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Timur Skeini

Bio: Timur Skeini is an academic researcher from Ohio University. The author has contributed to research in topics: Surface plasmon resonance & Plasmon. The author has an hindex of 4, co-authored 7 publications receiving 1109 citations. Previous affiliations of Timur Skeini include National Institute of Standards and Technology.

Papers
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TL;DR: In this article, the peculiar conditions under which optically driven gold nanoparticles (NPs) can significantly increase temperature or even melt a surrounding matrix were described, and the heating and melting processes occurred under light illumination and involve the plasmon resonance.
Abstract: We describe the peculiar conditions under which optically driven gold nanoparticles (NPs) can significantly increase temperature or even melt a surrounding matrix. The heating and melting processes occur under light illumination and involve the plasmon resonance. For the matrix, we consider water, ice, and polymer. Melting and heating the matrix becomes possible if a nanoparticle size is large enough. Significant enhancement of the heating effect can appear in ensembles of NPs due to an increase of a volume of metal and electric-field amplification.

596 citations

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TL;DR: In this paper, the physical properties of excitons in hybrid complexes composed of semiconductor and metal nanoparticles are described as an enhancement or suppression of emission, and the interaction between individual nanoparticles is revealed as an enhancing or suppressing of emission.
Abstract: We describe the physical properties of excitons in hybrid complexes composed of semiconductor and metal nanoparticles. The interaction between individual nanoparticles is revealed as an enhancement or suppression of emission. Enhanced emission comes from electric field amplified by the plasmon resonance, whereas emission suppression is a result of energy transfer from semiconductor to metal nanoparticles. The emission intensity and energy transfer rate depend strongly on the geometrical parameters of the superstructure and the physical and material properties of the nanoparticles. In particular, the emission enhancement effect appears for nanoparticles with relatively small quantum yield, and silver nanoparticles have stronger enhancement compared to gold ones. Using realistic models, we review and analyze available experimental data on energy transfer between nanoparticles. In hybrid superstructures conjugated with polymer linkers, optical emission is sensitive to environmental parameters such as, for example, temperature. This sensitivity comes from expansion or contraction of a linker. With increasing temperature, emission of polymer-conjugated complexes can decrease or increase depending on the organization of a superstructure. The structures described here have potential as sensors and actuators.

479 citations

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TL;DR: Recently, metamaterials based on metallic composites have received special attention as these are expected to display negative values for permittivity and refractive index, which should lead to a multitude of unique optical effects.
Abstract: The hybrid assembly of inorganic and metallic nanomaterials by means of chemical and biological bonding to yield manifold optical and electromagnetic properties has received widespread attention. Currently available highly monodispersed nanomaterials such as semiconductors and noble metals that can be conjugated by ligand–receptor, antigen– antibody reactions, polymer tethering, and DNA hybridization are used as building blocks for 2D or 3D superstructures in which new collective properties of these artificial assemblies have been obtained. They represent a large class of newmaterials (i.e., metamaterials) in which the properties are determined not only by classical atomic composition, but also by nanoscale organization of structural components. Recently, metamaterials based on metallic composites have received special attention as these are expected to display negative values for permittivity and refractive index. This property should lead to a multitude of unique optical effects. Many of these effects are related to surface plasmons on Au or Ag nanoparticles (NPs), which generate exceptionally high localized electromagnetic fields, and have been exploited in surface-enhanced Raman spectroscopy and some optoelectronic devices. 22] Metamaterials from semiconductors and their combinations with metals can also produce optical effects that are useful for development of advanced sensing and imaging technologies. Recently, we

118 citations

Journal ArticleDOI
11 Jan 2018-ACS Nano
TL;DR: This work investigates how β-carotene and chlorophyll-a form mixed molecular phases on a Au(111) surface using low-temperature scanning tunneling microscopy and molecular manipulation at the single-molecule level supported by density functional theory calculations.
Abstract: Carotenoids and chlorophyll are essential parts of plant leaves and are involved in photosynthesis, a vital biological process responsible for the origin of life on Earth. Here, we investigate how β-carotene and chlorophyll-a form mixed molecular phases on a Au(111) surface using low-temperature scanning tunneling microscopy and molecular manipulation at the single-molecule level supported by density functional theory calculations. By isolating individual molecules from nanoscale molecular clusters with a scanning tunneling microscope tip, we are able to identify five β-carotene conformations including a structure exhibiting a three-dimensional conformation. Furthermore, molecular resolution images enable direct visualization of β-carotene/chlorophyll-a clsuters, with intimate structural details highlighting how they pair: β-carotene preferentially positions next to chlorophyll-a and induces switching of chlorophyll-a from straight to several bent tail conformations in the molecular clusters.

3 citations


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TL;DR: Plasmon-enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic-metal building blocks is focused on, and recently reported plasMon-mediated photocatallytic reactions on plAsmonic nanostructures of noble metals are discussed.
Abstract: Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we review recent progress in using plasmonic metallic nanostructures in the field of photocatalysis. We focus on plasmon-enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic-metal building blocks, and recently reported plasmon-mediated photocatalytic reactions on plasmonic nanostructures of noble metals. We also discuss the areas where major advancements are needed to move the field of plasmon-mediated photocatalysis forward.

4,074 citations

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TL;DR: The basic concepts behind plasmonics-enabled light concentration and manipulation are discussed, an attempt to capture the wide range of activities and excitement in this area is made, and possible future directions are speculated on.
Abstract: The unprecedented ability of nanometallic (that is, plasmonic) structures to concentrate light into deep-subwavelength volumes has propelled their use in a vast array of nanophotonics technologies and research endeavours. Plasmonic light concentrators can elegantly interface diffraction-limited dielectric optical components with nanophotonic structures. Passive and active plasmonic devices provide new pathways to generate, guide, modulate and detect light with structures that are similar in size to state-of-the-art electronic devices. With the ability to produce highly confined optical fields, the conventional rules for light-matter interactions need to be re-examined, and researchers are venturing into new regimes of optical physics. In this review we will discuss the basic concepts behind plasmonics-enabled light concentration and manipulation, make an attempt to capture the wide range of activities and excitement in this area, and speculate on possible future directions.

3,953 citations

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TL;DR: This work compares and evaluates the differences in physicochemical properties of common fluorescent labels, focusing on traditional organic dyes and QDs, to provide a better understanding of the advantages and limitations of both classes of chromophores.
Abstract: Suitable labels are at the core of Luminescence and fluorescence imaging and sensing. One of the most exciting, yet also controversial, advances in label technology is the emerging development of quantum dots (QDs)--inorganic nanocrystals with unique optical and chemical properties but complicated surface chemistry--as in vitro and in vivo fluorophores. Here we compare and evaluate the differences in physicochemical properties of common fluorescent labels, focusing on traditional organic dyes and QDs. Our aim is to provide a better understanding of the advantages and limitations of both classes of chromophores, to facilitate label choice and to address future challenges in the rational design and manipulation of QD labels.

3,399 citations

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TL;DR: This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials, and highlights crucial issues that should be addressed in future research activities.
Abstract: Semiconductor photocatalysis has received much attention as a potential solution to the worldwide energy shortage and for counteracting environmental degradation. This article reviews state-of-the-art research activities in the field, focusing on the scientific and technological possibilities offered by photocatalytic materials. We begin with a survey of efforts to explore suitable materials and to optimize their energy band configurations for specific applications. We then examine the design and fabrication of advanced photocatalytic materials in the framework of nanotechnology. Many of the most recent advances in photocatalysis have been realized by selective control of the morphology of nanomaterials or by utilizing the collective properties of nano-assembly systems. Finally, we discuss the current theoretical understanding of key aspects of photocatalytic materials. This review also highlights crucial issues that should be addressed in future research activities.

3,265 citations

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TL;DR: An overview of the key aspects of graphene and related materials, ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries are provided.
Abstract: We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

2,560 citations