The direct excitation cross section for the atomic oxygen P-3 --> S-3(0) tr
ansition (lambda 1304 Angstrom) has been measured at four incident energies
between 13.4 and 40 eV. These measurements were made to add sufficient det
ail to previous direct excitation measurements to allow the near-threshold
cross section to be determined. Previous optical measurements of the 1304 A
ngstrom emission cross section disagree by up to a factor of 2 in this impo
rtant energy region. We have also compared the atomic hydrogen e + H(1s) --
> H(2s + 2p) cross section, used previously as a secondary standard for our
direct excitation measurements of atomic oxygen cross sections, to recent
measurements of the total e + H --> Lyman alpha cross section and have foun
d agreement at the +/-15% level, making a revision of our previously report
ed atomic oxygen cross sections unnecessary. The new direct excitation atom
ic oxygen cross section results, combined with previous measurements, suppo
rt the emission cross section measured by Stone and Zipf [1974] and revised
by Zipf and Erdman [1985] over the measurement of Wang and McConkey [1992]
. Except for the region just above threshold at 10-25 eV incident energy, a
ll the cross section measurements now agree to within +/-20%. The 100 eV va
lue of the atomic oxygen P-3 --> S-3(0) emission cross section from a combi
nation of the emission and direct excitation cross section experiments is 8
.6 +/- 11% x 10(-18) cm(2).