Photochemical synthesis of biphasic gold-silver nanoalloys for optical fiber surface-enhanced Raman scattering sensor

Optical fiber surface-enhanced Raman scattering (SERS) probes based on coexistent biphasic gold silver nanoalloys are first developed by photochemical co-reduction methods. The nanoalloys are deposited around the core of the fiber. The surface morphology features of the two phases are characterized by Scanning Electronic Microscope (SEM): those in the central circular area show flower-like morphology, while those in the concentric ring region seem more like spike. The distribution of these two phases can be tuned by varying the irradiation time. The paper reveals that the proportion of the spike-like nanoalloys and flower-like nanoalloys is increasing with the time. SERS detections of rhodamine 6G (R6G, 10^-5M) solution are made in remote detection mode to test the SERS activities of the probes. As seen in the paper, the SERS intensity of the probes is increasing with the irradiation time. The fiber SERS probes show excellent SERS activities and good controllability.