Transition and Electron Impact Excitation Collision Rates for O III

Transition probabilities, electron excitation collision strengths, and rate coefficients for a large number of O III lines over a broad wavelength range, from the infrared to ultraviolet, have been reported. The collision strengths have been calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method in combination with B-spline expansions is employed for an accurate representation of the target wave functions. The close-coupling expansion contains 202 O2+ fine-structure levels of the 2s(2)2p(2), 2s2p(3), 2p(4), 2s(2)2p3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, and 2s2p(3)3s, 3p, 3d configurations. The effective collision strengths are obtained by averaging electron excitation collision strengths over a Maxwellian distribution of velocities at electron temperatures ranging from 100 to 100,000 K. The calculated effective collision strengths have been reported for the 20,302 transitions between all 202 fine-structure levels. There is an overall good agreement with the recent R-matrix calculations by Storey et al. for the transitions between all levels of the ground 2s(2)2p(2) configuration, but significant discrepancies have been found with Palay et al. for transitions to the 2s(2)2p(2) S-1(0) level. Line intensity ratios between the optical lines arising from the 2s(2)2p(2) P-3(0,1,2) - D-1(2) transitions have been compared with other calculations and observations from the photoionized gaseous nebulae, and good agreement is found. The present calculations provide the most complete and accurate data sets, which should allow a more detailed treatment of the available measured spectra from different ground and space observatories.