Raman spectroscopic studies on hydrogen bonding in methanol and methanol/water mixtures under high temperature and pressure

Ebukuro, Tokuro; Takami, Akinori; Oshima, Yoshito; Koda, Seiichiro

doi:10.1016/s0896-8446(98)00126-0

Cited by 63 publications

(45 citation statements)

References 13 publications

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“…A methanol cluster bound with hydrogen bonds is generated in the supercritical state as well as water. This result is consistent with the Raman spectra 1) and NDIS results. …”

Section: Resultssupporting

confidence: 93%

“…The Q resolution was ±0.48 nm 1 . The IXS experiments were carried out at eight Q values from 1.3 to 22 nm 1 . A typical energy scan of incident X-rays ranged ±40 meV.…”

Section: Methodsmentioning

confidence: 99%

“…Fig. 1 shows the selected IXS spectra normalized with the respective integral intensity S(Q, )/S(Q) as a function of the excitation energy at Q = 6.77 nm 1 at different values. The circles represent the experimental data with error bars, and the dashed lines show the experimentally obtained resolution function.…”

Section: Methodsmentioning

confidence: 99%

“…Raman spectral 1) , NMR chemical shift 2) , and NMR relaxation 3) measurements, and MD simulations 4) for SCM have revealed that the hydrogen bonds of methanol decrease with increasing temperature but remain even in the supercritical state. Detailed information on the cluster formation in SCM has been reported by small angle neutron scattering measurements.…”

Section: Introductionmentioning

confidence: 99%

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Inelastic X-ray Scattering of Sub- and Supercritical Methanol

et al. 2007

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Inelastic X-ray scattering experiments have been performed on methanol as a function of density from the ambient condition to the supercritical state by using third-generation synchrotron radiation. The positive dispersion of the sound velocity as compared to the hydrodynamic values was observed over ~4 nm -1 of the momentum transfer (Q) for ambient methanol. This finding in methanol is similar to that in water; however, the positive dispersion in methanol is smaller (~50 %) than that in water (~100 %). With decreasing density of methanol, the positive dispersion first decreased in the range 0.791 < < 0.60 gcm -3 at Q = 1-10 nm -1 and then increased over the range 0.50 < < 0.20 gcm -3 again only at higher Q (> ~4 nm -1 ) in supercritical methanol. These results have suggested that small clusters of a few methanol molecules are formed in the supercritical region as observed for supercritical water at low densities. It is consistent with the Raman spectra and neutron diffraction results.

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“…A methanol cluster bound with hydrogen bonds is generated in the supercritical state as well as water. This result is consistent with the Raman spectra 1) and NDIS results. …”

Section: Resultssupporting

confidence: 93%

“…The Q resolution was ±0.48 nm 1 . The IXS experiments were carried out at eight Q values from 1.3 to 22 nm 1 . A typical energy scan of incident X-rays ranged ±40 meV.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inelastic X-ray Scattering of Sub- and Supercritical Methanol

et al. 2007

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“…18 Despite a large number of reports on SCW data at the molecular level, 18 there are much fewer studies on SCM. Raman spectra, 36 NMR chemical shift, [37][38][39] relaxation 40 measurements and MD simulations 41,42 for SCM have shown that the number of hydrogen bonds of methanol decreases with increasing temperature, but that hydrogen bonds still remain even in the supercritical state. The microscopic structures of the clusters in SCM have been revealed in detail from neutron diffraction studies with isotopic substitution measurements.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen bond dynamics of superheated water and methanol by ultrafast IR-pump and EUV-photoelectron probe spectroscopy

Vöhringer‐Martinez

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Lugovoy

et al. 2014

Phys. Chem. Chem. Phys.

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Supercritical water and methanol have recently drawn much attention in the field of green chemistry. It is crucial to an understanding of supercritical solvents to know their dynamics and to what extent hydrogen (H) bonds persist in these fluids. Here, we show that with femtosecond infrared (IR) laser pulses water and methanol can be heated to temperatures near and above their critical temperature T c and their molecular dynamics can be studied via ultrafast photoelectron spectroscopy at liquid jet interfaces with high harmonics radiation. As opposed to previous studies, the main focus here is the comparison between the hydrogen bonded systems of methanol and water and their interpretation by theory. Superheated water initially forms a dense hot phase with spectral features resembling those of monomers in gas phase water. On longer timescales, this phase was found to build hot aggregates, whose size increases as a function of time. In contrast, methanol heated to temperatures near T c initially forms a broad distribution of aggregate sizes and some gas. These experimental features are also found and analyzed in extended molecular dynamics simulations. Additionally, the simulations enabled us to relate the origin of the different behavior of these two hydrogen-bonded liquids to the nature of the intermolecular potentials. The combined experimental and theoretical approach delivers new insights into both superheated phases and may contribute to understand their different chemical reactivities.

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