Here we report on Mie assisted Raman scattering amplification (MARS) signal of molecular species attached to silicon nanoparticles (SiNPs) resulting from the evanescent field of their Mie resonant modes [1]. In contrast with common plasmon-assisted surface-enhanced Raman scattering (SERS) spectroscopy, here the field enhancement does not come from the collective excitation of electrons [2], but from the resonances of the whispering gallery modes (WGMs) of high refractive index nanoparticles [3]. The very large scattering cross-sections of Mie modes induce enormous scattered fields around the particles that enhance the Raman scattering cross section. Although the enhancement factor provided by this process is slightly smaller than the normal SERS amplification by gold [4], the interest on Si nanoparticles is manifold. A) the wide range of experimental configurations that can be implemented including photonic crystals [5], B) the sharp spectral resonances easily tunable with the particle size [6], C) the biocom-patibility and biodegradability of silicon [7], and D) the possibility of direct analysis of mole-cules that do not contain functional groups with high affinity for gold and silver. Additionally, silicon nanoparticles are non-metallic and they present Raman enhancement effects at larger sizes than for gold.

References:

[1] Rodriguez, I. ; Shi, L. ; Lu, X.; Korgel, B. A. ; Alvarez-Puebla, R. A.; Meseguer, F.; Submitted for publication

[2] Stiles, P. L.; Dieringer, J. A.; Shah, N. C.; Van Duyne, R. P. ; An. Rev. Anal. Chem. 2008, 1, 601.

[3] Bohren, C. F.; Huffman, D. R.; Absorption and scattering of light by small particles; Wiley, 1983.

[4] Rodriguez-Lorenzo, L.; Alvarez-Puebla, R. A.; Pastoriza-Santos, I.; Mazzucco, S.; Stephan, O.; Kociak, M.; Liz-Marzan, L. M.; Garcia de Abajo, F. J. ; J. Am. Chem. Soc. 2009, 131, 4616.

[5] Shi, L.; Harris, J. T.; Fenollosa, R.; Rodriguez, I.; Lu, X.; Korgel, B. A.; Meseguer, F.; Nat Comm 2013, 4, 1904.

[6] Shi, L.; Tuzer, T. U.; Fenollosa, R.; Meseguer, F.; Advanced Materials 2012, 24, 5934-5938.

[7] Shabir, Q.; et al. ; Silicon 2011, 3, 173-176.

Francisco Meseguer

Universidad Polit&#233;cnica de Valencia, CSIC

Appearances

Universidad Politécnica de Valencia, CSIC