218
11 Liquid Phase
resolve the network O:H–O bond segmental cooperative relaxation induced by salt
solvation and molecular undercoordination. It is yet to be known how the cation and
anion mediate the O:H–O network and properties of salt solutions such as the surface
stress, solution viscosity, solution temperature, and critical pressures and temperatures for phase transition [27, 47]. It is also unclear how the undercoordinated water
molecules define the supercooling and superheating processes and the unusual performance of nanodroplets, nanobubbles, and the skins of water ice. Fine–resolution
detection and consistently deep insight into the intra- and intermolecular interactions
and their consequence on the solution and undercoordination derived properties of
water have been an area of increasingly active study.
According to Pauling [48], the nature of the chemical bond bridges the structure
and property of a crystal and molecule. Therefore, bond formation and relaxation
and the associated energetics, localization, entrapment, and polarization of electrons
mediate the macroscopic performance of substance accordingly [32]. O:H–O bond
segmental disparity and O–O repulsivity form the soul dictating the extraordinary
adaptivity, cooperativity, recoverability, and sensitivity of water and ice [43]. One
must focus on the chemical bond relaxation [48] and the valence electron polarization
[32, 43] in the skin region or in the hydration volume with the afore–mentioned
multiscale approaches for improved knowledge.
This section shows the electronic and phononic spectrometric evidence for the
bond–electron–phonon correlation of the undercoordinated and the hydrated O:H–O
bond network and the supersolid state. Ions in salt solutions form each a center of
electric field that clusters, stretches and polarizes its neighboring H 2 O molecules
that in turn screen the electric field of the ions to form the hydration shell of limited sizes [33]. Molecular undercoordination shortens the H–O bond spontaneously
and lengthens the O:H nonbond associated with the polarization [33]. Molecular
undercoordination and salt solvation share the same effect of O:H–O relaxation and
polarization on the bonding network and properties such as the prolonged H–O
phonon lifetime and the mediated critical conditions of phase transition.
11.2 O:H–O Bond Oscillator Pair
11.2.1 Basic Rules for Water
Water prefers the statistic mean of the tetrahedrally–coordinated, two–phase structure
in a core–shell fashion of the same geometry but different O:H–O bond lengths [1,
43]. Figure 11.1a illustrates the 2H 2 O unit cell having four oriented O:H–O bonds
bridging oxygen anions. Transiting from the V-shaped H 2 O motif of C 2v symmetry to
the 2H 2 O unit cell of C 3v symmetry aims to resolving the O:H–O cooperativity. As the
basic structure and energy storage unit, the O:H–O bond integrates the intermolecular
weaker O:H nonbond (or called van der Waals bond with ~0.1 eV energy) and the
intramolecular stronger H–O polar–covalent bond (~4.0 eV).
11 Liquid Phase
resolve the network O:H–O bond segmental cooperative relaxation induced by salt
solvation and molecular undercoordination. It is yet to be known how the cation and
anion mediate the O:H–O network and properties of salt solutions such as the surface
stress, solution viscosity, solution temperature, and critical pressures and temperatures for phase transition [27, 47]. It is also unclear how the undercoordinated water
molecules define the supercooling and superheating processes and the unusual performance of nanodroplets, nanobubbles, and the skins of water ice. Fine–resolution
detection and consistently deep insight into the intra- and intermolecular interactions
and their consequence on the solution and undercoordination derived properties of
water have been an area of increasingly active study.
According to Pauling [48], the nature of the chemical bond bridges the structure
and property of a crystal and molecule. Therefore, bond formation and relaxation
and the associated energetics, localization, entrapment, and polarization of electrons
mediate the macroscopic performance of substance accordingly [32]. O:H–O bond
segmental disparity and O–O repulsivity form the soul dictating the extraordinary
adaptivity, cooperativity, recoverability, and sensitivity of water and ice [43]. One
must focus on the chemical bond relaxation [48] and the valence electron polarization
[32, 43] in the skin region or in the hydration volume with the afore–mentioned
multiscale approaches for improved knowledge.
This section shows the electronic and phononic spectrometric evidence for the
bond–electron–phonon correlation of the undercoordinated and the hydrated O:H–O
bond network and the supersolid state. Ions in salt solutions form each a center of
electric field that clusters, stretches and polarizes its neighboring H 2 O molecules
that in turn screen the electric field of the ions to form the hydration shell of limited sizes [33]. Molecular undercoordination shortens the H–O bond spontaneously
and lengthens the O:H nonbond associated with the polarization [33]. Molecular
undercoordination and salt solvation share the same effect of O:H–O relaxation and
polarization on the bonding network and properties such as the prolonged H–O
phonon lifetime and the mediated critical conditions of phase transition.
11.2 O:H–O Bond Oscillator Pair
11.2.1 Basic Rules for Water
Water prefers the statistic mean of the tetrahedrally–coordinated, two–phase structure
in a core–shell fashion of the same geometry but different O:H–O bond lengths [1,
43]. Figure 11.1a illustrates the 2H 2 O unit cell having four oriented O:H–O bonds
bridging oxygen anions. Transiting from the V-shaped H 2 O motif of C 2v symmetry to
the 2H 2 O unit cell of C 3v symmetry aims to resolving the O:H–O cooperativity. As the
basic structure and energy storage unit, the O:H–O bond integrates the intermolecular
weaker O:H nonbond (or called van der Waals bond with ~0.1 eV energy) and the
intramolecular stronger H–O polar–covalent bond (~4.0 eV).