Edge defect

NO Dissociation Dissociation at edge/defect/(100) sites Enhanced dissociation in the presence of atomic N... 

Preferential occupation of / edge/defect sites by atomic O/N... 

Figure 3.8 Scheme showing the more common covalent reactions at the CNT edge/defects and at the CNT sidewalls. The figure also shows the typical defects in a SWNT (a) five- or seven-membered rings in the C network, instead ofthe normal six-membered ring, leads to a bend in the tube, (b) sp -hybridized defects... 

Toughened glass used in fume cupboard windows can occasionally shatter explosively when edge defects are present. Although a physical hazard, it is possible to imagine it triggered by a small chemical explosion, which could even amplify the... 

FIGURE 1 Cross-sectional TEM image of GaN on c-plane sapphire (grown by MOCVD) taken near the [1100] zone with diffraction vector g-2g (g = 1120). Threading dislocations extend from a highly defective low temperature GaN buffer layer to the film surface. The density of threading dislocations is 1010 cm 2. The majority of dislocations are edge defects with b = <1120>. 

The optical properties of this new family of semiconductors are the subject of Volume 21, Part B. Phenomena discussed include the absorption edge, defect states, vibrational spectra, electroreflectance and electroabsorption, Raman scattering, luminescence, photoconductivity, photoemission, relaxation processes, and metastable effects. 

The visible and near ultra-violet (1-6 eV), and vacuum ultra-violet (4-8.5 eV) spectroscopic studies focus on transitions from the occupied states at the top of the valence band, primarily O 2p tt nonbonding states to the conduction band states, primarily O 2p ir and cr antibonding states that are mixed TM atomic states in the context of SLAC s. These spectra also include intra-d-state d-d transitions between occupied ground states and empty excited states of band edge defects these are not be confused with d-d transitions that terminate in virtual bound resonance antibonding states within the vacuum continuum. In the context of many-electron theory as applied to X-ray measurements, these states are referred to respectively as shake-up and shake-off states. The SE instruments used in these studies were developed by D.E. Aspnes during his research studies at Bell Labs, and more recently at NCSU [4,5]. 

Fig. 10 SXPS spectrum of valence band for nanocrystalline Ti02 log of photoelectron counts versus binding energy. Also includes are two band edge defects...

We will not address the densities of band edge defects until the discussion section of this chapter. The remainder of Sect. 3, and all of the research results discussed in Sects. 4 and 5 are effectively x-axisphysics, the relatively easy, but yet important aspect of this study that is addressing symmetry changes associated with J-T effect bonding distortions that reduce the local symmetry to remove d-state degeneracies. 

Fig. 12 OK edge XAS 2nd derivative spectra for Ti02 (a) conduction and valence band edge defects, (b) virtual bound resonance states defect states and shallow Ti and O core states...

Spectroscopic Studies of TM Elemental Oxides II Empty Conduction Band States and Band Edge Defects... 

Figure 15 compares second derivative O K edge XAS spectra in the spectral regime corresponding to the vacuum continuum for m-Hf02 and t-Hf02, for two of the samples included in Figs. 13 and 14. Paralleling the discussion for the spectral features in Fig. 12, the four features between 545 and 547.6 eV are assigned to antibonding states of the occupied valence band edge defects that will be displayed later on in this chapter in Fig. 19. These states are above the estimated continuum...

Figure 18(a) is the second derivative O K edge XAS spectra for conduction band edge defects in nano-crystalline t-Hf02 thin film 6 nm thick. The spectral features are different in detail than those in Figs. 17(a) and (b), and this is attributed to... 

Fig. 19 SXPS spectrum of nano-crystallineHfOj log of photoelectron counts, versus binding energy, (a) valence band and band edge defects, (b) expanded defect state plot...

---