Surface-Enhanced Raman Scattering from Individual Au Nanoparticles and Nanoparticle Dimer Substrates

Talley, Chad E.; Jackson, J. B.; Oubre, Chris; Grady, Nathaniel K.; Hollars, Christopher W.; Lane, Stephen M.; Huser, Thomas; Nordlander, Peter; Halas, Naomi J.

doi:10.1021/nl050928v

Cited by 1,089 publications

(950 citation statements)

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“…With these parameters, we find that a photonic band gap appears between frequencies 0.8225 and 0.9843 eV. Note that the lower edge of the band gap lies near ω x sp and the QD transition frequencies ω 12 and ω 13 . The vacuum decay rates for the QD are taken as 0 2 = 0 3 = 0.2 μeV, and in the presence of the photonic crystal it is found that 21 = 1.1370 μeV and 31 = 1.1127 μeV.…”

Section: Resultsmentioning

confidence: 77%

“…They arise due to the dielectric contrast between graphene and the surrounding dielectric medium. Plasmonics is widely studied due to applications in ultrasensitive optical biosensing, 13 photonic metamaterials, 14 light harvesting, 15 optical nanoantennas, 16 and quantum information processing. 17 Generally, noble metals are considered as the best available materials for the study of surface plasmon polaritons.…”

Section: Introductionmentioning

confidence: 99%

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Dipole-dipole interaction between a quantum dot and a graphene nanodisk

et al. 2012

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We study theoretically the dipole-dipole interaction and energy transfer in a hybrid system consisting of a quantum dot and graphene nanodisk embedded in a nonlinear photonic crystal. In our model, a probe laser field is applied to measure the energy transfer between the quantum dot and graphene nanodisk, while a control field manipulates the energy transfer process. These fields create excitons in the quantum dot and surface plasmon polaritons in the graphene nanodisk which interact via the dipole-dipole interaction. Here, the nonlinear photonic crystal acts as a tunable photonic reservoir for the quantum dot, and is used to control the energy transfer. We have found that the spectrum of power absorption in the quantum dot has two peaks due to the creation of two dressed excitons in the presence of the dipole-dipole interaction. The energy transfer rate spectrum of the graphene nanodisk also has two peaks due to the absorption of these two dressed excitons. Additionally, energy transfer between the quantum dot and the graphene nanodisk can be switched on and off by applying a pump laser to the photonic crystal or by adjusting the strength of the dipole-dipole interaction. We show that the intensity and frequencies of the peaks in the energy transfer rate spectra can be modified by changing the number of graphene monolayers in the nanodisk or the separation between the quantum dot and graphene. Our results agree with existing experiments on a qualitative basis. The principle of our system can be employed to fabricate nanobiosensors, optical nanoswitches, and energy transfer devices.

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Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Dipole-dipole interaction between a quantum dot and a graphene nanodisk

et al. 2012

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“…The electromagnetic (EM) enhancement near the metal surface, which is caused by the resonant excitation of surface plasmon [5], is the dominating reason for the surface-enhanced Raman scattering (SERS) [1,6]. Huge SERS with single molecule sensitivity can be obtained when molecules are located in the nano-gap between two metallic nano-structures [1,2,7,8,9]. A lot of efforts have been made to seek extreme sensitive SERS substrates [10,11,12].…”

mentioning

confidence: 99%

Effects of quantum tunneling in metal nanogap on surface-enhanced Raman scattering

Mao¹,

Li²,

Wu³

et al. 2009

Applied Physics Letters

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The quantum tunneling effects between two silver plates are studied using the time dependent density functional theory. Our results show that the tunneling depends mainly on the separation and the initial local field of the interstice between plates. The smaller separation and larger local field, the easier the electrons tunnels through the interstice. Our numerical calculation shows that when the separation is smaller than 0.6 nm the quantum tunneling dramatically reduces the enhancing ability of interstice between nanoparticles.PACS numbers: 33.20.Fb, 03.65.Xp, 78.67.Bf Metal nano-gaps offering strong surface plasmon couplings have very rich physical properties. The related studies have been very hot topics in the field of plamonics, e.g., single molecule surface-enhanced Raman spectroscopy [1,2], optical nano-antennas [3], high-harmonic generation [4]. The electromagnetic (EM) enhancement near the metal surface, which is caused by the resonant excitation of surface plasmon [5], is the dominating reason for the surface-enhanced Raman scattering (SERS) [1,6]. Huge SERS with single molecule sensitivity can be obtained when molecules are located in the nano-gap between two metallic nano-structures [1,2,7,8,9]. A lot of efforts have been made to seek extreme sensitive SERS substrates [10,11,12].Theoretically, people have used many methods based on the classical electrodynamics [13,14,15] to estimate the SERS enhancement. These classical results indicate that the smaller the nano-gap, the higher the enhancement. However, as the separation decreases to 1 nm, the displacive current would partly become electron tunneling current which can reduce the EM enhancement substantially [16]. A recent experiment on the four-wave mixing at coupled gold nanoparticles clearly demonstrated that the quantum tunneling (QT) effect becomes significant for the distance smaller than 0.2 nm [17], and a recent study of the plasmon resonance of a nanoparticle dimer gave quantum description of such a phenomenon [18]. It is well known that the EM enhancement is the main contribution to SERS. Its enhancement factor is proportional to the fourth power of the local field enhancement, i.e. M 4 , where M =|E loc |/|E 0 | with E loc and E 0 being the local enhanced electric field and the incident electric field, respectively. Therefore, even for small QT effects on M , after a fourth power, the influence to SERS could be huge. In this Letter we investigate the effects of QT on SERS with the time dependent density functional theory [19]. Our studies are able to quantify these effects and point out at exactly what conditions the QT has to be taken into account.As the "hot spot", where the SERS is strongest, is lo- * Electronic address: bwu@aphy.iphy.ac.cn † Electronic address: hxxu@aphy.iphy.ac.cn FIG. 1: Schematic drawing of the "hot spot" between two silver nano-spheres. As the "hot spot" (shaded area) is small, its local field is almost identical to the one computed by replacing the sphere with a plate. E0 is the incident laser field.calized i...

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“…Often, a further simplified formula is used (as in [30]) that expresses the Raman enhancement as the product of the local intensity enhancement factors at the excitation and Raman-shifted frequencies at the position of the Raman-emitting molecule. As we noted in the Introduction, proposed in [9], this formula is given by (1).…”

Section: Sers Enhancement Factor In Green's Function Theorymentioning

confidence: 99%