Measurement of inelastic electron impact on ozone: Absolute differential cross sections for excitation of the Hartley band

By means of a crossed-beam technique, we have conducted absolute differential cross-section measurements for the excitation of ozone's Hartley band by electron impact. The angular range covered was from 12 degrees to 156 degrees, while the impact energies employed were 7, 10, 15, and 20 eV. The angular distributions indicate that the Hartley band has a composite nature, arising from at least one optically allowed and at least one optically forbidden transition. Candidates for these transitions are indicated with help from the results of theoretical calculations. Unfortunately, aside from the well known 1 B-1(2) <-- X (1)A(1) allowed transition observed in optical spectra, definitive assignments for these transitions cannot yet be made. Integrated cross sections were calculated from the measured differential cross sections. The former exhibit a maximum near 15-eV impact.