Water vibrational bands

Ethynylhydroxy carbene [13] has been obtained by photoreaction (A>400 nm) of a triatomic carbon cluster with water in an argon matrix and studied by IR spectroscopy (Ortman et al., 1990). Five frequencies were measured for [13] and a vibrational band at 1999.8 cm has been assigned to the C=C stretch. This value is more than 100 cmlower than the C=C stretching vibrations in acetylene derivatives, indicating that the C=C bond in the carbene [13] has lost some of its triple bond character. At the same... 

As the molecule vibrates it can also rotate and each vibrational level has associated rotational levels, each of which can be populated. A well-resolved ro - vibrational spectrum can show transitions between the lower ro-vibrational to the upper vibrational level in the laboratory and this can be performed for small molecules astronomically. The problem occurs as the size of the molecule increases and the increasing moment of inertia allows more and more levels to be present within each vibrational band, 3N — 6 vibrational bands in a nonlinear molecule rapidly becomes a big number for even reasonable size molecules and the vibrational bands become only unresolved profiles. Consider the water molecule where N = 3 so that there are three modes of vibration a rather modest number and superficially a tractable problem. Glycine, however, has 10 atoms and so 24 vibrational modes an altogether more challenging problem. Analysis of vibrational spectra is then reduced to identifying functional groups associated... 

The Earth s atmosphere is composed primarily of non-polar molecules like N2 and O2, especially at greater altitudes where the H2O concentrations are small. One would therefore expect collision-induced contributions to the absorption of the Earth s atmosphere from N2-N2, N2-O2 and O2-O2 pairs. The induced rototranslational absorption of nitrogen has not been detected in the Earth s atmosphere, presumably because of strong interference by water absorption bands, but absorption in the various induced vibrational bands is well established (Tipping 1985). Titan (the large moon of Saturn) has a nitrogen atmosphere, somewhat like the Earth methane is also present. Collision-induced absorption by N2-N2 and N2-CH4 is important in the far infrared. 

Cu Y. The absorption spectra of hydrated and dehydrated CuIJY zeolites are shown in Figs. 5 and 6, respectively. The dehydrated Cu Y zeolite also displayed a weak photoluminescence at 540 nm, in qualitative accord with the reports of partial autoreduction of Cu to Cu upon dehydration, which amounts to approximately 20% of Cu converted to Cu at the dehydration temperature of 400°C (3). The sharp peaks at 5200 and 7000 cm- in Fig. 5 are the (v+6) and (2v) vibrational bands of water (14). Their absence in Fig. 6 demonstrates that the dehydration of Cu Y is complete. Also, absence of the silanol (2v) band at 7300 cm- (I5) shows that hydroxyl groups are absent in the dehydrated Cu Y as well as in all subsequently treated copper zeolites. The broader bands between 9000 and 16000 cm and above 30000 cm- are electronic absorption spectra of the copper species in the hydrated and dehydrated Cu Y, as follows from their comparison with the spectra of NaY and CuxY. 

Fig. 7.26. The spectral evidence of the formation of hydroperoxide Si-O-O-H groups in reaction DOSG with water molecules, (a) Registering two new types of hydroxyls that are responsible for the SiO-H and SiOO-H stretching vibration bands at 3743 and 3584 cm-1 in the reaction products (b) appearance of a structureless wing of a UV band whose form is close to that observed in absorption spectrum of the HOOH molecule.

In a recent research, effect of hydrophobic surfactant proteins SP-B and SP-C on binary phospholipid monolayers was studied by IRRAS [65], The phospholipids examined were DPPC plus either DPPG or 1,2-dioleoyl-5 -glycero-3-phosphoglycerol (DOPG). IRRAS obtained at the air-water interface for a monolayer film of 7 1 DPPC-d62 DPPG plus 5 wt.% SP-B/C are shown in Fig. 5. Both C-H and C-D vibrational bands grow in intensity as the surface pressure increases and the surface density of the lipid molecules increases. As the average surface area per molecule is reduced, hydrophobic... 

High-resolution spectroscopic experiments provide a detailed experimental information on the shape of the intermolecular potential in the attractive regions. Recent improvements in supersonic beams and new laser techniques increased dramatically the sensitivity and resolution in the near-infrared region and opened to high-precision measurements the difficult far-infrared region. The latter development made it possible to investigate directly intermolecular vibration bands which are very sensitive probes of the shape of intermolecular potentials. The new spectroscopic techniques provide a lot of accurate data on interaction potentials for atom-molecule complexes, as well as on more complicated systems such as the HF, ammonia or water dimers. 

The visible spectrum of this intermediate consists of a band at Amax = 614 nm. Excitation at 614 nm gives resonance Raman enhanced bands at 416 and 666 cm-1 that shift to 408 and 638 cm-1 upon addition of H21sO, indicating exchange with water. These bands are unaffected by the addition of D20. This behavior is consistent with an FeO stretch and the shift observed upon substitution agrees with the expected shift of 29 cm-1. The second peak at 416 cm-1 was attributed to a metal-ligand vibration coupled to the iron-oxo stretch. 

Table 3.48 Magnifications of intensity of vibrational bands occurring upon dimerization of water .

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