478
24 Water and Aqueous Solutions
solute H-O
contraction
ω H (cm
-1 )
ΔI(a.u.)
0.02
0.04
0.06
0.08
0.10
(a) NaOH/H 2 O
solvent H-O
elongation
compression
polarization
ΔI(a.u.)
ω L (cm
-1
)
0.02
0.04
0.06
0.08
0.10
(b)
NaOH/H 2 O
compression
ω H / cm
-1
ΔI / a.u.
0.77 GPa
1.03
1.33
(c)
H 2 O
solvent H-O
elongation
2600 2800 3000 3200 3400 3600 3800
50
100
150
200
250
300
2800
3000
3200
3400
3600
3800
50
100
150
200
250
300
0.77 GPa
1.03
1.33
ω L (cm
-1
)
ΔI(a.u.)
(d)
polarization
compression
Fig. 24.4 The ω x DPS for the a, b concentrated NaOH/H 2 O solutions [8] and the c, d mechanically
compressed water [22] under the ambient conditions. O:⇔:O compression and polarization have
the same but stronger effect of pressure on the ω H softening and ω L stiffening. The 3610 cm −1
sharp feature arises from the undercoordinated solute H–O bond contraction that is the same to the
dangling H–O radicals of 90% length of its bulk value
L for the YOH solutions at lower concentrations duplicates the L feature of the
mechanically compressed water, because of the compression and polarization [18].
Compression lengthens the solvent H–O bond and softens its phonon but relaxes the
O:H nonbond contrastingly. The strong effect of compression overtones the effect of
Y
+ polarization. The excessive peak at 3610 cm
−1 features the bond-order-deficiency
induced H–O contraction of the due HO − solute, which is identical to the surface H–
O dangling bond of 10% shorter, shorter and stiffer than the skin H–O bond featured
at 3450 cm
−1 for ice and water, and bulk water at 3200 cm
−1 [33].
The broad hump at ω H <3100 cm
−1 shows the distant dispersion of the O:⇔:O
compression forces acting on subsequent H 2 O neighbors. The sharp feature at
3610 cm
−1 for the YOH indicates the strong localized nature of the solute H–O bond
contraction. These DPS H–O vibration peaks clarify the origin for the two ultrafast
processes in terms of phonon lifetime [29, 34]. The longer 200 ± 50 fs lifetime features the slower energy dissipation of higher-frequency solute H–O bond vibrating at
3610 cm
−1 and the other shorter time on 1–2 ps characterizes the elongated solvent
H–O bond at lower-frequency of vibration <3100 cm
−1 upon HO − solvation [35]. In
24 Water and Aqueous Solutions
solute H-O
contraction
ω H (cm
-1 )
ΔI(a.u.)
0.02
0.04
0.06
0.08
0.10
(a) NaOH/H 2 O
solvent H-O
elongation
compression
polarization
ΔI(a.u.)
ω L (cm
-1
)
0.02
0.04
0.06
0.08
0.10
(b)
NaOH/H 2 O
compression
ω H / cm
-1
ΔI / a.u.
0.77 GPa
1.03
1.33
(c)
H 2 O
solvent H-O
elongation
2600 2800 3000 3200 3400 3600 3800
50
100
150
200
250
300
2800
3000
3200
3400
3600
3800
50
100
150
200
250
300
0.77 GPa
1.03
1.33
ω L (cm
-1
)
ΔI(a.u.)
(d)
polarization
compression
Fig. 24.4 The ω x DPS for the a, b concentrated NaOH/H 2 O solutions [8] and the c, d mechanically
compressed water [22] under the ambient conditions. O:⇔:O compression and polarization have
the same but stronger effect of pressure on the ω H softening and ω L stiffening. The 3610 cm −1
sharp feature arises from the undercoordinated solute H–O bond contraction that is the same to the
dangling H–O radicals of 90% length of its bulk value
L for the YOH solutions at lower concentrations duplicates the L feature of the
mechanically compressed water, because of the compression and polarization [18].
Compression lengthens the solvent H–O bond and softens its phonon but relaxes the
O:H nonbond contrastingly. The strong effect of compression overtones the effect of
Y
+ polarization. The excessive peak at 3610 cm
−1 features the bond-order-deficiency
induced H–O contraction of the due HO − solute, which is identical to the surface H–
O dangling bond of 10% shorter, shorter and stiffer than the skin H–O bond featured
at 3450 cm
−1 for ice and water, and bulk water at 3200 cm
−1 [33].
The broad hump at ω H <3100 cm
−1 shows the distant dispersion of the O:⇔:O
compression forces acting on subsequent H 2 O neighbors. The sharp feature at
3610 cm
−1 for the YOH indicates the strong localized nature of the solute H–O bond
contraction. These DPS H–O vibration peaks clarify the origin for the two ultrafast
processes in terms of phonon lifetime [29, 34]. The longer 200 ± 50 fs lifetime features the slower energy dissipation of higher-frequency solute H–O bond vibrating at
3610 cm
−1 and the other shorter time on 1–2 ps characterizes the elongated solvent
H–O bond at lower-frequency of vibration <3100 cm
−1 upon HO − solvation [35]. In