angstroms

An angstrom (symbol Å; plural angstroms or ångströms) is a unit of length equal to 10^-10 meters. It is also defined as 0.1 nanometers or 100 picometers. The unit is named after the Swedish physicist Anders Jonas Ångström, who made important contributions to spectroscopy. The angstrom is not an official SI base unit, but the symbol Å is accepted for use with SI units.

In science, the angstrom is convenient for expressing atomic- and molecular-scale distances and wavelengths of light. Wavelengths in the ultraviolet, visible, and near-infrared ranges are often quoted in angstroms, or more commonly in nanometers. Atomic and molecular dimensions such as bond lengths, interatomic spacings, and crystal lattice constants are frequently given in Å. For example, typical covalent bond lengths are around 1.0–1.5 Å, and many crystal lattice constants are a few Å.

Usage and standards: While the angstrom is widely used in physics, chemistry, and materials science, it is not an SI unit. In formal quantitative work, nanometers or picometers are often preferred for consistency with SI. When converting, 1 Å equals 0.1 nm or 100 pm. The symbol Å is a letter A with a ring and is case-sensitive in most fonts.