Diffraction Methods

Locking into surface structure

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Science  11 Jul 2014:
Vol. 345, Issue 6193, pp. 176-177
DOI: 10.1126/science.345.6193.176-e

Knowing the surface structure of functional materials such as catalysts is an essential part of understanding how they work. Lock-in amplifiers are instruments that extract weak signals from noisy data, which can help investigators who employ high-energy x-ray diffraction techniques to probe surfaces. Ferri et al. studied palladium nanoparticles on cerium-zirconium oxides, which are similar to catalysts used to control automotive exhaust emissions. They detected reduced Pd nanocrystals, as well as changes in oxygen coordination around the cerium cations, using phase-sensitive detection of diffraction peaks. Exposing the sample to alternating pulses of reducing CO and oxidizing O2 led to those phase shifts.

Angew. Chem. Int. Ed. 10.1002/ange.201403094 (2014).

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