Study of electrons with a traditional scanning microscope

Physicists at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) designed a framework which allows scientists to observe the interactions between light and electrons using a traditional scanning electron microscope. The procedure is considerably cheaper than the technology used so far and also allows for a wider range of experiments.

The quantum computer is just one example of the importance of understanding the fundamental processes underlying the interactions between photons and electrons. Combined with ultra-short laser pulses, it is possible to measure how photons change the energy and speed of electrons. This photon-induced electron microscopy (PINEM) has until now relied entirely on transmission electron microscopes (TEM). Although these have the resolution needed to locate individual atoms, they are however considerably more expensive than scanning electron microscopes (SEM), and their sample chamber is extremely small, only a few cubic millimeters.

Measure differences down to a few hundred thousandths of a whole

Researchers from Dr. Peter Hommelhoff’s Chair of Laser Physics have now succeeded in modifying a traditional SEM to conduct PINEM experiments. They designed a special spectrometer based on magnetic forces that are integrated directly into the microscope. The underlying principle is that the magnetic field deflects the electrons more or less depending on their speed. By using a detector that transforms electron collisions into light, an accurate reading of this deviation is given. The method allows researchers to measure even the smallest changes in energy, down to differences of only a few hundred thousandths of the original value – enough to differentiate the contribution of a single quanta of light energy – a photon.

A wider range of possible experiences in the future

The discovery of the Erlangen physicists is pioneering in more ways than one. From a financial point of view, being able to search for photon-electron interactions without using TEM, which costs several million euros, could make research more accessible. Additionally, since the chamber of an SEM typically has a volume of up to 20 cubic centimeters, a much wider range of experiments is now possible, as additional optical and electronic components such as lenses, prisms and mirrors can be placed directly next to the samples. Researchers expect that in a few years the entire field of microscopic quantum experiments will shift from TEM to SEM.

– This press release was provided by the Friedrich Alexander University