The effect of the presence of gold nanoparticles on the laser induced breakdown in argon gas

Noble metal nanoparticles can greatly affect the sensitivity and selectivity of many spectroscopic techniques, thus they are widely used in the analytical chemistry. In this current study we investigated the effects of the presence of gold nanoparticles on the formation of laserinduced breakdown plasmas in argon gas

Laser-induced breakdown spectroscopy signal enhancement effect for argon caused by the presence of gold nanoparticles

The effect of the presence of nanoparticles (NPs) on the laser induced breakdown spectroscopy (LIBS) signal of argon gas was studied experimentally. 10–20 nm diameter gold NPs, produced by a spark discharge nanoparticle generator, were suspended in argon gas. The effect of particle size, number concentration and mass concen- tration, as well as laser pulse energy on the LIBS argon signal was systematically investigated. It was found that the breakdown threshold of the gas decreases considerably, facilitating the detection of Ar emission at such laser fluences, which do not allow plasma formation without the presence of the NPs. Our observations persist even at aerosol mass concentrations that are too low to allow the direct detection of nanoparticles. The effect, which is attributed to electron thermo- and field emission induced by the high intensity laser pulse, shows an asymp- totically increasing magnitude with the aerosol mass concentration. The signal enhancement was found to be 102–104 and the effect is suggested to be useful in trace gas analysis or for the indirect detection of NPs. The achievable indirect aerosol mass concentration detection limit was estimated to be in the parts per trillion regime (as low as 50 ng⋅m 3) which is comparable to the best literature values reported for direct analysis

Study of the composition and size distribution of gold-containing bimetallic nanoparticles synthesized in a spark discharge generator

Nanotechnology is one of the most dynamically growing fields of science, which requires the production of engineered nanoparticles (ENP) for various applications. Chemical synthesis procedures were dominating the field for many years, but physical procedures, that are based on laser or discharge ablation, are becoming more and more popular nowadays. One of these ablation-based methods is spark discharge generation, which is a versatile method for the preparation of mono- or bimetallic nanoparticles. In a spark discharge generator (SDG), a high voltage oscillating discharge is produced between two electrodes made of at least moderately conducting material. The erosion of the electrodes produce an atomic vapor in the spark gap, which is carried away by a gas flow. Nucleation and coagulation processes lead to nano-sized aggregates, which are then compacted to form spherical nanoparticles (NP). This method produces high purity NPs. SDGs can also be run continuously, thus industrial rate production is also possible. Control of the particle properties (e.g. concentration and size) can be achieved by tuning the operating conditions of the generator. The SDG method can also be considered cost-efficient and environmentally friendly. The goal of the present work was to study how the operating parameters of SDGs influence the composition and size distribution NPs in the case of certain bimetallic particles (BNPs). In particular, we intended to study the influence of the electrode polarity, gap size and compaction on Au-Ag and Au-W particles

Assessment of the usefulness of libs and ICP-MS for the characterization of nanoparticles in industrial and environmental samples

The need for analytical techniques capable for the detection and characterization of nanoparticles (NPs) in industrial and environmental matrices also grows along with the quickly expanding use of NPs in various products. Two candidate analytical techniques are laser induced breakdown spectroscopy (LIBS) and inductively coupled plasma mass spectrometry (ICP-MS). Both of these sensitive and versatile techniques provide elemental compositional information. Based on the success of the application of LIBS in aerosol analysis this technique can be expected to be similarly useful in NP monitoring applications, such as the detection of NPs in liquid or gaseous matrices, or for the monitoring of the properties of NPs produced by physical generation methods (e.g. electrical discharges or laser ablation). ICP-MS on the other hand has already proven itself useful in the literature, both in the solution or single particle analysis (spICP-MS) modes, for the characterization of nanoparticles. In recent years we also reported about the successful development of several ICP-MS based analytical methods for the compositional and dimensional analysis of NPs (e.g. [1, 2]). In our study we assessed the potential of LIBS and ICP-MS for nanoparticle detection and characterization both in on-line (only for LIBS) or off-line (following collection on a filter) mode. Dispersions of various types of nanoparticles (e.g. monometallic, bimetallic, oxide) in simulated or real liquid and gaseous industrial and environmental matrices were measured. Some NPs were obtained commercially, while others were generated by inlaboratory developed electrical (spark or arc) discharge generators. Additional and reference characterization of the nanoparticles were performed by electron microscopy (SEM, TEM) and scanning mobility particle sizer (SMPS). Size and mass detection limits were also calculated for on-line LIBS detection of nanoaerosols and for spICP-MS detection of NPs in aqueous nanodispersions