The effect of the Fermi resonance on the Raman scattering cross sections of the Fermi doublet ν1 and 2ν2 of liquid carbon disulfide in benzene

Li, Dongfei; Shu-Qin, Gao; Sun, Chenglin; Jiang, Xiu-Lan; Li, Zuowei

doi:10.1016/j.saa.2011.12.038

Cited by 6 publications

(4 citation statements)

References 37 publications

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“…(See Figure .) For example, for bulk binary mixtures of carbon disulfide in benzene, a blue shift is observed for the fundamental mode (ν 1 ) and Fermi resonance mode (2ν 2 ) of carbon disulfide with decreasing concentrations. − For liquid methanol at the silica interface, we observed a blue shift with decreasing MeOH concentration for the r + FR band at 2945 cm –1 as well as in our Raman measurements of MeOH/MeCN- d 3 , as shown in Figure S4. However, the Raman intensity of the r + FR mode decreases proportionally with decreasing MeOH concentration in the bulk measurements, whereas at the interface, the vSFG intensity clearly increases, as shown in Figure a.…”

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confidence: 53%

Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Bui

Colón

Velarde

2021

J. Phys. Chem. Lett.

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The buried solid/liquid interface between hydrophilic fused silica and binary solvent mixtures of acetonitrile (MeCN) and methanol (MeOH) was studied with vibrational sum-frequency generation (vSFG) spectroscopy. Our data showed that at high relative concentrations of methanol, the Fermi resonance peak in the vSFG spectrum is greatly suppressed, and it progressively gains intensity as methanol is diluted with perdeuterated acetonitrile. This phenomenon is quantified by the Fermi resonance coupling coefficient, W, extracted using a two-level model, as well as the experimental intensity ratio, R, of the methyl Fermi resonance band to that of the symmetric stretch. At a 1.0 MeOH mole fraction, W and R values were 10 ± 10 cm–1 and 0.01 ± 0.02, respectively, whereas at a 0.1 mole fraction, W and R increased to 46 ± 4 cm–1 and 0.43 ± 0.16, respectively. This indicates that solvation with acetonitrile effectively tunes the Fermi coupling of methanol vibrations at the silica/liquid interface.

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confidence: 53%

Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Bui

Colón

Velarde

2021

J. Phys. Chem. Lett.

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“…This means that the intermolecular couplings and FR in D 2 O are perturbed in the hydration shell. It is reported that the intramolecular coupling has lesser effect on the intensity and the position/width of the OD (OH) stretch band than the FR and intermolecular coupling in water. − , Raman cross section of water increases either due a reduction in FR or due to an increase in intermolecular coupling. , On average, a water molecule in the first hydration shell of Br – interacts with lesser number of neighboring water molecules compared to those in the bulk, and experiences a rapidly varying electric field. , In a sense, the water in the first hydration shell experiences an anisotropic environment with lower probability of interaction with neighboring water and the intermolecular interaction is expected to be weaker; that is, σ H /σ b is expected to be <1.46. On the contrary, the experimentally determined σ H /σ b (1.81) is higher than that in the isotopically diluted water.…”

Section: Resultsmentioning

confidence: 99%

“…In aqueous electrolyte solutions or charged interfaces, water is preferentially oriented in the hydration shell of the charged groups/ions. − Water in the first hydration shell experiences an anisotropic environment, since it is sandwiched between charged group/ion and the water molecules in the second hydration shell. − The anisotropic environment (at the vicinity of halide ions) is likely to affect the intermolecular coupling and FR of hydrating water, which in turn would alter the Raman scattering cross section (σ) of water. − Moreover, the charge transfer from halide ions to the hydrating water leads to enhanced Raman intensity in the OH stretch regions. , Therefore, it is important to understand the intermolecular coupling and Fermi resonance of water and the role of these couplings on the Raman cross section of water while interacting with halide ions.…”

Section: Introductionmentioning

confidence: 99%

Water in the Hydration Shell of Halide Ions Has Significantly Reduced Fermi Resonance and Moderately Enhanced Raman Cross Section in the OH Stretch Regions

et al. 2013

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Water in the presence of electrolytes plays an important role in biological and industrial processes. The properties of water, such as the intermolecular coupling, Fermi resonance (FR), hydrogen-bonding, and Raman cross section were investigated by measuring the Raman spectra in the OD and OH stretch regions in presence of alkali halides (NaX; X = F, Cl, Br, I). It is observed that the changes in spectral characteristics by the addition of NaX in D2O are similar to those obtained by the addition of H2O in D2O. The spectral width decreases significantly by the addition of NaX in D2O (H2O) than that in the isotopically diluted water. Quantitative estimation, on the basis of integrated Raman intensity, revealed that the relative Raman cross section, σ(H)/σ(b) (σ(H) and σ(b) are the average Raman cross section of water in the first hydration shell of X(-) and in bulk, respectively), in D2O and H2O is higher than those in the respective isotopically diluted water. These results suggest that water in the hydration shell has reduced FR and intermolecular coupling compared to those in bulk. In the isotopically diluted water, the relative Raman cross section increases with increase in size of the halide ions (σ(H)/σ(b) = 0.6, 1.1, 1.5, and 1.9 for F(-), Cl(-), Br(-), and I(-), respectively), which is assignable to the enhancement of Raman cross section by charge transfer from halide ions to the hydrating water. Nevertheless, the experimentally determined σ(H)/σ(b) is lower than the calculated values obtained on the basis of the energy of the charge transfer state of water. The weak enhancement of σ(H)/σ(b) signifies that the charge transfer transition in the hydration shell of halide ions causes little change in the OD (OH) bond lengths of hydrating water.

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“…In other words, the physicochemical properties of water in the hydration shells are important. Extensive experimental − and theoretical − efforts have been devoted to understand the properties of water in the hydration shell of ions/solutes.…”

Section: Introductionmentioning

confidence: 99%

How Ions Affect the Structure of Water: A Combined Raman Spectroscopy and Multivariate Curve Resolution Study

et al. 2013

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Raman spectroscopy in combination with multivariate curve resolution (Raman-MCR) is used to explore the interaction between water and various kosmotropic and chaotropic anions. Raman-MCR of aqueous Na-salt (NaI, NaBr, NaNO3, Na2SO4, and Na3PO4) solutions provides solute-correlated Raman spectra (SC-spectra) of water. The SC-spectra predominantly bear the vibrational characteristics of water in the hydration shell of anions, because Na(+)-cation has negligible effect on the OH stretch band of water. The SC-spectra for the chaotropic I(-), Br(-), and NO3(-) anions and even for the kosmotropic SO4(2-) anion resemble the Raman spectrum of isotopically diluted water (H2O/D2O = 1/19; v/v) whose OH stretch band is largely comprised by the response of vibrationally decoupled OH oscillators. On the other hand, the SC-spectrum for the kosmotropic PO4(3-) anion is quite similar to the Raman spectrum of H2O (bulk). Comparison of the peak positions of SC-spectra and the Raman spectrum of isotopically diluted water suggests that the hydrogen bond strength of water in the hydration shell of SO4(2-) is comparable to that of the isotopically diluted water, but that in the hydration shell of I(-), Br(-), and NO3(-) anions is weaker than that of the latter. Analysis of integrated area of component bands of the SC-spectra reveals ∼80% reduction of the delocalization of vibrational modes (intermolecular coupling and Fermi resonance) of water in the hydration shell of I(-), Br(-), NO3(-), and SO4(2-) anions. In the case of trivalent PO4(3-), the vibrational delocalization is presumably reduced and the corresponding decrease in spectral response at ∼3250 cm(-1) is compensated by the increased signal of strongly hydrogen bonded (but decoupled) water species in the hydration shell. The peak area-averaged wavenumber of the SC-spectrum increases as PO4(3-) < SO4(2-) < NO3(-) < Br(-) < I(-) and indeed suggests strong hydrogen bonding of water in the hydration shell of PO4(3-) anion.

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The effect of the Fermi resonance on the Raman scattering cross sections of the Fermi doublet ν1 and 2ν2 of liquid carbon disulfide in benzene

Cited by 6 publications

References 37 publications

Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Intermolecular Interactions at the Silica–Liquid Interface Modulate the Fermi Resonance Coupling in Surface Methanol

Water in the Hydration Shell of Halide Ions Has Significantly Reduced Fermi Resonance and Moderately Enhanced Raman Cross Section in the OH Stretch Regions

How Ions Affect the Structure of Water: A Combined Raman Spectroscopy and Multivariate Curve Resolution Study

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