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A new light driven spectrometer for the determination of complex heat capacities and conductivities by combination of effusivity and diffusivity measurements

Albrecht, T. and Armbruster, S. and Stühn, B. and Vogel, K. and Strobl, G. (2001):
A new light driven spectrometer for the determination of complex heat capacities and conductivities by combination of effusivity and diffusivity measurements.
377, In: Thermochimica Acta, (1-2), pp. 159-172, [Article]

Abstract

We describe the construction, performance and first application of a spectrometer for measurements of frequency-dependent complex thermal diffusivities and effusivities. Knowledge of these quantities enables the complex dynamic specific heat and the thermal conductivity to be calculated. The technique uses the properties of thermal waves initiated at the surface of platelike samples by the absorption of light with an oscillating intensity. A registration of the resulting temperature oscillations in the absorbance layer at the upper surface of the sample yields the effusivity, an analogous measurement at the bottom gives the diffusivity. The detection of both amplitudes and phases of the signals leads to complex quantities. Measurements encompass a frequency range from 10(-2) to 10(2) Hz. The apparatus was used in a study of the reversible surface melting of poly(ethylene oxide). Both the magnitude and the characteristic time range of this process could be determined. (C) 2001 Elsevier Science B.V. All rights reserved.

Item Type: Article
Erschienen: 2001
Creators: Albrecht, T. and Armbruster, S. and Stühn, B. and Vogel, K. and Strobl, G.
Title: A new light driven spectrometer for the determination of complex heat capacities and conductivities by combination of effusivity and diffusivity measurements
Language: English
Abstract:

We describe the construction, performance and first application of a spectrometer for measurements of frequency-dependent complex thermal diffusivities and effusivities. Knowledge of these quantities enables the complex dynamic specific heat and the thermal conductivity to be calculated. The technique uses the properties of thermal waves initiated at the surface of platelike samples by the absorption of light with an oscillating intensity. A registration of the resulting temperature oscillations in the absorbance layer at the upper surface of the sample yields the effusivity, an analogous measurement at the bottom gives the diffusivity. The detection of both amplitudes and phases of the signals leads to complex quantities. Measurements encompass a frequency range from 10(-2) to 10(2) Hz. The apparatus was used in a study of the reversible surface melting of poly(ethylene oxide). Both the magnitude and the characteristic time range of this process could be determined. (C) 2001 Elsevier Science B.V. All rights reserved.

Journal or Publication Title: Thermochimica Acta
Volume: 377
Number: 1-2
Divisions: 05 Department of Physics > Institute for condensed matter physics
05 Department of Physics
Date Deposited: 27 Feb 2010 13:17
Additional Information:

6th Lahnwitzeseminar on Calorimetry, Kühlungsborn, Germany, June, 2000

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