Electron affinities of B, Al, Bi, and Pb

Abstract

A sputter ion source has been used to obtain beams of B−, Al−, Bi−, and Pb− ions. A mass analyzed beam of each of these ions was crossed with a fixed frequency argon ion laser operating at 488 nm, and a photoelectron spectrum obtained at a resolution of 60 meV. From an analysis of these data the following electron affinities were obtained: B, 0.278±0.010 eV; Al, 0.442±0.010 eV; Bi, 0.947±0.010 eV; Pb, 0.365±0.008 eV. In addition, a1D excited state of Al− was observed 0.332±0.010 eV above the ground state of the negative ion.

Electronegativity equalization and the electronic structure of polyhedral clusters of main‐group atoms

“…The use of empirical parameters implicitly incorporates relativistic effects into the model. For example, the recently reported [7] EA value of 0.365 eV for Pb is quite small compared to the values for Ge and Sn, reflecting the spin-orbit destabilization of the subshell which is unoccupied in Pb' but occupied in Pb-. As a consequence the electronegativity of Pb is less than that of Ge or Sn for atomic charges near -k(N = +k), although the customary ordering with x(Pb)>X(Sn) obtains for positive oxidation states such as +2.…”

“…[6] except for B, Al, Pb, and Bi which are from Ref. [7]. Uncertainties -in the last figure given in parenthe\es.…”

“…Thus The data used are the ionization energies [ 5 ] , (IE), of 9.81 and 7.29 eV and the electron affinities of 0.80 and 0.947 eV for As [6] and Bi [7], respectively. We note that while the experimental energies of subshell structure, so a quadratic fitting to the energies of Bi', Bi", and Bi-, differing in the occupancy of the destabilized 6~~~~ subshell, underestimates the energies of Bi2+ and Bi3+, which involve removal of electrons from the spin-orbit stabilized 6~112 subshell.…”

Quantum Monte Carlo with variable spins

“…For example, the respective EAs of C, Si, Ge and Sn are 1.2629 eV, 1.385 eV, 1.2 eV, and 1.2 eV 41 . However, due to the strong spin-orbit effect on the 3 P 0 ground state of Pb, the EA is significantly reduced which was experimentally determined to be 0.365(8) eV 42 . Theoretical calculations that did not include spin-orbit predict an EA of 1.284 eV, which is comparable to Ge and Sn where the spin-orbit interaction is significantly weaker 43 .…”

Once upon Anion: A Tale of Photodetachment

“…Much of the grist of atomic electron-affinity data leading to the above-mentioned reviews came from the thesis research of Charles Feigerle (23)(24)(25), who also rebuilt the anion photoelectron spectrometer to obtain an order-of-magnitude higher resolution (5 meV) and sensitivity. This improved resolution enabled the observation of fine structure levels of many atoms, providing unequivocal identification of the transition that corresponded to the atomic electron affinity.…”