Measurements are reported of the absolute total cross sections for scattering of electrons between ∼ 35 meV and 2 eV by C 6 H 6 , C 6 H 5 D and C 6 D 6 . Data are also recorded for scattering in the presence of an axial magnetic field over an energy range which extends from between 5 and 10 meV to 2.5 eV. Absolute values of the total scattering cross sections agree well with those of other groups down to 500 meV below which no other data are available. No differences in scattering cross sections are found within experimental error between C 6 H 6 and its deuterated derivatives.The 2 E 2u shape resonance around 1.1 eV in C 6 D 6 is found at an energy ∼ 25 meV above that for C 6 H 6 . This shift in energy is ascribed to the different zero-point energies of C 6 H 6 and C 6 D 6 , with a contribution from Jahn-Teller distortion in the temporary negative ion. Data at low electron collision energies show that the scattering cross section rises rapidly below 100 meV to values of 170-180 Å2 at the lowest energies ¶. A combination of data obtained in the absence and presence of the axial magnetic field leads to the conclusion that C 6 H 6 attaches electrons at very low energy, in agreement with earlier high-pressure attachment studies. The lifetime of the (benzene) − moiety, however, appears to be of the order of microseconds-very much greater than had previously been suggested.

Low-energy scattering has been studied in , , , , , and in a transmission experiment using a synchrotron radiation photoionization source. Backward scattering cross-sections have been determined over the energy range 10-175 meV. The variation of these cross-sections with electron impact energy has been analysed for non-polar and weakly polar species using modified effective range theory, yielding scattering lengths and low-energy limiting cross-sections. Rotationally inelastic scattering cross-sections have been calculated for and using the first Born point-dipole approximation. Results suggest that rotationally inelastic events contribute strongly to low energy scattering in but only weakly in , reflecting the larger dipole moment in .

Experiments are reported which show that currents of low energy ("cold") electrons pass unattenuated through crystalline ice at 135 K for energies between zero and 650 meV, up to the maximum studied film thickness of 430 bilayers, indicating negligible apparent trapping. By contrast, both porous amorphous ice and compact crystalline ice at 40 K show efficient electron trapping. Ice at intermediate temperatures reveals metastable trapping that decays within a few hundred seconds at 110 K. Our results are the first to demonstrate full transmission of cold electrons in high temperature water ice and the phenomenon of temperature-dependent trapping.