| Autor: |
Malfait, Benjamin, Moréac, Alain, Jani, Aïcha, Lefort, Ronan, Huber, Patrick, Fröba, Michael, Morineau, Denis |
| Rok vydání: |
2022 |
| Předmět: |
|
| Zdroj: |
Journal of Physical Chemistry C, American Chemical Society, In press |
| Druh dokumentu: |
Working Paper |
| Popis: |
The temperature dependence of the structure of water confined in hydrophilic mesostructured porous silica (MCM-41) and hydrophobic benzene-bridged periodic mesoporous organosilicas (PMO) is studied by Raman vibrational spectroscopy. For capillary filled pores (75% relative humidity, RH), the OH-stretching region is dominated by the contribution from liquid water situated in the core part of the pore. It adopts a bulk-like structure that is modestly disrupted by confinement and surface hydrophobicity. For partially filled pores (33% RH), the structure of the non-freezable adsorbed film radically differs from that found in capillary filled pores. A first remarkable feature is the absence of the Raman spectral fingerprint of low density amorphous ice, even at low temperature (-120{\textdegree}C). Secondly, additional bands reveal water hydroxyls groups pointing towards the different water/solid and water/vapor interfaces. For MCM-41, they correspond to water molecules acting as weak H-bond donors with silica, and dangling hydroxyl groups oriented towards the empty center of the pore. For benzene-bridged PMO, we found an additional type of dangling hydroxyl groups, which we attribute to water at hydrophobic solid interface. |
| Databáze: |
arXiv |
| Externí odkaz: |
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