Mordenite band assignments

Upon adsorption of benzophenone on oxides with strongly acidic properties, the phosphorescence spectrum exhibits a structureless band with a Atnax at about 490 nm in addition to the normal phosphorescence of benzophenone. The A max of the excitation spectrum of this band was observed at approximately 380 nm, and its intensity increased in the order of the aluminosilicate, H-mordenite, and HY zeolite. In the spectrum of HY zeolite containing benzophenone, only one structureless phosphorescence band could be observed. A similar phosphorescence band could be observed for benzophenone dissolved in CHCI3, which also involves dry HCl. We can therefore assign phosphorescence at about 490 nm to the protonated form ofbenzophenone. These findings correspond with studies of the photoluminescence of benzophenone dissolved in various concentrated acidic solutions (277). Consequently, since the presence of a phosphorescence spectrum at about 490 nm with benzophenone adsorbed on the aluminosilicate, H-mordenite, or HY zeolite is associated with the presence of the protonated form of benzophenone, the data indicate the existence of proton-donor centers on these oxides with acid strengths < for benzophenone (about 5.6) (216). On HY zeolite, almost all the adsorbed benzophenone changes into protonated benzophenone. On aluminosilicate surfaces, the relative intensities of the phosphorescence spectra attributed to the protonated and unprotonated forms are approximately the same. 

After evacuation of the Cu(II)zeolite samples at 973 K, the EPR signal assigned to the Cu species became very weak and could hardly be observed, indicating the reduction of Cu" to Cu. With the Cu(I)zeolite catalysts prepared in this way, as shown in Figs. 31 and 32, characteristic photoluminescence became observable at about 400-450 nm upon excitation at about 300 nm. As shown in Fig. 32, the relative intensity of the photolumincscence spectra attributed to the Cu monomer and the (Cu -Cu+) dimer species strongly depends on the type of zeolite. The photolumi-nescence band at about 430-460 nm is the major component for the Cu(I)ZSM-5 and Cu(I)mordenite. Moreover the Cu(I)Y zeolite exhibits two different intense photoluminescence bands at about 450 and 525 nm. 

The interpretation of the above IR results of the H20/zeolite system was supported by inelastic neutron scattering (INS) studies by Jobic et al. [658] of H2O adsorbed on hydrogen mordenite. These experiments were carried out in the range below 2000 cm. Activated and water-free H-mordenite gave INS bands at 320 and 1060 cm. On the basis of quantum mechanical calculations, these were assigned to the out-of-plane (yoh) and in-plane (6oh) deformation vibrations of the zeolitic OH groups, since these were predicted at 322 and 1047 cm". On... 

It is relevant to re-examine data acquired using XPS, of the polypyrrole formed within the channels of copper mordenite. The Cls region [Fig. 4 (b)] contained a profile which could be deconvoluted into three peaks at 284.7, 286.9 and 289.1 eV. The main peak at 284.7 eV is ascribed to the a and P carbons of polypyrrole(56), and the feature at 289.1 eV to a "shake-up" peak due to the interband n-n transition (79). Finally the peak at 286.9 eV has been previously assigned to a "shake-up" structure caused by simultaneous electron excitation and transition from the valence band to a polaron level in the band gap (79). Since the "shake-up" process corresponds to a transition between an initially neutral state and a final ionized species the value obtained for the band gap using XPS would not... 

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