Advanced Topic 932 of 1102 Analytical, Lab & Spectroscopy
Scanning Tunneling Microscopy
Images surfaces atom by atom using quantum tunneling current.
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In-depth explanation of Scanning Tunneling Microscopy
Scanning tunneling microscopy images surfaces by moving a sharp conducting tip a few angstroms above a conducting or semiconducting sample while a small voltage is applied. Electrons tunnel quantum mechanically across the gap, producing a current that depends exponentially on the tip-sample distance, so even a small change in height produces a large change in current. Keeping the current constant while scanning builds a topographic map that can show individual atoms on a surface. The same instrument can move individual atoms or molecules to build structures, a capability demonstrated by IBM researchers in 1989. Gerd Binnig and Heinrich Rohrer shared the 1986 Nobel Prize in Physics for the invention.
Going deeper: Scanning Tunneling Microscopy
Key ideas: Tunnelling current falls by about a factor of 10 for each 0.1 nm increase in gap, which gives vertical resolution of about 0.01 nm and lateral resolution near 0.1 nm. Two modes: constant current (feedback adjusts height) and constant height (current recorded). The tip is often etched tungsten or cut Pt-Ir wire. Operation needs vibration isolation, and many instruments work in ultra-high vacuum.
Common mistakes and connections: The sample must conduct, so insulators need atomic force microscopy instead. Images represent electron density near the Fermi level, not just atomic positions. Students assume it uses light or electrons striking the sample, but no beam is used. A tip that is blunt or has two apexes produces ghost images. Related to quantum tunnelling, surface science and AFM.
Visualization of Scanning Tunneling Microscopy
Tunnelling current falls roughly tenfold for each 1 angstrom increase in gap, so tiny height changes give large signals that resolve single atoms. The interactive lesson shows this as a live animation or chart.
Worked example and use case
IBM researchers arranged 35 individual xenon atoms on a nickel surface to spell the letters IBM.
Frequently asked questions about Scanning Tunneling Microscopy
What is Scanning Tunneling Microscopy?
Images surfaces atom by atom using quantum tunneling current.
Is Scanning Tunneling Microscopy a beginner, intermediate or advanced topic?
Scanning Tunneling Microscopy is a advanced topic in Analytical, Lab & Spectroscopy. It builds on beginner and intermediate topics, so review those first if needed.
What should I learn before Scanning Tunneling Microscopy?
Study these earlier topics in Analytical, Lab & Spectroscopy first: ICP-MS, X-ray Crystallography, Electron Microscopy.
What comes after Scanning Tunneling Microscopy?
The next topics in Analytical, Lab & Spectroscopy are Gravimetric Analysis and Titrimetric Analysis.
Can I practise Scanning Tunneling Microscopy with quizzes?
Yes. The interactive lesson includes a self-check question on Scanning Tunneling Microscopy, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Scanning Tunneling Microscopy fits in Analytical, Lab & Spectroscopy
Scanning Tunneling Microscopy is topic 56 of 99 in Analytical, Lab & Spectroscopy.