Ångström

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An ångström or aangstroem (the official transliteration), or angstrom (symbol Å) is a non-SI unit of length that is internationally recognized, equal to 0.1 nm. It is sometimes used in expressing the sizes of atoms, lengths of chemical bonds and visible-light spectra. It is named after Anders Jonas Ångström.

History

The ångström is named after the Swedish physicist Anders Jonas Ångström (1814–1874), one of the founders of spectroscopy. Besides astrophysics, Ångström was also a student of heat transfer, terrestrial magnetism, and the aurora borealis, which was so prominent for him in his northern skies. He created a spectrum chart of solar radiation that expresses the length of electromagnetic radiation in the electromagnetic spectrum on the order of multiples of one ten-millionth of a millimetre, or 1×10⁻¹⁰ metres. This unit of length became known as the ångström, Å.

From 1927 to 1960, the ångström was a secondary unit of length for use in spectroscopy, defined separately from the metre, which was still defined based on a physical prototype. In 1960, the metre itself was redefined in spectroscopical terms, making the ångström obsolete.

Representation in computers

Unicode includes the "angstrom sign" at U+212B (Å). However, the "angstrom sign" is normalized into U+00C5 (Å), and is thereby seen as a (pre-existing) encoding mistake, and it is better to use U+00C5 (Å) directly.

When typing “ångström” or “Å”, the following key sequences create the needed characters on various English-language keyboard layouts:

Microsoft Windows

Å: ALT+0197 (Holding ALT, press and release 0, then 1, then 9, then 7, then release ALT.)

å: ALT+0229 (Holding ALT, press and release 0, then 2, then 2, then 9, then release ALT.)

ö: ALT+0246 (Holding ALT, press and release 0, then 2, then 4, then 6, then release ALT.)

Alternatively, you can use the "character map" on a Windows computer, found under the Start Menu, Programs, Accessories, System Tools. This program allows you to find a character in one of many different fonts and then copy and paste the character where ever you want to put it.

Apple Computer’s Mac OS (including Mac OS X)

Å: Option-A

å: Option-a

ö: Option-u, then o

Or, in the Mac OS X, in the “Edit” menu, select “Special Characters…” to open a palette to find and use any character.

See also

• Conversion of units
• 1 E-10 mast:Ángstrom

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Wikipedia information about Ångström This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ångström". It may not have been reviewed by professional editors (see full disclaimer). Help contribute to Americola and edit this article.