Solid state physicists and material developers have a great interest in investigating these smallest building blocks of materials in more detail. For example, in electronic circuits, which are sometimes so miniaturized that quantum mechanical effects are already noticeable. Photoelectron spectroscopy allows such a view of the atoms, their energetic states and their electrons. The principle: high-energy photons, i.e. light particles, are shot at the surface of the solid to be examined, for example an electronic circuit. The high-energy light strikes electrons out of the atomic bond. Depending on the energetic band in which the electrons are located, they reach the detector faster or slower. Over the time the electrons need to reach the detector, material developers can draw conclusions about the energetic states of the electron bands and the structure of the atomic bond in the solid state. The higher the frequency of the laser pulses, the better the data basis achieved.
Researchers at the Fraunhofer Institutes for Applied Optics and Precision Engineering IOF and for Laser Technology ILT, together with their colleagues at the Max Planck Institute for Quantum Optics, have developed the first photoelectron spectrometer that operates at 18 megahertz rather than kilohertz. This means that several thousand times more pulses hit the surface than in conventional spectrometers. This has a drastic effect on the time required for such a measurement. "Measurements that used to take five hours can now be performed in ten seconds," says Dr. Oliver de Vries, scientist at Fraunhofer IOF.