Efficiency of homonuclear Hartmann-Hahn and COSY-type mixing sequences in the presence of scalar and residual dipolar couplings

In the presence of scalar (J) and residual dipolar (D) couplings, the transfer efficiency of homonuclear Hartmann-Hahn and COSY-type mixing depends on the ratio D/J and on the mixing sequence. This dependence is analyzed theoretically and the results are confirmed experimentally. At least two different mixing sequences are required to yield good transfer efficiencies for all ratios D/J. In contrast to COSY-type experiments, homonuclear Hartmann-Hahn sequences can provide efficient transfer even if the sum of D and J is zero, i.e., if the coupling vanishes in the weak coupling limit.     

Light-scattering study of a supercooled epoxy resin

The dynamics of the fragile glass-forming liquid diglycidyl ether of bisphenol-A was studied by depolarized Rayleigh-Brillouin light-scattering and photon correlation spectroscopy above the glass transition, in the temperature range from 261 to 473 K and in the frequency range from 1 Hz to 300 GHz. The structural (alpha-) relaxation process was revealed and no signature of the secondary relaxation previously evidenced by dielectric spectroscopy at about 0.1 GHz was observed. The characteristic time of the alpha process differs from that determined by dielectric spectroscopy of an amount, which increases with increasing temperature. The relaxation times were compared with viscosity data to test the predictions of the classic Stokes-Einstein-Debye model. The tau proportional, variant eta behavior was verified for dielectric data, while a fractional power law of viscosity tau proportional, variant eta(0.89) was obtained for light-scattering relaxation times, extending over more than seven decades in viscosity and time. This deviation of light scattering from viscosity data could be interpreted in terms of cooperative motion in the supercooled liquid with a characteristic length xi(a) proportional, variant(T-T0)(-v) where T(0)=229 K is the Vogel temperature and v is close to 2 / 3 which is consistent with the prediction of the fluctuation theory of glass transition.     

Cooperative and Non-Cooperative Differential Game Solutions to an Investment and Pricing Problem

A monopoly possesses a finite stock of a resource and wishes to determine an optimal pricing policy. The competitive fringe invests in production capacity and wishes to select an optimal investment rate. Demand towards the monopoly depends on price as well as on the sales rate of the competition. Modelling the situation as a differential game, non-cooperative (Nash and Stackelberg) and cooperative (Pareto) equilibria are determined. Owing to the special structure of the game, these solutions can be found in closed form.     

Surface states of Sc(0001) and Ti(0001)

Calculated electronic properties are compared for 11-layer Sc(0001) and Ti(0001) films. Prominent surface states are found whose locations conform to expectations based on the respective bulk band structures establishing a roughly rigid band picture of the surface bands. Surface core-level shift and work function results are qualitatively explained.     

Strahlungsverhalten von Festkörperlasern hoher Pumpleistung

Ohne Zusammenfassung