ROTATIONAL RELAXATION IN NONPOLAR DIATOMIC GASES.
CORNELL AERONAUTICAL LAB INC BUFFALO N Y
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The rotational-translational energy transfer in collisions between homonuclear diatomic molecules and the rotational relaxation time in diatomic gases have been investigated classically. Results are presented for the shear viscosity, thermal conductivity, and rotational relaxation time in N2 which compare favorably with experimental values. Results are included for both a coplanar and three-dimensional collision model. An approximate solution for the rotational energy transfer in coplanar collisions has been obtained for arbitrary initial values of the collision parameters. The rotational relaxation time was also evaluated using this approximate result and found to agree very well with the Monte-Carlo calculation over a range of temperatures. The approximate expression derived for the rotational relaxation time was evaluated for a wide range of potential parameters. The effect of unequal rotational and translational temperatures was also studied and found to be significant. The approximate results for the relaxation time are compared with experimental data for N2 and O2, obtained using a variety of techniques, including ultrasonic, shock-wave, and free-jet experiments. The agreement with experiment is very good, particularly with ultrasonic data recently obtained over a wide temperature range for N2 and O2. Author
- Atomic and Molecular Physics and Spectroscopy