We present a detailed investigation of the acene series using high-level wave function theory. Our ab initio density matrix renormalization group algorithm has enabled us to carry out complete active space calculations on the acenes from napthalene to dodecacene correlating the full -valence space. While we find that the ground state is a singlet for all chain lengths, examination of several measures of radical character, including the natural orbitals, effective number of unpaired electrons, and various correlation functions, suggests that the longer acene ground states are polyradical in nature.

We investigate the temperature dependence of the emission wavelength and reflection band of polymer Distributed Bragg Reflector (DBR) and defect Distributed FeedBack (DFB) lasers fabricated using a coextrusion melt-process. We show the measured spectral shifts are a direct consequence of the optical path modifications associated with layer expansion and thermo-optic coefficients. By varying the choice of polymer bilayers and sandwiching the DBR laser films between glass coverslips, we fabricated DBR lasers that are either readily tunable up to 0.36 nm/ • C or made thermally stable at 0.035 nm/ • C.

Nowadays the high availability of more powerful portable devices paves the way to a new set of applications for a wide range of human activities. One important area of applications is related to road safety services, where human life is at stake. This paper describes an automated mobile system for the support of rescue and safety services personnel, as ambulance crew, fire brigades, and so on. The system is designed to accomplish several goals: to facilitate the rescue mission, to give update to a mission control center, to communicate additional information to rescue crew, to automate mission management. The work described in this paper has been accomplished in the framework of the European project GST.

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We study the effects of temperature changes on the operating wavelength of all-polymer microresonator lasers, particularly on multilayered defect distributed feedback and distributed Bragg reflector lasers. The parameters that change the operating wavelength are discussed with comparisons between experiments and simulations.