Frontiers in Forensic Science Seminar Series
Abstract:* The use of nanostructures as ‘spectroscopic enhancers’ is receiving growing interest in analytical chemistry. Many theoretical and experimental works have demonstrated that when a substrate is irradiated with a laser after nanoparticles (NPs) have been deposited on its surface, a local enhancement of the laser electromagnetic field is induced. This phenomenon can strongly affect the ablation mechanisms by increasing, locally on the sample surface, the energy of the laser by orders of magnitude. In the case of Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), since the laser ablation process is how the sample is transported into the probing plasma, the use of NPs can be exploited to considerably decrease the Limit of Detection (LOD) of these techniques, enabling interesting medical and forensic applications.
The recently proposed Nanoparticle Enhanced LIBS (NELIBS) [1,2] is an effective method to improve the sensitivity and decrease the LOD in elemental analysis up to two orders of magnitude as compared to traditional LIBS. NELIBS is a variant of the LIBS technique, based on the direct deposition of metal nanoparticles on the sample surface without the necessity to change the instrumental set-up.
In this lecture the application of NELIBS to metallic samples , to microdrops of inorganic and biological solution , to glasses and precious stones  as well as to molecular detection  will be shown and critically discussed in order to give a general idea of the potential of this new analytical approach.
Moreover we applied this same approach to LA-ICP-MS for the elemental analysis of metallic samples. These preliminary results suggest that the use of NPs deposited on sample surface can improve the sensitivity of commercial LA-ICP-MS systems by 1 order of magnitude.
The results of the NPs enhanced ablation demonstrate the possibility of improving the sensibility of LIBS and LA-ICP-MS to ppb scale using very small amount of sample and suggest a promising impact on forensic applications.
Bio:* Prof. Alessandro De Giacomo is a staff research professor in the Chemistry Department of the University of Bari in Italy and an associate researcher in the Institute of Nanotechnology of the National Research Council (CNR-NANOTEC) where he has been carrying out fundamental studies on laser induced plasmas in different applications ranging from materials science to analytical chemistry, such as plasma assisted pulsed laser deposition, laser spectroscopy, nanoparticle and carbon nanostructure synthesis by pulsed laser ablation in liquid, and laser induced breakdown spectroscopy (LIBS). At present he is the head of the laser-matter interaction labs in the joint collaboration on laser plasmas between the University of Bari and the CNR-NANOTEC where laser induced plasma techniques are applied for the production of metal nanoparticles for applications in biological science and for the development of diagnostic tools for space exploration, cultural heritage and geological applications. Within this research activity and the academic work, Prof. Alessandro De Giacomo is an active member of many scientific committees of international conferences and a member of some editorial boards of international journals, as well as a reviewer of several funding agencies in Europe and North America. Up to now he has published 75 ISI papers with more than 2500 citations and he has presented more than 30 invited and plenary lectures in international conferences.