Cross sections for the production of the N₂⁺(B→X), CO⁺(B→X) and N₂O⁺(A→X) fluorescence by photoionisation

The cross sections for the production of the N 2 + (B 2 Sigma u + to X 2 Sigma g + ), CO + (B 2 Sigma + to X 2 Sigma + ) and N 2 O + (A 2 Sigma + to X 2 Pi ) fluorescence in the 3000-6000 AA region are measured with synchrotron radiation from their fluorescence thresholds to 175 AA. The technique used to correct the second-order effect is described. The present results are compared with previous data. Near 540 AA the cross section for the production of the N 2 + fluorescence shows structure at the positions of the Rydberg states converging to the N 2 + (C 2 Sigma u + ) state. The cross section for the production of the CO + fluorescence shows a broad band with its peak at 400 AA. The cross sections for the production of the N 2 O + fluorescence shows structure at the positions of the Rydberg series VI-IX.