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Thermal diffusivity analysis of doped poly(methyl-methacrylate) with electron donor and acceptor molecules
Marinônio L Cornélio, Marcelo M Toma

A computer-assisted method for analysing photoacoustic spectra has been developed in the Windows™ environment with the use of an easy graphical interface. The computer simulation was carried out with the aim of using the entire expression of the Rosencwaig – Gersho theory, thus permitting multiple applications. The simulation was applied to a system that mimics the electron transfer process in which the concentration of octaethylporphin donor molecules was constant whereas the concentration of duroquinone and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone acceptor molecules varied. The increment of the acceptor concentration influenced the photoacoustic amplitude and phase signals. In the phase signal a significant shift to smaller values was observed, denoting a faster heat generation. The analysis of the photoacoustic signal enabled the determination of the thermal diffusivity. The result obtained through the simulation was about (7 ± 1) x 10-7 m2 s-1, indicating that changes in the photoacoustic phase signals were due to the electron transfer process rather than changes in the thermal properties of the sample.

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