Investigation into a surface plasmon related heating effect in surface enhanced Raman spectroscopy.
The irreversible loss of surface enhanced Raman spectroscopy (SERS) intensity derived from electrostatically immobilized Au colloidal substrate is studied. The total intensity of the SERS scattering from crystal violet molecules adsorbed onto the substrate was monitored for up to 240 s under continuous laser irradiation. The rate of signal decay was found to depend upon the thickness of the liquid layer over the coated substrate. On the basis of this observation, we propose a plausible mechanism in which surface plasmon related heating induced a small but significant lateral particle diffusion in closely spaced Au particles. The result of the shifting is an increase in the average interparticle distance, which subsequently reduces the electromagnetic coupling between the Au nanoparticles, and in turn causes a reduction in the SERS activity. Finally, a three-state model is proposed and shown to satisfactorily describe the observed decays.
Kho
Kiang Wei
KW
National Cancer Centre, Division of Medical Sciences, 11 Hospital Drive, 169610 Singapore.
Shen
Ze Xiang
ZX
Lei
Zhou
Z
Watt
Frank
F
Soo
Khee Chee
KC
Olivo
Malini
M
D002853:Chromatography, Liquid; D003198:Computer Simulation; D004058:Diffusion; D006358:Hot Temperature; D013058:Mass Spectrometry; D013059:Spectrum Analysis, Raman / Q000379:methods*; D055672:Static Electricity; D020349:Surface Plasmon Resonance / Q000379:methods*