Page 192 - Tunable Lasers Handbook

170 F. J. Duorte

by the ground, and first excited electronic states are represented by cross sections
and
o~~~~,,,, CT~~~~,~,, respectively. The decay lifetime of N2,0 toward the first excited
electronic state (zZ1) is very fast relative to the other processes, such as zl,, that
occur in the nanosecond regime. The singlet to triplet intersystem crossing occurs
at a rate ksT and is a loss process detrimental to laser action, because it may
deplete the available population at the ground electronic state. Decay from T, to
So occurs at a rate Ut, mainly through collision deactivation but also by a weak
radiative transition called phosphorescence.
Thus, the dynamics of the upper laser level Nl,o. the laser pumping intensity
$(t). and the broadband emission intensity Z,(x,t,A) can be described by the fol-
lowing set of equations:

and