The Tl I absorption spectrum in the vacuum ultraviolet

New observations of the absorption spectrum of neutral Tl, in the wave­length range 320‒1300 Ň are reported. Earlier observations and an analysis by Connerade (1972) are confirmed and extended. Present obser­vations include 142 new transitions, mostly outside the previous energy range, which have been classified, mainly within the scheme proposed by Connerade (1972). The absence of some series due to excitation of one electron from the 5d subshell is noted and is attributed to the occurrence of strong series due to simultaneous excitation of two electrons.