The dynamics of water molecules confined in MCM-41 was investigated by quasi-elastic neutron scattering. The measurement was performed for three water-filled MCM-41 samples with different pore sizes in the temperature range 200-300 K. The spectra were analyzed by using a model employed by Teixeria et al. in a study for bulk water. This model is composed of two motions of water molecules: rotational and translational diffusions. For the translational diffusion, water molecules in MCM-41 are, on the whole, less mobile than those in bulk water, and the mobility is decreased by narrowing of the pore size. The residence time of translational diffusion of the confined water molecules shows the Arrhenius type of temperature dependence, which is in contrast to a non-Arrhenius behavior for bulk water. This implies that a growth of the hydrogenbond network of water is hindered in a confined space by surface field. Spectra of MCM-41 sample having monolayer water were also measured and could be analyzed with a model in which only rotational diffusion is an allowed motion of the monolayer water molecules.

The changes of structure and electronic state of copper ion species during the heat treatment of copper ionexchanged ZSM-5 zeolite (CuZSM-5) as well as the interaction with CO molecules have been investigated by using various spectroscopic techniques such as infrared (IR) and emission spectroscopy (ES), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) consisting of a XANES (X-ray absorption near edge structure) and an EXAFS (extended X-ray absorption fine structure) and through the measurements of heat of adsorption and adsorption isotherm. About 70% of the divalent copper ions (Cu 2+ ) exchanged in CuZSM-5 were found to be reduced to the monovalent copper ions (Cu + ) during the heat treatment at 873 K in vacuo, the latter species having a linear or a planar coordination structure with a coordination number of 2 or 3 with respect to the nearest-neighboring oxygen atoms at a distance of 1.98 Å. It was found from the ES data that the Cu + species strongly interact with CO molecules at room temperature. The ratios of the number of CO species interacting with Cu + species, the former being obtained from the adsorption isotherm data and the latter being obtained from the XANES data, are estimated to be 0.97 for the irreversible CO adsorption and 1.14 for the reversible CO adsorption, respectively. Furthermore, it was revealed that there exist at least two types of Cu + species differing in the strength of the interaction with CO; one gives a heat of adsorption of about 120 kJ mol -1 and an IR absorption band at 2159 cm -1 due to the irreversibly adsorbed CO species, and the other exhibits 100 kJ mol -1 and a band at 2151 cm -1 , which is also ascribed to a similar species. When CO is adsorbed on the Cu + species, the coordination structure around the Cu + species changes and the distance between the Cu + ion and the nearest-neighboring oxygen atom changes from 1.98 to 2.05 Å, as is evidenced from the EXAFS data. The coordination number of the carbon atom in the adsorbed CO is estimated to be 1.4, and a value of 1.89 Å is obtained as a distance of Cu-C. The coordination structure recovers by the heat treatment at 573 K. This implies that the irreversible adsorption of CO molecules is responsible for the change of coordination structure around the Cu + species. Combination of IR and XAFS data leads to the interpretation that in the irreversible CO adsorption the Cu + species on which a CO molecule is strongly adsorbed to give an IR band at 2159 cm -1 is coordinated to two lattice oxygen atoms and that the Cu + species on which a CO molecule is weakly adsorbed to give a 2151 cm -1 -band is coordinated to three lattice oxygen atoms.

X-ray scattering measurements on water confined in the cylindrical pores of MCM-41 with different pore sizes C10 (diameter ) 21 Å) and C14 (28 Å) have been performed over a temperature range of 223-298 K. Both samples were sealed in glass capillaries at relative water vapor pressures p/p 0 ) 0.3 and 0.6 under monolayer and capillary-condensed adsorption conditions, respectively. The X-ray radial distribution functions showed the presence of a distorted tetrahedral-like hydrogen-bonded network of water in both pores, characterized by peaks at ∼2.8, ∼4.2, and ∼4.9 Å, with non-hydrogen-bonded H 2 O-H 2 O interactions at ∼3.3 Å and H 2 O-Si interactions at ∼3.8 Å between water and the silica wall. With decreasing temperature, the number of the hydrogen-bonded H 2 O-H 2 O interactions at 2.8 Å increases, accompanied by the shifts of the 2.8 and 4.9 Å peaks to shorter distances and of the 4.2 Å peak to larger distances, for the capillarycondensed samples, showing a tendency to form more tetrahedral-like hydrogen-bonded water structure at subzero temperatures in both pores. The amount of the hydrogen-bonded water molecules is larger with less non-hydrogen-bonded H 2 O molecules in the C14 pores than in the C10 ones, showing that decreasing pore size leads to increasing distortion and/or breaking-down of hydrogen bonds in adsorbed water structure. No significant structural change of water was observed for the monolayer sample with decreasing temperature.

Adsorption properties of copper ion-exchanged mordenite (CUM) for dinitrogen molecules ( N 2 ) were examined at 298 K. The intensive IR absorption band observed at 2299 cm-' was attributed to the NZ species strongly adsorbed on CUM. The interaction of NZ with CUM is explored using adsorption calorimetry, X-ray absorption fine structure (XAFS), electron spin resonance (ESR), and photoemission spectroscopy. The differential heat and entropy of adsorption for N2 on CUM were 60 kJ mol-' and 60 J K-' mol-' at the initial stage of adsorption, respectively, and those for NZ on NaM (sodium-type mordenite) gave the values of 32 kJ mol-' and 130 J K-' mol-', revealing that the N2 molecules are in the localized state resulting from the strong interaction with CUM. The monolayer capacity is estimated to be 4.12 cm3 g-' for NZ on CUM-150, which gives a value of 0.22 for the Nz/Cu ratio. XAFS and emission data for CUM degassed at 873 K exhibit pair bands at 8.983 and 8.994 keV and 18 700 and 20 800 cm-I, respectively. The former pair band is assigned to the 1s-4p transition, and the latter pair band is assigned to the 3d94s1-3dl0 transition. It is also found that the ESR band intensity for Cu(I1) decreases with increasing pretreatment temperature. These spectral data are reasonably explained by assuming the presence of Cu(1) species in mordenite. It is proved from the emission data that the adsorption site including Cu(1) species easily formed by heat treatment at 873 K in vacuo is effective for N2 adsorption. Such easy conversion of Cu(II) to Cu(1) may be due to the spatial distribution of ion-exchanged sites on mordenite. The appearance of a strong IR band at 2299 cm-' is due to the adsorption of N2 on the Cu(1) species and to the induction of a transition moment by the strong field of this site. Although a rather high value of heat of adsorption might suggest chemisorption, it is made plausible that this type of N2 adsorption is physisorption.