Quantitative Absorption Spectroscopy of a Single Gold Nanorod

Muskens, Otto L.; Bachelier, Guillaume; Fatti, Natalia Del; Vallée, Fabrice; Brioude, Arnaud; Jiang, Xuchuan; Pileni, Marie‐Paule

doi:10.1021/jp8012865

Cited by 153 publications

(259 citation statements)

References 37 publications

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“…This result is in agreement with previous single NR scattering (9) and extinction measurements (32). The solid lines in Fig.…”

Section: Resultssupporting

confidence: 93%

“…One of the best studied metallic nanoparticles with an anisotropic shape are Au NRs that have longitudinal and transverse SP modes polarized parallel to the long and short axes of the NRs, respectively (27). Several single-particle techniques such as dark-field imaging (28,29), confocal microscopy (30), spatial modulation extinction spectroscopy (31,32), and two photon luminescence (5) have been used to measure the polarization anisotropy of the longitudinal SP oscillation in single Au NRs. The most widely used technique among these methods is dark-field microscopy, which is based on SP scattering (8,9,28,29,33).…”

mentioning

confidence: 99%

“…Recently developed methods employing intensity or spatial modulation coupled with high sensitivity lock-in detection have indeed been able to visualize individual nanoparticles based on their absorption (6,7,24,(34)(35)(36)(37) or total extinction (31,32), respectively. In particular, absorption-based photothermal imaging, which detects the heat generated through fast nonradiative decay after photoexcitation (38), is capable of detecting metallic nanoparticles with diameters as small as 2 nm (34).…”

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confidence: 99%

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Plasmonic nanorod absorbers as orientation sensors

Chang¹,

Ha²,

Slaughter³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

265

288

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Nanoparticles are actively exploited as biological imaging probes. Of particular interest are gold nanoparticles because of their nonblinking and nonbleaching absorption and scattering properties that arise from the excitation of surface plasmons. Nanoparticles with anisotropic shapes furthermore provide information about the probe orientation and its environment. Here we show how the orientation of single gold nanorods (25 × 73 nm) can be determined from both the transverse and longitudinal surface plasmon resonance by using polarization-sensitive photothermal imaging. By measuring the orientation of the same nanorods separately using scanning electron microscopy, we verified the high accuracy of this plasmon-absorption-based technique. However, care had to be taken when exciting the transverse plasmon absorption using a large numerical aperture objective as out-of-plane plasmon oscillations were also excited then. For the size regime studied here, being able to establish the nanorod orientation from the transverse mode is unique to photothermal imaging and almost impossible with conventional dark-field scattering spectroscopy. This is important because the transverse surface plasmon resonance is mostly insensitive to the medium refractive index and nanorod aspect ratio allowing nanorods of any length to be used as orientation sensors without changing the laser frequency.gold nanorod | surface plasmon | single-particle spectroscopy | photothermal imaging O ptical probes for biological imaging should yield large photon count rates with little background noise due to autofluorescence or scattering, have a high photostability and good biocompatibility, and cause only minimal interference (1-5). A high degree of polarization anisotropy is also desirable because it gives access to the orientation of the probe, and thereby provides important information about the conformation and dynamics of the biological system (1-3, 5). The surface plasmon (SP) absorption of individual metallic nanoparticles recorded by high-sensitivity photothermal imaging presents an excellent step toward the realization of optimized optical probes with the aforementioned properties (6, 7). Here we show that, by tuning the shape of gold nanoparticles and hence the anisotropy of the SP oscillation, the orientation of single gold nanorods (Au NRs) can be determined very accurately based on the SP absorption. We found excellent agreement for NR orientations determined using SEM compared to polarization-sensitive photothermal imaging of the longitudinal SP mode. Furthermore, our studies show that the transverse SP mode along the smaller NR dimension also yields accurate NR orientations if a low N.A. objective was used. This cannot be accomplished using conventional dark-field scattering spectroscopy (8, 9). In addition, because the transverse SP resonance is insensitive to the NR aspect ratio (10), the orientations of NRs with different lengths in environments with varying local refractive indices can be measured using only one laser frequency.Singl...

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“…This result is in agreement with previous single NR scattering (9) and extinction measurements (32). The solid lines in Fig.…”

Section: Resultssupporting

confidence: 93%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Plasmonic nanorod absorbers as orientation sensors

Chang¹,

Ha²,

Slaughter³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

265

288

View full text Add to dashboard Cite

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“…The scattering of >100 nm gold nanoparticles dominates their absorption, and such nanoparticles can be detected with high sensitivity using a dark-field configuration. 46,47 This is not the case for nanoparticles <55 nm in diameter, for which the scattering cross section drops dramatically and the absorption cross section starts to dominate. 46,48 However, the latter remains very weak for such small gold nanoparticles, which makes their detection quite challenging, so that only a few complicated techniques have been successfully demonstrated so far.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Multiscattering-Enhanced Absorption Spectroscopy

2015

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An original scheme for sensitive absorption measurements, particularly well-suited for low analyte concentrations, is presented. The technique is based on multiscattering-enhanced absorption spectroscopy (MEAS) and benefits from the advantages of conventional absorption spectroscopy: simplicity, rapidity, and low costs. The technique relies on extending the optical path through the sensing volume by suspending dielectric beads in the solution containing the analytes of interest, resulting in multiple scattering of light, which increases the optical path length through the sample. This way, a higher sensitivity and lower limit of detection, compared to those of conventional absorption spectroscopy, can be achieved. The approach is versatile and can be used for a broad variety of analytes. Here, it is applied to the detection of phenol red, 10 nm gold nanoparticles, and envy green fluorescence dye; the limit of detection is decreased by a factor of 7.2 for phenol red and a factor of 3.3 for nanoparticles and dye. The versatility of this approach is illustrated by its application in increasing the sensitivity of colorimetric detection with gold nanoparticle probes and a commercially available hydrogen peroxide bioassay. The influence of different parameters describing the scattering medium is investigated in detail experimentally and numerically, with very good agreement between the two. Those parameters can be effectively used to tailor the enhancement for specific applications and analytes.

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“…4 As an example, silver or gold nanorods support two plasmon modes, which can be easily tuned by adjusting their aspect ratio, i.e., the ratio between the minor and the major axes of NPs. 5,6 Thus, the control of NP shape is crucial for designing nanoscale devices with uniform properties. Common bottom up elaboration processes are known to produce NPs with a shape distribution which induces drastic changes in the optical properties of NP assembly.…”

mentioning

confidence: 99%