Ultraviolet Nanoplasmonics: A Demonstration of Surface-Enhanced Raman Spectroscopy, Fluorescence, and Photodegradation Using Gallium Nanoparticles

Yang, Yang; Callahan, John M.; Kim, Tong-Ho; Brown, April S.; Everitt, Henry O.

doi:10.1021/nl401145j

Cited by 127 publications

(123 citation statements)

References 54 publications

(87 reference statements)

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“…Further confirmation of this comes from recently reported measurements of UV surface-enhanced Raman spectra of the analyte crystal violet deposited on all three samples. 31 In that study, the strongest Raman enhancement occurred for a laser energy (3.815 eV = 325 nm) that nearly coincides with the energy of the depolarizing feature in the bimodal sample S3. This suggests that NP ensembles containing strongly coupled asymmetric NP dimers or n-mers produce strong local field enhancements when their depolarizing behavior coincides with the laser energy and θ i is small.…”

Section: ■ Depolarizing Behavior Of Nanoparticles With a Bimodal Sizementioning

confidence: 71%

“…56 Considering that these behaviors occur precisely where UV surface-enhanced Raman spectra indicated strong local field enhancements, 31 we conclude that VAMM analyses may be used to characterize heterogeneous arrays of metal NPs to ascertain the spectral regions and optical geometries that produce the strongest local field enhancements.…”

Section: Acs Photonicsmentioning

confidence: 81%

“…First, unlike gold and silver, gallium has plasmonic activity in the ultraviolet: the plasma energy and damping constant are 14.0 and 1.54 eV, respectively. 13,31,32,38 Because of growing interest in UV plasmonics, investigations of Ga NPs are particularly timely. 31,39−41 Second, during room-temperature deposition gallium forms hemispherical droplets.…”

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confidence: 99%

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Ultraviolet–Visible Plasmonic Properties of Gallium Nanoparticles Investigated by Variable-Angle Spectroscopic and Mueller Matrix Ellipsometry

et al. 2014

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Self-assembled, irregular ensembles of hemispherical Ga nanoparticles (NPs) were deposited on sapphire by molecular beam epitaxy. These samples, whose constituent unimodal or bimodal distribution of NP sizes was controlled by deposition time, exhibited localized surface plasmon resonances tunable from the ultraviolet to the visible (UV/ vis) spectral range. The optical response of each sample was characterized using a variable-angle spectroscopic ellipsometer, and the dielectric response of the ensemble of NPs on each sample was parametrized using Lorentz oscillators. From this, a relationship was found between NP size and the deduced Lorentzian parameters (resonant frequency, damping, oscillator strength) for most unimodal and bimodal samples at most frequencies and angles of incidence. However, for samples with a bimodal size distribution, Mueller matrix ellipsometry revealed nonspecular scattering at particular frequencies and angles, suggesting a resonant interparticle coupling effect consistent with recently observed strong local field enhancements in the ultraviolet. KEYWORDS: plasmonics, ultraviolet, gallium, nanoparticles, variable-angle spectroscopic ellipsometry, variable-angle Mueller matrix ellipsometry R esearch into the optical response of confined electronic plasma oscillations in metallic nanostructures has become the foundation of modern plasmonics. Metallic nanostructures are routinely fabricated with desired spatial geometries for specific applications including single-molecule detection, enhanced fluorescence, toxic remediation, and catalysis. 1−6 Because the optical response depends sensitively on nanostructure composition, size, and shape, increasingly sophisticated characterization tools are required: aggregate behavior may be characterized by absorption spectroscopy or dark-field microscopy, while single-particle behavior may be characterized by confocal microscopy, near-field scanning optical microscopy, and cathodoluminescence. 7−12 These tools provide incredibly detailed understanding of the absorption and scattering properties of plasmonic metal nanoparticles, especially when complemented by sophisticated electromagnetic modeling techniques such as finite difference time domain, finite element codes, and the discrete dipole approximation. 13−19 Of growing interest is the need to monitor the plasmonic properties of substrate-supported nanoparticle (NP) ensembles during fabrication. Because it is impractical to use single-particle imaging tools for this application, advances in the more traditional tools are needed to understand single-particle behaviors from aggregate measurements. Spectroscopic ellipsometry (SE) has been used to monitor how NP ensembles alter the polarization state of an incident light beam as a function of wavelength and incidence angle. 20−24 Recently, a fixed incidence angle spectroscopic ellipsometer mounted on a molecular beam epitaxy (MBE) chamber has been used to monitor in real time the deposition of nanometer-scale metallic films and NPs through...

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Section: ■ Depolarizing Behavior Of Nanoparticles With a Bimodal Sizementioning

confidence: 71%

Section: Acs Photonicsmentioning

confidence: 81%

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Ultraviolet–Visible Plasmonic Properties of Gallium Nanoparticles Investigated by Variable-Angle Spectroscopic and Mueller Matrix Ellipsometry

et al. 2014

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“…This image also shows the large central Ga NP surrounded by a halo of smaller NPs, a typical feature of Ga NP arrays grown by MBE that is clearly visualized in a normal-incidence SEM image of the sample ( Figure 1C). 15 From this image, we extract a size distribution by fitting each particle with a circle using a generalized Hough transform ( Figure 1C, inset). The resulting size distribution (N = 387) shows a welldefined peak, and fitting the primary distribution with a Gaussian curve yields a mean diameter of 72 ( 15 nm.…”

Section: Resultsmentioning

confidence: 99%

“…62 This effect offers the potential for selfmonitoring of environmental remediation efforts by simultaneous SERS and fluorescence spectroscopies. 15 …”

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confidence: 99%

Gallium Plasmonics: Deep Subwavelength Spectroscopic Imaging of Single and Interacting Gallium Nanoparticles

et al. 2015

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Gallium has recently been demonstrated as a phasechange plasmonic material offering UV tunability, facile synthesis, and a remarkable stability due to its thin, self-terminating native oxide. However, the dense irregular nanoparticle (NP) ensembles fabricated by molecular-beam epitaxy make optical measurements of individual particles challenging. Here we employ hyperspectral cathodoluminescence (CL) microscopy to characterize the response of single Ga NPs of various sizes within an irregular ensemble by spatially and spectrally resolving both in-plane and out-of-plane plasmonic modes. These modes, which include hybridized dipolar and higher-order terms due to phase retardation and substrate interactions, are correlated with finite difference time domain (FDTD) electrodynamics calculations that consider the Ga NP contact angle, substrate, and native Ga/Si surface oxidation. This study experimentally confirms previous theoretical predictions of plasmonic size-tunability in single Ga NPs and demonstrates that the plasmonic modes of interacting Ga nanoparticles can hybridize to produce strong hot spots in the ultraviolet. The controlled, robust UV plasmonic resonances of gallium nanoparticles are applicable to energy-and phase-specific applications such as optical memory, environmental remediation, and simultaneous fluorescence and surface-enhanced Raman spectroscopies.

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Metal‐Enhanced Fluorescence and Its Applications

Sugawa¹

2018

Encyclopedia of Analytical Chemistry

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The fluorescence‐enhancement phenomenon of fluorophores positioned near metal nanostructures (metal‐enhanced fluorescence, MEF) is the result of the interaction between the fluorophores and the localized surface plasmon resonance (LSPR) of the nanostructures. This enhancement phenomenon can contribute to the development of novel sensors based on unprecedented mechanisms, as well as improving the sensitivity of existing biosensors and imaging techniques. In this article, the two main mechanisms for MEF are briefly explained: the light‐harvesting nanoantenna effect and the increase in the radiative decay rate. This is followed by an introduction to metal nanostructures and nanoparticles (substrate‐based platforms and solution‐dispersed colloidal nanoparticle‐based platforms), which can act as MEF platforms. In addition, the efficient suppression of fluorescence blinking and photobleaching induced by the interaction with LSPR are described, as these are secondary advantages for fluorescence‐based sensors. Subsequently, the generation of hot spots, which could be one of the key phenomena for significant fluorescence enhancement, is outlined. An examination of usability of MEF platforms consisting of Al and Cu (metal species other than Au and Ag) to further improve their applicability is also discussed. Finally, some recent applications such as the development of imaging techniques, nanoprobes, and biosensors utilizing the MEF phenomenon are briefly introduced.

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Ultraviolet Nanoplasmonics: A Demonstration of Surface-Enhanced Raman Spectroscopy, Fluorescence, and Photodegradation Using Gallium Nanoparticles

Cited by 127 publications

References 54 publications

Ultraviolet–Visible Plasmonic Properties of Gallium Nanoparticles Investigated by Variable-Angle Spectroscopic and Mueller Matrix Ellipsometry

Ultraviolet–Visible Plasmonic Properties of Gallium Nanoparticles Investigated by Variable-Angle Spectroscopic and Mueller Matrix Ellipsometry

Gallium Plasmonics: Deep Subwavelength Spectroscopic Imaging of Single and Interacting Gallium Nanoparticles

Metal‐Enhanced Fluorescence and Its Applications

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