Fig. 1. (a) Specific surface area of spherical particle as a function of radius; (b) localized surface plasmon resonance induced field enhancement effect for a gold nanosphere with the radius of 15 nm; (c) schematic of nonradiative transition for the nanoparticles absorber photons; (d) simulated results of the absorbed optical power spectra for gold nanoparticles with different radii

Fig. 2. (a) Thermal confinement time as a function of nanoparticle size; (b) thermal diffusion length as a function of laser pulse width; (c) temperature field distribution versus time when a gold nanosphere with the radius of 15 nm is irradiated by the laser with the pulse width of 10 ns

Fig. 3. PA signal generated by thermal expansion of the thermal environment for the gold nanosphere and its surrounding water

Fig. 4. PA signal amplitudes as a function of thermal diffusion length under different Grueneisen parameter relations

Fig. 5. (a) Simulated results of thermal energy deposited in the gold nanosphere as a function of the laser pulse width, the inset is the thermal diffusion length as a function of laser pulse width; (b) thermal energy deposited in water as a function of laser pulse width with different sizes of nanospheres