STM-TERS measurements were performed on a top illumination TERS instrument that combines STM with a Raman spectrometer (NT-MDT, Russia, NTEGRA Spectra Upright). Electrochemically etched Ag tips were used to obtain both the topography and TER spectra. A 632.8 nm He-Ne laser was used as the excitation source. For all measurements, the tunneling current setpoint was 200 pA and the tunneling bias 0.6 V, and the intensity of the laser was 70 µW with a 1 s exposure time per spectrum.