Accurate Electron Affinity of Iron and Fine Structures of Negative Iron ions

Electron affinity of atomic scandium and yttrium and excited states of their negative ions

The latest experimental electron affinity (EA) values of atomic scandium and yttrium were 0.189(20) and 0.308(12) eV as reported by Feigerle et al. in 1981. The measurement accuracy of these was far lower than that of other transition elements, and no conclusive result had been made on the excited states of their negative ions. In the current work, we report more accurate EA values of Sc and Y and the electronic structure of their negative ions using the slow-electron velocity-map imaging method. The EA values of Sc and Y are determined to be 0.179 378(22) and 0.311 29(22) eV, respectively. The ground state of Sc^- is identified as 3d4s²4p ¹D₂, and the ground state is 4d5s²5p ¹D₂ for Y^-. Furthermore, several excited states of Sc^- and Y^- are observed: Sc^- (³D₁) and Y^- (³D₁, ³D₂, ³D₃, ³F₂, and ³F₃), and their energy levels are determined to be 1131.8(28), 1210.0(13), 1362.3(30), 1467.7(26), 1747(16), and 1987(33) cm^-1, respectively.

Iron L3-edge energy shifts for the full range of possible 3d occupations within the same oxidation state of iron halides

Oxidation states are integer in number but dⁿ configurations of transition metal centers vary continuously in polar bonds. We quantify the shifts of the iron L₃ excitation energy, within the same formal oxidation state, in a systematic L-edge X-ray absorption spectroscopy study of diatomic gas-phase iron(II) halide cations, [FeX]⁺,where X = F, Cl, Br, I. These shifts correlate with the electronegativity of the halogen, and are attributed exclusively to a fractional increase in population of 3d-derived orbitals along the series as supported by charge transfer multiplet simulations and density functional theory calculations. We extract an excitation energy shift of 420 meV ± 60 meV spanning the full range of possible 3d occupations between the most ionic bond in [FeF]⁺ and covalently bonded [FeI]⁺.

Electron affinity of tantalum and excited states of its anion

Tantalum anion has the most complicated photoelectron spectrum among all atomic anions of transition elements, which is the main obstacle to accurately measuring its electron affinity via the generic method. The latest experimental value of the electron affinity of Ta was 0.323(12) eV reported by Feigerle et al. in 1981. In the present work, we report the high-resolution photoelectron spectroscopy of Ta- via the slow electron velocity-map imaging (SEVI) method in combination with a cryogenic ion trap. The electron affinity of Ta was measured to be 2652.38(17) cm-1 or 0.328 859(23) eV. Three excited states 5 D1, 3 P0, and 5 D2 of Ta- were observed and their energy levels were determined to be 1169.64(17) cm-1 for 5 D1, 1735.9(10) cm-1 for 3 P0, and 2320.1(20) cm-1 for 5 D2 above the ground state 5 D0, respectively.

Accurate electron affinity of Ga and fine structures of its anions

We report the high-resolution photoelectron spectra of negative gallium anions obtained via the slow-electron velocity-map imaging method. The electron affinity of Ga is determined to be 2429.07(12) cm^-1 or 0.301 166(14) eV. The fine structures of Ga are well resolved: 187.31(22) cm^-1 or 23.223(27) meV for ³P₁ and 502.70(28) cm^-1 or 62.327(35) meV for ³P₂ above the ground state ³P₀, respectively. The photoelectron angular distribution for photodetachment from Ga^-(4s²4p^{2 3}P₀) to Ga(4s²5s ²S_1/2) is measured. An unexpected perpendicular distribution instead of an isotropic distribution is observed, which is due to a resonance near 3.3780 eV.

MELEXIR: maximum entropy Legendre expanded image reconstruction. A fast and efficient method for the analysis of velocity map imaging or photoelectron imaging data

The MELEXIR program obtains a Legendre expansion of the 3D velocity distribution from 2D images of ions or photoelectrons. The maximum entropy algorithm avoids inverse Abel transforms, is fast and applicable to low-intensity images.

Observation of Rhenium Anion and Electron Affinity of Re

It was believed that the rhenium anion Re^- was not stable, just like Mn^-. We report the observation of Re^- in the laser ablation ion source and the further confirmation via the high-resolution photoelectron spectra of Re^-. The ground state of Re^- ions is 5d⁶6s^2 5D₄. The electron affinity of rhenium is determined to be 487.13(51) cm^-1 or 60.396(63) meV.