Determination of Momentum Transfer and Inelastic Collision Cross Sections for Electrons in Nitrogen Using Transport Coefficients

Momentum transfer and inelastic collision cross sections for electrons in ${\mathrm{N}}_2$ have been obtained from electron transport coefficients for values of the electron energy between about 0.003 and 30 eV. The recently proposed polarization correction to the rotational excitation cross sections of Gerjuoy and Stein leads to less satisfactory agreement between theory and experiment than do the unmodified cross sections. The cross sections for vibrational excitation are consistent with those of Schulz provided the total cross section is normalized to 5.5×${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$ at 2.2 eV. Furthermore, a tail extending down to the threshold of 0.29 eV is postulated for the $v=1\mathrm{}$ vibrational level. Electronic excitation is approximated by a set of six effective cross sections which, for the most part, are consistent with previous results. The ionization cross section of Tate and Smith was used. The mean energy of electrons in ${\mathrm{N}}_2$ subjected to high-frequency ac electric fields is found to be a single-valued function of the electric field $E$ divided by the ac radian frequency $\omega$, although there are regions of $\frac{E}{\omega }$ where the mean energy increases extremely rapidly with $\frac{E}{\omega }$.