Flash-photolysis time-resolved microwave conductivity measurement

Osuka, Anderson, and Warman have investigated the polarizability of two different covalently bridged porphyrin oligomers by flash photolysis time-resolved microwave conductivity measurements. When the bridge forbids electronic interactions, only electrostatic interactions are present and the excitation generates Frenkel-type excitons. Upon photoexcitation, only a slight increase of polarizability is observed (<20 A ). When electronic communication is permitted by... 

A. Saeki, S. Seki, T. Sunagawa, K. Ushida, S. Tagawa, Charge-carrier dynamics in polythiophene films studied by in situ measurement of flash-photolysis time-resolved microwave conductivity (FP-TRMC) and transient optical spectroscopy (TOS). Philos. Mag. 86, 1261-1276 (2006)... 

The electrical conductivity of the i-stacked polymer was investigated by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) method [57-68]. We could observe the charge mobility in 22e through the stacked r-electron systems in a single polymer chain using this noncontact measurement technique [30], Polymer 22e was dispersed in a polystyrene film without any dopants, and the cast film on quartz was excited by a laser pulse at 355 nm. The kinetic traces of microwave... 

A laser pulse can be used instead of the van der Graff generator to produce the electron-hole pair, which is a technique known as flash photolysis, time-resolved, microwave conductivity or FP-TRMC. The main disadvantage is that the concentration of electron-hole pairs formed in this way is more difficult to estimate. Usually, it can only be used to measure the product of the quantum yield and the sum of the mobilities (oriented films [15,16]. More recently a variation on this method has been introduced in which the transient absorption spectrum is measured simultaneously. This provides structural information on the charge carriers and (provided assumptions are made) allows their concentration to be determined yielding Sp, [17,18]. 

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