Absolute emission cross sections for electron-impact excitation of Zn+(4p 2P) and (5s 2S) terms

Absolute emission cross sections for electron-impact excitation of the 3d104p 2P and 3d105s 2S terms of Zn+ have been measured from below threshold to about 790 eV 2P and 390 eV 2S using the crossed-charged-beams technique. Both transitions have the abrupt onset at threshold characteristic of positive-ion excitation. The 2P cross section shows considerable structure in the interval from threshold to near 20 eV, above which it falls off smoothly. Agreement with five-state close-coupling theory is excellent below 100 eV when cascading is included in the theory. Above 100 eV, the data lie above the theory. The peak value of the 2P cross section is 9.4 x 10-16 cm2 essentially at threshold, while the peak value of the 2S cross section is about 0.47 x 10-16 cm2. The net linear polarization of the 3d104p 2P emission was measured (unresolved from the 3d104d 2D→3d104p 2P cascading transition), and these data were used to correct the cross-section data for anisotropy of the emitted light. The effective lifetime of the 3d94s22D/sub 3/2/ level was measured by observing exponential decay of the 589.6-nm photons resulting from its decay