129Xe NMR spectra of xenon adsorbed in Na-Y, K-Y, Mg-Y, Ca-Y, and B-Y zeolites have been measured as a function of the xenon loading at 144 and 293 K. At low xenon loadings, the 129Xe chemical shift shows two types of dependence on the xenon density in the supercage: linearly increasing and paraboliclike with a minimum. At 144 K, all the zeolites except Ca-Y have a linear dependence, whereas at 293 K, both Ca-Y and Mg-Y show a paraboliclike curvature. These dependences can be explained in terms of rapid exchange between xenon atoms adsorbed at special sites in the supercage and those remaining in the gas phase in the cages. Strong xenon adsorption at the special sites leads to the paraboliclike behavior, whereas weak adsorption yields the linear dependence. Formation of a partial bond between the xenon atom and 2+ cation by donation of one of the xenon 5p electrons to the empty s-orbital of the cation is proposed to explain the strong xenon adsorption in zeolites with 2+ cations. The bond formation introduces low-lying electronic excited states which lead to a large paramagnetic contribution to the chemical shift. By variation of the rate by which a sample is cooled to 144 K, it is shown that there is only one special adsorption site per supercage in the Y zeolites. In Na-Y, Mg-Y, and K-Y, the site can accommodate one xenon atom while in Ca-Y and Ba-Y, two xenon atoms can share the same site. At 144 K, a gas-liquid phase transition is observed when the xenon loading is between 7 and 9 xenon atoms/cage. The transition is characterized by rapid increase in the chemical shift and collapse of the line width. Before the transition, there are large increases in the line width that may be interpreted as the inhomogeneous broadening due to large fluctuations in the xenon number density in the cages. Measurements at 144 K with high loadings of xenon indicate that the supercage in Y zeolite can hold between 10 and 11 xenon atoms. The resulting chemical shift is between 250 and 270 ppm downfield from the resonance of 2 atm of xenon gas (at 293 K). At even higher xenon loading, the excess xenon condenses on the exterior surface of the zeolite microcrystallites to form solid xenon, which has a chemical shift of 304 ppm downfield.

The singularity index α of the asymmetric C(1s) x-ray photoelectron spectrum (XPS) of vitreous carbon is determined to be 0.19±0.01, independent of the interlayer separation of the graphitic layers. This result is interpreted within the framework of the many-electron theory; two mechanisms are suggested: (1) the modulation of the two-dimensional graphite band structures by the random interlayer perturbation, and (2) the excitonic screening. By assigning the value α=0.19 to be characteristic of carbon atoms associated with polynuclear aromatic rings, we show that the fraction of carbon in these rings in coal can be determined by the asymmetry of the C(1s) XPS line.

The structures of amorphous (noncrystalline) domains in polyethylene, conditioned (at 150 °C for 15 min) and unconditioned polypropylene films and a vitrain portion of Kentucky No. 6 coal have been investigated using the Goldman-Shen NMR pulse sequence which monitors the transfer of 1H magnetization from the amorphous to the crystalline domains. The diffusion equation is solved with respect to such transfer. The size and shape of the amorphous domain is inferred by fitting the theoretical results to the experimental data. It seems that the layer-like configuration is a poor description for the polyethylene and polypropylene films unless the spatial orientation of the amorphous domain is isotropic. However the spherical configuration is inadequate for Kentucky No. 6 vitrain. The average width b̄ of the amorphous domain is 90–150 Å for polyethylene, 20–30 Å for uncontinued polypropylene film, and 30–50 Å for the conditioned films. The diffusion of magnetization in the amorphous domain of Kentucky No. 6 is faster than that of the polymers, though the dipolar interaction is much weaker in the former. A transfer process due to tranlational motion of small mobile chemical species is suggested.

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