Infrared Attenuated Total Reflection Spectroscopy of Quartz and Silica Micro- and Nanoparticulate Films
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- 作者：Christian Menno M眉ller ; Alexandra Molinelli ; Manfred Karlowatz ; Alexandr Aleksandrov ; Thomas Orlando ; Boris Mizaikoff
- 刊名：The Journal of Physical Chemistry C
- 出版年：2012
- 出版时间：January 12, 2012
- 年：2012
- 卷：116
- 期：1
- 页码：37-43
- 全文大小：855K
- 年卷期：v.116,no.1(January 12, 2012)
- ISSN：1932-7455
文摘
Studies on particulate quartz and silica films were performed using Fourier transform infrared spectroscopy (FT-IR) via attenuated total reflection (ATR). Based on the fact that measurements in the visible and near-infrared (vis/NIR) spectral range are already applied to spectrally distinguish disturbed from undisturbed soils, measurements in the mid-infrared (MIR) regime were performed to further investigate the utility of longer wavelengths toward this analytical problem. Natural particulate quartz samples were selected to provide a simplified surrogate for the dominating component of most soil matrices; water was added to simulate weathering processes of this matrix. Adding water to the pristine quartz particulate film resulted in a strong spectral shift of the asymmetric Si鈥揙鈥揝i stretch vibration at 1090 cm鈥?, thus substantiating the hypothesis of a size-related shift of the absorption wavelength due to changes in the particle size distribution within the evanescent field that is extending a few micrometers into the particle layer near the ATR surface. Monodisperse soda lime glass spheres and silica microsphere samples were then investigated at simulated weathering conditions to corroborate this assumption. The obtained results indeed demonstrate that spectra recorded at monodisperse particles do not reveal any spectral shifts during simulated weathering, which again confirms a particle size-related effect. In addition, studies using unpolarized and polarized IR radiation revealed a distinct correlation between the shifts of the major absorption features, i.e., the TO modes, and the particle size.