Disscussing old, rare, very specific or otherwise uncommon units and measurements

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Fri Oct 05, 2007 10:27 am

how do i convert (cm)^-1 to joules!!!?????

Fri Oct 05, 2007 6:11 pm

In what context? The only context I can think of that makes any sense is the energy of a photon.

Inverse centimeters are sometimes used as a "wave number" the number of cycles of any electromagnetic wave in a centimeter (mostly used for infrared and light). It is a quasifrequency, as a real frequency would be the number of waves in one second or about 3 x 10^8 m. Hence real frequency is 3 x 10^10 greater than this wave number.

The energy of a photon is given by E = h*nu or h*c*/lamda where nu is frequency and lambda is wavelength. h is Planck's constant, Google for value

Tue May 05, 2009 10:58 pm

To get from wavenumber (cm-1) to Joules is easy.

E = planks constant x wavenumber x speed of light.

Wed Mar 09, 2011 12:15 am

same as above but speed of light needs to be in cm i think 3 x 10^10 cm/s as opposed to 10^8 m/s

Sun Mar 11, 2012 11:40 pm

1 cm−1=1.986*10−23 J.

source:
A Critical Compilation of Atomic Transition Probabilities for Neutral
and Singly Ionized Iron
J. R. Fuhra… and W. L. Wiese

### More info

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