Photoelectron spectra and structure of the Mn_n⁻ anions (n = 2–16)

Photoelectron spectra of the Mn_n⁻ anion clusters (n = 2–16) are obtained by anion photoelectron spectroscopy. The electronic and geometrical structures of the anions are computed using density functional theory with generalized gradient approximation and a basis set of triple-ζ quality. The electronic and geometrical structures of the neutral Mn_n clusters have also been computed to estimate the adiabatic electron affinities. The average absolute difference between the computed and experimental vertical detachment energies of an extra electron is about 0.2 eV. Beginning with n = 6, all lowest total energy states of the Mn_n⁻ anions are ferrimagnetic with the spin multiplicities which do not exceed 8. The computed ionization energies of the neutral Mn_n clusters are in good agreement with previously obtained experimental data. According to the results of our computations, the binding energies of Mn atoms are nearly independent on the cluster charge for n > 6 and possess prominent peaks at Mn₁₃ and Mn₁₃⁻ in the neutral and anionic series, respectively. The density of states obtained from the results of our computations for the Mn_n⁻ anion clusters show the metallic character of the anion electronic structures