330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re, -er, American spelling) is a units of measurement, unit of length in the International System of Units (SI), equal to one

billionth This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantities and probabilities. Each number is given a name in the short scale, which is used in English-speaking countries, as well as a ...

( short scale) 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 ...

() and to 1000

picometres The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the International System of Units (SI), equal to , or one trillionth of ...

. One nanometre can be expressed in scientific notation as , and as metres.

History

The nanometre was formerly known as the millimicrometre – or, more commonly, the millimicron for short – since it is of a micron (micrometre), and was often denoted by the symbol mμ or (more rarely and confusingly, since it logically should refer to a ''millionth'' of a micron) as μμ.

Etymology

The name combines the SI prefix '' nano-'' (from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

, ', "dwarf") with the parent unit name ''metre'' (from Greek , ', "unit of measurement").

Usage

Nanotechnologies Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal o ...

are based on phenomena typically occurring on a scale of nanometres (see nanoscopic scale). The nanometre is often used to express dimensions on an atomic scale: the diameter of a

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

atom, for example, is about 0.06 nm, and that of a ribosome is about 20 nm. The nanometre is also commonly used to specify the

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...

of electromagnetic radiation near the visible part of the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

: visible light ranges from around 400 to 700 nm.Hewakuruppu, Y., et al.,
Plasmonic " pump – probe " method to study semi-transparent nanofluids
', Applied Optics, 52(24):6041-6050 The

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 ...

, which is equal to 0.1 nm, was formerly used for these purposes. Since the late 1980s, in usages such as the

32 nm The 32 nm node is the step following the 45 nm process in CMOS (MOSFET) semiconductor device fabrication. "32-nanometre" refers to the average half-pitch (i.e., half the distance between identical features) of a memory cell at this technology le ...

and the

22 nm The 22 nm node is the process step following 32 nm in CMOS MOSFET semiconductor device fabrication. The typical half-pitch (i.e., half the distance between identical features in an array) for a memory cell using the process is around 22 nm. ...

semiconductor node A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

, it has also been used to describe typical feature sizes in successive generations of the ITRS Roadmap for miniaturized

semiconductor device fabrication Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuit (IC) chips such as modern computer processors, microcontrollers, and memory chips such as NAND flash and DRAM that are p ...

in the semiconductor industry.

Unicode

The

CJK Compatibility CJK Compatibility is a Unicode block containing square symbols (both CJK and Latin alphanumeric) encoded for compatibility with East Asian character sets. In Unicode 1.0, it was divided into two blocks, named CJK Squared Words (U+3300–U+337F) ...

block in

Unicode Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, wh ...

has the symbol .

References

External links

Near-field Mie scattering in optical trap nanometry
{{SI units of length Metre