The spectra of light reflection by plasmonic metal films deposited in vacuum on dielectric substrates and subsequently annealed at high temperatures are investigated. To explain the optical properties of plasmonic films, a theoretical model of a flat-layered metal-dielectric medium is used. One of the layers of such a structure has the dielectric constant of the metal under study, and the second layer has the dielectric constant calculated within the Maxwell-Garnett approximation for a heterogeneous medium consisting of a suspension of metallic nanoellipsoids in air. The introduction of this layer makes it possible to qualitatively take into account the inhomogeneities of the plasmonic film surface. It is shown that the developed model makes it possible to explain a number of features in the experimental reflection spectra

The spectra of light reflection by plasmonic metal films deposited in vacuum on dielectric substrates and subsequently annealed at high temperatures are investigated. To explain the optical properties of plasmonic films, a theoretical model of a plane-layered metal-dielectric medium is used. One of the layers of such a structure has the dielectric constant of the metal under study, and the second layer has the dielectric constant calculated within the Maxwell-Garnett approximation for a heterogeneous medium consisting of a suspension of metallic nanoellipsoids in air. The introduction of this layer makes it possible to qualitatively take into account the inhomogeneities of the plasmon film surface. It is shown that the developed model allows a number of features in the experimental reflection spectra to be explained.

Effective enhancement of the fluorescence signal of chromophores adsorbed directly onto plasmonic films can be observed under conditions of strong spectral resonance between plasmon and chromophore absorptions. This effect seems to contradict the established mechanisms of complete quenching of the fluorescence of chromophores under their adsorbtion directly onto the metal surface. However, under certain conditions, enhancement of the fluorescence signal is observed for both inorganic and organic chromophores. To understand the effect and conditions of its observation, we propose to use the quantum concept of virtual photon exchange in the near optical field - dressed photons. This concept is borrowed from the physics of elementary particles and is already well adapted to the problems of nanophotonics by M. Otsu. In this paper, we discuss exclusively the key factors responsible for enhancement of fluorescence of CdSe/ZnS nanocrystals and the effective dressed photons exchange: the size of nanoparticles, the distance between them, and the presence of spectral overlap indicating the possibility of resonant interactions between plasmons and chromophores.

Photo-induced change of the electrical properties of diarylethenes in nanocomposites/ G.T. Vasilyuk [ и др.] // Book of abstracts : the 4th International symposium 'Molecular photonics' dedicated to academician A.N. Terenin, Peterhof, St. Petersburg, July 21-24, 2016.- Санкт-Петербург : [Б. и.], 2016 .- С.73 Статья

Разделение вкладов КР и люминесценции в спектрах хромофоров в ближнем поле у поверхности с плазмонными свойствами Н. Д. Стрекаль 1 , В. Ф

Методами спектрофотометрии, спектроскопии гигантского комбинационного рассеяния (ГКР) света и квантовой химии изучены структура и фотохромные превращения композитных металлоорганических наноструктурированных систем, состоящих из наночастиц

The structure and photochromic transformations of composite organometallic nanosystems composed of Ag nanoparticles covered with a layer of indoline-spiropyran (ISP) molecules from solutions were studied by spectrophotometry, surface Raman scattering spectroscopy (SERS) and quantum chemistry. Analysis of experimental data showed that studied nanostructured systems have photochromic properties, manifested in the reversible photo-induced changes both of the electronic-absorption spectra and of the relative intensity of the SERS bands. The open form of ISP, formed in the organometallic nanostructured film as a result of photochromic transformations, has an adsorption geometry, and, possibly, a conformation different from that formed as a result of chemisorption of ISP molecules on silver colloids.

Methods of fabrication of solid-phase composite Ag- and Au-containing nanostructured systems with a shell of photochromic diarylethenes molecules (DAE) have been developed. The samples of nanocomposite systems were obtained. These nanocomposites exhibit photochromic properties similar to the properties of DAE in solution and solid-phase layers not containing metal nanoparticles. A chemical interaction between nanoparticles and sulfur-containing derivatives of DAE in solid-phase nanocomposites was detected.

The structure and photochromic transformations of nanostructured organometallic composites consisting of Ag nanoparticles with shells of photochromic diarylethenes (DAEs) deposited from various solutions onto the nanoparticles were studied using infrared absorption and surface enhanced Raman scattering (SERS) vibrational spectroscopy and quantum chemistry. The studied nanostructures exhibited photochromic properties manifested as reversible photoinduced changes of the relative intensities of SERS bands related to vibrations of bonds participating in the reversible photoisomerization. Spectral manifestations of chemical interaction between metal nanoparticles and DAE molecules were detected.

Methods for fabricating solid-state Ag- and Au-containing nanostructured composites with shells of photochromic diarylethenes (DAEs) were developed. The obtained nanocomposites exhibited photochromic properties similar to photochromic transformations of DAEs in solutions and solid-state layers without metal nanoparticles. Chemical interaction between the nanoparticles and S-containing DAE derivatives were detected in the solid-state nanocomposites.

Absorption and Raman spectra of the tetra(4-sulfonatophenyl)porphyrin (TSPP) zwitterion in aqueous solutions under conditions at which porphyrin nanotubes (PNT) form (pH 1) are presented. TSPP was immobilized on the surface of plasmonic silver films (PSF) via quick transfer of a suspension of the molecules into a solution at pH 5 and onto the film surface in order to avoid degrading the film. Images of PNT and spheroidal TSPP aggregates on the PSF surface were visualized using confocal microscopy. Spatially resolved surface-enhanced Raman spectra (SERS) of these objects were recorded. Differences in SERS of PNT and TSPP globular aggregates are discussed based on quantum-chemical calculations of TSPP vibrational spectra. Vibrational bands sensitive to the tube–spherulite transition are found.

Physics, Chemistry and Applications of Nanostructures, pp. 73-76 (2015) No AccessGIANT DIPOLE RESONANCE AS A POSSIBLE MECHANISM OF PLASMOPHORE FORMATIONN. STREKAL, V. ASKIRKA, I. MOTEVICH, I. SVEKLO, and S. MASKEVICHN. STREKALYanka Kupala State University, Ozheshko Str. 22, 230023 Grodno, Belarus, V. ASKIRKAYanka Kupala State University, Ozheshko Str. 22, 230023 Grodno, Belarus, I. MOTEVICHYanka Kupala State University, Ozheshko Str. 22, 230023 Grodno, Belarus, I. SVEKLOYanka Kupala State University, Ozheshko Str. 22, 230023 Grodno, Belarus, and S. MASKEVICHYanka Kupala State University, Ozheshko Str. 22, 230023 Grodno, Belarushttps://doi.org/10.1142/9789814696524_0018Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: It is well known fact that either fluorescence enhancement or fluorescence quenching for the molecules near the surface of plasmonic substrate may be achieved by the varying the distance between the molecule and the substrate. We show the first experimental measurement demonstrating the transition from fluorescence enhancement to fluorescence quenching due to spectral detuning in the core/shell CdSe/ZnS nanocrystalls (NCs) deposited directly on the surface of plasmonic gold film (PGF). Strong resonant fluorescence enhancement needs to minimize the spectral shift between the position of localized surface plasmon (LSP) band maximum and first ecxitonic peak in NCs absorbtion spectrum. FiguresReferencesRelatedDetails Physics, Chemistry and Applications of NanostructuresMetrics History PDF download

Plasmon films of noble metals (gold PGF and silver PSF) evaporated onto quartz in vacuum shows possibility of selective exciting of fluorescence or SERS of molecules. We discovered plasmon-assisted fluorescence from PGF versus surface enhanced fluorescence from PSF.

Plasmonic gold films (PGF) prepared by vacuum deposition of gold onto quartz slides possess unique property to enhance electromagnetic signal in the near field. Spectral tuning of PGF’s plasmon band to resonance with the electronic spectra of adsorbed molecules provides selective enhancement of fluorescence or surface-enhanced Raman scattering in the far field. Plasmon-enhanced fluorescence (PEF) of mitoxantrone (mitox) as a function of the distance between gold surface and adsorbed molecules for different polarization and incidence angle of exciting light is analyzed in this work. Spectrophotometric data reveal that probability of localized plasmon excitation in gold grains increases with growth of incidence angle for s-polarized and decrease for p-polarized excitation. This fact correlates well with oblate shape of gold particles detected by Atomic force microscope. However, the fluorescence intensity of dyes deposited at fixed distance from gold surface increase with angle of incidence of p-polarized light more noticeably than for s-polarized one. Nevertheless, the behavior of mitox PEF signal upon p-polarized laser excitation and different angle of incidence are similar in appearance to such phenomenon as selective photoelectric effect. According to this observation, the near-field interactions between plasmons and molecule as possible mechanism of PEF is discussed.

The properties of the antitumoral preparation mitoxantrone in aqueous and water-dioxane solutions have been investigated by steady-state and time-resolved fluorescence. Two fluorescing forms of the molecule have been revealed.