# Nanometre

1 nanometre =
SI units
1×10−9 m 1×10−3 μm
US customary units (Imperial units)
3.2808×10−9 ft 39.370×10−9 in

The nanometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- (from the Ancient Greek νάνος, nanos, "dwarf") with the parent unit name metre (from Greek μέτρον, metrοn, "unit of measurement"). It can be written in scientific notation as 1×109Lua error: Unmatched close-bracket at pattern character 67., in engineering notation as 1 E−9 m, and is simply 1/1,000,000,000 m. One nanometre equals ten ångströms.

## Use

The nanometre is often used to express dimensions on an atomic scale: the diameter of a helium atom, for example, is about 0.1 nm, and that of a ribosome is about 20 nm. The nanometre is also commonly used to specify the wavelength of electromagnetic radiation near the visible part of the spectrum: visible light ranges from around 400 to 800 nm.[1] The angstrom, which is equal to 0.1 nm, was formerly used for these purposes.

## History

The nanometre was formerly known as the millimicrometre – or, more commonly, the millimicron for short – since it is 1/1000 of a micron (micrometre), and was often denoted by the symbol or (more rarely) µµ.[2][3][4] In 1960, the U.S. National Bureau of Standards adopted the prefix "nano-" for "a billionth".[5] The nanometre is often associated with the field of nanotechnology. Since the late 1980s, it has also been used to describe generations of the manufacturing technology in the semiconductor industry.

## References

1. ^ Hewakuruppu, Y., et al., Plasmonic “ pump – probe ” method to study semi-transparent nanofluids, Applied Optics, 52(24):6041-6050
2. ^ Svedberg, The; Nichols, J. Burton (1923). "Determination of the size and distribution of size of particle by centrifugal methods". Journal of the American Chemical Society 45 (12): 2910–2917. doi:10.1021/ja01665a016.
3. ^ Sweden, The; Rinde, Herman (1924). "The ulta-centrifuge, a new instrument for the determination of size and distribution of size of particle in amicroscopic colloids". Journal of the American Chemical Society 46 (12): 2677–2693. doi:10.1021/ja01677a011.
4. ^ Terzaghi, Karl (1925). Erdbaumechanik auf bodenphysikalischer Grundelage. Vienna: Franz Deuticke. p. 32.
5. ^ Asimov, Isaac (1960), Realm of Measure, Fawcett Premier, pg 42.