[SERS mechanism for rhodium electrode in the ultraviolet region]

Stable and good quality of Surface-Enhanced Raman Scattering (SERS) signal from net rhodium electrode in the ultraviolet region was observed for the first time by our group recently. In this paper, both qualitative and quantitative analyses are given to interpret the new experimental results mainly based on the electromagnetic field theory. The mechanisms of SERS for rhodium electrode in the ultraviolet region are mainly attributed to the lightning rod effect together with the weak surface plasmon resonance. According to the calculation, the surface-averaged enhancement factor (SEF) for rhodium electrode in the ultraviolet region is about two orders of magnitude when the surface of the substrate is roughened properly, which is in good agreement with the experimental results. The authors also give a comparative study to show why silver, which is the best SERS active substrate in the visible and near infrared region, can't give any SERS signal when the 325 nm excitation line is used.