Assuming the system is in thermal equilibrium before excitation with a laser pulse, its response is determined through convolution of g(x ′ , t) with a Green's function G(x, t|x ′ , t ′ ). Green's function represents the temperature at any location x within the domain, at any time t, due to an instantaneous volumetric source, located at the position x ′ , releasing its energy spontaneously at time t = t ′ into a medium at steadystate conditions. To find G and solve Eq.( ) and ( ), we use assumptions that have been previously shown to describe the thermal behavior of AFM-IR experiments well 7 :