what is the wavelength um
d(Wavelength in Âµm) = (10,000 * d(cm-1)/(cm-1)2) The notation is a little awkward, sorry. What this means is that you take the peak width [d(cm-1)], divide it by the square of the absolute wavenumber of the center of the peak [(cm-1)] and multiply it by 10,000 to get the peak width in Âµm.