Nonequilibrium Chemical Excitation and Chemical Pumping of Lasers

Chemical processes are reviewed which give rise to atomic or molecular products with spectroscopically observable nonequilibrium distributions among internal energy levels. Relevant theoretical considerations are reviewed, and for several types of reactions, experimental results are discussed in terms of specific examples. In several cases the existence of a population inversion seems clearly established, but it is by no means clear that the inversion density is sufficient for laser action. Certain features of molecular spectroscopy and collisional energy transfer processes bearing on the laser problem are discussed briefly.