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Localized surface plasmon polaritons can confine the optical field to a single-nanometer-scale area, strongly enhancing the interaction between photons and molecules. Theoretically, the ultimate enhancement might be achieved by reducing the "photon size" to the molecular extinction cross-section. In addition, desired control of electronic transitions in molecules can be realized if the "photon shape" can be manipulated on a single-nanometer scale. By matching the photon shape with that of the molecular electron wavefunction, optically forbidden transitions can be induced efficiently and selectively, enabling various unconventional photoreactions. Here, we demonstrate the possibility of forming single-nanometer-scale, highly intense fields of optical vortices using designed plasmonic nanostructures. The orbital and spin angular momenta provided by a Laguerre–Gaussian beam are selectively transferred to the localized plasmons of a metal multimer structure and then confined into a nanogap. This plasmonic nano-vortex field is expected to fit the molecular electron orbital shape and spin with the corresponding angular momenta. [ABSTRACT FROM AUTHOR]

Localized surface plasmon resonance (LSPR) has been shown to exhibit a strong potential for nanoscale electromagnetic field manipulation beyond the diffraction limit. Particularly dark mode plasmons circumvent radiation loss and store the energy long in time, which raise the prospect of interesting plasmonics applications, for example biochemical sensing and nanoscale lasing. Here we theoretically investigate a method of exciting multipole plasmons, including dark modes, using normally incident light. By performing numerical calculations, we show that multipole plasmons in metal nanodisks can be selectively excited by circularly-polarized optical vortex beams. We study the electromagnetic fields of the beam cross-sections and their correspondence with the excited multipole plasmon modes with respect to spin and orbital angular momenta. The transfer of angular momentum between photons and plasmons is also discussed. [ABSTRACT FROM AUTHOR]

Abstract: To clarify the influence of trap states on the emission dynamics of CdSe/ZnS colloidal quantum dots on metal and glass substrates, we measured the trap state lifetimes of single QDs on different substrates using the photon inter-detection time analysis method. The results indicate that the trap state lifetimes as well as the emission counting rates changed depending on the substrate. Although the reduction in the counting rate can only be understood by the fast energy transfer to the metal substrate, the changes in the trap state lifetime suggest the influence of the substrate on the trap state. Thus, we concluded that the blinking suppression on metal substrate is caused not only by the fast energy transfer, but also by the shortening of recovering time from the trap state. [Copyright &y& Elsevier]

The article discusses the result of a study concerning nanoparticle plasmon-assisted two-photon polymerization induced by incoherent excitation source. It was demonstrated that two-photon absorption can be induced under exposure to a continuous-wave, incoherent radiation course and that the two-photon absorption theory proposed in 1931 can be verified without a coherent light source.