Two-beam photoacoustic phase measurement of the thermal diffusivity of solids

Pessoa, Osvaldo; César, Carlos L.; Patel, Nimesh; Vargas, H.; Ghizoni, C. C.; Miranda, L. C. M.

doi:10.1063/1.336524

Cited by 141 publications

(40 citation statements)

References 7 publications

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“…[1][2][3][4][5] The photothermal techniques are essentially based upon sensing the temperature fluctuation of a given sample due to nonradiative deexcitation processes following the absorption of modulated or pulsed light. Apart from having been extensively used in the optical and thermal characterization of a wide spectrum of materials, ranging from semiconductors 6 to glasses 7,8 and biological specimens, 9,10 a growing number of applications of these photothermal techniques have been used for investigating the different physicochemical properties of polymers, [11][12][13] as well as how the processing conditions [14][15][16][17] of these materials affect their physical properties. Despite this growing interest and the importance of the applications of these techniques to the polymer research area, so far the photothermal measurements have been carried out mostly at near room-temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

Thermal lens scanning of the glass transition in polymers

Rohling

Caldeira

Pereira

et al. 2001

Journal of Applied Physics

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In this article we discuss the use of the thermal lens technique for investigating the thermal properties of polymers as a function of temperature. It is also discussed how the experimentally determined thermal lens parameters can be used to locate the glass transition in polymers. The methodology is tested using a solution casted films of poly͑vinyl chloride͒ as a testing sample. A comparison with conventional differential scanning calorimetry data is made. It is proposed that the current transient thermal lens methodology, with minor changes in its experimental configuration, could be adapted to develop a new methodology called differential thermal lens scanning especially designed for the investigation of the phase transitions in polymers. It is shown that this new methodology could be equally used for the measurement of the thermal expansion coefficient, above and below the glass transition.

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Section: Introductionmentioning

confidence: 99%

Thermal lens scanning of the glass transition in polymers

Rohling

Caldeira

Pereira

et al. 2001

Journal of Applied Physics

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“…An alternate PA technique well suited for thermal analysis without the experimental pitfalls of the conventional rear-surface illumination methods is a combination of front and back techniques, introduced by Pessoa et al [38] and shown in Fig. 5.…”

Section: C) Alternate Fd Photoacoustic Detection Schemesmentioning

confidence: 99%

“…5. Using the thermal diffusion model of Rosencwaig and Gersho [7] for the production of the PA signal, the ratio SF/SR of the signal amplitude and phase difference, A~ = ~F-r for front (F) and rear (R)-surface illumination are given by [38] derive as. Extensive measurements of thermal diffusivities have been reported using the setup of Fig.…”

Section: C) Alternate Fd Photoacoustic Detection Schemesmentioning

confidence: 99%

Photothermal applications to the thermal analysis of solids

Mandelis

1991

Journal of Thermal Analysis

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Major application of optically-induced thermal waves to the thermal and thermodynamic analysis of solids are reviewed. The spectrum of available techniques,from the conventional photoaeoustic detection to novel photothermal laser probing and frequency multiplexing is discussed, and their utilization for the measurement of thermophysical thermal transport-related parameters of solids is presented. These include the thermal diffusivity, effusivity, conductivity and specific heat. The ability of photothermal methods to perform thermal analysis on large classes of solids, including conducting and insulating bulk materials, crystals, layered porous and coated structures, thin films and inhomogeneous thermal profiles is highlighted. Finally, special capabilities of photothermal analysis, such as the monitoring of surface thermodynamic phenomena and phase transition studies, including high-Tc superconductors, are described in order to give a complete overview of the rich potential of photothermal-based methodologies.Exposure of a sample to radiation results in local heating due to absorption and subsequent thermalization of the incident radiation. The extent of absorption and the thermalized volume fraction depend on the interplay between the absorption profile and the thermal transport properties of the material under investigation. If the irradianee of the incident radiation is modulated harmonically or pulsed, an oscillatory or transient heat source, respectively, is generated in the sample. Thermal waves are thus created,

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“…4,5 In particular, photoacoustic (PA) spectroscopy is an important technique because it allows studies in nonhomogeneous materials; it is nondestructive and demands minimal sample preparation. [6][7][8][9][10] Since the PA signal responds only to the absorbed light, the effects of scattered light play no significant roles in the measurements. Apart from several different apparatuses for the PA detection, the simplicity and the usefulness of the open-photoacoustic-cell (OPC) make this technique easily applicable to thermal characterization of solid materials such as the measurement of thermal diffusivity and thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%

Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

Astrath

Baesso

et al. 2012

Journal of Applied Physics

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Thermal diffusivity and conductivity of dental cements have been studied using open photoacoustic cell (OPC). The samples consisted of fast hardening cement named CER, developed to be a root-end filling material. Thermal characterization was performed in samples with different gel/powder ratio and particle sizes and the results were compared to the ones from commercial cements. Complementary measurements of specific heat and mass density were also performed. The results showed that the thermal diffusivity of CER tends to increase smoothly with gel volume and rapidly against particle size. This behavior was linked to the pores size and their distribution in the samples. The OPC method was shown to be a valuable way in deriving thermal properties of porous material.

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Two-beam photoacoustic phase measurement of the thermal diffusivity of solids

Abstract: A simple method is demonstrated for obtaining the thermal diffusivity of solids, by measuring t~e phase lag between a front and rear illumination, at a single chopping frequency. The method IS tested using some semiconductor and glass samples.

Cited by 141 publications

References 7 publications

Thermal lens scanning of the glass transition in polymers

Thermal lens scanning of the glass transition in polymers

Photothermal applications to the thermal analysis of solids

Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

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