Photoionization spectra and electronic structure of small iron clusters

Abstract

Laser photoionization spectra over the range 4.5–6.5 eV have been taken for iron clusters of from 2 to 25 atoms. From the observed ionization thresholds, the cluster ionization potentials are determined and trends in I.P. vs cluster size are examined. In the case of the iron dimer, a sharp, vertical threshold is seen which places the I.P. of Fe2 at 6.30±0.01 eV. Finally, SCF Xα scattered wave molecular orbital calculations have been carried out on the iron dimer and iron trimer. These results show the importance of ferromagnetic spin polarization in the electronic structure of Fe2 and Fe3.

Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

“…This leads to a total of −3 /4 ≤ 7 T z + S 3d−4s ≤ 3 /4 per atom for Fe Our estimate is a conservative one because it takes into account both, maximum T z and maximum 3d σ/4s σ electron transfer contributions at the same time. For Co + 2 , one might even expect a cancellation of T z because of the opposite signs of T z in 3d 7 …”

“…Our results show that the ground states of neutral and cationic diatomic molecules of 3d transition elements cannot generally be assumed to be connected by a one-electron process. 1-4 The complexity of the electronic structure of 3d diatomics is further reflected in a number of conflicting results from theoretical predictions and experimental studies [5][6][7][8][9][10][11][12] on the electronic ground states of Fe 2 and Co 2 that have extensively been discussed in the literature. [1][2][3][4] The current agreement among theory for neutral Fe 2 and…”

“…[13][14][15][16][17][18][19][20][21][22][23] Experimental data, on the other hand, has resisted to yield a conclusive picture. [5][6][7][8][9][10][11][12] From a different point of view, the possibility of aligning molecules in magnetic fields 24,25 and the question of the fundamental limits of the magnetic anisotropy energy that is responsible for a preferred axis of alignment of the magnetic moment naturally lead to diatomic molecules of 3d transition elements and their complexes. [17][18][19][20] Again, the predicted magnetic anisotropy energy relies on an accurate determination of the electronic states and their relative energies.…”

Vibrational Frequencies of Small Metal Clusters. The Beryllium Tetramer

“…During the past two years, the generation of well-defined metal clusters in the gas phase has progressed from dream to reality [1][2][3][4][5][6]. It is now becomin~ possible to study both the spectroscopic properties [1][2][3] and reactivity [4][5][6] of such small metal clusters.…”

A multireference perturbation theory study on the Fe2molecule: in quest of the ground state

“…The computational work on the iron dimer has been largely committed to DFT (Density Functional Theory) studies, most of which [12][13][14][15][16][17][18][19][20][21] agree in designating 7 ∆ u as the ground state with more or less reasonable values for the equilibrium distance but with too large values for ω e . A noticeable exception in the DFT studies is provided by Irigoras et al [22] and by Kulik et al [23], where the 9 Σ − g term turns out to be the ground state, with reasonable values of R e and ω e .…”