Simultaneous Monitoring of Macroscopic and Microscopic Diffusion of Guest Molecules in Silica and Organosilica Aerogels by Spatially and Time-Resolved Electron Paramagnetic Resonance Spectroscopy

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• 作者：Martin Spitzbarth ; Martin Wessig ; Tobias Lemke ; Andreas Schachtschneider ; Sebastian Polarz ; Malte Drescher
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 30, 2015
• 年：2015
• 卷：119
• 期：30
• 页码：17474-17479
• 全文大小：360K
• ISSN：1932-7455

文摘

We used spatially and time-resolved electron paramagnetic resonance (EPR) spectroscopy to study diffusion of guest molecules within solvent filled aerogel monoliths. We experimentally obtained the time-dependent spin density of EPR active guest molecules 蟻_1d(y,t), numerically solved the diffusion equation to simulate 蟻_1d(y,t), and determined the macroscopic translational diffusion coefficients for different aerogels and guest molecules. Simultaneously, we determined the microscopic diffusion coefficient by spectral simulation. We show that diffusion in the aerogels under study is dominated by the tortuosity of the pore system but not by surface effects.