The picometre (international
spelling
Spelling is a set of conventions that regulate the way of using graphemes (writing system) to represent a language in its written form. In other words, spelling is the rendering of speech sound (phoneme) into writing (grapheme). Spelling is one ...
as used by the
International Bureau of Weights and Measures
The International Bureau of Weights and Measures (french: Bureau international des poids et mesures, BIPM) is an intergovernmental organisation, through which its 59 member-states act together on measurement standards in four areas: chemistry ...
;
SI symbol: pm) or picometer (
American spelling
Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography, the two most notable variations being British and American ...
) is a
unit of length
A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. The most common units in modern use are the metric units, used in every country globally. In the United States the U.S. customary uni ...
in the
International System of Units (SI), equal to , or one trillionth of a
metre
The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its prefi ...
, which is the
SI base unit of length.
The picometre is one thousand
femtometres, one thousandth of a
nanometre ( nm), one millionth of a
micrometre
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
(also known as a micron), one billionth of a
millimetre, and one trillionth of a metre.
The symbol μμ was once used for it.
It is also one hundredth of an
ångström
The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...
, an internationally known (but non-SI) unit of length.
Use
The picometre's length is of an order so small that its application is almost entirely confined to
particle physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) an ...
,
quantum physics,
chemistry and
acoustics.
Atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, ...
s are between 62 and 520 pm in diameter, and the typical
length of a carbon–carbon
single bond is 154 pm. Smaller units still may be used to describe smaller particles (some of which are the components of atoms themselves), such as
hadron
In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the e ...
s and the upper limits of possible size for
fermion point particles.
The
Laser Interferometer Space Antenna
The Laser Interferometer Space Antenna (LISA) is a proposed space probe to detect and accurately measure gravitational waves—tiny ripples in the fabric of spacetime—from astronomical sources. LISA would be the first dedicated space-based gr ...
(LISA) probe is planned for launch in 2034 to directly detect
gravitational waves and will measure relative displacements with a resolution of 20 picometres over a distance of 2.5 gigametres, yielding a strain sensitivity of better than 1 part in 10
20.
References
{{SI units of length
Metre
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