Knowledge Bank

The first step of the hybrid excitation in the experiment was achieved by using a pulse broadband ($\sim$200 {\AA}) dye laser beam through a heat pipe oven. But the total covered pumping wavelength region from 4600 {\AA} to 6800 {\AA} the populated upper electronic state in $Na2$ should be either $A\prime \Sigma u$ or $B\prime \Pi u$ state. The excited sodium dimers $Na2\ast$ transfered their energy to sodium atoms Na by near resonace collisions and the Na then would populate up the 3P level from ground state 3s. The Na were consequentely pumped up to 4D, 5D, 5S or 6S level from 3P by using a narrowband dye laser pumped by the same $N2$ laser. The infrared stimulated radiation corresponding to the transitions of 4D-4P(2.34 $\mu$m). 5D-4P(5.02$\mu$m), 5S-4P(3.42 $\mu$m) and 6S-5P(7.52 $\mu$m) with cascade stimulated emission from 4P to 4S (2.20 $\mu$m) and from 5P to 5S (5.43 $\mu$m) were then obtained, Furthermore the dependence of the output energy on the pumping wavelengthes was measured and discussed.