Tunable photoacoustic properties of gold nanoshells with near-infrared optical responses

Photoacoustic (PA) properties of liquid-immersed gold nanoshells (GNSs) with near-infrared optical responses are investigated using the finite element method. We focus on the dependence of the PA signal of the GNS on the geometry, surrounding medium, laser fluence, and laser pulse width. It is found that the PA signal of the GNS is strongly sensitive to the optical absorption of the GNS and can be greatly modulated by changing the geometry. At the wavelength of 800 nm, the maximal PA signal could be obtained for the GNS with the optimized size of the inner radius (r(1) = 48.5 nm) and outer radius (r(2) = 57 nm). The increased laser fluence enhances the optical absorption and PA signal. The decreased laser pulse width induces the decreased PA pulse width, the increased bandwidth of the PA signal, and the increased PA conversion efficiency, resulting in the enhanced PA signal. In addition, we find that the larger Gruneisen parameter of the embedding medium leads to a stronger PA signal. Published by AIP Publishing.