Illustrates the effect of an optically active material (Karo corn syrup) on plane-polarized light.

of spin in cp should be considered). The final potential application we mentioned is the two-band Hubbard model called the Anderson-lattice model, currently the vogue in the mixed-valence problem.One of us (T.A.K.) was the recipient of an Alexander von Humboldt Senior Scientist Award. f Permanent address: Michigan State University, Synchrotron-radiation experiments were performed at ultralow (<0.1 monolayer) coverages to test the weakly-interacting-cluster model for Al adsorption on GaAs(llO). The evolution of the Al 2p peak revealed two different submonolayer adsorption states, one below and one above 0.1 monolayer coverage, as predicted by the model. These results demonstrate that experiments at ultralow coverages are crucial to the understanding of the Schottky barrier formation.

Pure cobalt and cobalt-nickel alloys have been plated from simple electrolytic baths with and without additive and with and without ac superimposed upon the dc plating current.X-ray analysis reveals preferred orientation in the polycrystalline deposits generally and extreme preferred orientation (characterized by [00.2] and [11.0] fiber axes) in the case of those samples obtained with additive-free electrolyte. It is shown that a change in the pH of the bath or the addition of an ac component are equally effective in determining the type of fiber axis in the deposit. The effects on plating texture owing to the use of additive KCNS in the bath are described. Finally, the correlation between the texture and the magnetic properties of the plating Is discussed.

Magnesium oxide crystallites having mean dimensions in the range of 25–1000 A can be prepared by controlled thermal decomposition of the carbonate.Following some earlier investigations of Birks and Friedman, we have determined the mean size and size distribution of several such MgO samples from the broadened X-ray diffraction lines which they exhibit. Contrary to the procedure of the above investigators, the harmonic analysis due to Stokes has been used to correct for instrumental broadening and values of mean-size and size-distribution functions obtained from the Fourier coefficients by the methods of Warren and Averbach.The results obtained are compared with average sizes and distributions obtained by direct examination of the samples in an electron microscope.A composite sample has been prepared by mixing known quantities of the sample previously studied. The distribution function obtained by harmonic analysis of one diffraction line of the composite sample is compared with the function calculated from the distributions of its components.Conclusions are drawn concerning the significance of the results obtained by the Warren technique: in particular, the average sizes obtained by this method are compared with those given by the approximate method used by Birks and Friedman.