Nickel atomic energy levels

J. Sugar, C. Corliss Atomic energy levels of the iron-period elements Potassium through Nickel, Phys. Chem. Ref. Data 14, Suppl. 2 (1985)... 

Sugar, J. and Corliss, C., Atomic Energy Levels of the Iron Period Elements Potassium through Nickel, /. Phys. Chem. Ref Data, Vol.l4, Suppl. 2,1985. 

Fig. 3. Splitting of atomic energy levels in a scaled magnetic field. The value A = 1 corresponds to the self consistent atomic XC-field. At this value, the exchange splitting of the Ni 3d states ( 0.6 eV) is much larger than the spin-orbit splitting of these states (fti 0.2 eV). Thus, the 3d states in nickel have almost pure spin character (see also Fig. 9 below). On the contrary, the 4p states show a much smaller exchange splitting and thus remain almost pure K-states.

In a nickel-containing enzyme various groups of atoms in the enzyme form a complex with the metal, which was found to be in the +2 oxidation state and to have no unpaired electrons. What is the most probable geometry of the Ni2+ complex (a) octahedral (b) tetrahedral (c) square planar (see Exercise 16.96) Justify your answer by drawing the orbital energy-level diagram of the ion. 

Recent studies using high resolution electron energy loss and photoelectron spectroscopy to investigate the effect of sulfur on the CO/Ni(100) system are consistent with an extended effect by the impurity on the adsorption and bonding of CO. Sulfur levels of a few percent of the surface nickel atom concentration were found sufficient to significantly alter the surface electronic structure as well as the CO bond strength. 

Figure 2 also shows a d-band, arising from the four nickel atoms with d electrons explicitly included, extending downward from about -0.5 a.u. for the clean surface, adsorbed CH and coadsorbed CH and H cases. In a Ni atom, for this basis, the average d orbital energy is -0.44 a.u., a value close to the Hartree-Fock result. Photoemission measurements position the d ionization peaks of nickel near the Fermi level, a result also obtained by most density functional treatments of nickel clusters. Application of Koopmans theorem would therefore suggest that the present d-ionization... 

The adsorption of CO on the 100 face of nickel, for instance, has been calculated to take place on top of the atom as shown in Fig. 4.8.5 This is the type of adsorption discussed previously for 100 face atoms using only the d orbitals. However, since nickel is a djo element the d orbitals on this site are filled, so this simplified adsorption scheme does not apply. The 100 site energy levels shown in Fig. 4.8b indicate, though, that the pz is the LUMO and is ideally situated for accepting the 2ct electrons from the CO. The HOMO of this site is the dxy that is directed toward the neighboring atoms in the 100 plane so it is not available for backbonding. Neither is the next lower orbital, the dx2.y2 which is also oriented in the 100 plane. Backbonding can only take place with me dxz or dyz orbitals. 

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