Collisional population of the 23Πg state in K2

We have measured the effect of potassium vapour pressure within the heat-pipe oven on the shape of the 23Πg-13Σu+ fluorescence induced by collision energy transfer from the C1Πu state which was optically excited by the 457.9 nm argon-ion laser line. The estimated cross section of that process is 300 A2. The simulation of the diffuse band shape indicates a non-thermalised vibrational distribution in the 23Πg state. (orig.)