Understanding temperature-modulated calorimetry through studies of a model system

Temperature modulated calorimetry is widely used but still raises some fundamental questions. In this paper we study a model system as a test sample to address some of them. The model has a nontrivial spectrum of relaxation times. We investigate temperature-modulated calorimetry at constant average...

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Veröffentlicht in:Physical review. E 2022-03, Vol.105 (3-1), p.034144-034144, Article 034144
Hauptverfasser: Garden, Jean-Luc, Peyrard, Michel
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Sprache:eng
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Zusammenfassung:Temperature modulated calorimetry is widely used but still raises some fundamental questions. In this paper we study a model system as a test sample to address some of them. The model has a nontrivial spectrum of relaxation times. We investigate temperature-modulated calorimetry at constant average temperature to precise the meaning of the frequency-dependent heat capacity, its relation with entropy production, and how such measurements can observe the aging of a glassy sample leading to a time-dependent heat capacity. The study of the Kovacs effect for an out-of-equilibrium system shows how temperature-modulated calorimetry could contribute to the understanding of this memory effect. Then we compare measurements of standard scanning calorimetry and temperature-modulated calorimetry and show how the two methods are complementary because they do not observe the same features. While it can probe the timescales of energy transfers in a system, even in the limit of low-frequency temperature-modulated calorimetry does not probe some relaxation phenomena which can be measured by scanning calorimetry, as suggested by experiments with glasses.
ISSN:2470-0045
2470-0053
DOI:10.1103/PhysRevE.105.034144