Inelastic electron--dipole-molecule scattering at sub-milli-electron-volt energies: CH3I and CH2Br2

Studies of Rydberg-atom destruction in collisions with the polar targets CH3I and CH2Br2 for values of principal quantum number n in the range 100--400 are reported. Analysis of the data using the essentially-free-electron model suggests that, for ultralow electron energies (∼80 μeV to 1 meV), the cross section σ(var-epsilon) for rotationally inelastic scattering of electrons by a polar target varies approximately as 1/var-epsilon, where var-epsilon is the electron energy. The Born approximation does not predict such behavior at very low collision energies, and possible reasons for this discrepancy are discussed