Analysis of the Spectrum of Neutral Atomic Bromine (Br I).

The spectrum of the neutral bromine atom, Br I, has been newly investigated by using electrodeless discharge tubes as light sources. The observations have led to a list of wavelengths and estimated intensities for 1253 spectral lines in the range 1067 to 24100 Å. The number of known energy levels has been increased to 123 even and 128 odd levels, as compared with the 27 even and 33 odd levels previously known. All predicted energy levels of the 4s ²4p ⁴ ns, up, nd, nf electron configurations from 0 to ~93250 K have been discovered. The observations in the vacuum ultraviolet establish that the positions of all the levels lying above those of the ground configuration as given in the compilation Atomic Energy Levels, Vol. II (1952) should be increased by 6.7 K. All but 26 faint lines of Br I have been classified. A total of 67 levels has been ascribed to the 4s ² 4p* nf configurations. It is demonstrated that the nf configurations exhibit almost pure pair coupling. The very regular (³P₂)nf[5]°_11/2 series yields for the principal ionization energy of Br I the value 95284.8 K.