The possibility of black Au to be used in plasmonically induced reactions was tested using the MBD self-assembled monolayer and monitored by in-situ SERS measurements. Four different wavelengths were used, and the results were also compared to typical silver nanoparticles (AgNPs) and gold nanoflowers (AuNFs) aggregated similarly to black Au. Using 633 nm, the SERS spectra of the black gold exhibit3.5 times higher peak intensities than AgNPs and AuNFs (Figure ). The reaction was further initiated by irradiating the samples continuously for at least 300 seconds using a laser power of 1 mW in the focal point. The overall result is similar in all studied cases. As shown in figure , over time there is a decrease in intensity of all the vibrational peaks and at the same time, a broadening of the peak around 1590 cm -1 . The loss of the diazonium moiety (C-N=N-C) is mainly observed by the intensity decrease of the peaks at 1391 and 1438 cm - 1 , associated with the diazonium vibrations. It is often expected that new peaks appear due to the formation of a reaction product, which is not the case here. However, these results suggest the dissociation of the N=N groups and coupling of the remaining benzene rings into a molecular carbonaceous layer, as evidenced later by the of amorphous carbon bands after prolonged irradiation (1.5 h). Recently, It was reported using tip-enhanced Raman spectroscopy (TERS) that due to the light irradiation of plasmonic nanoparticles, a broadening of the peaks in the spectrum is observed because of the formation of non-organized carbonaceous compounds, carbon nanomembranes, or amorphous carbon. It was shown that such broadening is not due to a fully thermal reaction but that the hot-electrons generated in the gold nanotips are the main driver of the reaction. At the same time, control experiments by heating the samples in the dark showed thermal-induced desorption of the molecules from the surface rather than their crosslinking. In the present case, where MBD serves as a starting material, a similar reaction route is most likely followed. Due to the light irradiation, hot-carriers are generated in the black gold nanoparticles leading to crosslinking reactions within the self-assembled molecules, which induce the peak broadening at 1590 cm -1 . However, due to the excellent photothermal properties of black Au, the surface is also heated up very strongly, leading to the partial desorption of the molecules from the surface. This second part is better observed at the low-frequency vibrations, Figure . By comparing the spectra at the beginning and after 300 s of irradiation, we observe that the peaks related to the Au-S loses intensity, indicating that those bonds are broken, and some molecules possibly left the NP surface. At the same time, the very stable band at 423 cm -1 , related to the Au-C or the C-S stretching of thiol-linked molecule, kept the same intensity throughout the irradiation. Although we do not have a complete picture of the final material on the black Au NP surface yet, we hypothesize that the aromatic rings are linked together forming a carbon nanomembrane atop of the black gold film, Figure .