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Zeitschrift für Physikalische Chemie

International journal of research in physical chemistry and chemical physics

Editor-in-Chief: Rademann, Klaus

12 Issues per year


IMPACT FACTOR 2016: 1.012

CiteScore 2016: 0.99

SCImago Journal Rank (SJR) 2016: 0.463
Source Normalized Impact per Paper (SNIP) 2016: 0.470

Online
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2196-7156
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Volume 226, Issue 11-12

Issues

Relaxation Exchange in Nanoporous Silica by Low-Field NMR

Eva Paciok
  • RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Aachen, Deutschland
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Agnes Haber
  • RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, Aachen, Deutschland
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Maxime Van Landeghem / Bernhard Blümich
Published Online: 2012-11-12 | DOI: https://doi.org/10.1524/zpch.2012.0293

Abstract

Investigating the 2D-T2-T2-relaxation exchange of inter-stitial water in a packing of sedimented Stöber-silicate spheres, we come the conclusion that contrary to its behaviour in macro-pores, water confined in nano-pores of silica exhibits enhanced diffusivity. The 2D-experiments, performed at different temperatures, reveal a temperature-dependent bimodal relaxation distribution and two-site relaxation exchange. Our recently introduced kinetic multi-site exchange model is applied to derive the according exchange rates. The resulting Arrhenius plot produces an exchange activation energy of 7 kJ/mol, which is well below the hydrogen bond energy or the activation energy for self-diffusion of water in the bulk. A possible hopping-mechanism as the source of enhanced proton-diffusion in nanoporous silica is discussed, as well as its significance to mass transfer in porous media.

Keywords: Low Field NMR; Relaxation Exchange; Nanoporous Silica

About the article

* Correspondence address: RWTH Aachen University, Institut für Technische und Makromolekulare Chemie, 52074 Aachen, Deutschland,


Published Online: 2012-11-12

Published in Print: 2012-12-01


Citation Information: Zeitschrift für Physikalische Chemie, Volume 226, Issue 11-12, Pages 1243–1258, ISSN (Online) 2196-7156, ISSN (Print) 0942-9352, DOI: https://doi.org/10.1524/zpch.2012.0293.

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Angewandte Chemie International Edition, 2017

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