TEM images of synthesised gold nanoparticles. (a) gold nanoparticles (approximately20 nm) prepared with 243 kJ (30 min with 135 W ultrasonic power) of sonication; (b) gold nanoparticles (20 to 50 nm) prepared with 729 kJ (90 min with 135 W ultrasonic power) of sonication. Initial HAuCl4 concentration was 0.25 mM and molar ratio between HAuCl4 and sodium citrate was set at 1:3.5.
Lee et al. Nanoscale Research Letters 2012 7:420 doi:10.1186/1556-276X-7-420