How big is Smallest Thing Visible to an Electron Microscope?

An electron microscope forms images with a beam of electrons instead of light, and it can show single atoms. As of 2026, the best electron microscopes can pick out details about 20 picometers apart, about a fifth of the width of a hydrogen atom. A picometer is a trillionth of a meter.

Size

This figure is a resolution, not the size of an object. A microscope's resolution is the smallest distance at which two points still appear as two separate points instead of one blur. The smallest things an electron microscope shows are single atoms, and the best instruments now resolve details a fraction of an atom's width apart.

Flaws in the magnetic lenses that focus the electron beam once limited the sharpest images to about 100 picometers. Lens correctors changed that. In 2008, Lawrence Berkeley National Laboratory unveiled TEAM 0.5, a microscope designed to reach half an angstrom, or 50 picometers. Its team later reported resolving pairs of germanium atoms 47 picometers apart.

A computer method called electron ptychography then pushed the record further. A team at Cornell University reached 39 picometers in 2018, and about 20 picometers in 2021. In 2024, a team at Tsinghua University in China reported details down to 14 picometers, using a different measure of resolution. The exact record depends on how resolution is measured.

Size comparisons

A hydrogen atom, about 0.1 nanometers across, is about five times as wide as the finest detail these microscopes resolve.
If a hydrogen atom were enlarged to the size of a basketball, about 24 centimeters (9.4 inches) across, the microscope could pick out details about 4.5 centimeters (1.8 inches) apart.
An ordinary light microscope cannot resolve details closer than about 0.2 micrometers. That is 10,000 times the distance the best electron microscopes can resolve. A micrometer is a millionth of a meter.
Twenty picometers is 0.2 angstroms. Bonds between atoms are generally 1–2 angstroms long, 5–10 times as long as the finest detail resolved.
About 4–5 million of the finest resolvable details would fit across the width of a human hair.

Why electrons show finer detail than light

Conventional microscopes cannot resolve details much smaller than the wavelength of what they use to see. A wavelength is the distance from one crest of a wave to the next. For an ordinary light microscope, the limit is about 0.2 micrometers, as the microscopist Ernst Abbe worked out in 1873.

Electrons also behave as waves, with much shorter wavelengths than light. The fast electrons used in many such microscopes have a wavelength of about 2 picometers. In principle that allows far finer detail than light ever could. In practice, flawed lenses kept electron microscopes well short of that limit, and correctors and computer methods have since narrowed the gap.

How the newest images are made

Electron ptychography does not rely only on lenses. The microscope scans its beam across a sample in overlapping spots and records how the electrons scatter at each one. Computer algorithms then work out what shape of sample would produce those patterns, and rebuild the image from them.

The 2021 images from Cornell showed a crystal magnified 100 million times. At that resolution, the main blur left comes from the atoms themselves, which jiggle constantly because of heat. The team's leader, David Muller, described this as effectively an ultimate limit for resolution.