Wavenumber
Physical size  

Surname  Wavenumber  
Formula symbol  ,  

The term wave number (also called repetition) is used in the physical literature for various physical quantities in connection with the frequency and the phase velocity of waves or the wavelength .
Depending on the subject, two different definitions are used:
 or.
Here is the angular frequency . The two forms differ only by the constant factor . To avoid confusion, it is also called circular wave number .
Spectroscopy
In spectroscopy , the wave number is the reciprocal of the wavelength :
 ,
where c stands for the speed of light in a vacuum and for the frequency.
The wave number is thus also the quotient of the number N of the wavelengths allotted to the length l .
It is clear the number of oscillations that it performs in a unit length (in the case of the circular wave number in a length of ).
Its SI unit is m ^{−1} , especially in spectroscopy the CGS unit is cm ^{−1} , i.e. H. Number of oscillations of a wave per centimeter , given. This unit is also called Kayser , after Heinrich Kayser . For example, rotational spectra are in the range of 1–100 cm ^{−1} , while vibrational spectra are in the range of 100–10,000 cm ^{−1} . In parlance, the unit cm ^{−1 is} usually called the wave number, so instead of “the band is 120 inverse centimeters” it is said “the band is 120 wave numbers”.
Since 1 cm corresponds to about 1 / 30,000,000,000 light second , there is a proportionality factor of 30 billion between wave number and frequency (1 cm ^{−1} corresponds to 30 GHz)
Wave number in cm ^{−1}  Wavelength in µm  Frequency in THz  application 

10,000  1  300  Infrared spectroscopy 
1,000  10  30th  Infrared / Terahertz Spectroscopy 
100  100  3  Terahertz Spectroscopy 
10  1000  0.3  Microwave spectroscopy 
Amount of the wave vector
In the multidimensional case, the circular wave number is the magnitude of the wave vector . She calculates too
The wave number is sometimes also referred to as the spatial frequency .
Individual evidence
 ↑ German Institute for Standardization (Ed.): DIN 13041 formula symbols  general formula symbols . Beuth Verlag GmbH, Berlin, p. 3 .
 ↑ OttoAlbrecht Neumüller (Ed.): Römpps ChemieLexikon. Volume 6: TZ. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1988, ISBN 3440045161 , p. 4614.