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Journal ArticleDOI

Synergistic switching of plasmonic resonances and molecular spin states

TL;DR: Results show that molecular spin state switching can be very efficiently triggered by the photo-thermal effect, which - in turn - allows for an active tuning of the plasmon resonance.
Abstract: Plasmonic resonance properties of a series of lithographically patterned gold nanorod arrays, spin coated by thin films of an iron(II)–triazole type spin crossover complex, were investigated upon heating/cooling and also under 633 nm laser irradiation. In both cases a reversible shift of the localised surface plasmon resonance wavelength was observed and quantitatively linked to the refractive index change accompanying the spin transition. These results show that molecular spin state switching can be very efficiently triggered by the photo-thermal effect, which – in turn – allows for an active tuning of the plasmon resonance.
Citations
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Journal ArticleDOI
TL;DR: In this progress report, a brief overview on the current state-of-the-art of experimental and theoretical studies of nanomaterials displaying spin transition is presented, and detailed analysis and discussions in terms of finite size effects and other phenomena inherent to the reduced size scale are provided.
Abstract: Nanoscale spin crossover materials capable of undergoing reversible switching between two electronic configurations with markedly different physical properties are excellent candidates for various technological applications. In particular, they can serve as active materials for storing and processing information in photonic, mechanical, electronic, and spintronic devices as well as for transducing different forms of energy in sensors and actuators. In this progress report, a brief overview on the current state-of-the-art of experimental and theoretical studies of nanomaterials displaying spin transition is presented. Based on these results, a detailed analysis and discussions in terms of finite size effects and other phenomena inherent to the reduced size scale are provided. Finally, recent research devices using spin crossover complexes are highlighted, emphasizing both challenges and prospects.

352 citations

Journal ArticleDOI
TL;DR: In this article, a review highlights recent progress on different strategies used for improving the sensitivity of plasmonic nanosensors, classified into three categories based on their different sensing mechanisms: (1) sensing based on target-induced local refractive index changes, (2) colorimetric sensing, and (3) amplification of detection sensitivity based on nanoparticle growth.

337 citations

Journal ArticleDOI
TL;DR: In the past few years, we have witnessed the spectacular development of nano-materials of spin crossover complexes of 3d4-3d7 transition metal ions, including thin films, nanoparticles, nanopatterns and nanoscale assemblies.
Abstract: In the past few years we have witnessed the spectacular development of nano-materials of spin crossover complexes of 3d4–3d7 transition metal ions, including thin films, nanoparticles, nanopatterns and nanoscale assemblies These developments were primarily motivated by fundamental questions concerning size reduction effects on the bistability properties On the other hand, spin crossover nano-objects require new characterization techniques (scanning probe microscopy, micro-magnetometry, etc), revealing unknown details of the SCO mechanism at the nanoscale and giving access also to properties, which have been largely unexplored until now In this Highlight, we review these recent experimental developments and discuss perspectives for societal applications as well

143 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented a quantitative study of the sensing behavior of micro-patterned gratings based on the metal-organic framework type spin crossover complex Fe(bpac)[Pt(CN)4] (1) in the presence of vapors of various organic compounds.
Abstract: We present a quantitative study of the sensing behavior of micro-patterned gratings based on the metal–organic framework type spin crossover complex Fe(bpac)[Pt(CN)4] (1) in the presence of vapors of various organic compounds. The gratings of 1 were fabricated by combining a sequential assembly technique and a photolithographic method. The guest absorption driven change of the spin state and the associated variation of the refractive index were in situ monitored by optical diffraction on a grating of 1. Our sensor is characterized by good reversibility, room temperature operation, a low limit of detection (∼30 ppm for molecules of iodobenzene) as well as a linear dynamic range of detection (from 300 to 1500 ppm). The possibility of selectively desorbing the analytes by thermal annealing confers also selectivity to the sensor.

93 citations

Journal ArticleDOI
TL;DR: In this article, the state of the art of the elaboration and the application of nanoparticles and nanohybrid/nanocomposite materials based on spin-crossover (SCO) complexes is reported.

76 citations

References
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Journal ArticleDOI
TL;DR: While nanorods with a higher aspect ratio along with a smaller effective radius are the best photoabsorbing nanoparticles, the highest scattering contrast for imaging applications is obtained from nanorod of high aspect ratio with a larger effective radius.
Abstract: The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica−gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed (∼40 nm)...

4,065 citations

Journal ArticleDOI
TL;DR: How the unique tunability of the plasmon resonance properties of metal nanoparticles through variation of their size, shape, composition, and medium allows chemists to design nanostructures geared for specific bio-applications is emphasized.
Abstract: Noble metal nanostructures attract much interest because of their unique properties, including large optical field enhancements resulting in the strong scattering and absorption of light. The enhancement in the optical and photothermal properties of noble metal nanoparticles arises from resonant oscillation of their free electrons in the presence of light, also known as localized surface plasmon resonance (LSPR). The plasmon resonance can either radiate light (Mie scattering), a process that finds great utility in optical and imaging fields, or be rapidly converted to heat (absorption); the latter mechanism of dissipation has opened up applications in several new areas. The ability to integrate metal nanoparticles into biological systems has had greatest impact in biology and biomedicine. In this Account, we discuss the plasmonic properties of gold and silver nanostructures and present examples of how they are being utilized for biodiagnostics, biophysical studies, and medical therapy. For instance, takin...

3,617 citations

Journal ArticleDOI

3,326 citations

Journal ArticleDOI
TL;DR: A survey of the most common methods of preparation and arraying of materials with localized surface plasmon resonance (LSPR), and of the optical manifestations of LSPR can be found in this article.
Abstract: Recent advances in the exploitation of localized surface plasmons (charge density oscillations confined to metallic nanoparticles and nanostructures) in nanoscale optics and photonics, as well as in the construction of sensors and biosensors, are reviewed here. In particular, subsequent to brief surveys of the most-commonly used methods of preparation and arraying of materials with localized surface plasmon resonance (LSPR), and of the optical manifestations of LSPR, attention will be focused on the exploitation of metallic nanostructures as waveguides; as optical transmission, information storage, and nanophotonic devices; as switches; as resonant light scatterers (employed in the different near-field scanning optical microscopies); and finally as sensors and biosensors.

2,450 citations

Journal ArticleDOI
TL;DR: In this article, the basic physics of surface-plasmon excitations occurring at metal/dielectric interfaces with special emphasis on the possibility of using such excitations for the localization of electromagnetic energy in one, two, and three dimensions, in a context of applications in sensing and waveguiding for functional photonic devices.
Abstract: We review the basic physics of surface-plasmon excitations occurring at metal/dielectric interfaces with special emphasis on the possibility of using such excitations for the localization of electromagnetic energy in one, two, and three dimensions, in a context of applications in sensing and waveguiding for functional photonic devices. Localized plasmon resonances occurring in metallic nanoparticles are discussed both for single particles and particle ensembles, focusing on the generation of confined light fields enabling enhancement of Raman-scattering and nonlinear processes. We then survey the basic properties of interface plasmons propagating along flat boundaries of thin metallic films, with applications for waveguiding along patterned films, stripes, and nanowires. Interactions between plasmonic structures and optically active media are also discussed.

1,881 citations