Figure 6.

PA is proportional to the thermal expansion coefficient of the solvent. Thermal expansion coefficient and the Grüneisen parameter are directly proportional to each other. The PA amplitude of gold nanospheres with varying shell thicknesses as a function of temperature in various solvents: (a) water, (b) silicon oil, (c) toluene. The silica thicknesses are 0 nm (circle), 6 nm (triangle), 18 nm (square), and 38 nm (rhombus). (d) Temperature dependence of the Grüneisen parameter (left axis) for water (open circles) and toluene (open triangles) as well as the measured photoacoustic signal (right axis) of water (solid circle) and silicon oil (solid square). The error bar represents the standard error of 16 signals of 8 pulses each. Reprinted with permission from ref 94. Copyright 2011 John Wiley and Sons.