skannauskääntömikroskopia

Scanning tunneling microscopy, or STM, is a powerful technique used to image surfaces at the atomic level. Developed in the early 1980s by Gerd Binnig and Heinrich Rohrer, it earned them the Nobel Prize in Physics in 1986. STM relies on the principle of quantum mechanical tunneling. A very sharp conducting tip, often a single atom, is brought extremely close to a conducting surface. When a voltage is applied between the tip and the surface, electrons can tunnel across the small gap.

The tunneling current is highly sensitive to the distance between the tip and the surface. Even sub-atomic changes in height can cause significant variations in the current. STM instruments typically operate in one of two modes. In constant height mode, the tip is scanned across the surface at a fixed height, and the variations in tunneling current are recorded to create an image. In constant current mode, a feedback loop adjusts the tip's vertical position to maintain a constant tunneling current as it scans, effectively tracing the surface topography.

STM requires the sample to be conductive or semi-conductive. It can operate in vacuum, air, or even liquid environments, although vacuum is often preferred for cleaner surfaces. Beyond imaging, STM can also be used to manipulate individual atoms on a surface, making it a valuable tool for nanoscale research, materials science, and the development of nanodevices. The ability to visualize and interact with matter at such a fundamental scale has opened up new avenues of scientific exploration.