Interchannel interactions and series quenching in the 5d and 6s spectra of Pb I

The absorption spectrum of lead vapour in the range 320-1070 A has been obtained. More than 60 transitions have been, found, mostly arrangable in series, which are due to excitation of either a 5d or 6s electron. Pronounced inter-channel interactions occur, similar to those in the corresponding spectrum of Tl I. Our observations confirm the applicability of a ‘ spectator model ’ for 6s excitation. The comparatively low energy of the double ionization threshold results in quenching of all but one 5d excitation series.