Determination of absolute transition probabilities in neutral cerium from branching ratio and lifetime measurements

We have used the 1-m Fourier-transform spectrometer at the National Solar Observatory, Kitt Peak, Arizona, to record the emission spectrum of 140Ce from an electrodeless discharge lamp in the 4000–27 600-cm−1 range. Branching ratios are determined from the intensity data for transitions originating from common upper levels. These measurements are combined with lifetimes determined by a delayed photoionization technique to yield transition probabilities or gA values for 30 transitions. A plot of the logarithm of intensity divided by gA versus upper energy was constructed; the excitation temperature of the source was determined from this plot. Also from this plot, absolute gA values were derived for 228 of the most intense observed lines of Ce i between 10 706 and 22184 cm−1. To our knowledge, the gA values obtained here are the first reported for neutral cerium.