Acetaldehyde-oxide (CH3CHOO) is an atmospherically pertinent reactive intermediate that exists in syn (right) and anti (left) conformational forms. Experiment and theory reveal that the reaction of anti with dimethylamine is several orders of magnitude faster than that of syn with dimethylamine, despite both reactions being energetically downhill. Read more »
A {Ni12}-Wheel-Based Metal–Organic Framework for Coordinative Binding of Sulphur Dioxide and Nitrogen Dioxide
SO2 and NO2 are important air pollutants, and understanding the mechanism of capture materials drives the development of new clean-up technologies. In situ synchrotron x-ray crystallographic and spectroscopic experiments were used to establish a detailed molecular mechanism consisting of reversible coordination of SO2 and NO2 at the six open NiII sites on the unprecedented {Ni12}-wheel of a robust metal–organic framework material at crystallographic resolution. Read more »
Atomic-Scale Insights into Nickel Exsolution on LaNiO3 Catalysts via In Situ Electron Microscopy
In situ electron microscopy provides atomic-scale insight into the dynamic structure evolution of LaNiO3 perovskite during vacuum heating. This research established a sequential two-step process in the decomposition of LaNiO3 and gives evidence of the diffusion pathway for the lattice oxygen released during the perovskite decomposition. Read more »
Direct Observation of Surface-Bound Intermediates During Methanol Oxidation on Platinum Under Alkaline Conditions
A comprehensive mechanism for the methanol oxidation reaction (MOR) in alkaline media is presented, and it is shown that the MOR proceeds via two different pathways (via COad or H3C–Oad intermediates). The latter dominates the overall MOR current, suggesting that the H3C–Oad oxidation could be a viable pathway to accelerate the MOR in alkaline systems. Read more »
Trace Key Mechanistic Features of the Arsenite Sequestration Reaction with Nanoscale Zerovalent Iron
The advancing in situ XAS technique made it possible to uncover the As-nZVI reaction pathway, especially capturing transient reaction process at subsecond scale. Combining the in situ XAS experimental data with computational chemistry enabled the reaction steps to be verified, clarifying the unambiguous identification of the transit reactive intermediates. Read more »
Chemical (and Strategic) Transformations at Beamline 9.0
The Chemical Dynamics beamline, used for gas-phase vacuum ultraviolet (VUV) experiments, was one of the first beamlines built at the ALS. Since then, the program has undergone several strategic transformations, enabling the study of complexity in clusters, aerosols, and nanoparticles using both VUV and soft x-ray radiation. Read more »
Key to Cleaner Combustion? Look to the Stars
Researchers made the first real-time, lab-based measurement of free radicals reacting under cosmic conditions, prompting elementary carbon and hydrogen atoms to coalesce into primal benzene rings. The findings are key to understanding how the universe evolved with the growth of carbon compounds and could also help the car industry make cleaner combustion engines. Read more »
Understanding the Hydrothermal Formation of NaNbO3: Its Full Reaction Scheme and Kinetics
To understand and tune the properties of hydrothermally produced NaNbO3, the reaction was studied in situ with powder x-ray diffraction, small-angle scattering, and total scattering with pair-distribution function analysis. The full reaction scheme and kinetics were revealed, showing two different temperature-dependent growth mechanisms. Read more »
Tuning of One Atomic Layer Unlocks Catalytic Pathway
An atomically precise surface probe helped researchers discover that a catalyst can be activated by tuning the composition of just one atomic surface layer. The work sharpens our understanding of how surface changes can improve the production of hydrogen fuel from water using efficient catalysts made of inexpensive materials. Read more »
Gas-phase synthesis of corannulene—a molecular building block of fullerenes
Fullerenes have been implicated to play a key role in the astrochemical evolution of the interstellar medium. However, the formation mechanism of even their simplest molecular building block—corannulene—has remained elusive. Here we demonstrate that corannulene can be synthesized in the gas phase through reactions mimicking conditions in carbon-rich circumstellar envelopes. Read more »
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