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Organic semiconductors (OSCs) have been of great interest over the last couple of decades owing to their mechanic\ud flexibility, ease of processing, high tuneability and availability. One area of OSCs that is of growing interest is\ud polymers as they possess many of the desirable properties, in particular print processing and tunability of electronic\ud properties, necessary for application in devices such as organic solar cells and the spin valves being engineered for\ud hard disks and logic devices. Much focus has been given in recent years to the areas of research including the electron\ud and hole dynamics, transport mechanisms and spin relaxation in OSCs in order to utilise them in novel organic\ud devices. In this paper the µSR technique is applied to carry out an in depth study of the electron dynamics and spin\ud relaxation in the commonly used Poly(triarylamine) polymer (PTAA). It is shown that the electron wavefunction can\ud be considered localised to the aromatic rings providing a strong hyperfine coupling interaction with the muon. In\ud addition the presence of an electron spin relaxation (eSR) is demonstratated that resembles that previously reported in\ud the small organic molecule series.\ud

The hydrogenation of Li3N at low chemical potential has been studied in situ by time-of-flight powder neutron diffraction and the formation of a nonstoichiometric\ud Li4_2xNH phase and Li4NH observed. The results are interpreted in terms of a model for the reaction pathway involving the production of Li4NH and Li2NH, which subsequently react together to form Li4_2xNH. Possible\ud mechanisms for the production of Li4NH from the hydrogenation of Li3N are discussed.

Azurite, a natural mineral made up of CuO chains, is also an intriguing spin-1/2 quantum magnet. There has been much debate as to the 1-dimensional (1D) nature of this material by theorists and experimentalists alike. The focus of this debate lies in the interactions between Cu-ions within the antiferromagnetically ordered state below 1.9 K. We present high-resolution inelastic neutron scattering data which highlight the complexity of the magnetic ground state of azurite. The application of magnetic fields and temperatures were used to probe the excitations revealing important information about the dynamics in this system. From this we are able to conclude that the 1D Heisenberg antiferromagnetic spin chain model is not sufficient to describe the dynamics in azurite. Instead additional coupling including interchain interactions and an anisotropic staggered field are necessary to fully model the observed excitations., Comment: 8 pages, 11 figures

The dynamics of polyisobutylene at 407 K is investigated by means of quasi-elastic neutron scattering. By proper data reduction, data from two different instruments were combined to provide the incoherent intermediate scattering function, I-s(Q,t), over 3 decades in time. The data were interpreted in terms of a superposition of exponentials with a distribution of characteristic times. The data provide an indication of the existence of three different relaxation processes in the time range between 0.1 and 1000 ps, thus confirming recent results from molecular dynamics simulations. The two fastest processes are spatially localized, while the slow one shows a momentum transfer dependence. Analysis in terms of the alternative phenomenological approach of stretched exponential is also discussed.