ABSTRACT:The interactions between methyl tert-butyl ether (MTBE) and differently defected tetrahedral and octahedral fragments of clay minerals containing Si 4ϩ , Al 3ϩ , and Mg 2ϩ central cations have been studied at the B3LYP and MP2 levels of theory in conjunction with the 6-31G(d) basis set. MTBE interacts with defect clay structures due to the formation of multiple COH . . . O and OOH . . . O hydrogen bonds. Interactions of MTBE with systems containing different types of defected mineral fragments were found to vary. Systems containing the same type of defected mineral fragment with different central cation interact almost the same way with MTBE. The formation of hydrogen bonds leads to changes in the geometrical parameters and to the polarization of MTBE. The values of the interaction energies depend on the charge of the mineral fragment. They amount to 5 kcal/mol-35 kcal/mol. MTBE interacts more preferably with octahedral fragments than with tetrahedral fragments that contain an Al 3ϩ central cation.
Photochemically patterned metal nanoparticle Strontium Barium Niobate (SBN) surfaces are shown to exhibit tunable surface wettability which depends on the UV photodeposition time and the type of deposited metal nanoparticle, namely, silver or gold. Taking advantage of plasmonic properties of noble metal nanoparticles, we demonstrate enhanced Raman scattering and fluorescence emission of a probe molecule from the metal nanoparticle SBN surfaces. Further, ferroelectric lithography enables the creation of stable oppositely polarized ferroelectric domains, at the microscale, giving rise to spatially distinct metal particle deposition patterns and corresponding Raman responses. The results clearly demonstrate that metal nanoparticle/SBN surfaces suitable for enhanced chemical sensing can be designed using ferroelectric lithography and could have implications for realization of microfluidic or liquid droplet-based Surface Enhanced Raman Scattering (SERS) sensors.
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