Diffuse reflectance infrared and photoluminescence spectra of surface vanadyl groups. Direct evidence for change of bond strength and electronic structure of metal-oxygen bond upon supporting oxide

1983 ◽  
Vol 105 (11) ◽  
pp. 3719-3720 ◽  
Author(s):  
Masakazu Iwamoto ◽  
Hiroshi Furukawa ◽  
Kazuto Matsukami ◽  
Toshihisa Takenaka ◽  
Shuichi Kagawa
Keyword(s):  
Electronic Structure ◽  
Bond Strength ◽  
Diffuse Reflectance ◽  
Direct Evidence ◽  
Photoluminescence Spectra ◽  
Structure Of Metal ◽  
Diffuse Reflectance Infrared ◽  
Oxygen Bond

Dynamic Effects in CO Adsorption on Ru/ZSM-5. Part I: Oxidative Disruption of Ru

1992 ◽  
Vol 46 (8) ◽  
pp. 1279-1287 ◽  
Author(s):  
J. Y. Shen ◽  
A. Sayari ◽  
S. Kaliaguine
Keyword(s):  
Diffuse Reflectance ◽  
Direct Evidence ◽  
Co Adsorption ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Diffuse Reflectance Infrared Spectroscopy ◽  
Adsorption Of Co ◽  
Diffuse Reflectance Infrared

In situ diffuse reflectance infrared spectroscopy of CO adsorption on reduced Ru/ZSM-5 reveals that, under appropriate conditions, in addition to the linearly adsorbed CO on metallic Ru particles (at 2045 ± 10 cm−1), two multicarbonyls involving oxidized Ru can be generated. These multicarbonyl species are characterized by IR doublets at 2080 and 2138 cm−1 and at 2086 and 2150 cm−1, respectively. Direct evidence for the consumption of both types of the ZSM-5 surface hydroxyl groups (silanol and Brønsted) during the oxidative adsorption of CO has been obtained. Each of these two OH types is believed to be associated with one of the multicarbonyl species.

scholarly journals Changes of Pd Oxidation State in Pd/Al2O3 Catalysts Using Modulated Excitation DRIFTS

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 116
Author(s):  
Gian Luca Chiarello ◽  
Ye Lu ◽  
Miren Agote-Arán ◽  
Riccardo Pellegrini ◽  
Davide Ferri
Keyword(s):  
Particle Size ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Oxidation State ◽  
Diffuse Reflectance ◽  
X Ray ◽  
Spectral Changes ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Reversible Reduction

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.

Figures of Merit for a Diffuse Reflectance Accessory Using an On-Axis Ellipsoidal Collecting Mirror

1988 ◽  
Vol 42 (3) ◽  
pp. 428-433 ◽  
Author(s):  
E. H. Korte
Keyword(s):  
Infrared Spectroscopy ◽  
Noise Level ◽  
Diffuse Reflectance ◽  
Field Of View ◽  
Figures Of Merit ◽  
Size Dependent ◽  
Diffuse Reflectance Infrared Spectroscopy ◽  
Diffuse Reflectance Infrared

The attainable efficiency of an accessory for diffuse reflectance infrared spectroscopy where both the irradiation and detection optics are located on the same side of the sample is analyzed, the size-dependent noise level of the detector being taken into account. The resulting figures of merit are found to reach up to more than 0.3, when standard detectors of 60° field-of-view are considered.

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