Fig. 4.

(a) Cavitation probability as a function of laser fluence around mixed gold nanorods (5.7 × 10⁸ nanoparticles/ml) at peak negative pressures of 1.8, 2.0, 2.5 and 3.0 MPa. Solid lines are fitted using Eq. (1). (b) Cavitation threshold fluences around gold nanospheres (2.2 × 10⁸ nanoparticles/ml) and gold nanorods (5.7 × 10⁸ nanoparticles/ml) at different peak negative pressures. The vertical dashed line is the mechanical index limit for diagnostic ultrasound at 1.0 MHz. The horizontal dashed line is the nanorod damage threshold.