Support and Temperature Effects in Platinum Clusters. 1. Spatial Structure
| Autor: | Boyan Boyanov, Timothy I. Morrison |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Absorption spectroscopy
Extended X-ray absorption fine structure Fermi level Binding energy General Engineering chemistry.chemical_element Antibonding molecular orbital XANES symbols.namesake Crystallography chemistry Chemical physics symbols Cluster (physics) Physical and Theoretical Chemistry Platinum |
| Zdroj: | The Journal of Physical Chemistry. 100:16310-16317 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/jp9614005 |
| Popis: | The effects of Bronsted acidity on the spatial structure and electronic properties of platinum clusters supported on zeolite Y have been examined with X-ray absorption (XANES and EXAFS) and X-ray photoelectron spectroscopy. The clusters contain 10−25 Pt atoms on average, with a nearest-neighbor distance of 2.70 ± 0.01 A. Static disorder in the atomic distribution−while certainly present in the supported metal−is shown to be symmetric on average. Increasing Bronsted acidity of the zeolite support has no measurable systematic effect on the spatial structure of the clusters but results in reproducible 5−10% enhancement of near-edge features in the L2,3 X-ray absorption spectra, as well as 0.2−0.3 eV shifts in Pt 4f and 4d core-level binding energies and valence-band thresholds. Evidence is presented that the interaction between the electronic levels of the cluster and the support is not dominated by charge-transfer effects but results in the creation of unoccupied antibonding states above the Fermi level. St... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|