The physics of the photothermal detection of single absorbing nano-objects: A review

The literature on the theory of the photothermal imaging of single nano objects is reviewed. Several models have been devised to describe the signals magnitude, phase and shape in dependence on the experimental and sample parameters (particle position and optical properties, laser beams and their offset, modulation frequency, (thermo-)refractive coefficients, thermal constants). The benefits and limitations of these models are summarized allowing the proper choice of a framework for future investigations using photothermal microscopy of single absorbers.