  Light absorption and scattering of plasmonic metal nanoparticles can lead to
non-equilibrium charge carriers, intense electromagnetic near-fields, and heat
generation, with promising applications in a vast range of fields, from
chemical and physical sensing, to nanomedicine, and photocatalysis for the
sustainable production of fuels and chemicals. Disentangling the relative
contribution of thermal and non-thermal contributions in plasmon driven
processes is however difficult. Nanoscale temperature measurements are
technically challenging and macroscale experiments are often characterized by
collective heating effects, which tend to make the actual temperature increase
unpredictable. This work is intended to help the reader experimentally detect
and quantify photothermal effects in plasmon-driven chemical reactions, to
discriminate their contribution from the one due to photochemical processes,
and to cast a critical eye on the current literature. To this aim, we review,
and in some cases propose, seven simple experimental procedures, which do not
require the use of complex or expensive thermal microscopy techniques. These
proposed procedures are adaptable to a wide range of experiments and fields of
research where photothermal effects need to be assessed, such as
plasmonic-assisted chemistry, heterogeneous catalysis, photovoltaics,
biosensing and enhanced molecular spectroscopy.
