Differential Cross Sections with Spin Analysis for4S122−4P12,322Excitation of Potassium by Electrons

The atomic-beam recoil technique has been used to obtain the ratio of spin-flip to full differential cross sections, for $4{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}-4\mathrm{}{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2},\frac{3}{2}}^{}{}_{}{}^{}$ excitation in potassium by electrons. Data are presented at energies of from 3 to 10 eV, and for electron scattering angles of from $\theta \approx 0° \mathrm{to} 20°$, in 5-deg intervals. Additional data at $\theta \approx 0°$, for energies from threshold to 20 eV, are also presented. Appropriate scattering amplitudes are calculated using the Born, Ochkur, and close-coupling approximations, and comparison with our experiments is made. Exchange is necessary to account for the $\theta \approx 0°$ data; the close-coupling results are in fair agreement with all of the angular data, while the Ochkur approximation gives good agreement at very small angles.