The ratio of optical to infrared emission-line strengths in O III as electron temperature diagnostics for planetary nebulae

Electron impact excitation rates for transitions in O III, calculated with the R-matrix code, are used to derive electron temperature diagnostics involving the ratio of optical (4363, 4959, 5007 A) to infrared (52, 88 microns) emission-line strengths, for a range of Ne( = 0.01-0.0001/cu cm) and Te( = 6000-20,000 K) applicable to planetary nebulae. Temperatures deduced from the observed values of these ratios for several planetaries show good internal agreement and are also similar to those estimated from the I(7135 A)/I(5192 A) ratio in Ar III, which provides observational support for the accuracy of the theoretical O III diagnostics. 24 refs