Appl Phys A (2013) 110:857–861 DOI 10.1007/s00339-012-7165-2 Effect of picosecond laser induced cavitation bubbles generated on Au targets in a nanoparticle production set-up M. Tiberi · A. Simonelli · G. Cristoforetti · P. Marsili · F. Giammanco · E. Giorgetti Received: 26 May 2011 / Accepted: 3 August 2012 / Published online: 28 August 2012 © Springer-Verlag 2012 Abstract This work is aimed at an analysis of the influ- ence on the efficiency of nanoparticle production of a cavita- tion bubble (CB), which forms during the laser ablation pro- cess in high-fluence regime. The CB is produced on an Au metal target immersed in water by 1064 nm ps Nd:YAG laser pulses at different fluences. Its time–space evolution is mon- itored by a shadowgraphic set-up, while the Au nanoparti- cles production rate is tagged by the growth of the plasmon resonance, which is detected by measuring shot-by-shot the UV-Vis absorbance. We analyze the dependence of bubble size on the experimental parameters. Our results appear of interest to enhance the nanoparticle production efficiency in a liquid medium. 1 Introduction Nanoparticles (NPs) of coinage metals and, above all, of gold, have been largely investigated up to date, due to their perspective applications to several fields, including medical diagnostic, sensing, drug delivery and the development of smart materials [1, 2]. In spite of the high degree of versatil- ity, the currently used preparation methods, based on chem- ical reduction, are seldom compatible with applications to M. Tiberi ( ) · A. Simonelli · F. Giammanco Dept. of Physics “E. Fermi”, University of Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy e-mail: tiberi.marco@gmail.com G. Cristoforetti ILIL, National Institute of Optics, Research Area of National Research Council, Via G. Moruzzi 1, 56124 Pisa, Italy P. Marsili · E. Giorgetti Institute of Complex Systems of the National Research Council ISC-CNR, Via Madonna del Piano 10, Sesto Fiorentino, FI, Italy biology or nanomedicine, due to the presence of contamina- tion coming from reaction by-products [3, 4]. In this sense the method of pulsed laser ablation of a metallic target in a liquid environment, which has been widely studied for at least ten years (see for example [5] and references therein), although it is more expensive, is slow and less versatile in terms of particle shape. Moreover, it is extremely simple, fully compatible with different solvents and, above all, it exhibits the enormous advantage over chemical reduction methods of the purity of the final products. Although extensively investigated, metal NP production through laser interaction with a solid target still presents some aspects not fully understood, mainly due to the inter- play among short-term collisions leading to particle aggre- gation and NP formation and to the macroscopic behavior of the ablated material as a whole. Depending on the laser pulse duration, NP production can be achieved also at very low fluences (<4J/cm 2 ) where the ablated material hardly resembles a plasma and the target modifications are barely detectable. At the very large fluences (>10 J/cm 2 ) required to enhance the NP production rate, which is mandatory for many applications the pulsed laser ablation process cam be sketched as follows: a hot, dense plasma is ejected from the target and its fast expansion in the surrounding liquid gen- erates a shock wave. Typically, the onset of a shock wave occurs in tens of ns, depending on the energy deposited onto the target. Behind the shock front, which moves fast away from the target on a time scale of hundreds of ns, the plasma heat-exchange with the liquid causes the formation of a cav- itation bubble (CB) that contains vapor, gas and nanopar- ticles, which first expands and then collapses on the time scale of hundreds of μs; a more detailed and accurate de- scription of pulsed laser ablation in liquids (PLAL) process is given in [6]. This phenomenon has been investigated in various configurations to explore its potential benefits for