Rigid Arrangements of Ionic Charge in Zeolite Frameworks Conferred by Specific Aluminum Distributions Preferentially Stabilize Alkanol Dehydration Transition States.

Zeolite reactivity depends on the solvating environments of their micropores and the proximity of their Brønsted acid sites. Turnover rates (per H ) for methanol and ethanol dehydration increase with the fraction of H sites sharing six-membered rings of chabazite (CHA) zeolites. Density functional theory (DFT) shows that activation barriers vary widely with the number and arrangement of Al (1-5 per 36 T-site unit cell), but cannot be described solely by Al-Al distance or density.

Dust Library of Plasmonically Enhanced Infrared Spectra of Individual Respirable Particles.

This work characterizes collections of infrared spectra of individual dust particles of ∼4 µm size that were obtained from three very different environments: our lab air, a home air filter, and the 11 September 2001 World Trade Center event. Particle collection was done either directly from the air or by placing dust powder from various samples directly on the plasmonic mesh with 5 µm square holes as air is pumped through the mesh. This arrangement enables the recording of "scatter-free" infrared absorption spectra of individual particles of size comparable to the probing wavelengths whose vibrational signatures are otherwise dominated by scattering and dispersive line shape distortions.