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Titolo:
Water dynamics on the surface of MCM-41 via H-2 double quantum filtered NMR and relaxation measurements
Autore:
Hwang, DW; Sinha, AK; Cheng, CY; Yu, TY; Hwang, LP;
Indirizzi:
Natl Taiwan Univ, Dept Chem, Taipei, Taiwan Natl Taiwan Univ Taipei Taiwan l Taiwan Univ, Dept Chem, Taipei, Taiwan Acad Sinica, Inst Atom & Mol Sci, Taipei, Taiwan Acad Sinica Taipei Taiwan d Sinica, Inst Atom & Mol Sci, Taipei, Taiwan
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 24, volume: 105, anno: 2001,
pagine: 5713 - 5721
SICI:
1520-6106(20010621)105:24<5713:WDOTSO>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY-DIFFRACTION; SPECTRAL-ANALYSIS; NEUTRON-SCATTERING; MOLECULAR-DYNAMICS; H-1-NMR; RESONANCE; BEHAVIOR; SYSTEMS; BENZENE; NA-23;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
34
Recensione:
Indirizzi per estratti:
Indirizzo: Hwang, LP Natl Taiwan Univ, Dept Chem, Taipei, Taiwan Natl Taiwan Univ Taipei Taiwan niv, Dept Chem, Taipei, Taiwan
Citazione:
D.W. Hwang et al., "Water dynamics on the surface of MCM-41 via H-2 double quantum filtered NMR and relaxation measurements", J PHYS CH B, 105(24), 2001, pp. 5713-5721

Abstract

Dynamics of water adsorbed on MCM-41 has been investigated by line shape analyses of H-2 double quantum filtered (DQF) NMR and T-1 measurements. Fromtemperature-dependent studies with various water loadings on MCM-41, it isfound that there are three sites for water adsorption on MCM-41, namely, a"slow site", a "fast site I", and a "fast site II". The signal of water molecules in the slow site dominates in the observed DQF NMR. Fast site I is adjacent to the slow site, and the water molecules are exchangeable in these two sites. The fast site II is next to the fast site I, and water in the fast site II is only exchangeable with that in the fast site I. The influence of silanol groups on the MCM-41 surface strongly affects the motion of water molecules in the slow site, resulting in a residual quadrupolar interaction. As the signal of water in the fast site I dominates that observed insingle quantum spectra, it also appears in DQF spectra through an exchangeprocess. We found that when the fast site I is saturated, it has no influence on the internal rotation, but the wobbling motion of adsorbed D2O in the slow site becomes faster, i.e., the translational diffusion of D2O in thefast site I may increase the wobbling motion of adsorbed D2O through collision.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 14/08/20 alle ore 05:01:16