2.3.2. FTIR

To confirm the SDS coating/stabilization capacity of Cu-Au NPs, infrared spectroscopy (FTIR-4200 spectrometer, Jasco, Tokyo, Japan) was used. The colloidal nanoparticle solutions and the initial polymer solution were spread in a thin layer on a ZnSe window and measured in transmission mode in the spectral range of 4000–500 cm⁻¹, at a resolution of 1 cm⁻¹, and 200 scans for each spectrum.