Visualized method of chemical enhancement mechanism on SERS and TERS

We review our developed visualization method of charge transfer (CT) for chemical enhancement mechanism on surfaceenhanced Raman scattering (SERS) and tip-enhanced Raman spectroscopy (TERS). Firstly, we describe our visualization method of charge difference density, which provides direct visual evidence for photoinduced CT. And then, using the visualization method of CT, we interpreted the mechanism of SERS and TERS. Photoinduced charge transfer in the processes of SERS and TERS can be clearly seen. Our visualization method provides a visual and easy understanding way for the mechanism of SERS and TERS.