# Energy unit

1. Feb 25, 2008

### somy

I have seen in text that it used an unfamiliar unit for fine-structure energy difference in a species. The unit was: cm^-1.
I need these energies to do some statistical calculations in exp(-beta*E). Can anyone tell me how can I convert this unit or convert beta to this unit?

Thanks!

2. Feb 25, 2008

### f95toli

cm^-1 probably means that the the figures are given in units of inverse wavelengths (i.e. the wavenumber, but in this case without the $2\pi$).
You can either convert using the relation between energy and frequency which can also be written $E= hc /\lambda$, or simply look at the wiki-page on wavenumbers where you can find the conversion factor

http://en.wikipedia.org/wiki/Wavenumber

3. Feb 25, 2008

### pam

I believe the cm^-1 is the wave number k.
A simple conversion from cm^-1 to keV is
E(in eV)=[1.97X10^-5] k(in cm^-1).