Enhancement of the photoacoustic effect during the light-particle interaction.

Exogenous photoacoustic contrast agents such as gold nanoparticles are widely utilized in photoacoustic imaging. Enhancing the photoacoustic performance of gold nanoparticles is pivotal for improving the quality and expanding the application scope of photoacoustic imaging. In this work, the photothermal and photoacoustic responses of gold nanospheres surrounded by water excited with a pulsed laser are obtained a two-temperature model. The interplay between pulse duration and interface thermal resistance and its effect on the photothermal and photoacoustic performances are uncovered quantitatively. The results reveal that, as the pulse duration decreases, increasing the interfacial thermal conductivity can substantially enhance heat transfer between the gold nanosphere and the surrounding water. However, this approach does not effectively enhance the photoacoustic performance. Interestingly, when increasing the thermal conductivity, it was found that there is an optimal pulse duration within the range of 10 ps-10 ns. Employing an incident pulse laser with this optimal pulse duration can maximize the enhancement of the photoacoustic signal.