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The results of a relativistic tight-binding energy-band model for Pt and Au, utilizing parameters derived from Smith s empirically adjusted combined interpolation scheme, are applied to calculate the one-electron contribution to various x-ray and energy-loss spectra involving 4f and 2p core states in these materials. These results show that the unoccupied holes in the Pt 5d bands have predominantly j = 5/2 character (h», ) such that the (h5/2/A3/2) ratio ranges from -3.5 within 0.5 eV of EF to -2.9 over the entire unoccupied conduction band. Taking into account dipole transition probabilities, the former ratio leads to a predicted line-strength ratio I",/I", -2.9 near threshold for excitations involving the 4fj = 7/2 (N,) and j = 5/2 {N,) core levels in Pt. This result is in good agreement with the corresponding experimental ratios that are derived from electron energy-loss {2. 5) and x-ray-absorption (2.3) spectra. Comparable agreement is obtained between the calculated and observed {electron-energy-loss)

Three samples of polystyrene in cyclohexane were studied at the theta temperature by photon correlation spectroscopy. The photon correlation data were analyzed using the moments (or cumulants) method which, under appropriate conditions, yields the Z−average diffusion coefficient ?Z of the solute and one or two higher moments of the diffusion coefficient distribution [D.E. Koppel, J. Chem. Phys. 57, 4814 (1972)]. ?Z can be combined in the Svedberg equation with the weight−average sedimentation coefficient to yield the weight−average molecular weight. The samples studied comprised an essentially monodisperse fraction of polystyrene, a mixture of two monodisperse fractions and a single fraction of broader molecular weight distribution; they had been extensively characterized by other techniques. Our results indicate that, indeed, the Z−average diffusion coefficient is provided by the moments−analysis method. The values of ?W obtained from the Svedberg equation were, within experimental error, in good agreement with those determined by other techniques. The second moment of the diffusion coefficient distribution provides a useful index of polydispersity.

Magnetic relaxation in one-dimensional exchange-coupled (CH^NMnC^ is found to be dramatically different than it is in three-dimensional exchange-narrowed paramagnets. A theory which accounts properly for the special long-time persistence of spin-correlation functions in one dimension is shown to explain the observed behavior.

The synthesis of compound (11) and of some 2-substituted derivatives (I)The compounds show aromatic properties, and their spectra is reported. resemble those of corresponding naphthalene derivatives.Nomenclature.-A nomenclature was desired which would take into account the fact that the group -BH-=NH+-(equivalent to -BH-NH-) is isoconjugate with -CH=CHin an aromatic system. For instance, a name was desired which (a) would show that compound (I; R = H) (equivalent to 11) is isoconjugate with naphthalene and (b) would not relate it to dihydronaphthalene as would strict systematic use of azabora-prefixes." After consultation with the Editor, the prefix '' aro " has been adopted, to be placed between the -a prefixes and the name of the cyclic hydrocarbon with which the compound is isoconjugate. Thus, compound (I; R = H) is named 2,l-borazaronaphthalene. For six-and fivemembered rings the composite suffixes -arene and -arole, respectively, are proposed. The following are further examples : (111) 9,lO-borazarophenanthrenePREVIOUS papers in this series recorded boron compounds isoconjugate with indole, 2 : 3benzofuran, thionaphthen,l and phenanthrene.2 In this paper a new heteroaromatic system isoconjugate with naphthalene is described.Reaction of 2-aminostyrene with boron trichloride in benzene in the absence of a catalyst gave hydrogen chloride and a white, sublimable solid, containing chlorine, which was hydrolysed with extreme ease. This chloro-compound with phenylmagnesium bromide gave a compound Cl,H1,NB, identical with the product of the direct reaction