Optical properties of poly(phenylene pyridine) derivatives, poly(2,5-dialkoxy-1,4phenylenealt-2,5-pyridine) (PHOnPY25), such as optical absorption, photoluminescence (PL), and electroluminescence (EL), have been studied. The electronic energy structures of PHOnPY25 have been determined by optical and electrochemical measurements. Strong PL with high quantum efficiency has been clarified in the films, and spectral narrowing has been observed by pulse excitation of a nitrogen laser. Intense blue EL has also been demonstrated.
Optical properties of conducting polymers with Si atoms in main chains, such as optical absorption, photoluminescence ͑PL͒, and electroluminescence ͑EL͒, have been studied. The electronic energy structures have been determined by optical and electrochemical measurements. The strong PL with high quantum efficiency has been clarified, and spectral narrowing has been observed by pulse excitation of a nitrogen laser. Intense blue or red EL has also been demonstrated and the emission efficiency has been improved by anode surface modification and annealing.
The calibration of modern automatic RLC bridges requires a set of impedance standards. Each standard needs in turn a calibration, i.e. the knowledge of its four-terminal-pair impedance Z 4TP at frequencies up to 10-100 MHz-frequencies beyond the capabilities of standard metrological setups for impedance traceability (transformer bridges).It is possible to think of an impedance standard as a multiport linear radiofrequency network; the properties of the network can be mathematically related to its Z 4TP . In the literature, such a connection is made using the relation between the impedance matrix Z i j and Z 4TP , and with careful identification of an ad hoc lumped-parameter electrical model of the standard. A vector network analyser is employed to measure diagonal elements of Z i j directly; non-diagonal elements are measured in an indirect way.Here we derive a new relation between the scattering parameter matrix s i j and Z 4TP of the impedance standard. All s i j elements can be directly measured with a network analyser: we measure scattering parameter spectra of a set of commercial gas-dielectric capacitors. Computed Z 4TP spectra are compatible with those obtained with the Z i j technique, but the new method proves much more sensitive, permitting estimates of the frequency behaviour of an impedance standard even when electrical modelling is inconvenient or impossible.
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