Understanding and designing photothermal responses in complex layered systems

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Understanding heat transport and thermoelasticity in nanostructures is vital for advanced materials.
• Characterizing multilayer thin films requires precise, non-contact methods.

Purpose of the Study:

• To present a novel photothermal mirror-infrared (PTM-IR) spectroscopy approach for depth-sensitive thermal characterization.
• To analyze thermal dynamics and thermoelastic behavior in multilayer polymer systems.

Main Methods:

• Utilized PTM-IR spectroscopy on a PMMA/SU-8 trilayer system.
• Developed a 1D Green's function framework for analyzing photothermal signals.
• Validated experimental data with a 2D finite element model.

Main Results:

• Extracted layer-specific optical absorption coefficients.
• Probed time-resolved temperature and surface displacement evolution.
• Demonstrated that thermal rise time is shorter than thermoelastic relaxation time.

Conclusions:

• PTM-IR spectroscopy is a powerful tool for in situ analysis of multilayer systems.
• The developed analytical framework provides physical insight into thermal and mechanical responses.
• Results are applicable to thermal metrology, photonic, and quantum materials.