Here, we find another utility of the FEM based model, namely that it also allows us model the heat flow across the interface between PMMA and PE, such as interfacial roughness, compositional disorder or general interfacial thermal resistance which could affect the thermal diffusion and thus the AFM-IR signal. To address these potential effects, we incorporated interfacial thermal resistance (R P M M A/P E ) between PMMA and PE into the finite element simulations. However, to the best of our knowledge, no literature values exist for the interfacical thermal resistance between R P M M A/P E and interfacial thermal resistance values are generally associated with high uncertainties . We found the best match between experimental data and model to lie around 2.2 m 2 K/MW, with higher (2.5 m 2 K/MW) and lower (2.0 m 2 K/MW) R P M M A/P E leading to results that still lie inside the error bars of the measurement (see Figure ). These values are comparable to those used by others to simulate AFM-IR experiments. The model and experiment both show a decrease in FWHM of the AFM-IR signal with increasing repetition rate (see Figure ).