Preliminary Analysis of the Spectrum of Triply Ionized Gadolinium (Gd iv)*

The emission spectrum of doubly and triply ionized gadolinium from 1200 to 6000 Å is reported. A pulsed hollow-cathode light source was used with a 5-m Czerny–Turner vacuum spectrograph to obtain wavelengths and photoelectric intensities for 12 000 lines of doubly ionized gadolinium and 8000 lines of triply ionized gadolinium. For the fourth spectrum, a preliminary analysis indicates that the 4f66s–4f66p transitions occur at 45 000 cm−1 and the 4f7–4f65d transitions at 75 000 cm−1. The stronger lines from these regions determine 32 low-lying levels of these configurations.