Fig. 5
Photoacoustic signal comparison for silica-coated nanospheres. a Ten-nanosecond-wide laser pulse. b Two-nanosecond-wide laser pulse. Silica shell of size \(5\) nm shell size are used for nanosphere in water at two levels of interfacial thermal conductance, \({G}_{1s}=200\,{\mathrm{{{MW}}}}\,{\mathrm{{{m}}}}^{-2}\,{\mathrm{{{K}}}}^{-1}\) and \({G}_{1s}=20\,{\mathrm{{{MW}}}}\,{\mathrm{{{m}}}}^{-2}\,{\mathrm{{{K}}}}^{-1}\) against an uncoated nanosphere (\(a=30\) nm) in water with \({G}_{12}=20\,{\mathrm{{{MW}}}}\,{\mathrm{{{m}}}}^{-2}\,{\mathrm{{{K}}}}^{-1}\). Significant signal enhancement due to coating only with the sharper pulse and only at the higher silica–gold interfacial thermal conductance coefficient is seen
