Thermal Mode Spectroscopy for Thermal Diffusivity of Millimeter-Size Solids

Area of Science:

• Physics
• Materials Science
• Thermodynamics

Background:

• Heat conduction exhibits modes analogous to acoustic modes, even in the absence of oscillations.
• Measuring thermal properties of small specimens is challenging due to limitations in conventional techniques.
• Understanding thermal transport at the microscale is crucial for advanced materials and devices.

Purpose of the Study:

• To establish a novel technique, thermal mode spectroscopy, for measuring thermal diffusivity.
• To enable the characterization of thermal properties in small-sized specimens.
• To provide a method applicable to various materials, including crystalline solids.

Main Methods:

• Excitation of thermal modes using localized light pulse heating.
• Photothermal detection at antinodes to selectively measure mode relaxation.
• Application of the Ritz method for analyzing arbitrary specimen geometries.

Main Results:

• Demonstration of thermal mode spectroscopy for selective relaxation time measurement.
• Correlation of relaxation time with thermal diffusivity of the specimen.
• Successful application to a millimeter-sized diamond crystal, showcasing versatility.

Conclusions:

• Thermal mode spectroscopy is an effective method for determining thermal diffusivity in small samples.
• The proposed Ritz method extends the applicability of thermal mode spectroscopy to complex geometries.
• This technique offers a powerful tool for microscale thermal characterization of advanced materials.