INELASTIC ELECTRON DIPOLE-MOLECULE SCATTERING AT SUB-MILLI-ELECTRON-VOLT ENERGIES - HF AND NH3

Studies of destruction of very-high-n (100 < n < 400) Rydberg atoms in collisions with the polar targets HF and NH3 are reported. Analysis o f the data using the essentially-free-electron model suggests that, fo r ultralow electron energies (approximately 80 mueV-1.4 meV), the cros s section sigma(epsilon) for rotationally inelastic scattering of elec trons by a polar target varies approximately as 1/epsilon, where epsil on is the electron energy.