ABSOLUTE DIFFERENTIAL AND INTEGRAL ELECTRON-EXCITATION CROSS-SECTIONS FOR ATOMIC OXYGEN .9. IMPROVED CROSS-SECTION FOR THE 3P-]1D TRANSITION FROM 4.0 TO 30 EV

The O I (3P --> 1D) transition cross section has been remeasured for a new set of incident energies. In addition, a new O2 (a 1DELTA(g) <-- X 3SIGMA(g)-) reference cross section set has been used to normalize the relative measurements. The previous results of Doering and Gulcicek (1989) have been revised to reflect the improved reference cross section set. The new results combined with the revised Doering and Gulcicek (1989) values show that theory and experiment are in excellent agreement at incident energies greater than 9 eV. However, at lower incident energies, the experimental cross section rises to a sharp peak near 6 eV. The peak in the experimental cross section is 5.4 X 10(-17) cm2 (+/-35%) at 6 eV, approximately a factor of 2 larger than the theoretical cross section. The shape of this cross section vs. incident energy has many implications for aeronomy.