|\epsilon|-Near-Zero materials in the near-infrared

We consider a mixture of metal coated quantum dots dispersed in a polymer matrix and, using a modified version of the standard Maxwell-Garnett mixing rule, we prove that the mixture parameters (particles radius, quantum dots gain, etc.) can be chosen so that the effective medium permittivity has an absolute value very close to zero in the near-infrared, i.e. |Re(epsilon)|<<1 and |Im (epsilon)|<<1 at the same near-infrared wavelength. Resorting to full-wave simulations, we investigate the accuracy of the effective medium predictions and we relate their discrepancy with rigorous numerical results to the fact that |epsilon|<<1 is a critical requirement. We show that a simple method for reducing this discrepancy, and hence for achieving a prescribed value of |\epsilon|, consists in a subsequent fine-tuning of the nanoparticles volume filling fraction.Comment: 3 pages, 3 figure

Optical properties of metal doped ZnO thin films on glass and polymer substrates

Date du colloque : 09/2013International audienc

Energy transfer with semiconductor nanocrystals

Fo¨ rster (or fluorescence) resonant energy transfer (FRET) is a powerful spectroscopic technique to study interactions, conformational and distance changes, in hybrid nanosystems. Semiconductor nanocrystals, also known as colloidal quantum dots, are highly efficient fluorophores with a strong band-gap luminescence tuneable by size as a result of the quantum confinement effect. Starting from a short summary on the FRET formalism and on the basic properties of semiconductor nanocrystals, this Feature Article provides an overview of the major classes of hybrid FRET systems with semiconductor nanocrystals as at least one component. Systems under consideration include thin solid films containing differently sized semiconductor nanocrystals, solution-based complexes of differently sized semiconductor nanocrystals, nanocrystal-based bioconjugates, and hybrid structures of semiconductor and gold nanoparticles. We focus in particular on the directional energy transfer in layer-by-layer assembled multilayers of differently sized CdTe semiconductor nanocrystals and on the energy transfer from individual rod-like semiconductor CdSe/CdS nanoantennae to single dye molecules, which can be efficiently controlled by external electric fields leading to the realisation of the FRET optical switch

Industry 4.0-Compliant Wavelet-Based Power Transformer Fault Classification Method During Data Missing Conditions

This paper introduces a novel fault classification method for power transformers using the Real-Time Boundary Stationary Wavelet Transform (RT-BSWT), which is robust to data-missing conditions. Addressing the challenges of fault classification in power transformers, particularly under data-missing conditions, the proposed method offers a threshold-based logic approach, enhancing accuracy and speed in fault classification. The method is robust against gaps in data analysis, making it suitable for real-world applications, and aligning with Industry 4.0 concepts, especially regarding the wide use of data transmission expected in modern industries. A comprehensive evaluation of an extensive database covering various fault types and conditions demonstrated the method\u27s efficacy, with high accuracy rates in complete data and data-missing scenarios

Fluorescence quenching of dye molecules near gold nanoparticles: radiative and nonradiative effects

The radiative and nonradiative decay rates of lissamine dye molecules, chemically attached to differently sized gold nanoparticles, are investigated by means of time-resolved fluorescence experiments. A pronounced fluorescence quenching is observed already for the smallest nanoparticles of 1  nm radius. The quenching is caused not only by an increased nonradiative rate but, equally important, by a drastic decrease in the dye’s radiative rate. Assuming resonant energy transfer to be responsible for the nonradiative decay channel, we compare our experimental findings with theoretical results derived from the Gersten-Nitzan model.\ud \u

Supplement 1. SEM micrographs of the scent gland channel of Dysodius lunatus’ cuticle under the wing. In the left column of the figure, several images are stitched together showing the whole channel length with the three liquid secreting pores (indicated by white arrows). The middle and the right column show magnified details with oriented pointed microstructures. from Bioinspired polymer microstructures for directional transport of oily liquids

Nature has always served as an inspiration for scientists, helping them to solve a large diversity of technical problems. In our case, we are interested in the directional transport of oily liquids and as a role model for this application we used the flat bug <i>Dysodius lunatus</i>. In this report, we present arrays of drops looking like polymer microstructures produced by the two-photon polymerization technique that mimic the micro-ornamentation from the bug's cuticle. A good directionality of oil transport was achieved, directly controlled by the direction of the pointed microstructures at the surface. If the tips of the drop-like microstructures are pointing towards the left side, the liquid front moves to the right and vice versa. Similar effects could be expected for the transport of oily lubricants. These results could, therefore, be interesting for applications in friction and wear reduction

Supplement 3. Video of oily liquid dynamics on the polymer microstructures array (tips oriented to the right) enclosed in between the glass slide and the cover slip. The video is speeded up 10 times. from Bioinspired polymer microstructures for directional transport of oily liquids

Nature has always served as an inspiration for scientists, helping them to solve a large diversity of technical problems. In our case, we are interested in the directional transport of oily liquids and as a role model for this application we used the flat bug <i>Dysodius lunatus</i>. In this report, we present arrays of drops looking like polymer microstructures produced by the two-photon polymerization technique that mimic the micro-ornamentation from the bug's cuticle. A good directionality of oil transport was achieved, directly controlled by the direction of the pointed microstructures at the surface. If the tips of the drop-like microstructures are pointing towards the left side, the liquid front moves to the right and vice versa. Similar effects could be expected for the transport of oily lubricants. These results could, therefore, be interesting for applications in friction and wear reduction

Highly resolved absolute cross-sections for dissociative electron attachment to SF5CF3

Using two complementary experimental methods, we have measured partial (mass-resolved) cross-sections for dissociative electron attachment to the molecule trifluoromethyl sulfurpentafluoride (SF5CF3) at the gas temperature TG = 300K over a broad range of electron energies (E = 0.001–12 eV)

The Ultraviolet Spectrograph on NASA’s Juno Mission

The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS