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Quantum-mechanical effects in photoluminescence from thin crystalline gold films

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Light(Science & Applications) 2024年第4期13卷 783-794页

作者： Alan R.Bowman Alvaro Rodríguez Echarri fatemeh Kiani fadil Iyikanat Ted V.Tsoulos Joel D.Cox Ravishankar Sundararaman f.javier garcía de abajo Giulia Tagliabue Laboratory of Nanoscience for Energy Technologies(LNET) STIÉcole Polytechnique Fédérale de Lausanne(EPFL)LausanneSwitzerland ICfO–Institut de Ciencies fotoniques The Barcelona Institute of Science and TechnologyCastelldefels(Barcelona)Spain. MBI–Max-Born-Institut BerlinGermany. POLIMA–Center for Polariton-driven Light–Matter Interactions University of Southern DenmarkOdense MDenmark. Danish Institute for Advanced Study University of Southern DenmarkOdense MDenmark. department of Materials Science&Engineering Rensselaer Polytechnic InstituteTroyNYUSA. department of Physics Applied Physicsand AstronomyRensselaer Polytechnic InstituteTroyNYUSA. ICREA–Institucio Catalana de Recerca i Estudis Avancats BarcelonaSpain

Luminescence constitutes a unique source of insight into hot carrier processes in metals,including those in plasmonic nanostructures used for sensing and energy applications.However,being weak in nature,metal luminescence remains poorly understood,its microscopic origin strongly debated,and its potential for unraveling nanoscale carrier dynamics largely unexploited.Here,we reveal quantum-mechanical effects in the luminescence emanating from thin monocrystalline gold flakes.Specifically,we present experimental evidence,supported by first-principles simulations,to demonstrate its photoluminescence origin(i.e.,radiative emission from electron/hole recombination)when exciting in the interband regime.Our model allows us to identify changes to the measured gold luminescence due to quantum-mechanical effects as the gold film thickness is reduced.Excitingly,such effects are observable in the luminescence signal from flakes up to 40 nm in thickness,associated with the out-of-plane discreteness of the electronic band structure near the fermi level.We qualitatively reproduce the observations with first-principles modeling,thus establishing a unified description of luminescence in gold monocrystalline flakes and enabling its widespread application as a probe of carrier dynamics and light-matter interactions in this material.Our study paves the way for future explorations of hot carriers and charge-transfer dynamics in a multitude of material systems.

关键词： luminescence quantum crystalline

Thermal manipulation of plasmons in atomically thin films

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Light(Science & Applications) 2020年第1期9卷 1179-1189页

作者： Eduardo J.C.Dias Renwen Yu f.javier garcia de abajo ICfO-Institut de Ciencies fotoniques The Barcelona Institute of Science and Technology08860 Castelldefels(Barcelona)Spain ICREA-Institucio Catalana de Recerca i Estudis Avançats Passeig Lluis Companys 2308010 BarcelonaSpain

Nanoscale photothermal effects enable important applications in cancer therapy,imaging and catalysis.These effects also induce substantial changes in the optical response experienced by the probing light,thus suggesting their application in all-optical modulation.Here,we demonstrate the ability of graphene,thin metal films,and graphene/metal hybrid systems to undergo photothermal optical modulation with depths as large as>70%over a wide spectral range extending from the visible to the terahertz frequency domains.We envision the use of ultrafast pump laser pulses to raise the electron temperature of graphene during a picosecond timescale in which its mid-infrared plasmon resonances undergo dramatic shifts and broadenings,while visible and near-infrared plasmons in the neighboring metal films are severely attenuated by the presence of hot graphene electrons.Our study opens a promising avenue toward the active photothermal manipulation of the optical response in atomically thin materials with potential applications in ultrafast light modulation.

关键词： pump visible films

Spontaneous and stimulated electron-photon interactions in nanoscale plasmonic near fields

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Light(Science & Applications) 2021年第5期10卷 867-880页

作者： Matthias Liebtrau Murat Sivis Armin feisto Hugo Lourenco-Martins Nicolas Pazos-Pérez Ramon A.Alvarez Puebla f.javier garcia de abajo Albert Polman Claus Ropers Center for Nanophotonics AMOLF1098 XG AmsterdamThe Netherlands th Physical Institute-Solids and Nanostructures University of GÖttingen37077 GÖttingenGermany Max Plank Institute for Biophysical Chemistry 37077 GottingenGermany department of Physical Chemistry and EMaS Universitat Rovira i Virgili43007 TarragonaSpain ICREA-Institucio Catalana de Recerca i Estudis Avangats 08010 BarcelonaSpain ICfO-Institut de Ciencies fotoniques The Barcelona Institute of Science and Technology08860 Castelldefels(Barcelona)Spain

The interplay between free electrons,light,and matter offers unique prospects for space,time,and energy resolved optical material characterization,structured light generation,and quantum information processing.Here,we study the nanoscale features of spontaneous and stimulated electron–photon interactions mediated by localized surface plasmon resonances at the tips of a gold nanostar using electron energy-loss spectroscopy(EELS),cathodoluminescence spectroscopy(CL),and photon-induced near-field electron microscopy(PINEM).Supported by numerical electromagnetic boundary-element method(BEM)calculations,we show that the different coupling mechanisms probed by EELS,CL,and PINEM feature the same spatial dependence on the electric field distribution of the tip modes.However,the electron–photon interaction strength is found to vary with the incident electron velocity,as determined by the spatial fourier transform of the electric near-field component parallel to the electron trajectory.for the tightly confined plasmonic tip resonances,our calculations suggest an optimum coupling velocity at electron energies as low as a few keV.Our results are discussed in the context of more complex geometries supporting multiple modes with spatial and spectral overlap.We provide fundamental insights into spontaneous and stimulated electron-light-matter interactions with key implications for research on(quantum)coherent optical phenomena at the nanoscale.

关键词： photon quantum coupling

Double-layer graphene for enhanced tunable infrared plasmonics

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Light(Science & Applications) 2017年第1期6卷 761-768页

作者： Daniel Rodrigo Andreas Tittl Odeta Limaj f.javier garcía de abajo Valerio Pruneri Hatice Altug Institute of BioEngineering École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland ICfO-Institut de Ciències fotòniques The Barcelona Institute of Science and Technology08860 Castelldefels(Barcelona)Spain ICREA-InstitucióCatalana de Recerca i Estudis Avançats 08010 BarcelonaSpain

Graphene is emerging as a promising material for photonic applications owing to its unique optoelectronic properties.Graphene supports tunable,long-lived and extremely confined plasmons that have great potential for applications such as biosensing and optical communications.However,in order to excite plasmonic resonances in graphene,this material requires a high doping level,which is challenging to achieve without degrading carrier mobility and stability.Here,we demonstrate that the infrared plasmonic response of a graphene multilayer stack is analogous to that of a highly doped single layer of graphene,preserving mobility and supporting plasmonic resonances with higher oscillator strength than previously explored single-layer devices.Particularly,we find that the optically equivalent carrier density in multilayer graphene is larger than the sum of those in the individual layers.furthermore,electrostatic biasing in multilayer graphene is enhanced with respect to single layer due to the redistribution of carriers over different layers,thus extending the spectral tuning range of the plasmonic structure.The superior effective doping and improved tunability of multilayer graphene stacks should enable a plethora of future infrared plasmonic devices with high optical performance and wide tunability.

关键词： graphene infrared nanophotonics optoelectronic plasmonics

free-electron interactions with van der Waals heterostructures: a source of focused X-ray radiation

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Light(Science & Applications) 2023年第7期12卷 1370-1380页

作者： Xihang Shi Yaniv Kurman Michael Shentcis Liang Jie Wong f.javier garcia de abajo ldo Kaminero Solid State Institute and faculty of Electrical and Computer Engineering Technion-Israel Institute of TechnologyHaifa 32000Israel School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798Singapore ICfO-Institut de Ciencies fotoniques The Barcelona Institute of Science and TechnologyCastelldefels 08860Spain iCREA-lnstitucio Catalana de Recerca i Estudis Avangats Passeig Lluis Companys23Barcelona08010Spain

The science and technology of X-ray optics have come far,enabling the focusing of X-rays for applications in highresolution X-ray spectroscopy,imaging,and irradiation.In spite of this,many forms of tailoring waves that had substantial impact on applications in the optical regime have remained out of reach in the X-ray regime.This disparity fundamentally arises from the tendency of refractive indices of all materials to approach unity at high frequencies,making X-ray-optical components such as lenses and mirrors much harder to create and often less effcient.Here,we propose a new concept for X-ray focusing based on inducing a curved wavefront into the X-ray generation process,resulting in the intrinsic focusing of X-ray waves.This concept can be seen as effectively integrating the optics to be part of the emission mechanism,thus bypassing the effciency limits imposed by X-ray optical components,enabling the creation of nanobeams with nanoscale focal spot sizes and micrometer-scale focal lengths.Specifically,we implement this concept by designing aperiodic vdw heterostructures that shape X-rays when driven by free electrons.The parameters of the focused hotspot,such as lateral size and focal depth,are tunable as a function of an interlayer spacing chirp and electron energy.Looking forward,ongoing advances in the creation of many-layer vdw heterostructures open unprecedented horizons of focusing and arbitrary shaping of X-ray nanobeams.

关键词： optics integrating arbitrary

Quantum nonlocal effects in individual and interacting graphene nanoribbons

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Light(Science & Applications) 2015年第1期4卷 513-517页

作者： Ivan Silveiro Juan Manuel Plaza Ortega f.javier garcia de abajo ICfO-Institut de Ciencies fotoniques Mediterranean Technology Park08860 Castelldefels(Barcelona)Spain ICREA-Institucio Catalana de Recerca i Estudis Avanc¸ats Passeig Lluis Companys 2308010 BarcelonaSpain

We show that highly doped graphene ribbons can support surface plasmons at near-infrared frequencies when their width is in the nanometer range,leading to important nonlocal and finite quantum-size corrections,such as sizable blueshifts.The magnitude of these effects is assessed by comparing classical and quantum-mechanical models to describe graphene plasmons.More precisely,we examine individual and interacting 6–8 nm wide zigzag and armchair ribbons doped to 0.4–1.5 eV fermi energies.We find a strong influence of nonlocal effects on the orientation of graphene edges,with plasmons in zigzag ribbons undergoing strong quenching when their energy is below the fermi level.Nonlocality is also affecting the hybridization between ribbon plasmons in dimers and arrays for separations below a few nanometers.Remarkably,the removal of a single row of atomic bonds in a ribbon produces a strong plasmon frequency shift,whereas the removal of bonds along an array of rows separated by several nanometers in an extended sheet causes a dramatic increase in the absorption.Besides the fundamental interest of these results,our work supports the use of narrow ribbons to achieve electro-optical modulation in the near infrared.

关键词： graphene graphene plasmons graphene ribbons metamaterials plasmonics

An optical fiber network oracle for NP-complete problems

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Light(Science & Applications) 2014年第1期3卷 304-308页

作者： Kan Wu javier garcia de abajo Cesare Soci Perry Ping Shum Nikolay I Zheludev Centre for Disruptive Photonic Technologies Nanyang Technological UniversitySingapore 637371Singapore Optoelectronics Research Centre University of SouthamptonSouthampton SO171BJUK IQfR-CSIC 28006 MadridSpain

The modern information society is enabled by photonic fiber networks characterized by huge coverage and great complexity and ranging in size from transcontinental submarine telecommunication cables to fiber to the home and local segments.This world-wide network has yet to match the complexity of the human brain,which contains a hundred billion neurons,each with thousands of synaptic connections on average.However,it already exceeds the complexity of brains from primitive organisms,i.e.,the honey bee,which has a brain containing approximately one million neurons.In this study,we present a discussion of the computing potential of optical networks as information carriers.Using a simple fiber network,we provide a proof-of-principle demonstration that this network can be treated as an optical oracle for the Hamiltonian path problem,the famous mathematical complexity problem of finding whether a set of towns can be travelled via a path in which each town is visited only once.Pronouncement of a Hamiltonian path is achieved by monitoring the delay of an optical pulse that interrogates the network,and this delay will be equal to the sum of the travel times needed to visit all of the nodes(towns).We argue that the optical oracle could solve this NP-complete problem hundreds of times faster than brute-force computing.Additionally,we discuss secure communication applications for the optical oracle and propose possible implementation in silicon photonics and plasmonic networks.

关键词： Hamiltonian path problem NP complete optical oracle

Identification of colorectal cancer metastasis markers by an angiogenesis-related cytokine-antibody array

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世界胃肠病学杂志：英文版 2012年第7期18卷 637-645页

作者： Ana abajo Nerea Bitarte Ruth Zarate Valentina Boni Ines Lopez Marisol Gonzalez-Huarriz javier Rodriguez Eva Bandres Jesus garcia-foncillas Laboratory of Pharmacogenomics Division of OncologyCenter for Applied Medical ResearchUniversity of NavarraAvda Pio XII 5531008 PamplonaSpain department of Oncology University Clinic of NavarraUniversity of NavarraAvda Pio XII 5531008 PamplonaSpain

AIM:To investigate the angiogenesis-related protein expression profile characterizing metastatic colorectal cancer (mCRC) with the aim of identifying prognostic markers.METHODS:The expression of 44 angiogenesissecreted factors was measured by a novel cytokine antibody array methodology.The study evaluated vascular endothelial growth factor (VEGf) and its soluble vascular endothelial growth factor receptor (sVEGfR)-1 protein levels by enzyme immunoassay (EIA) in a panel of 16 CRC cell lines.mRNA VEGf and VEGf-A isoforms were quantified by quantitative reverse-transcription polymerase chain reaction (Q-RT-PCR) and vascular endothelial growth factor receptor (VEGfR)-2 expression was analyzed by flow cytometry.RESULTS:Metastasis-derived CRC cell lines expressed a distinctive molecular profile as compared with those isolated from a primary tumor site.Metastatic CRC cell lines were characterized by higher expression of angiogenin-2 (Ang-2),macrophage chemoattractant proteins-3/4 (MCP-3/4),matrix metalloproteinase-1 (MMP-1),and the chemokines interferon γ inducible T cell α chemoattractant protein (I-TAC),monocyte chemoattractant protein I-309,and interleukins interleukin (IL)-2 and IL-1α,as compared to primary tumor cell lines.In contrast,primary CRC cell lines expressed higher levels of interferon γ (IfN-γ),insulin-like growth factor-1 (IGf-1),IL-6,leptin,epidermal growth factor (EGf),placental growth factor (PlGf),thrombopoietin,transforming growth factor β1 (TGf-β1) and VEGf-D,as compared with the metastatic cell lines.VEGf expression does not significantly differ according to the CRC cellular origin in normoxia.Severe hypoxia induced VEGf expression up-regulation but contrary to expectations,metastatic CRC cell lines did not respond as much as primary cell lines to the hypoxic stimulus.In CRC primary-derived cell lines,we observed a twofold increase in VEGf expression between normoxia and hypoxia as compared to metastatic cell lines.CRC cell lines express a similar pattern of VEGf isoforms (VEGf 121,VEGf 165 and VE

关键词：血管生成细胞因子血管内皮生长因子受体识别标记阵列抗体大肠癌逆转录聚合酶链反应

Low prevalence of germline hMSH6 mutations in colorectal cancer families from Spain

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World Journal of Gastroenterology 2005年第37期11卷 5770-5776页

作者： Ana Sánchez de abajo Miguel de la Hoya Alicia Tosar javier Godino Juan Manuel fernández Jose Lopez Asenjo Beatriz Perez Villamil Pedro Perez Segura Eduardo Diaz-Rubio Trinidad Caldes Laboratorio de Oncología Molecular Hospital Clinico San Carlos Madrid Spain Servicio de Anatomía Patológica Hospital Clinico San Carlos Madrid Spain Servicio de Oncología Médica Hospital Clinico San Carlos Madrid Spain

AIM: To investigate the prevalence and penetrance of hMSH6 mutations in Spanish HNPCC families that was negative for mutation in hMLH1 or hMSH2.METHODS: We used PCR-based DGGE assay and direct Sequencing to screen for hMSH6 gene in 91 HNPCC families.RESULTS: we have identified 10 families with germ-line mutations in the DNA sequence. These mutations included two intronic variation, three missense mutation, one nonsense mutation, and four silent mutations. Among the 10 germ-line mutations identified in the Spanish cohort,8 were novel, perhaps, suggesting different mutational spectra in the Spanish population. detailed pedigrees were constructed for the three families with a possible pathogenic hMSH6 mutation. The two silent mutations H388H and L758L, detected in a person affected of colorectal cancer at age 29, produce loss of the wild-type allele in the tumor sample. Immunohistochemical analysis showed that expression of MSH6 protein was lost only in the tumors from the carriers of V878A and Q263X mutations.CONCLUSION: Altogether, our results indicate that disease-causing germ-line mutations of hMSH6 are very less frequent in Spanish HNPCC families.

关键词：基因突变 hMSH6 结肠癌直肠癌西班牙遗传因素