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For example, a wavenumber in inverse centimeters can be converted to a frequency expressed in the unit gigahertz by multiplying by 29.979 2458 cm/ns (the speed of light, in centimeters per nanosecond); [5] conversely, an electromagnetic wave at 29.9792458 GHz has a wavelength of 1 cm in free space.
Spatial frequency is a reciprocal length, which can thus be used as a measure of energy, usually of a particle. For example, the reciprocal centimetre, cm −1, is an energy unit equal to the energy of a photon with a wavelength of 1 cm. That energy amounts to approximately 1.24 × 10 −4 eV or 1.986 × 10 −23 J.
where Δν̃ is the Raman shift expressed in wavenumber, λ 0 is the excitation wavelength, and λ 1 is the Raman spectrum wavelength. Most commonly, the unit chosen for expressing wavenumber in Raman spectra is inverse centimeters (cm −1). Since wavelength is often expressed in units of nanometers (nm), the formula above can scale for this ...
The SI unit of molar absorption coefficient is the square metre per mole (m 2 /mol), but in practice, quantities are usually expressed in terms of M −1 ⋅cm −1 or L⋅mol −1 ⋅cm −1 (the latter two units are both equal to 0.1 m 2 /mol). In older literature, the cm 2 /mol is sometimes used; 1 M −1 ⋅cm −1 equals 1000 cm 2 /mol.
The dimension of momentum is T −1 L M. The dimension of energy is T −2 L 2 M. Dividing a unit of energy (such as eV) by a fundamental constant (such as the speed of light) that has the dimension of velocity (T −1 L) facilitates the required conversion for using a unit of energy to quantify momentum.
Kilokaiser is a common but incorrect spelling of the unit KiloKayser, which equals 1000 wavenumber (cm −1). The unit is named after Heinrich Gustav Johannes Kayser (16 March 1853 – 14 October 1940), a German physicist.
In spectroscopy, the unit cm −1 ≈ 0.000 123 9842 eV is used to represent energy since energy is inversely proportional to wavelength from the equation = = /. In discussions of energy production and consumption, the units barrel of oil equivalent and ton of oil equivalent are often used.
Wavelength is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. [3] [4] The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter lambda (λ). For a modulated wave, wavelength may refer to the carrier wavelength of the signal.