Modelling photothermal induced resonance microscopy: the role of interface thermal resistances

TL;DR

This paper presents a detailed electromagnetic and thermal simulation of photothermal induced resonance microscopy, emphasizing the critical influence of interface thermal resistances on the measured IR signal.

Contribution

It provides a comprehensive analysis highlighting the importance of interface thermal resistances in PTIR signal modelling, filling a gap in theoretical benchmarks.

Findings

Interface thermal resistances significantly affect PTIR signals.

Thermal resistances must be included for accurate quantitative modelling.

Experimental validation confirms the role of interface resistances.

Abstract

Infrared (IR) nanospectroscopy by photothermal induced resonance (PTIR) is a novel experimental technique that combines the nanoscale resolution granted by atomic force microscopy (AFM) and the chemical labelling made possible by IR absorption spectroscopy. While the technique has developed enormously over the last decade from an experimental point of view, the theoretical modelling of the signal still varies significantly throughout the literature and misses a solid benchmark. Here, we report an analysis focused on the electromagnetic and thermal simulations of a PTIR experiment. Thanks to a control experiment where the signal is acquired as a function of the thickness of a polymer film and for different tip geometries, we find clear evidence that the interface thermal resistances play a key role in the determination of the measured signal and should therefore always be accounted for by any quantitative modelling.