Neutron scattering and dielectric studies on dynamics of methanol and ethanol confined in MCM-41

Shuichi Takahara, Shigeharu Kittaka, Toshinori Mori, Yasushige Kuroda, Toshiyuki Takamuku, Toshio Yamaguchi

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Abstract

The dynamics of methanol and ethanol molecules confined in MCM-41 with pore diameters d = 2.1, 2.8, and 3.7 nm has been investigated by quasi-elastic neutron scattering (QENS) and dielectric measurements. Two kinds of adsorbed amounts of liquids were studied: surface-adsorbed and capillary-condensed. The QENS measurements were performed only for methanol at room temperature and revealed that the molecular motions became slower in the following order: bulk, capillary-condensed, and surface-adsorbed liquid. The effect of confinement on the dynamics of capillary-condensed methanol molecules is stronger than in the case of acetonitrile, indicating higher cooperativity of molecular motions in liquid methanol. The dielectric measurements for methanol and ethanol in the frequency range 102-107 Hz and temperature range 120-300 K showed that the molecular motions became slower in the same order as for the QENS measurements. The slowest molecular motions of surface-adsorbed liquid must result from strong interaction between liquid molecules and the pore surface, which was demonstrated by adsorption isotherm and Fourier transform infrared spectra measurements. The slow molecular motions of capillary-condensed liquid can be explained by the influence of slow molecules near the pore surface through the cooperativity of molecular motions and/or formation of an ordered structure possibly due to van der Waals interactions between hydrogen-bonded chains.

Original languageEnglish
Pages (from-to)14385-14393
Number of pages9
JournalJournal of Physical Chemistry C
Volume112
Issue number37
DOIs
Publication statusPublished - Sep 18 2008

Fingerprint

Multicarrier modulation
Neutron scattering
Methanol
neutron scattering
Ethanol
ethyl alcohol
methyl alcohol
Elastic scattering
Liquids
liquids
elastic scattering
Molecules
porosity
molecules
Acetonitrile
Adsorption isotherms
acetonitrile
MCM-41
Hydrogen
Fourier transforms

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Neutron scattering and dielectric studies on dynamics of methanol and ethanol confined in MCM-41. / Takahara, Shuichi; Kittaka, Shigeharu; Mori, Toshinori; Kuroda, Yasushige; Takamuku, Toshiyuki; Yamaguchi, Toshio.

In: Journal of Physical Chemistry C, Vol. 112, No. 37, 18.09.2008, p. 14385-14393.

Research output: Contribution to journalArticle

Takahara, Shuichi ; Kittaka, Shigeharu ; Mori, Toshinori ; Kuroda, Yasushige ; Takamuku, Toshiyuki ; Yamaguchi, Toshio. / Neutron scattering and dielectric studies on dynamics of methanol and ethanol confined in MCM-41. In: Journal of Physical Chemistry C. 2008 ; Vol. 112, No. 37. pp. 14385-14393.
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