Wavenumber

Wavenumbers indicate the number of EM waves that would fit in a unit of length. The normal units for wavenumbers are inverse centimeters $[cm^{-1}]$.

Wavenumbers ($v'$), wavelength ($\lambda$), and frequency ($v$) are related:

$v'[cm^{-1}]={\frac {1}{\lambda [cm]}}={\frac {v[sec^{-1}]}{(c{\frac {m}{sec}})(100{\frac {cm}{m}})}}$