PES of atomic and molecular bismuth

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Abstract
HeI photoelectron spectra of Bi and Bi2 were recorded by studying bismuth vapor at 750°C. The spectrum of Bi was found consistent with a j–j coupling description of the ground state. However, relativistic effects seemed to have little influence upon the relative photoionization cross sections of the 3P0,1,2 lines. Satellite peaks 1D2 at 11.49 eV, and possibly also 3D1,2 at 17.12 eV and 3F2,3 at 17.47 eV, were observed. They were assigned to admixtures of the configurations [(6s1/2)26p1/2(6p3/2)2]3/2 and [6s26p6d2]3/2 into the main ground‐state configuration [(6s1/2)2(6p1/2)26p3/2]3/2. An autoionization process at the energy of HeIγ radiation (23.74 eV) was suggested by the large intensity of the HeIγ spectrum. The photoelectron spectrum of Bi2 showed three distinguishable bands at 7.53, 8.94, and 9.30 eV corresponding, respectively, to the ionic states 2Πu, 3/2 , 2Πu, 1/2 , and 2Σ+g due to ionization of a (πu6p) or (σg6p) electron. A probable fourth band was observed at 14.87 eV, and was tentatively assigned to 2Σ+u of Bi+2 formed from (σu6s) ionization. The spectrum of Bi2 was found similar to those of lighter Group VA diatomics. A relationship between the equilibrium internuclear distance and the difference between the binding energies of (σgnp) and (πunp) orbitals was established for the Group VA diatomics.