Helium-Neon Laser: Meaning of Fast Radiative Transition

[Gavroy]

hi

my question has to do with this energy level diagram

http://upload.wikimedia.org/wikipedia/en/e/ed/Hene-2.png" [Broken]

i was wondering, what the meaning of this "fast radiative transition is"?

as far as i understood this, the light that you mainly want to get is the transition from 3s to 2p. but the energy difference between 2p and 1s seems to be fairly huge too. therefore, my question is: what is the effect of this transition?

and as always: sry about my english...

 

[kith]

What you want is a population inversion, which means more population in the upper laser level (3s) than in the lower (2p). So it is really important that the lower laser level is depopulated more quickly than the higher laser level is populated. Maybe the link is helpful.

 

[Gavroy]

okay, but i was not referring to this transition, but to the transition from the 2p to the 1s level, as i do not know what this energy, that gets free in this transition, is actually used for.

 

[kith]

This energy is not used for anything, it just gets dissipated. The important feature is that the transition from 2s to wherever is fast, so the population inversion between 3s and 2p is maintained.