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How to convert cm-1to microns
Basics
Spectroscopists of the chemistry variety have found that inverse
cm is a wonderful way to measure light. It is proportional to the wavenumber and the frequency, but it makes those of us that
are trained in rational units pull our hair out. IF you are talking about ABSOLUTE wavelength (i.e. the wavelength of
CO2 laser is 10.6 microns) then the conversion goes as follows:
Wavelength in µm = 10,000/cm-1
So 300 cm-1 => 33 microns
How to convert microns to cm-1(inverse cm)
Wavenumbers in cm-1=
10,000/µm So 10.6 microns => 943 cm-1
How to convert delta microns to delta cm-1(inverse
cm)
Of course this is where it gets tricky, because the result
depends on the absolute wavenumber, in other words 10 cm-1 is 1000 microns at one wavelength, but 0.1 microns at
another. If you have a peak width of inverse centimeters converting to a peak width of microns could be painful. But taking the
derivative of the above equations
d(Wavelength in µm) = (10,000 * d(cm-1)/(cm-1)2
So a peak that is centered at 943
cm-1 and is 12 cm-1 wide would be also a peak centered at 10.6 microns and 0.13 microns wide.
How to convert delta cm-1 to delta microns
d(Wavenumber in cm-1) = (10,000 * d(µm)/(µm)2
Or a peak that has wavelength of
33 microns and is 0.2 microns wide would be centered at 303 cm-1 and be 1.84 cm-1 wide.
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