Silver nanoparticles are one of the most extensively used metallic nanomaterials due to their unusual physical and chemical properties as well as their promising applications in a wide range of different fields. In this study, a non-thermal atmospheric pressure helium plasma jet was used to successfully synthesize silver nanoparticles with silver nitrate as a precursor and trisodium citrate as a capping agent. The browning of the solution after only 5 min of plasma irradiation is a result of the surface plasmon resonance (SPR) from the obtained silver nanoparticles. The SPR was confirmed by the presence of an absorption band in the visible range between 400 and 450 nm demonstrated in the UV–vis spectra. The effect of different chemical parameters such as the concentration of silver nitrate and the concentration of citrate on the silver nanoparticles have been studied. These nanoparticles were further characterized using transmission electron microscopy and dynamic light scattering. Therefore, the plasma jet was advantageous to fast produce silver nanoparticles in friendly conditions. In addition, the used experimental setup allows further studies in different solvents conditions and with different capping agents. So, this methodology could be useful for the preparation of silver nanoparticles required for numerous applications such as bioactivity, catalysis, surface enhanced Raman scattering, and photonic.

Non-thermal atmospheric pressure plasma jets or plasma plumes have recently been largely investigated in applications like materials processing, biomedical treatment and analytical chemistry. In this paper He-discharges in an asymmetrical Dielectric Barrier Discharge (DBD) have been experimentally studied with an Intensified Charge Coupled Device (ICCD) camera, Optical Emission Spectroscopy (OES) and Time-Of-Flight Mass Spectrometry (TOF-MS) measurements. The development of the plasma plume, its apparent length and the spatial distribution of the excited and ionized species along the plasma plume have been characterized as a function of the applied voltage and the gas flow rate. A TOF-MS spectrometer has been used to characterize ionized species (positive and negative ions) produced by the plasma alone and the plasma with addition of ethanol, both as a function of the distance between the plasma plume and the vacuum interface of the spectrometer.