Zeolite blue-shift

E) Support Interactions in the Spectroscopy and Photoprocesses of Ag,+ in Zeolite X and Y It is interesting to compare the spectroscopic properties of site I, I isolated Agz in ZY with those for Agz entrapped in rare-gas solids (6). In the latter one finds a strongly blue shifted gas to matrix X,... 

Hgl2 is also a typical semiconductor material, and it is also easy to vaporize after thermal treatment. Therefore, Hgl2 may be loaded into various zeolites through a vapor-transportation approach. Because of the confinement of the zeolite framework, Hgl2 in zeolites may exhibit distinct quantum-size effects. The electronic transition absorption spectrum of Hgl2 loaded in AlPOs-5 single crystals shows an apparent blue-shift, and in... 

The most intense band in the far IR spectrum of Na-A is logically ascribed to a Na+(A) vibration. Its position compares to that seen for sodium ions in site II in zeolite Y (blue-shifted due to the higher lattice anionicity of A relative to Y). Confirmation... 

The zeolite matrix allows the preparation of dispersions with distinctly different and narrow particle size distributions in a range where size dependent electronic properties can be studied (quantum size particles). Quantum-mechanical calculations suggest that the energy level of the first excited state of the exciton increases with decreasing particle size of the semiconductors in correspondence with the experimentally observed blue-shift of the optical absorption edge (refs. 8-10). 

IR and UV-VIS spectroscopies. The use of IR method enables one to control the loading of precursors and their further transformation into the oxide moiety. At the metal loading as low as a few wt % (metal basis), the IR bands characteristic of metal oxides are too weak to judge on their formation. As to electron absorption spectra, this technique was successfully applied in [8] not only to identify the metal sulfide and solenoid nanoclusters encapsulated in zeolites but also to estimate their mean sizes basing on the blue-shift of absorption-edge in respect to bulk material. Unfortunately, this technique in studying the supported metal oxides turned out to be ineffective mainly because of too broad bands obtained for the samples subjected these investigation. 

The Co/zeolite catalyst (Fig. If) was reduced only to the extent of 60 wt% at 800°C. The unreduced cobalt is attributed to tetrahedral Co2+ species (phase III) since they exhibited the characteristic intense blue colour of tetrahedral Co2+ ions. The cobalt on magnesiun oxide (Fig. lg) also underwent reduction to only 60wt% up to 800°C. The shift of the phase II and III peaks to higher temperatures is evidence of a stronger metal-support interaction for these catalyst systems. Itoo reduction phases for cobalt on magnesium oxide have been... 

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