Electron scattering in chlorine dioxide

Cross-sections are reported for total integral and backward scattering of e lectrons from chlorine dioxide (OClO) for energies in the range 20-500 meV. The measurements were made in transmission experiments using a synchrotron radiation photoionization apparatus with an energy resolution in the incid ent electron beam of similar to 1.0 meV (FWHM). integral and backward scatt ering cross-sections are reported. The present integral cross-section Value s are a correction to those reported in an earlier publication (Gulley et a l 1998a J. Phys. B: At. Mol Opt. Phys. 31 5197) which have been found to be too low due to the presence of an impurity in the original OClO samples. T he absolute accuracy of the integral cross-sections is limited by experimen tal difficulties with respect to strong rotationally inelastic forward scat tering due to the dipolar nature of the target molecules. Backward scattering data provide good evidence that dissociative attachment occurs through p-wave attachment. Comparison is made with predictions of t he first Born pure dipole approximation for both total and backward scatter ing with excellent agreement above 100 meV with integral scattering data, b ut showing a significant underestimate for backward scattering cross-sectio ns. Behaviour at energies below 100 meV represents competition between inel astic scattering and attachment and is not well understood.