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.

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We report the first observation of sum frequency generation (SFG) photons on high-surface-area powders, critically important materials in heterogeneous catalysis. We utilize SFG in total internal reflection (TIR) geometry and show that the TIR-SFG approach markedly reduces the destructive interference associated with nonlinear optical spectroscopy of small particle surfaces, making SFG studies of high-surface-area powders possible. The index of refraction of materials and their distance from the TIR-SFG prism are key parameters in generating and detecting the sum frequency signal. We find that TIR-SFG is highly sensitive to capillary condensation. To demonstrate the capability of the TIR-SFG technique, we measure the thermodynamics of methanol adsorption and desorption on high-surface-area SiO2.

case of indirect excitons 9 this interaction is not forbidden by translational symmetry. It may be realized in the form of simultaneous scattering of electrons and holes between different X points by either Coulomb or electron-phonon interaction.A quantitative determination of the matrix elements in question and the deformation potentials is difficult because of uncertainties in the decomposition of overlapping bands A, B, and C. At the present time we can only give a rough estimate of these quantities. Using the hydrostatic deformation potential 10 to eliminate A x we find that A 3 »7 eV per unit shear deformation \e ee -?(e xx + e yy ). This rather large value again indicates that the exciton transition does not take place at the center of the Brillouin zone but that a star degeneracy is involved. Preliminary analysis shows that E X

The Knight shift and electric quadrupole coupling constant have been measured as a function of lithium concentration in the continuous intercalation phase LixTiS2 where 0⩽x⩽1. These NMR data, when compared with observations of c axis dilation and thermodynamics of this phase, suggest the donation of an appreciable fraction of the Li 2s electron to the TiS2 layers during intercalation, with the fraction diminishing as x increases. The relation of the charge donated to each of the observed quantities is discussed.

seems rather difficult when M is the tungsten.The MoS2 final product has been characterized by both HREM and LRS. A correlation exists to indicate that the Raman lines characteristic of MoS2 are sensitive to their crystal size. Dehydration of a sample before sulfidation noticeably affects the size of the supported MoS2 slabs.

Articles you may be interested inThe effects of pressure and temperature on molecular dynamics during linearchain polymerization by dielectric measurements A constrained maximum entropy method for the interpretation of experimental data: Application to the derivation of single particle orientationconformation distributions from the partially averaged nuclear spin dipolar couplings of nalkanes dissolved in a liquid crystalline solvent NonGaussian behavior and the dynamical complexity of particle motion in a dense twodimensional liquidWe have extended two previously introduced models of n-alkanes to numerically investigate the liquid-state dynamics of branched alkanes. We compare our results with new experimental measurements of diffusion and 13 C-NMR T 1 relaxation. Significant systematic and quantitative agreement is found between simulated and experimental values. We demonstrate the role of branching in controlling the temperature dependence of diffusion and point out the effect of global single-chain relaxation processes on the local intramolecular dynamics probed by the 13 C-NMR experiment.

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