Semiconductor orbital orientation

NEXAFS data analysis to extract orbital orientation follows simple equations that are trigonometric expansions of the cos 5 relationship described in Section 4.1.3. The typical orientation of interest for organic semiconductors is a surface-relative orientation uniformly distributed about the surface normal. In this case, the azimuth-ally averaged tilt of the orbital can be determined. For a vector orbital, the intensity can be expressed as [31]... 

Molecular orbitals, in organic semiconductors, 22 211 Molecular orbital theory, 16 737 Molecular orientation, in linear low density polyethylene, 20 188-189 Molecular oxygen, 17 746. See also Oxygen (0)... 

A surface is created by breaking interatomic bonds-for brittle materials, quite often literally by cleavage of a bulk crystal. This picture works especially well for semiconductors with their almost directional covalent bonds. When creating a surface of a certain orientation the directional bonds are truncated. In the case of bulk termination, the sp hybridized orbitals are directed out of the surface and remain unbonded. The orientation of the broken bonds at the surface is determined by the tetrahedral bonding geometry of the bulk atoms of the diamond structure crystal. These unsaturated orbitals are called dangling bonds. 

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