Angstrom
Definition
The ångström or angstrom (Å) is a unit of length equal to 10−10 m (one ten-billionth of a meter) or 0.1 nanometer (nm). Named after the Swedish physicist Anders Jonas Ångström, it is often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts.
History
The angstrom was first introduced in the mid-19th century by the Swedish physicist Anders Jonas Ångström, who used it in his pioneering work in spectroscopy. Ångström's work involved the study of the spectrum of light emitted or absorbed by substances, and the angstrom provided a convenient unit for characterizing the wavelengths of light involved.
Usage
The angstrom is used extensively in crystallography, chemistry, and physics. In crystallography, it is used to measure the distances between atoms within a crystal structure. In chemistry, it is used to express the sizes of atoms, lengths of chemical bonds, and the dimensions of molecular structures. In physics, it is used to measure the wavelengths of light and other forms of electromagnetic radiation.
Measurement
The angstrom is not a part of the International System of Units (SI), which prefers the meter as the basic unit of length. However, it is recognized by the International Committee for Weights and Measures, which allows its use alongside the SI. The angstrom is defined precisely as 0.1 nanometers, which is equivalent to 10-10 meters.
Relation to Other Units
The angstrom is smaller than most units of length. For example, it is 10-10 times the size of a meter and 10-1 times the size of a nanometer. It is, however, larger than some atomic-scale and quantum-scale units, such as the Bohr radius (the size of a hydrogen atom) and the Compton wavelength (a quantum mechanical property of particles).
See Also
