108
3 The Interaction of Electromagnetic Waves with Ice
Fig. 3.2 The infrared
spectra of ice (blue) and
water (red) in two different
representations: a
logarithmic, and b linear.
Numbers with µm are the
wavelengths, which
correspond to the frequency
of the peak maxima
The mode ν s near 200 cm
−1 (5.3 THz), which is associated with the intermolecular
proton transfer following the shortening of intermolecular distances (see Sect. 2.6.1),
splits into two components for ice that appear at 140 and 190 cm
−1 (65 and 45 µm),
and presumably indicate transverse-longitudinal optical (LO–TO) splitting, which
assumes long-ranged Coulomb interactions. Note that the 140 cm
−1 mode disappears in the Raman spectrum of ice [10], which indirectly confirms this idea. Note
that Walrafen concluded [11] that the single Raman peak is connected with longitudinal spherical acoustic dilatational waves and involves the displacement of the
molecular center of mass. He identified that optic and multiphononic modes, which
mainly involve proton motion, appear above ≈ 330 cm
−1 , while pure acoustic modes,
which involve H 2 O center-of-mass motion, appear below ≈ 330 cm
−1 . Nevertheless,
Abe and Shigenari [12] present the first experimental confirmation of the LO–TO
splitting of the mode near 200 cm
−1 in ice. They showed that the splitting of the
mode ν s is 6.0 cm
−1 , which is close to the value previously reported by Bertie et
al. [13], confirming long-range electrostatic interaction in ice. Bertie also showed
that the transverse-acoustic (TA) branch appears only as a negligibly small shoulder
at 65 cm
−1 in the direct infrared spectrum of ice, and thus cannot be responsible for
the ν s mode.
3 The Interaction of Electromagnetic Waves with Ice
Fig. 3.2 The infrared
spectra of ice (blue) and
water (red) in two different
representations: a
logarithmic, and b linear.
Numbers with µm are the
wavelengths, which
correspond to the frequency
of the peak maxima
The mode ν s near 200 cm
−1 (5.3 THz), which is associated with the intermolecular
proton transfer following the shortening of intermolecular distances (see Sect. 2.6.1),
splits into two components for ice that appear at 140 and 190 cm
−1 (65 and 45 µm),
and presumably indicate transverse-longitudinal optical (LO–TO) splitting, which
assumes long-ranged Coulomb interactions. Note that the 140 cm
−1 mode disappears in the Raman spectrum of ice [10], which indirectly confirms this idea. Note
that Walrafen concluded [11] that the single Raman peak is connected with longitudinal spherical acoustic dilatational waves and involves the displacement of the
molecular center of mass. He identified that optic and multiphononic modes, which
mainly involve proton motion, appear above ≈ 330 cm
−1 , while pure acoustic modes,
which involve H 2 O center-of-mass motion, appear below ≈ 330 cm
−1 . Nevertheless,
Abe and Shigenari [12] present the first experimental confirmation of the LO–TO
splitting of the mode near 200 cm
−1 in ice. They showed that the splitting of the
mode ν s is 6.0 cm
−1 , which is close to the value previously reported by Bertie et
al. [13], confirming long-range electrostatic interaction in ice. Bertie also showed
that the transverse-acoustic (TA) branch appears only as a negligibly small shoulder
at 65 cm
−1 in the direct infrared spectrum of ice, and thus cannot be responsible for
the ν s mode.