Electromagnetic interactions of molecules with metal surfaces

Ford, G. W.; Weber, W. H.

doi:10.1016/0370-1573(84)90098-x

Cited by 894 publications

(698 citation statements)

References 109 publications

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“…However, for QDs strongly coupled to plasmonic modes, temperature-independent nonradiative decay processes (nonplasmonic quenching due to the metal) should be taken into account. This is the case of emitters at close proximity to the metal surface, typically at distances below 5 nm (27,28). In this work, however, QDs are separated by ∼10 nm from the silver film, which should be enough to minimize metallic quenching while ensuring strong interaction with nanofocused plasmonic modes.…”

Section: Resultsmentioning

confidence: 94%

“…As a consequence, owing to the wide spectral range of the plasmonic resonance, both geometrical and spectral matchings are naturally realized between intense plasmonic fields and individual QDs over the entire wafer. The thickness of the GaN capping layer, serving as a spacer between the InGaN QDs and the silver film, was about 10 nm to ensure strong coupling to plasmonic nanofocused modes while minimizing metallic (nonplasmonic) quenching (i.e., nonplasmonic excitations in the metal such as interband absorption, electron scattering losses, and electron-hole excitations) (27,28).…”

Section: Significancementioning

confidence: 99%

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Self-aligned deterministic coupling of single quantum emitter to nanofocused plasmonic modes

Gong

Kim

et al. 2015

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

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The quantum plasmonics field has emerged and been growing increasingly, including study of single emitter-light coupling using plasmonic system and scalable quantum plasmonic circuit. This offers opportunity for the quantum control of light with compact device footprint. However, coupling of a single emitter to highly localized plasmonic mode with nanoscale precision remains an important challenge. Today, the spatial overlap between metallic structure and single emitter mostly relies either on chance or on advanced nanopositioning control. Here, we demonstrate deterministic coupling between three-dimensionally nanofocused plasmonic modes and single quantum dots (QDs) without any positioning for single QDs. By depositing a thin silver layer on a site-controlled pyramid QD wafer, three-dimensional plasmonic nanofocusing on each QD at the pyramid apex is geometrically achieved through the silver-coated pyramid facets. Enhancement of the QD spontaneous emission rate as high as 22 ± 16 is measured for all processed QDs emitting over ∼150-meV spectral range. This approach could apply to high fabrication yield onchip devices for wide application fields, e.g., high-efficiency light-emitting devices and quantum information processing.exciton-photon coupling | plasmonic nanofocusing | deterministic coupling | single-quantum emitter | Purcell effect S olid-state quantum photon sources based on semiconductor quantum dots (QDs) are a promising platform to realize scalable quantum technology (1-7). However, owing to the extremely small size of QDs (a few tens of nanometers) compared with the wavelength of light (a few hundreds of nanometers), the QD interaction with the photon field is very poor. This poor interaction results in rather low intrinsic spontaneous emission (SE) rates (8, 9), limiting the optical properties of single QDs: low repetition rate, higher sensitivity to thermally activated nonradiative processes and to dephasing from solid-state environment, etc. To overcome these limitations, there have been extensive efforts during the past decade to achieve deterministic coupling of a QD to intense photonic modes for strong Purcell effect (10-13), which demands spectral and spatial overlap between them. Due to the uncertainty of the size and position of the QD, it is still quite challenging and requires sophisticated control techniques, such as scanning probe microscopy and nanoscale positioning system (12,14,15). Therefore, demonstration of deterministic coupling is limited to few devices because the process has to be customized for each QD on the wafer.Nanofocusing of surface plasmon polaritons, beyond the light diffraction limit, has recently seen rapid development. This nanofocusing can be achieved using various tapered metallic structures, such as a sharp metal edge, V-shaped wedges, and tapered waveguides (16-21). Tapering a metallic structure in all three dimensions, instead of only two, is considered ideal for ultimate light focusing (20, 21). The resulting extremely small mode volume can permit strong coupl...

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Section: Resultsmentioning

confidence: 94%

Section: Significancementioning

confidence: 99%

Self-aligned deterministic coupling of single quantum emitter to nanofocused plasmonic modes

Gong

Kim

et al. 2015

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

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“…[5][6][7] The second reason for using thicker protection layer is to avoid the well-known quenching effect of aluminum. 15,20,21 Because of earlier reports of quenching on aluminum surfaces, we first examined the freespace emission of spin-coated samples on quartz and an aluminum-coated quartz (Figure 2). Emission spectra were recorded for illumination and observation from the same side of the sample.…”

Section: Resultsmentioning

confidence: 99%

Ultraviolet Surface Plasmon-Coupled Emission Using Thin Aluminum Films

et al. 2004

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Surface plasmon-coupled emission (SPCE) is the directional radiation of light into a substrate due to excited fluorophores above a thin metal film. To date, SPCE has only been observed with visible wavelengths using silver or gold films. We now show that SPCE can be observed in the ultraviolet region of the spectrum using thin (20 nm) aluminum films. We observed directional emission in a quartz substrate from the DNA base analogue 2-aminopurine (2-AP). The SPCE radiation occurs within a narrow angle at 59° from the normal to the hemicylindrical prism. The excitation conditions precluded the creation of surface plasmons by the incident light. The directional emission at 59° is almost completely p-polarized, consistent with its origin from surface plasmons due to coupling of excited 2-AP with the aluminum. The emission spectra and lifetimes of the SPCE are those characteristic of 2-AP. Different emission wavelengths radiate at slightly different angles on the prism providing intrinsic spectral resolution from the aluminum film. These results indicate that SPCE can be used with numerous UV-absorbing fluorophores, suggesting biochemical applications with simultaneous surface plasmon resonance and SPCE binding assays.Surface plasmon resonance (SPR) is widely used for detection of bioaffinity reactions on surfaces. [1][2][3] Surface plasmons are oscillating electrical charges on a metallic surface. When a thin metal film is illuminated through a glass prism, and the angle of incidence is appropriate, the surface plasmons in resonance with the incident light occur at the metal-air or water interface. This results in strong absorption, which is measured as a decrease of reflectivity. The SPR angle is sensitive to the refractive index of the sample above the metal, distal from the glass prism. The origin of this sensitivity is the evanescent field from the plasmons, which penetrates approximately λ/3 into the sample.In several recent reports we described a related phenomenon, surface plasmon-coupled emission (SPCE). 4,5 We found that excited fluorophores near a thin metal surface can couple with the surface plasmons, resulting in directional radiation into the glass substrate. The spectral properties of the radiation were found to be essentially identical to those of the fluorophore, except for a highly p-polarized emission, too large to be due to optical photoselection. The angular dependence of the radiation, as well as the p-polarization, are consistent with radiating surface plasmons, the reverse process of surface plasmon absorption.Our previous studies of SPCE used thin silver 5-7 or gold 8 surfaces. This choice of metals restricts the selection of fluorophores to those absorbing and emitting at visible or longer wavelengths. However, many widely used fluorophores absorb or emit at ultraviolet wavelengths. We now report that SPCE at UV wavelengths can be observed using thin *To whom correspondence should be addressed: lakowicz@cfs.umbi.umd.edu. NIH Public Access MATERIALS AND METHODS Sample PreparationQuar...

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“…The measured emission rates and a simple emission model show that the β-factor of the plasmonic mode is as high as 80% for a gap width of 5 nm (see Supplementary Information). For gap widths below 5 nm, the exciton recombination is too close to the metal surface, causing rapid non-radiative quenching [29]. While nanowires placed in direct contact with the metal surface show the highest spontaneous emission rates, these devices exhibit weak luminescence and do not lase.…”

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confidence: 99%