angstrom

The ångström, symbol Å, is a unit of length equal to 10^-10 meters, or 0.1 nanometers. It is named after the Swedish physicist Anders Jonas Ångström, renowned for his work in spectroscopy. The ångström is not an SI unit, but it is accepted for use with the SI.

The unit is commonly used to express dimensions at atomic and molecular scales. It appears in descriptions of interatomic spacings, bond lengths, and wavelengths of light in spectroscopy, as well as lattice constants in crystallography and structural details in materials science and biology. Its usage remains prevalent in legacy literature and in fields where convenient shorthand for small distances is valued.

Conversions and relationships: 1 Å = 10^-10 meters. Therefore, 1 nanometer (nm) = 10 Å, and 1 Å equals 100 picometers (pm). This makes the ångström convenient for discussing wavelengths and spacings in the ultraviolet, visible, and X-ray regions.

Status and usage: The angström is a non-SI unit accepted for use with the SI and is still encountered in scientific writing. In modern practice, many researchers and journals prefer nanometers or picometers for SI consistency, but the Å remains widely understood and used in various disciplines.