In situ Optical Study of Gold Nanorod Coupling with Graphene

Abstract

been demonstrated to create photodetectors, photovoltaic devices, and plasmonenhanced infrared spectroscopy. [10][11][12] To optimize the performance of hybrids system, a central question is to understand the electron or energy transfer between 2D material and metallic nanostructures. [13][14][15] Optical method is a versatile way to characterize the time scales for this process. In general, the transfer process is an additional decay channel for surface plasmon resonance of the gold nanoparticles. That would lead to a broadened linewidth and decreased amplitude of localized surface plasmon (LSP) resonances. [16] However, most early optical investigations of the hybrid structures rely on the ensemble measurements. [17,18] The hybrids have been proposed for SERS substrate to increase signal-to-noise ratio [19][20][21][22][23][24] since it can suppress continuum background (i.e., photoluminescence (PL) from the gold nanostructures). [25,26] The decreased background is attributed to the electron or energy transferring from gold to graphene [27,28] but ensemble measurement method cannot quantify the time scale of the transfer because of size and shape inhomogeneity of nanoparticles. [17] By contrast, single particle method enables measurement of homogeneous plasmon linewidth to determinate the transfer time scale. [16] Recently, Hoggard et al. employed single particle spectroscopy to investigate the interaction between gold nanorods (GNRs) and monolayer graphene. They statistically analyzed and compared the scattering spectra of hundreds of individual GNRs on quartz or on graphene substrates. [29] A time scale of ≈160 fs and a transfer efficiency of ≈10% were obtained. However, they did not observe intensity suppression of the scattering and PL spectra with comparison to previous ensemble measurements. That should be explained as the scattering intensity of individual nanoparticles vary more dramatically rather than the linewidth varying despite minor differences in the size. [30] At single particle level, this property hinders the statistical analysis method to determinate the changes of scattering and PL intensity. So far, previous reports about the scattering and PL of the hybrids were not always consistent each other. [17,29] This controversy is due to the limitation of measurement methods.In this study, we proposed to perform in situ single particle measurements to circumvent previous experimental limitation. We combined atomic force microscope (AFM) nanomanipulation technique with single particle spectroscopy method. [31,32] We directly measured and compared the scattering and PL spectra of Electron or energy transfer process is critical to understand the interaction between graphene and metal nanostructures. Combining atomic force microscope nanomanipulation with single-particle spectroscopy enables in situ investigation of the interaction between single gold nanorod and monolayer graphene. This paper reveals that scattering and photoluminescence intensity of the nanorod decreased after coupling with monolayer...

Plasmon–Exciton Coupling Effect on Plasmon Damping

“…The GNR–graphene hybrid results in the decrease of scattering intensity and the FWHM broadening of the GNR, as shown in Figure 3c. [ 15 ] These results confirm the aforementioned conclusion that the plasmon–exciton coupling would induce the plasmon damping. Generally, the hybrid system couples with the external electromagnetic field mainly through plasmon resonances.…”

“…The numerical results can explain the spectral shift and split due to the classic electromagnetic interaction. [ 15,22 ] But the variations of scattering intensity by the FDTD simulation are inconsistent with the experimental results. The dielectric interaction between the GNRs and 2D materials is limited to explain the interfacial interaction effect.…”

“…The dielectric interaction between the GNRs and 2D materials is limited to explain the interfacial interaction effect. [15] Furthermore, a bulk material effect on the plasmon damping has been demonstrated by comparison the linewidth of Ag clusters in SiO 2 and Al 2 O 3 . [23] Here, we find that the first contact layer between the GNR and 2D materials is critical for the interfacial interaction effect.…”

Ultrasensitive and Recyclable Upconversion‐Fluorescence Fibrous Indicator Paper with Plasmonic Nanostructures for Single Droplet Detection

“…Figure 1a is a picture of Au@SiO 2 nanorods dispersed in N,Ndimethylformamide (DMF) that shows five distinct colors and uniform dispersions. [25,26] In addition, X-ray diffraction (XRD) was also measured ( Figure S2, Supporting Information), and it confirms that the composite nanofibers consist of PS, Au@SiO 2 and upconversion nanorods. Figure 1b displays scanning electronic microscopy (SEM) images of as-prepared NaYF 4 :Yb 3+ ,Er 3+ upconversion nanorods whose diameter is ≈50 nm and length is ≈200 nm.…”

Controlling plasmon-exciton interactions through photothermal reshaping

“…To investigate the plasmon-exciton interaction, the GNR-MoS 2 hybrids were assembled by using the AFM nanomanipulation technique 46 . We moved the GNRs from the glass surface onto the monolayer MoS 2 flake.…”