Molecular Constraints Implied by Kinetic Coupling Schemes and Maximal Work in Chemical Lasers

The efficiency of molecular lasers is known to be enhanced when certain relaxation processes (which dissipate some energy) are allowed to take place. We consider a thermodynamic interpretation of such observations with special applications to chemical lasers operating in the limits of slow and fast rotational relaxation. Specifically it is shown that kinetic coupling schemes which reflect the hierarchy of rate processes in a nonequilibrium molecular system can be expressed as thermo dynamic constraints on the internal state distribution function. The lower the number of constraints the higher is the work which can be extracted from the nonequilibrium populations. The lower laser efficieney in the absence of rotational relaxation is due to the existence of an isolating constraint on the vib-rotational populations of the lasing molecules.