The ratio of diffusion coefficient to mobility for slow electrons in dry air

Using Huxley's solution of the diffusion equation for electron-attaching gases, the ratio of diffusion coefficient D to mobility μ for electrons in dry air was measured over the range 3·06 × 10-17 <E/N <76·6 × 10-17 V cm2, where E is the electric field strength (V cm-1) and N the gas density (cm -3). The results agreed with those of earlier workers who used the diffusion equation for non-attaching gases.