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We investigate the formation of nanoparticles of Au in SiO(2) by multiple ion implantation steps and intermediate anneals to isolate nucleation and growth, thereby producing a narrow particle size distribution. We discuss the effects of varying the initial nucleation dose and the growth temperature and establish guidelines for synthesizing nanoparticles with improved size uniformity. By this method, we have obtained a standard deviation of 16% on an average diameter of 1.68 nm, compared to 28% when no attempt is made to isolate nucleation and growth.

Cross polarization between dilute effectively isolated {sup 13}C-{sup 31}P spin pairs provides a unique method to examine selectively the microenvironment around the phosphorus atom in organophosphorus substances. Strong oscillations occur during cross polarization between these isolated spin pairs in MAS experiments on microcrystalline powders. The oscillation frequency is proportional to the {sup 13}C-{sup 31}P dipolar interaction and hence allows specific internuclear distance determinations on powder samples. Maximum carbon signal intensity and experimental simplicity are achieved in double cross polarization (DCP)/MAS {sup 13}C NMR experiments that impose a short T{sub 1p} on the {sup 31}P magnetization by {sup 31}P radio frequency phase modulation. This experimental stratagem suppresses cross-polarization oscillations and yields simple exponential kinetics for the transfer process. It also relaxes the tolerance on the match condition and MAS speed for cross polarization between weakly coupled dipole pairs.

Results of reactions of Na-K alloy in the solvent system glyme-triglyme on a series of compounds, bibenzyl, 1,2-diphenylpropane, diphenylmethane, and phenyl-p-tolylmethane, to determine whether the Birch-Hueckel reduction could be used in this solvent system to cleave C-C bonds are reported. Both methyl-/sup 14/C iodide and water were studied as quenchers, and the products from all reactions were analyzed by gas chromatography. The results indicated that coal can be efficiently degraded at low-temperatures by cleavage of aliphatic as well as aromatic-aliphatic C-C bonds by the action of Na-K alloy under conditions studied in this work. (BLM)