14
1 Introduction
core band—entrapment or polarization. The extent of entrapment is proportional
to the local bond energy at equilibrium. Polarization of the nonbonding states by
the densely locally entrapped bonding electrons or by the nonbonding electrons can
screen and split the crystal potential, which in turn offsets the entrapped states in the
core band negatively.
Most strikingly, the entrapment dominance entitles the Pt adatoms and the Cu/Pd
alloy acceptor-type catalysts while polarization dominance makes the Rh adatoms
and the Ag/Pd alloy donor-type catalysts. Isolation and polarization of the dangling σ
bond electrons by the entrapped bonding electrons create the Dirac-Fermi polaritons
surrounding graphite atomic vacancies and graphene zigzag edges.
1.3 Scope
The part 1 starts with Chapter 1 overviewing the significance of chemical bonds
and energetic electrons in discriminating the performance, for catalytic ability and
Dirac-Fermion generation instances, of a substance at the irregularly- (under- and
hetero-) coordinated atomic site from that of the ideally full coordinated atoms in
the bulk or from that of an isolated atom. Chapter 1 also summarizes advantages and
limitations of existing electron spectroscopic techniques, and available mechanisms
for the electron binding energy shift.
Chapter 2 describes notions of the bond order-length-strength (BOLS) correlation
[2, 3], the nonbonding electron polarization (NEP) [9], and the local bond average
(LBA) approach [4], as well as correlation between the valence and the core electrons. Incorporation of the original BOLS-NEP-LBA approach into the tight-binding
(TB) theory [174] has enabled the correlation, clarification, formulation, and quantification of the binding energies of the core and the valence electrons pertaining to
the irregularly-coordinated atoms. The variation of bond length and bond energy, and
the core electron entrapment and the subjective valence electron polarization with
the coordination and chemical environment originate intrinsically the energy shift of
electrons in various bands [45, 139], while the extrinsic effects of charging and the
initial-final state relaxation could be treated as background to be corrected.
Chapter 3 presents the atomistic zone-resolved photoelectron spectrometrics (ZPS) [8]. Complementing the scanning tunneling microscopy/spectroscopy
(STM/S), Auger electron spectroscopy (AES), and photoelectron emission spectroscopy (PES including UPS using UV light and XPS using x-ray source, or synchrotron radiation of various wave lengths), the ZPS overcomes their limitations to
gain the specific information. By differencing two spectra of the same specimen collected under different conditions, the ZPS purifies the effect of conditioning on bond
relaxation and binding energy shift within the monolayer skin and at sites surrounding point defects. Besides, the combination of AES and XPS results in the Auger
photoelectron coincidence spectroscopy (APECS) that probes simultaneously the
energy shifts of two bands of a surface—one lower and one upper. The energy shift
of the Auger parameter equals twice the shift of the upper energy band rather than
1 Introduction
core band—entrapment or polarization. The extent of entrapment is proportional
to the local bond energy at equilibrium. Polarization of the nonbonding states by
the densely locally entrapped bonding electrons or by the nonbonding electrons can
screen and split the crystal potential, which in turn offsets the entrapped states in the
core band negatively.
Most strikingly, the entrapment dominance entitles the Pt adatoms and the Cu/Pd
alloy acceptor-type catalysts while polarization dominance makes the Rh adatoms
and the Ag/Pd alloy donor-type catalysts. Isolation and polarization of the dangling σ
bond electrons by the entrapped bonding electrons create the Dirac-Fermi polaritons
surrounding graphite atomic vacancies and graphene zigzag edges.
1.3 Scope
The part 1 starts with Chapter 1 overviewing the significance of chemical bonds
and energetic electrons in discriminating the performance, for catalytic ability and
Dirac-Fermion generation instances, of a substance at the irregularly- (under- and
hetero-) coordinated atomic site from that of the ideally full coordinated atoms in
the bulk or from that of an isolated atom. Chapter 1 also summarizes advantages and
limitations of existing electron spectroscopic techniques, and available mechanisms
for the electron binding energy shift.
Chapter 2 describes notions of the bond order-length-strength (BOLS) correlation
[2, 3], the nonbonding electron polarization (NEP) [9], and the local bond average
(LBA) approach [4], as well as correlation between the valence and the core electrons. Incorporation of the original BOLS-NEP-LBA approach into the tight-binding
(TB) theory [174] has enabled the correlation, clarification, formulation, and quantification of the binding energies of the core and the valence electrons pertaining to
the irregularly-coordinated atoms. The variation of bond length and bond energy, and
the core electron entrapment and the subjective valence electron polarization with
the coordination and chemical environment originate intrinsically the energy shift of
electrons in various bands [45, 139], while the extrinsic effects of charging and the
initial-final state relaxation could be treated as background to be corrected.
Chapter 3 presents the atomistic zone-resolved photoelectron spectrometrics (ZPS) [8]. Complementing the scanning tunneling microscopy/spectroscopy
(STM/S), Auger electron spectroscopy (AES), and photoelectron emission spectroscopy (PES including UPS using UV light and XPS using x-ray source, or synchrotron radiation of various wave lengths), the ZPS overcomes their limitations to
gain the specific information. By differencing two spectra of the same specimen collected under different conditions, the ZPS purifies the effect of conditioning on bond
relaxation and binding energy shift within the monolayer skin and at sites surrounding point defects. Besides, the combination of AES and XPS results in the Auger
photoelectron coincidence spectroscopy (APECS) that probes simultaneously the
energy shifts of two bands of a surface—one lower and one upper. The energy shift
of the Auger parameter equals twice the shift of the upper energy band rather than