Max in Ilmenau: Discover molecular wonders with the Cryo STM!

Max in Ilmenau: Discover molecular wonders with the Cryo STM!

Max, a dedicated physics student at the TU Ilmenau, successfully completed his bachelor's and master's degrees there and is staying at the university for his doctorate. Early after graduating from high school, he developed a strong interest in engineering courses as well as mathematics and physics. The choice of technical physics in Ilmenau was obvious, as this course combines engineering and physics training.

Max already had the opportunity to interact with various research groups during his bachelor's degree. The extensive equipment and modern laboratories made a lasting impression on him. In particular, the scanning tunneling microscope, the Cryo STM, which was newly purchased in 2021, gave him the opportunity to be one of the first to work with it and to research experimental physics at the molecular level.

Fascination with modern microscopy

With the Cryo STM, which works at extremely low temperatures, Max aims to combine optical spectroscopy methods with the atomic spatial resolution of the microscope. He is particularly fascinated by this possibility of measuring light from individual molecules. He emphasizes that TU Ilmenau offers students valuable opportunities to be involved in research during their bachelor's degree.

Max also had practical experience as a student assistant, where he was responsible for sample heating in an ultra-high vacuum. He regularly discusses with colleagues in group meetings and presents current publications, which deepens his research interests in the field of solid state physics and future electronics.

Technical background of scanning tunneling microscopy

Scanning tunneling microscopy (STM) was developed in 1984 and is based on the quantum mechanical tunneling effect. Two electrically conductive electrodes are separated by a thin insulating layer, for example vacuum. When a voltage is applied, electrons can tunnel across this barrier, creating a closed circuit. The tunneling current is a measure of the distances between the metal tip, often made of tungsten or an alloy of platinum and iridium, and the sample.

The precision of the STM is impressive. The distance between the tip and the sample is typically only 0.1 nm. During scanning, a height profile of the sample is created, which is kept constant using a feedback-controlled system while the tip is moved through the sample. This technique enables the characterization of conductive substrate surfaces and the identification of individual molecules, such as copper phthalocyanine on a gold surface.

The microscope's scanner unit uses a tube scanner with piezo crystals, which enables extremely precise positioning in all three spatial directions. The tunneling current depends strongly on the tip-to-sample distance, allowing atomic resolution to be achieved. The technique even has the ability to make moiré superstructures visible and offers a z-resolution of around 1 pm.

Max's research group at TU Ilmenau uses two scanning tunneling microscopes, including a helium-cooled low-temperature STM, which is known for its unique measurement capabilities. Max is aware of the advantages of modern equipment. He particularly highlights helium recovery and functional infrastructure, which are essential for successful research.