Coupling effect on charge-transfer mechanism of surface-enhanced resonance Raman scattering.

In this work, charge-transfer mechanism of surface-enhanced resonance Raman scattering (SERRS) spectroscopy of pyrazine absorbed on Ac@Au7 clusters is theoretically investigated, and the coupling effect between the nanoparticles is especially concerned. First, the contributions of coupling effect to surface-enhanced Raman scattering (SERS) are compared between the ground-state nanoparticles. Second, the visualization of charge transfer provides evidence for the coupling effect on the charge-transfer enhancement mechanism of SERRS spectroscopy. The theoretical results show that the coupling effect on charge-transfer mechanism of SERRS can significantly enhance the intensity of SERS spectra up to about 6 × 105 times. The different coupling ways not only result in different degree of charge transfer on electronic transitions, but also cause different intensity of charge-transfer absorption peaks. Both of them strongly influence the enhancement of charge-transfer mechanism of SERRS. This study promotes the understanding of charge-transfer enhancement mechanism of SERRS for ultrasensitive Raman spectral analysis at nanoscale. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]