Laser Assisted Nanosynthesis

There is currently great interest in methods for synthesising nanomaterials and in techniques for incorporating these materials as the active components in future devices.  The very high peak power density produced by a focused short (nanosecond) laser pulse allows the growth and processing of a large variety of nanomaterials, such as nanoparticles and nanowires. Using laser induced heating and ablation, rather than conventional synthesis methods, we can fabricate nanomaterials at much lower macroscopic temperatures than by many other means. In addition to synthesis, we also investigated lithography-free methods for depositing these materials in precisely defined patterns, using laser direct write technologies and using these patterned substrates for sensing applications.

We are using nanosecond duration laser pulses from excimer and Nd:YAG  lasers to synthesize a variety of nanomaterials, including metal and semiconducting nanoparticles and nanowires. The short lived extreme temperatures and pressures that are produced locally at the focus point of a pulsed laser beam, allows access to processing conditions that would be unavailable by conventional means. We can easily evaporate atoms from a solid target, or induce photo-decomposition of chemicals in solution, or combine the two to react ablated atoms with a chemical in solution.  By laser-induced heating and fragmentation of  particles in solution, we are able to selectively deposit metal nanoparticles onto low-cost glass substrates.

We have demonstrated that pulsed laser synthesis is a powerful and versatile technique for the production of nanomaterials. Many different metal (Au, Ag, Pt, Pd, Mo, Co and Ni) and semiconductor (NiO, CoO, ZnO, Fe203 and a-C) nanoparticles and nanowires have been produced by this route.   We can produce materials in solution (such as the iron oxide nanowires and nanoribbons) or form/deposit nanoparticles directly on substrates. We have demonstrated that Ag nanoparticles deposited using this technique can be used for trace-level chemical detection.