Inert gas condensation made bimetallic FeCu nanoparticles - plasmonic response and magnetic ordering

The inert gas condensation (IGC) technique has emerged as one of the most flexible physical vapour techniques. It provides the possibility to control the growth process of nanoparticles (NPs) with a well-controlled size and chemical composition. Such characteristics are highly desirable in the synthesis of multifunctional NPs. Here we show the application of the IGC technique to the production of active bimetallic magnetic-plasmonic FeCu NPs with narrow size distribution, in which characteristic collective properties depend on the different capabilities endorsed by the constituent elements of NPs. The present work reveals a tendency of NPs to agglomerate in the form of short chains and a significant oxidation of the Fe phase. Nevertheless, the magnetic response of Fe-rich NPs is clearly observed at cryogenic temperatures. The amplified surface-enhanced Raman scattering and surface-enhanced infrared absorption spectroscopy of Phe adsorbed onto FeCu NPs prove the plasmonic behaviour of the studied NPs. It is possible to detect Phe at a concentration of 0.1 mM for all samples, regardless of the Cu concentration. Protection against oxidation by the Au thin film leads to an improved magnetic response, which indicates that bimetallic FeCu NPs produced by IGC can be considered as a promising magnetic-plasmonic system for the development of biosensors. Bimetallic FeCu nanoparticles of narrow size distribution produced by inert gas condensation (IGC) technique exhibit functional plasmonic and magnetic properties and can be considered as a promising system for the development of biosensors.