Laser Power Dependent Surface-Enhanced Raman Spectroscopic Study of 4‑Mercaptopyridine on Uniform Gold Nanoparticle-Assembled Substrates

A facile procedure was introduced to prepare uniform and highly active substrates assembled with gold nanoparticles for surface-enhanced Raman spectroscopy (SERS). The laser power and time dependent SERS study of 4-mercaptopyridine (4-MPy) adsorbed on this substrate was investigated. The relative intensity of the characteristic Raman peak pair (1575 and 1610 cm^–1) was found to change with the laser power and the exposure time. The spectral changes may originate from change in the fraction of the double-end-bonded and the single-end-bonded states of 4-Mpy adsorbed on the gold nanoparticle-assembled substrate. In addition, this study offers a way to avoid the effect of laser power to achieve reliable spectral response to other factors.