What is a Scanning Tunneling Microscope?
The STM, as it is called, is a microscope that senses and records atomic-scale images. Its definitely dissimilar to the microscope you might know from high school science the STM has no eyepiece to peer through, and the sample is not prepared as a wet mount slide. The actual microscope operates in a chamber, and the scientist (or student) controls the tool with a computer mouse and observes results on the screen. Instead of the onion skin squished between glass slides you might have studied in biology class, the sample under the STM is a substrate composed of layers of atoms. (Sample and substrate are used interchangeably in this context.) The most important part of the STM is its tip, which looks like a little needle. The tip has many capabilities, but most fall into the categories of imaging or manipulation. Operating Conditions The graduate students at Dr. Hlas lab recently constructed their own STM. To manipulate molecules effectively, the STM must operate under low temperatures an
A scanning tunneling microscope (STM) is an innovative type of microscope which, instead of using reflecting light like conventional optical microscopes, uses quantum tunneling between a sample and a probe tip to image the surface. The resolutions achieved by an STM can be as high as 0.1 nm lateral resolution and 0.01 nm depth resolution. This is a few times higher than the resolutions achievable using the best electron microscopes. An STM can work in a variety of environments: besides from ultra high vacuum, it also works in environments saturated with water, air, etc. This makes the microscope very flexible. However, the surface must be very clean and the STM tip very sharp, causing practical challenges in imaging. The STM was developed by Gerd Binnig and Heinrich Rohrer in 1981. In 1986, they won a Nobel Prize in Physics for their work on STMs. An STM tip is so sharp that it consists of only a single atom. When the tip is “dull” and consists of two atoms rather than one, this leads
