Rotational Fluctuations of Water inside the Nanopores of SBA-Type Molecular Sieves
- The rotational molecular dynamics of water confined to nanoporous molecular sieves of a regular hexagonal (SBA-15) and of a foamlike pore structure was studied by dielectric spectroscopy in the frequency range from 10-2 to 109 Hz and in a broad temperature interval. Two relaxation processes were observed: the process at lower frequencies is related to water molecules forming a layer, which is strongly adsorbed at the pore surface, whereas the relaxation process at higher frequencies is assigned to fluctuations of water molecules situated close to the center of the pore. The relaxation times of the low-frequency process for both materials and of the high-frequency process for the SBA-15 material have an unusual saddlelike temperature dependence, reported here for the first time. To describe this temperature dependence, a model developed for water confined to nanoporous glasses by Ryabov et al. [J. Phys. Chem. B 2001, 105, 1845] was applied, which considers two competing effects. TheThe rotational molecular dynamics of water confined to nanoporous molecular sieves of a regular hexagonal (SBA-15) and of a foamlike pore structure was studied by dielectric spectroscopy in the frequency range from 10-2 to 109 Hz and in a broad temperature interval. Two relaxation processes were observed: the process at lower frequencies is related to water molecules forming a layer, which is strongly adsorbed at the pore surface, whereas the relaxation process at higher frequencies is assigned to fluctuations of water molecules situated close to the center of the pore. The relaxation times of the low-frequency process for both materials and of the high-frequency process for the SBA-15 material have an unusual saddlelike temperature dependence, reported here for the first time. To describe this temperature dependence, a model developed for water confined to nanoporous glasses by Ryabov et al. [J. Phys. Chem. B 2001, 105, 1845] was applied, which considers two competing effects. The characteristic features of these two competing processes were compared with those reported for other porous systems.…
Autor*innen: | L. Frunza, H. Kosslick, I. Pitsch, St. Frunza, Andreas SchönhalsORCiD |
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Dokumenttyp: | Zeitschriftenartikel |
Veröffentlichungsform: | Verlagsliteratur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | The journal of physical chemistry / B |
Jahr der Erstveröffentlichung: | 2005 |
Herausgeber (Institution): | American Chemical Society |
Verlag: | Soc. |
Verlagsort: | Washington, DC |
Jahrgang/Band: | 109 |
Ausgabe/Heft: | 18 |
Erste Seite: | 9154 |
Letzte Seite: | 9159 |
DOI: | 10.1021/jp044503t |
ISSN: | 1520-6106 |
ISSN: | 1520-5207 |
ISSN: | 1089-5647 |
Verfügbarkeit des Dokuments: | Physisches Exemplar in der Bibliothek der BAM vorhanden ("Hardcopy Access") |
Bibliotheksstandort: | Sonderstandort: Publica-Schrank |
Datum der Freischaltung: | 19.02.2016 |
Referierte Publikation: | Ja |
Datum der Eintragung als referierte Publikation: | 27.06.2005 |