STRUCTURE OF SELENIUM INCORPORATED INTO NANOCHANNELS OF MORDENITE - DEPENDENCE ON ION-EXCHANGE AND METHOD OF INCORPORATION

Influence of cations and method of preparation on the structure of mor denite-confined Se is studied by Raman and XANES spectra. It is shown that Se chains prepared by vapor adsorption are more regular than thos e prepared by injection of liquid Se. Concentration ratio between Se c hains and Sc, rings is practically independent of the method of prepar ation but it decreases when Na cations are substituted by K cations. A noticeable portion of Se-8 rings is formed, especially in Na form. XA NES of Se in mordenite for polarization perependicular to the channels (E perpendicular to c) is determined mainly by Se-6 rings, and that f or E parallel to c is a superposition of the absorption of chains and rings. (C) 1997 Elsevier Science B.V.