Zinc energy diagram

In Fig. 1 there is indicated the division of the nine outer orbitals into these two classes. It is assumed that electrons occupying orbitals of the first class (weak interatomic interactions) in an atom tend to remain unpaired (Hund s rule of maximum multiplicity), and that electrons occupying orbitals of the second class pair with similar electrons of adjacent atoms. Let us call these orbitals atomic orbitals and bond orbitals, respectively. In copper all of the atomic orbitals are occupied by pairs. In nickel, with ou = 0.61, there are 0.61 unpaired electrons in atomic orbitals, and in cobalt 1.71. (The deviation from unity of the difference between the values for cobalt and nickel may be the result of experimental error in the cobalt value, which is uncertain because of the magnetic hardness of this element.) This indicates that the energy diagram of Fig. 1 does not change very much from metal to metal. Substantiation of this is provided by the values of cra for copper-nickel alloys,12 which decrease linearly with mole fraction of copper from mole fraction 0.6 of copper, and by the related values for zinc-nickel and other alloys.13 The value a a = 2.61 would accordingly be expected for iron, if there were 2.61 or more d orbitals in the atomic orbital class. We conclude from the observed value [Pg.347]

C20-0107. One of the most common approaches to the investigation of metaiioproteins is to repiace the naturaiiy occurring metai ion with a different one that has a property advantageous for chemicai studies. For exampie, zinc proteins are often studied by visibie spectroscopy after Co has been substituted for Zn . Expiain, using crystai fieid energy diagrams, why Co is a better metai than Zn for visibie spectroscopy. 

Flo. 1. Proposed energy-level diagram for zinc oxide. 

Figure 1 is an energy level diagram showing a proposed model for the band structure of zinc oxide. The valence band and conduction band are shown separated by a forbidden gap. Two levels which correspond to the trapping of two electrons by the interstitial zinc are indicated in the forbidden gap. Surface levels associated with adsorbed oxygen are shown. 

To summarize the various results which suggest the energy level diagram of Fig. 1, many authors have shown (24,26,28) that zinc oxide has interstitial zinc as a donor impurity. As determined by conductivity and Hall effect measurements, the energy level for single ionization of this interstitial zinc is of the order of several hundredths of an electron volt below the conduction band when the concentration of donors is of the order of 10 cm. . The energy level for double ionization, from optical absorption measurements, appears to be at about 3.2 e.v. below the con-... 

Zinc selenide (ZnSe) doped with Ga has some Ga atoms in place of Zn atoms and is an n-type semiconductor. Draw an MO energy-level diagram for doped ZnSe, show the population of the bands, and explain why Ga substitution gives an n-type semiconductor. 

Fig. 1 Energy level diagram forthe zinc tetrabenzoporphyrin donor/chloroform acceptor system.

Figure 3. Energy level diagram for the zinc tetrabenzoporphyrin donor-chloroform acceptor...

The last electrons to be added to an orbital diagram for the atoms of the transition metal elements go into d orbitals. For example, the last electrons added to atoms of scandium. Sc, through zinc, Zn, are added to 5d orbitals. The elements yttrium, Y, through cadmium, Cd, have their highest-energy electrons in the Ad sublevel. The elements directly below them in rows 6 and 7 add electrons to the 5d and Gd orbitals. The transition metals can be called the block. (Figure 11.16). 

Fig. 7. Energy level diagram for the HOMOs and LUMOs of porphine, chlorin, iBC and BC complexes of zinc(II) (Taken from Ref. 93)...

If we can construct a cell from two half-cells such as that described above, the e.m.f. does give free energy information as long as certain rules are obeyed. As an example, consider the Daniell cell, in which a porous barrier separates zinc in zinc sulphate solution from copper in copper sulphate solution. Such a cell may be depicted by the cell-diagram ... 

Indium antimonide (InSb) forms crystals with the zinc blende structure (similar to diamond). These crystals are semiconductors. Describe the bonding in a crystal of InSb, and draw an orbital energy-level diagram for the compound. Atomic orbitals for Sb are lower in energy than those for In. 

The diagram of Figure 33.7 shows that zinc ions are removed quickly and with low energy input. This is caused by the low buffering capacity of the soil and the initially low pH of the sample (pH = 4). The zinc ions are desorbed easily and move into the direction of the cathode. There is no buildup of Zn concentration in the middle and at the cathode side. 

Fig.23 Energy level diagrams and photophysical mechanisms of prototype free-base (Fb), zinc- (Zn), and ruthenium-porphyrin (Ru)...

The molecular box 14 contains two types of chromophores, zinc-porphyrin and free-base porphyrin. The behaviors of the monomeric models of these units, Zn and Fb, have been summarized in Sect. 4.1. As expected for supramolecular species, the absorption spectrum of the box is a good superposition of those of the molecular components (Fig. 22). The energy level diagram for the molecular box, obtained as a combination of those of the Fb and Zn models (Fig. 23), shows a significant driving force for energy transfer from the Zn-porphyrin to the free base units. 

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