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We report high-energy-resolution X-ray absorption spectroscopy detection of ethylene and CO ligands adsorbed on catalytically active iridium centers isolated on zeolite HY and on MgO supports. The data are supported by density functional theory and FEFF X-ray absorption near-edge modelling, together with infrared (IR) spectra. The results demonstrate that high-energy-resolution X-ray absorption spectra near the iridium LIII (2p3/2) edge provide clearly ascribable, distinctive signatures of the ethylene and CO ligands and illustrate effects of supports and other ligands. This X-ray absorption technique is markedly more sensitive than conventional IR spectroscopy for characterizing surface intermediates, and it is applicable to samples having low metal loadings and in reactive atmospheres and is expected to have an increasing role in catalysis research by facilitating the determination of mechanisms of solid-catalyzed reactions through identification of reaction intermediates in working catalysts. [ABSTRACT FROM AUTHOR]

High‐energy‐resolution fluorescence detection (HERFD) X‐ray absorption spectroscopy at SSRL is combined with density functional theory and FEFF simulations ascribing spectral features to ethylene and CO ligands adsorbed on catalytically active iridium centers isolated on zeolite HY and on MgO, pushing detection limits below those of conventional infrared spectroscopy, and allowing XAS to identify reactionary intermediates. More information can be found in the Full Paper by D. A. Dixon, S. R. Bare, B. C. Gates et al. on page 14760. [ABSTRACT FROM AUTHOR]