A green Helium Neon Laser was used to induce fluorescence in an evacuated glass cell containing a small amount of iodine.
The LIF spectrum is superposed over a white light absorption spectrum. The left most emission line is the 543.2nm laser excitation. Notice how it is almost at the same wavelength as one of the vibrational absorption lines. The horizontal lines are caused by dust particles on the slit jaws. The Spectrum is from approximately 530nm to 555nm.
Light from a tungsten lamp was passed through A green Helium Neon Laser was used to induce fluorescence in an evacuated glass cell containing a small amount of iodine. You can see the vibrational absorption lines coming from the n"=0 and 1 to the excited state.
The enegery level diagram shows why the white light spectrum is so complex. Also notice that the energy spacing is closer together in the excited states for the absorption spectrum./
