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 mordenite-confined Se is studied by Raman and XANES spectra. It is shown that Se chains prepared by vapor adsorption are more regular than those prepared by injection of liquid Se. Concentration ratio between Se chains and Se6 rings is practically independent of the method of preparation but it decreases when Na cations are substituted by K cations. A noticeable portion of Se8 rings is formed, especially in Na form. XANES of Se in mordenite for polarization of radiation perpendicular to the channels (E⊥c) is determined mainly by Se6 rings, and that for E‖c is a superposition of the absorption of chains and rings.