On the theory of vibrational relaxation of diatomic molecules

The relaxation of diatomic molecules (harmonic oscillators) in a relatively light inert gas, which plays the part of a thermostat, is considered within the framework of classical mechanics. The gas-kinetic equation for the distribution function of diatomic molecules is approximated by the Fokker-Planck equation in the space of the energies of translational, rotational and vibrational motions on the assumption of strong nonadiabaticity of the collisions. In the approximation discussed, relaxation processes with different degrees of freedom develop independently, although the characteristic times of these processes are quantities of the same order. The vibrational relaxation time, expressed in terms of the gas-kinetic integral ^*(1,1) (T*), is obtained.     

Diffusion equation in the theory of vibrational relaxation of diatomic molecules

A kinetic equation is obtained for the distribution function of anharmonic oscillators with respect to the vibrational energy; it enables one in the diffusion approximation to describe the vibrational relaxation of diatomic molecules in a medium of inert gas when there is a weak interaction between the oscillators and a thermal bath. The main difference from the equation for harmonic oscillators is in the appearance in the diffusion coefficient of an adiabaticity function that characterizes the variation of the adiabaticity factor because of the anharmoni-city of the vibrations. It follows from the form of this function that the greatest difference between the relaxation of anharmonic and harmonic oscillators is to be expected in the case of adiabatic interaction of oscillators with particles of the inert gas.     

Theory of rotational relaxation in a diatomic gas

Journal of Applied Mechanics and Technical Physics - The three-dimensional problem of energy exchange between translational and rotational degrees of freedom in collisions of diatomic molecules...     

The noneouilibrium dissociation of diatomic molecules in a boundary layer

A study is made of the influence of the process of diffusion of diatomic molecules on the rate of their thermal dissociation. On the basis of the ladder model of the dissociation of molecules — truncated harmonic oscillators — an expression is obtained for the macroscopic reaction rate which depends explicitly and exponentially on the square of the gradient of the gas temperature. The molecules constitute a small admixture in a monatomic inert gas. The effect of the diffusion on the rate of dissociation is illustrated by the results of numerical calculation of the flow in the boundary layer around the stagnation point of a blunt body.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Shidkosti i Gaza, No. 1, pp. 161–170, January–February, 1985.     

Thermal dissociation of diatomic molecules in a nonisothermal two-temperature boundary layer

Nonequilibrium thermal dissociation in a nonisothermal boundary layer in a mixture of Morse anharmonic oscillators — molecules of a diatomic gas and its atoms — is considered within the framework of the ladder mechanism. The local nonlinear nonequilibrium corrections to the two-temperature macroscopic dissociation rate, which depend, in particular, on the translational and vibrational temperature gradients and the degree of dissociation, are determined.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 2, pp. 191–201, March–April, 1996.