INELASTIC ELECTRON DIPOLE-MOLECULE SCATTERING AT SUB-MILLI-ELECTRON-VOLT ENERGIES - POSSIBLE ROLE OF DIPOLE-SUPPORTED STATES

Studies of collisions between Rydberg atoms with values of principal q uantum number n in the range 100 less than or similar to n less than o r similar to 400 and H2S and C6H5NO2 are reported. These targets were selected because they have very different dipole moments: 0.97 and 4.2 2 D, respectively. Analysis of the data using the essentially-free-ele ctron model shows that at micro-electron-volt energies the cross secti ons for rotationally inelastic electron scattering by these targets ha ve very different energy dependences. This difference suggests that, i n the case of C6H5NO2, dipole-supported states might be important in t he scattering. To examine this further, the data are compared with the results of calculations using a free-electron cross section that assu mes the presence of dipole-supported states, and it is demonstrated th at, with a reasonable choice of parameters, it is possible to reproduc e the experimental observations.