Chapter 14
Principles: Bond-Band-Barrier
Correlation
Abstract Oxide tetrahedral bond formation with orbital occupation by the shared
bonding and nonbonding electron pairs determine uniquely the bond geometry,
valence density of states, and the surface potential barrier. Parameterization of all
involved parameters as a function of the bond angle and length and the origin of the
SPB not only simplified the calculations but also importantly ensured the solution
approaching true situations.
Highlights
• VLEED sums the Bragg and the SPB elastic and inelastic resonant diffractions.
• Bond geometry, valence states, and complex SPB dictate collectively the VLEED
fine structures.
• Proper modelling and parameterization of the bond geometry and E-resolved 3D
SPB is necessary.
• Dynamic VLEED resolves the bond-band-barrier evolution dynamics at reaction.
14.1 VLEED: Multibeam Resonant Diffraction
The earliest VLEED code with double-diffraction scheme [1] calculates the SPB by
integrating from infinitely far away of the surface to a point z c in the bulk where the
potential has become equal to the atomic muffin-tin inner potential constant. Good
agreement in simulating the VLEED spectra collected from pure Cu(001) surfaces
had been realized in the mono-atom scheme [2]. However, the double-diffraction
and single-atom wise could not work properly for the chemisorbed surfaces so the
multi-order diffraction on the reflectance intensities is necessary [3], which made
the calculation for the O–Cu(001) surface possible. The following highlight some
essential details of the multi-atom and multiple diffraction scheme.
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2020
C. Q. Sun, Electron and Phonon Spectrometrics,
https://doi.org/10.1007/978-981-15-3176-7_14
263
Principles: Bond-Band-Barrier
Correlation
Abstract Oxide tetrahedral bond formation with orbital occupation by the shared
bonding and nonbonding electron pairs determine uniquely the bond geometry,
valence density of states, and the surface potential barrier. Parameterization of all
involved parameters as a function of the bond angle and length and the origin of the
SPB not only simplified the calculations but also importantly ensured the solution
approaching true situations.
Highlights
• VLEED sums the Bragg and the SPB elastic and inelastic resonant diffractions.
• Bond geometry, valence states, and complex SPB dictate collectively the VLEED
fine structures.
• Proper modelling and parameterization of the bond geometry and E-resolved 3D
SPB is necessary.
• Dynamic VLEED resolves the bond-band-barrier evolution dynamics at reaction.
14.1 VLEED: Multibeam Resonant Diffraction
The earliest VLEED code with double-diffraction scheme [1] calculates the SPB by
integrating from infinitely far away of the surface to a point z c in the bulk where the
potential has become equal to the atomic muffin-tin inner potential constant. Good
agreement in simulating the VLEED spectra collected from pure Cu(001) surfaces
had been realized in the mono-atom scheme [2]. However, the double-diffraction
and single-atom wise could not work properly for the chemisorbed surfaces so the
multi-order diffraction on the reflectance intensities is necessary [3], which made
the calculation for the O–Cu(001) surface possible. The following highlight some
essential details of the multi-atom and multiple diffraction scheme.
© The Editor(s) (if applicable) and The Author(s), under exclusive license
to Springer Nature Singapore Pte Ltd. 2020
C. Q. Sun, Electron and Phonon Spectrometrics,
https://doi.org/10.1007/978-981-15-3176-7_14
263