid movements at the nanoscale in an ultrafast electron microscope

We know from our daily life how difficult it is to watch rapid movements when the moving objects are small. Seeing what a fly does in flight is impossible. Photographers have solved this problem by illuminating the object with sub-millisecond flashes of light that freeze the motion in the picture. However, in modern nanotechnology, the objects are much smaller than what we can see with conventional optics. Electron microscopes with high spatial resolution are needed but, unfortunately, do not have the necessary time resolution.

In the past years, a new observation technique has been developed that allows us to generate and use ultrashort flashes of electrons to record data in electron microscopes. Modern laser technology made this possible; femtosecond- to nanosecond laser flashes are used to stimulate extremely fast dynamics in nanoobjects. We record images, diffraction patterns, or electron spectra of the transient states in nanomaterials using ultrashort electron pulses generated by UV laser striking a photoemitter in the electron microscope.

Our USIAS project has helped us to develop a strategy for observing fast chemical reactions in nanoparticles with ultrafast electron microscopy. In the presentation, we will show how this technique works and what can be studied in the nanoworld.

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