Chapter 3
Probing Methods: STM/S, PES, APECS,
XAS, ZPS
Abstract A set of analytical strategies has enabled atomistic, local, dynamic, and
quantitative information on the bonding and electronic energetics induced by atomic
under- and hetero-coordination. With the aids of the ZPS, one can purify the energy
states with high precision without needing decomposition of the spectral peaks.
APECS and NEXAS probe simultaneously the shifts of a core and the valence
energy bands with provision of the screening and recharging information. Quantitative information includes the bond length, bond energy, core level shift, core
charge entrapment and valence electron polarization, atomic cohesive energy, and
binding energy density. Such a collection of information is fundamentally crucial to
designing and synthesizing functional materials.
Highlights
• STM/S maps electrons from a superficial skin in the energy window surrounding
the E F .
• PES scopes BE information of the core and the valence electrons from a mixture
of bulk and skin.
• APECS detects two-band BE shifts with information on potential screening and
charge transition.
• ZPS offers CN-resolved information on bond relaxation, valence and core band,
BE shift, etc.
3.1 Energy Band Structure and Electronic Dynamics
Figure 3.1 illustrates the energy bands of a solid. When a solid forms with N atoms,
the discrete energy levels expand into bands that contain each N sublevels because of
the degeneration by involvement of crystal potentials. E 0 = 0 is the vacuum level and
E F the Fermi energy. The separation between the E 0 and the E F is the work function
φ, which determines the easiness of the substance ejecting an electron. The separation
© 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_3
45
Probing Methods: STM/S, PES, APECS,
XAS, ZPS
Abstract A set of analytical strategies has enabled atomistic, local, dynamic, and
quantitative information on the bonding and electronic energetics induced by atomic
under- and hetero-coordination. With the aids of the ZPS, one can purify the energy
states with high precision without needing decomposition of the spectral peaks.
APECS and NEXAS probe simultaneously the shifts of a core and the valence
energy bands with provision of the screening and recharging information. Quantitative information includes the bond length, bond energy, core level shift, core
charge entrapment and valence electron polarization, atomic cohesive energy, and
binding energy density. Such a collection of information is fundamentally crucial to
designing and synthesizing functional materials.
Highlights
• STM/S maps electrons from a superficial skin in the energy window surrounding
the E F .
• PES scopes BE information of the core and the valence electrons from a mixture
of bulk and skin.
• APECS detects two-band BE shifts with information on potential screening and
charge transition.
• ZPS offers CN-resolved information on bond relaxation, valence and core band,
BE shift, etc.
3.1 Energy Band Structure and Electronic Dynamics
Figure 3.1 illustrates the energy bands of a solid. When a solid forms with N atoms,
the discrete energy levels expand into bands that contain each N sublevels because of
the degeneration by involvement of crystal potentials. E 0 = 0 is the vacuum level and
E F the Fermi energy. The separation between the E 0 and the E F is the work function
φ, which determines the easiness of the substance ejecting an electron. The separation
© 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_3
45