Near-field imaging of one-dimensional excitons delocalized over mesoscopic distances

Chattez avec Graph Search

Posez n’importe quelle question sur les cours, conférences, exercices, recherches, actualités, etc. de l’EPFL ou essayez les exemples de questions ci-dessous.

AVERTISSEMENT : Le chatbot Graph n'est pas programmé pour fournir des réponses explicites ou catégoriques à vos questions. Il transforme plutôt vos questions en demandes API qui sont distribuées aux différents services informatiques officiellement administrés par l'EPFL. Son but est uniquement de collecter et de recommander des références pertinentes à des contenus que vous pouvez explorer pour vous aider à répondre à vos questions.

Kasha's rule states that luminescence occurs from the lowest excited state; violating this rule could enable radiative release of excess electronic energy, otherwise lost as heat in electroluminescent devices. Here we demonstrate anti-Kasha narrowband electroluminescence from carbene-gold(I)-arylacetylide complexes. A rigid acetylide bridge links a (carbene)gold(I) moiety to a multiple-resonance chromophore, thereby spatially separating frontier orbitals to produce a dark long-range charge-transfer S1 and b

We explored the sub-femtosecond dynamics in lithium fluoride using transient reflection spectroscopy. This technique probes ultrafast dynamics initiated by a few-femtosecond infrared pump pulse with attosecond pulses in the 25−50 eV energy range, providing direct access to non-equilibrium charge dynamics in the deep conduction band. Under strong-field excitation, this energy region is characterized by a remarkably rich ultrafast response arising from the interplay between virtual charges and an excitonic st

Terahertz (THz) radiation occupies a spectral region between 100 GHz and 10 THz of growing interest for applications in spectroscopy, imaging, and high-speed communications. In free-space implementations, THz generation and detection are commonly achieved using nonlinear crystals through optical rectification and electro-optic sampling, photoconductive antennas based on III-V semiconductors, or more recently spintronic emitters. While these approaches provide large bandwidth and high fidelity, they typicall

Due to the wide distribution of construction sites and data heterogeneity, single site models struggle with cross-site generalization and privacy compliance. A collaborative prediction model is needed to integrate information from multiple sites and enhance governance. Traditional time series models fail to capture short-term disturbances and long-term dependencies, and construction site data often includes abrupt changes and multi-scale dynamics. Non-Independent and Identically Distributed (Non-IID) data a

Bio-inspired soft robotic swimmers offer a promising route toward efficient and agile underwater locomotion. Yet, most existing designs rely on single degree of freedom tails that couple propulsion and steering, limiting controllability and efficiency. In this work, we present a compliant, tendondriven robotic fish featuring an independently actuated caudal fin that decouples tail bending and fin orientation. Actuated via fishing cables, all motors are housed within the central body, minimizing rear-end ine

Carbon dioxide (CO2) is expected to become a critical feedstock for non-fossil carbon-based energy carriers in hard-to-electrify sectors, the so-called e-fuels. In particular, biogenic CO2 becomes an essential resource, especially after 2040 as specified in European regulation. However, CO2 emissions are expected to decrease significantly as industrial sectors decarbonise. This work builds a comprehensive database of current European industrial CO2 emitters, disaggregated by sector and emission type. Emissi

Control over the electron’s spin (up or down) within the field of spintronics introduces an additional degree of freedom compared to traditional electronics, opening up new opportunities for energy-efficient quantum information technologies. Such applications require a spin-polarized population on timescales ranging from nano- to microseconds. Recent studies on solution-processable lead-halide perovskite semiconductors demonstrated spin lifetimes on the order of a few picoseconds at room temperature — still

Junctions between p ‐ and n ‐doped semiconductors are ubiquitous in modern electronic devices and circuits. However, the tendency toward ‘natural’ defect doping (i.e., a fixed majority carrier polarity) has made the realization of pn ‐junctions between 2D/layered chalcogenide semiconductors challenging. Here, the formation of high‐quality, electrically active lateral junctions between Bi‐doped n ‐type SnSe and p ‐type SnS is demonstrated via a two‐step growth process, building on the successful integration

Extended efforts have been devoted to the study of strongly-interacting excitons and their dynamics, towards macroscopic quantum states of matter such as Bose-Einstein condensates of excitons and polaritons. Momentum-direct layer-hybridized excitons in transition metal dichalcogenides have attracted considerable attention due to their high oscillator strength and dipolar nature. However, the tunability of their interactions and dynamics remains unexplored. Here, we achieve an unprecedented control over the

Euclid is delivering optical and near-infrared imaging data over 14 000 deg2 on the sky at spatial resolution and surface brightness levels that can be used to understand the morphological transformation of galaxies within groups and clusters. Using the Early Release Observations (ERO) of the Perseus cluster, we demonstrate the capability offered by Euclid in studying the nature of perturbations for galaxies in clusters. Filamentary structures are observed along the discs of two spiral galaxies, UGC 2665 an

Advanced semiconducting materials such as transition metal dichalcogenides exhibit significant potential for the development of next‐generation optoelectronic devices. Specifically, the construction of an efficient heterostructure is imperative for achieving enhanced sensing capabilities, particularly in broadband light detection. In this study, a novel adaptive approach to enhance the photosensing abilities of multilayer MoS 2 is introduced, as it is more easily fabricable compared to its single‐layer coun

The goal of the DECARB research project is to investigate mixes of policy instruments that would allow Switzerland to respect its climate commitments and reach the net-zero emissions target by 2050. In this context, we focus on energy-related emissions which stem from four sectors, namely: power generation, transport, buildings and industry. We evaluate various policy measures, as well as combinations thereof, along several dimensions relevant to policymakers, including environmental effectiveness, economic

This work presents the changing abundance of surface functional groups (SFG) on polystyrene (PS) upon weathering within one or a few molecular monolayers from a molecular point of view. PS particles were aged by exposing them to a gas flow of typically (5%) O3 in air (PSO3), UV radiation using a solar simulator under controlled conditions in the laboratory (PSSS) and by exposing PS samples to the water/air interface immerged in a freshwater lake for 2 months (PSL). The chemical composition of the interface

The unavailability of highly transparent materials in the mid-infrared has been the main limitation in the development of ultra-sensitive molecular sensors or cavity-based spectroscopy applications. Whispering gallery mode microresonators have attained ultra-high-quality (Q) factor resonances in the near-infrared and visible. Here we report ultra-high Q factors in the mid-infrared using polished alkaline earth metal fluoride crystals. Using an uncoated chalcogenide tapered fibre as a high-ideality coupler i

The crossover from an exciton gas to an electron-hole plasma is studied in a GaN/(Al,Ga)N single quantum well by means of combined time-resolved and continuous-wave photoluminescence measurements. The two-dimensional Mott transition is found to be of continuous type and to be accompanied by a characteristic modification of the quantum well emission spectrum. Beyond the critical density, the latter is strongly influenced by band-gap renormalization and Fermi filling of continuum states. Owing to the large bi

We propose a full reproduction workflow for printing color images on metallic substrates. It relies on an ink spreading enhanced cellular Yule-Nielsen modified spectral Neugebauer model, calibrated with 35 color samples printed on the metal film and measured under specular reflection. The calibration accounts for the different phenomena contributing to the reflectance of halftone prints on metal: specular reflection by the metal film substrate of light traveling across the inks, illumination and viewing geo

We present a method to automatically detect shadows in a fast and accurate manner by employing the inherent sensitivity of digital camera sensors to the near-infrared (NIR) part of the spectrum. Shadows are generally found in the dark parts of an image, be it color or NIR. We consider these dark pixels as shadow candidates. By observing that commonly encountered light sources have very distinct spectra in the NIR, we propose that the ratios of the color channels (red, green and blue) to the NIR give valuabl

Micro-optics describes a family of elements and systems fabricated by modern micromachining. Optical structures with nearly arbitrary shapes and dimensions down to the nanometer can be realized offering a large degree of freedom for the design. The progress in novel light sources, detectors, materials and technology enable new opportunities and challenges for micro-optics and nanoscale photonics.

In this experimental work, we optically excite the eigenmodes of an elliptical resonator in a semiconductor micro-cavity. Using a pulsed excitation, we create a superposition of eigenmodes, and image the time evolution of the coherent emission pattern. Oscillations between vortex and anti-vortex states are observed, and remarkably well described within the Poincar sphere representation for an eigenmode containing an orbital angular momentum. A semiconductor quantum well is embedded in the microcavity struct

Energy demand continuously increases what contributes to higher emissions of GHG. Moreover, the primary energy sources like coal, natural gas and oil are depleting. To manage this problem, the scientists have worked on the different possibilities of renewable energy conversion technologies in order to get the most useful and cleanest type of energy. In this work, there are investigated possible biomass conversion technologies in order to satisfy energy demand for Poznan, the city in Poland. Actually, the en

Near-field imaging of one-dimensional excitons delocalized over mesoscopic distances

Chattez avec Graph Search

Anti-Kasha electroluminescence in carbene-gold-arylacetylide complexes

Ultrafast hybrid exciton dynamics in lithium fluoride

Hybrid silicon-organic integrated photonic circuits for broadband terahertz field-resolved detection

Parallel framework for intelligent prediction of multi-site fugitive dust: Combined with DustLSTM-Trans and FedProx-Dyn

Improving Efficiency and Maneuverability through Design of a Robotic Fish with Independent Control of Tail and Caudal Fin Deflection

Mapping and Evolution of Industrial CO 2 Point Sources in Europe: will biogenic CO 2 become a limiting resource by 2050?

Controlling spin lifetimes in lead-free halide perovskite semiconductors

Single‐Crystalline Lateral p ‐SnS/ n ‐SnSe van der Waals Heterostructures by Vapor Transport Growth with In Situ Bi Doping

Electrically tunable ultrafast dynamics and interactions of hybrid excitons in a 2D semiconductor bilayer

Euclid: Early Release Observations of ram-pressure stripping in the Perseus cluster: Detection of parsec-scale star formation within the low surface brightness stripped tails of UGC 2665 and MCG +07-07-070

Synergistic Enhancement of Photoresponse and Broadband Detection via Quantum Dot‐Sensitized Hexagonal Nanoporous MoS 2 matrix

DECARB - Mixes of policy instruments for full decarbonisation by 2050

Natural and Artificial Weathering of Polystyrene: A Molecular View of the Polymeric Interface

Mid-infrared ultra-high-Q resonators based on fluoride crystalline materials

High-temperature Mott transition in wide-band-gap semiconductor quantum wells

Specular color imaging on a metallic substrate

Automatic and Accurate Shadow Detection using Near-Infrared Information

CHALLENGES IN MICRO- AND NANO-OPTICS (plenary talk)

Coherent oscillations between polariton vortex and anti-vortex states in an elliptical resonator

The Optimized Integration of Biomass Fuel in the District Heating System in Poznan, Poland: Part 2