Inelastic J/ΨJ/\Psi Photoproduction off Nuclei: Gluon Enhancement or Double Color Exchange?

The nuclear enhancement observed in inelastic photoproduction of $J/\Psi$ should not be interpreted as evidence for an increased gluon density in nuclei. The nuclear suppression of the production rate due to initial and final state interactions is calculated and a novel two-step color exchange process is proposed, which is able to explain the data.Comment: Latex file, 23 pages including 5 Postscript figure

The Membrane Properties of Electroactive Polymer Films

Electroactive polymers fall into two categories. The first group are the redox polymers, which consist of an electronically insulating polymer matrix with attached redox sites.(1–4) The PVPy/Ru matrix represented in Fig. 3.1 is a typical example. The second group are the conjugated polymers, such as polypyrrole, polyaniline, or the poly(Nsulfopropylpyrrole-co-pyrrole) represented in Fig. 3.2. These consist of extended π-electron systems from which electrons can be withdrawn (see Fig. 3.2) or into which additional electrons can be injected.(5–12) The unpaired electrons of the produced radical cations or anions are delocalized over several monomer units of the polymer chain, forming polarons that interact with one another. With increasing concentration they associate to form bipolarons, i.e., electronspin-free dimers.(13)</sup