You can convert wavelength into wavenumber by simply dividing 10,000 by the wavelength expressed in micrometers. For example, wavelength of 10 micrometer is 10,000/10 = 1,000 cm-1.
Using the FT-IR spectrometer, the spectrum is already expressed in the wavenumber. You do not need to do anything.
you may want to have a look at https://en.wikipedia.org/wiki/Wavenumber
Generally it is considered as how many wave mode exist per meter. X-Y graph in an IR absorption states absorbtion of modes associated with this number of waves.
Mr. Manickam,
The IR-spectrum is "Intensity" versus "Energy" (E), given as wavenumber (ni*) in [cm-1] (NB! Not in [m-1])
The relationship wavenumber (ni*) versus wavelength (lambda) is:
ni* = 1/lambda
But the freqiency (ni) and lambda are joined in relationship:
ni = c/lambda (c = 299792458 m.s-1)
And this is, because of: E = h.(ni).
So that if you would like to know to each ni* in [cm-1], corresponding frequency ni or lambda, you should transform the units:
For example, for mid-IR region should be:
5000 - 400 cm-1 region (ni*) or
2000 - 25000 nm (lambda, wavelength) or
6.67 - 83.4 fs (or 10-15 s) (ni).
I am agreeing with some answer. Furthermore wave length is inversely proportional to energy but wavenumber is proportional to energy, since E= Hc/wave length
I agree, wave number is proportional to energy, since E= Hc/wave length
wavenumber is proportional to energy, since E= Hc/wave length; i am agree with this
If you consider that E = hc/lambda and that wave number = 1/lambda, you will obtain E = hc*wave number which agrees with the answers others have provided above.
Wavelength( λ) (cm): The distance over which the wave's shape repeats.
or : The spatial period of a periodic wave.
Wavenumber ( ʋ )(cm-1): The spatial frequency of a wave, measured in cycles per unit distance.
Relation between Wavelength and Wavenumber is according to the following equation:
ʋ = 1/λ
Wavenumber( ʋ ) is used in spectroscopy such as FTIR.
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