Mechanisms of laser-based synthesis and modifications of nanomaterials

International audience ; Lasers are known to be extremely versatile tools suitable both for the synthesis and modifications of numerous nanomaterials with unique and extremely interesting optical properties suitable for a wide range of applications in various fields ranging from optics and photonics to medical applications. Efficient control over these processes is still challenging and often requires numerical simulations because of the complex interplay of many physical and chemical processes involved that depend on the combination of both material properties and laser parameters. To simulate these processes, multi-physical modeling should be used including electromagnetic, thermal, mechanical, and chemical effects taking place at several time and space scales. Depending on the experimental conditions, nanoparticles can be formed, grow, aggregate, or on the contrary decay, so that a set of transient variations often take place, particularly when multipulse laser irradiation is applied. In the case of short and ultra-short laser pulses, strongly non-linear and time-dependent processes play a role involving not only ionization but also phase transitions, acoustic vibrations, shock waves, as well as void formation, and cavitation. If a considerable energy is released in a very short time, firstly aggregates decay, then nanoparticles are fragmented. Here, based on numerical calculations, the roles of several above-mentioned effects are analyzed. The performed simulations can be used for a better understanding of laser interactions with nanoobjects.