11.4 Electron Spectrometrics
225
“:” holds regardless of temperature. Even at extreme conditions of 2000 K temperature and 2 TPa pressure, when the 2H 2 O transits into H 3 O
+ :HO
− the superionic state
[75], the 2N number conservation of protons and lone pairs remains. According to the
bond–band–barrier correlation [32, 76], the HOMO located below E F corresponds to
the energy states occupied by electron lone pairs of oxygen, and the LUMO to states
yet to be occupied by electrons of antibonding dipoles. The image of the monomer
showing the directional lone pairs that point into the open end of the surface. As the
H
+ protons share its unpaired electron with oxygen, the Cl
− ion in the NaCl substrate
interacts with the H
+ only electrostatically.
11.4.2 Water Skin: Entrapment and Polarization
Following the same size trend of “normal” materials, molecular undercoordination imparts to water local charge densification [13, 14, 77–80], binding energy
entrapment [77, 81–83], and nonbonding electron polarization [79]. XPS shown in
Fig. 11.6a confirms that the O 1s level shifts more deeply from the bulk value of
536.6–538.1 eV and 539.7 eV when move from bulk water to its skin and monomer
in gaseous phase [84–86]. The O 1s binding energy shift is a direct measure of the
H–O bond energy and the contribution from the O:H nonbond is negligibly small
[87].
The nonbonding electrons are subject to dual polarization when the molecular
CN is reduced [1]. Firstly, H–O bond contraction deepens the H–O potential well
and entraps and densifies electrons in the H–O bond and those in the core orbitals
of oxygen. This locally and densely entrapped electrons polarize the lone pair of
oxygen from the net charge of −0.616 to −0.652 eV according to DFT calculation
for ice skin [65]. The increased charge of O ions further enhances the O–O repulsion
as the second round of polarization. This dual polarization raises the valence band
energy up, from the bulk value of 3.3 eV, as shown in Fig. 11.6b. The bound energy
of solvated electrons in the skin and in the bulk reduces further with the number n
of (H 2 O) n clusters toward zero [88–90] n = 2 − 11 [88]. (Fig. 11.4).
11.4.3 Ultrafast PES: Nonbonding Electron Polarization
Molecular undercoordination induced skin polarization have been detected using
an ultrafast pump—probe liquid—jet ultra-violet photoelectron spectroscopy (UPS)
[79]. A free electron injected into water [91] will be trapped by locally oriented solvent molecules and transiently confined within a roughly spherical cavity defined by
H–O bonds oriented toward the hydrated electron [92]. The hydrated electron serves
225
“:” holds regardless of temperature. Even at extreme conditions of 2000 K temperature and 2 TPa pressure, when the 2H 2 O transits into H 3 O
+ :HO
− the superionic state
[75], the 2N number conservation of protons and lone pairs remains. According to the
bond–band–barrier correlation [32, 76], the HOMO located below E F corresponds to
the energy states occupied by electron lone pairs of oxygen, and the LUMO to states
yet to be occupied by electrons of antibonding dipoles. The image of the monomer
showing the directional lone pairs that point into the open end of the surface. As the
H
+ protons share its unpaired electron with oxygen, the Cl
− ion in the NaCl substrate
interacts with the H
+ only electrostatically.
11.4.2 Water Skin: Entrapment and Polarization
Following the same size trend of “normal” materials, molecular undercoordination imparts to water local charge densification [13, 14, 77–80], binding energy
entrapment [77, 81–83], and nonbonding electron polarization [79]. XPS shown in
Fig. 11.6a confirms that the O 1s level shifts more deeply from the bulk value of
536.6–538.1 eV and 539.7 eV when move from bulk water to its skin and monomer
in gaseous phase [84–86]. The O 1s binding energy shift is a direct measure of the
H–O bond energy and the contribution from the O:H nonbond is negligibly small
[87].
The nonbonding electrons are subject to dual polarization when the molecular
CN is reduced [1]. Firstly, H–O bond contraction deepens the H–O potential well
and entraps and densifies electrons in the H–O bond and those in the core orbitals
of oxygen. This locally and densely entrapped electrons polarize the lone pair of
oxygen from the net charge of −0.616 to −0.652 eV according to DFT calculation
for ice skin [65]. The increased charge of O ions further enhances the O–O repulsion
as the second round of polarization. This dual polarization raises the valence band
energy up, from the bulk value of 3.3 eV, as shown in Fig. 11.6b. The bound energy
of solvated electrons in the skin and in the bulk reduces further with the number n
of (H 2 O) n clusters toward zero [88–90] n = 2 − 11 [88]. (Fig. 11.4).
11.4.3 Ultrafast PES: Nonbonding Electron Polarization
Molecular undercoordination induced skin polarization have been detected using
an ultrafast pump—probe liquid—jet ultra-violet photoelectron spectroscopy (UPS)
[79]. A free electron injected into water [91] will be trapped by locally oriented solvent molecules and transiently confined within a roughly spherical cavity defined by
H–O bonds oriented toward the hydrated electron [92]. The hydrated electron serves