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We investigate the effects of the A-isobar on proton-proton bremsstrahlung at a beam energy of 280 MeV. We find significant effects on both cross-section and analyzing power.

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The pp y reaction at intermediate energies is investigated using a modern relativistic meson-exchange potential model. Both the single-scattering and rescattering terms are treated including relativistic corrections. It is shown that for energetic photons in the region near the end-point energy the relativistic spin correction is very large and reduces the ppy cross section by a factor of -2. This large correction is dynamical in origin and can be traced in a very simple way to the strong energy dependence of the So state contribution. It is also shown that, under these kinematical conditions, the rescattering term reduces the cross section, which amplifies the relativistic effects on the ppy reaction. For the kinematical conditions of the recent TRIUMF experiment at Ti,b =280 MeV the rescattering contribution enhances the cross section and reduces the discrepancy between the data and the calculation. PACS number(s): 25.20. Lj, 25.10.+s

Brodsky and Tsarevsky (J. Phys. Chem. 1984, 88, 3790) developed a theory on solvated electrons (esolv-) which is based on the concept that the excess electron is localized in a medium predominantly by shortrange interactions. Including many-body collective effects of the solvent, they tried also to explain the temperature dependence of the optical absorption spectra of esolv-. To substantiate their point of view, they presented experimental spectra of esolv-in CH30H measured over a wide range of temperatures which were in "satisfactory quantitative agreement" with theory. We have carefully repeated optical absorption measurements on esolv-in CD30D in the temperature range 298 5 T 5 510 K. We report on these experimental results and on the static dipole polarizability (a(0)) of solvated electrons in different media determined by means of optical sum rules. Both results are inconsistent with the above-mentioned theory. The comparison of other ground-state properties of solvated electrons in methanol such as the mean dispersion in position (A$) and the mean quantum mechanical kinetic energy (Q following from the spectra with those obtained by a quantum molecular dynamics simulation shows poor agreement.

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The heterogeneous effects due to filler interactions and chain dynamics of reinforcing nano‐filler particles were characterized on a series of filled EPDM elastomers using the Payne effect and low field NMR, 1H transverse (T2), longitudinal (T1) and longitudinal in rotating frame (T1ρ) relaxation time measurements. Measurement of the Payne effect and NMR relaxation curves were used to obtain the distribution of filler/filler interactions and chain dynamics by one‐dimensional Laplace inversion. Distributions of shear‐strain constants in the Payne effect reveal the existence of weak, medium and strong filler/filler interactions which were correlated to filler properties and content. The analysis of relaxation‐time distributions leads to the identification of multimodal polymer network dynamics.magnified image

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