Photoactive Materials: Synthesis, Applications and Technology

This book presents a collection of 13 original research articles that focus on the science of light–matter interaction. This area of science has been led to some the greatest accomplishments of the past 100 years, with the discovery of materials that perform useful operations by collecting light or generating light from an outside stimulus. These materials are at the center of a multitude of technologies that have permeated our daily life; every day we rely on quantum well lasers for telecommunication, organic light emitting diodes for our displays, complementary metal–oxide–semiconductors for our camera detectors, and of course a plethora of new photovoltaic cells that harvest sunlight to satisfy our energy needs. In this book, top-rated researchers present their latest findings in the field of nano-particles, plasmonics, semi-conductors, magneto-optics, and holography

A new light-responsive resistive random-access memory device containing hydrogen-bonded complexes.

Acknowledgements: TSV acknowledges financial support from the Ministry of Higher Education of Malaysia through the Fundamental Research Grant Scheme [FP079-2018A]. AR acknowledges Ministerio de Economía y Competitividad (MINECO) for his PhD grant BES-2015-071235, under the project MAT2014-55205-P. VMA acknowledges the University Malaya for the grant RF004B-2018. AMF would like to thank the Royal Academy of Engineering, U.K., for the grant NRCP1516/4/61 (Newton Research Collaboration Programme), the University of Aberdeen, for the award of the grant SF10192, the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd., for the Research Grant RGS\R1\201397, and the Royal Society of Chemistry for the award of a mobility grant (M19-0000). AMF and TSV further acknowledge University Malaya for travelling support.Peer reviewedPostprin

Photo-control of nanointeractions.

The manipulation of physical interactions between structural moieties on the molecular scale is a fundamental hurdle in the realization and operation of nanostructured materials and high surface area microsystem architectures. These include such nano-interaction-based phenomena as self-assembly, fluid flow, and interfacial tribology. The proposed research utilizes photosensitive molecular structures to tune such interactions reversibly. This new material strategy provides optical actuation of nano-interactions impacting behavior on both the nano- and macroscales and with potential to impact directed nanostructure formation, microfluidic rheology, and tribological control

Nonlinear Excitation of Photoactivated Molecules: Two-Photon Absorption Spectroscopy, Dynamics, and Quantum Yields

Higher-lying excited electronic states of model, photoactivated molecules are studied using nonlinear excitation to explore the electronic spectroscopy, excited-state dynamics, and reaction quantum yields. The photoactivated molecules studied in this dissertation include two photochromic molecules, stilbene and 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)perfluoro-cyclopentene, that reversibly convert between different isomers following irradiation, as well as a photoactivated protecting group, para-hydroxyphenacyl, that photochemically releases a bound substrate. Studying higher-lying excited states above S1 following nonlinear excitation provides information about the initially excited state, the subsequent excited-state dynamics, and the reaction quantum efficiency. Much less is known about the higher-lying excited states as compared to the well-studied ground and lowest-lying excited states, which motivates the work in this dissertation to investigate the higher-lying excited states of photoactivated molecules following nonlinear excitation. The measurements of the higher-lying excited states reported here include a broadband pump-probe technique that is used to measure the two-photon absorption spectroscopy, as well as the excited-state dynamics following linear and nonlinear excitation of the studied photoactivated molecules. The broadband two-photon absorption spectroscopy measurements reveal the two-photon accessible states and their absolute two-photon absorption cross sections. Separate measurements of the excited-state dynamics and of the reaction quantum yields following nonlinear excitation collectively provide information about the behavior of the higher-lying excited-states, and how the identity of the excited states affect the outcome of the photochemical reactions. Probing the spectroscopy, dynamics, and quantum yields of the studied photoactivated molecules is important to develop a fundamental understanding of photochemical reactions from higher-lying excited states. The spectroscopy, dynamics, and quantum yield measurements in this dissertation can also serve as new benchmarks for computational studies of these model molecules

An investigation of the performance of photochromic dyes and their application to polyester and cotton fabrics

Six commercial photochromic dyes were applied to polyester and, to a lesser extent, cotton fabrics by different dyeing and printing methods. The photochromic performance of the dyed and printed fabrics was investigated in terms of the degree of photocoloration, background colour, fading characteristics, fatigue resistance and storage stability. A traditional aqueous-based disperse dyeing method was used to apply the photochromic dyes to polyester fabric. Solvent-based dyeing methods also were investigated for application of the photochromic dyes to polyester fabric. Solvent-based inks were formulated and applied to polyester and cotton fabrics by digital inkjet printing. The photochromic performance and colour fastness to light and washing of the photochromic fabrics were evaluated and comparison made. UV/visible spectra of the commercial photochromic dyes in a range of solvents were obtained and interpreted in terms of solvent polarity. On the basis of this study, the photochromic performance of the fabrics was improved by selecting the appropriate application solvents which transferred minimum background colours onto the fabrics. A new method of evaluating lightfastness of photochromic fabrics was established, aimed at replacing the conventional method by an instrumental method. This method was based on comparing the decrease in the degree of photocoloration of photochromic fabrics after light exposure with measured values of the colour differences of the blue wool references after fixed periods of light exposure. Two photochromic dyes were synthesized by azo coupling of a spironaphtho[2,1-b]oxazine with diazonium salts obtained from p-nitroaniline, and m-nitroaniline. Molecular modeling of the new photochromic systems, which are referred to as azospirooxazine dyes, showed that the dyes were predicted to have the potential to show photochromism. Thus, the photochromism of the azospirooxazine dyes in a range of solvents was investigated. The investigations showed that the dyes performed differently in different solvents in terms of the hue, the rate of the photochromic colour change and the colour reversibility

Towards label-free biosensing in compact disk technologies f or point-of-need analysis

Tesis por compendioThis thesis explores new analytical advances using compact disk biosensing technologies, and comprises six scientific publications distributed along four chapters. Special attention is herein payed to Thermochromic Etching Disks (TED) technology (Chapter 1), rational design of disk-based biorecognition assays (Chapter 2), and label-free detection systems for point-of-need analysis (Chapters 3 and 4). First, insights into a novel light-mediated signal developing system for biorecognition assays (based on TED disks and drives) are provided together with an overview of the state-of-the art and future trends in photo- and thermochromic biosensing. This signal developing approach exploits photo- and thermochromism for biosensing in an original manner and represents a potential strategy to simplify signaling processes in bioanalytical systems. Then, how to transform TED technology into lab-on-a-disk systems is addressed. TED has proven to be a very versatile tool to perform sensitive analysis of biorecognition assays, using platforms and scanners easily obtained from regular disks and drives, respectively. Biologically relevant assays of different nature (microarray, cell culture, immunofiltration, turbidimetry, etc.) have been arrayed in a single disk and sensitively analyzed by imaging. Regarding rational design, a theoretical-experimental method (INSEL) based on kinetics and mass-transport modelling for optimizing biorecognition assays and exploring their behavior is presented. INSEL has been implemented as an in silico tool that enables to characterize biointeractions with minimal experimentation, to perform optimizations directed towards custom objectives defined by the user, and to easily compute the effect of critical variables without further experiments. In another study included in this thesis, polycarbonate grooved structures obtained from standard recordable disks (CD-R and DVD-R) were coated with silver and tailored to become SERS-active. This strategy represents a cost-effective and industrially scalable alternative to the SERS substrates typically used for bioanalysis. These disk-based materials have presented tunable plasmonic responses, significant Raman enhancement, and have allowed complex biological targets (such as proteins and exosomes) to be analyzed by SERS without using labeled reagents as tracers. In addition to introduce inexpensive and large-scale SERS substrates for biosensing, this study also suggests the development of prospective Raman scanners based on disk drives. Another approach herein presented addresses the implementation of diffraction-based sensing (DBS) in TED technology in order to conceive disk-based label-free biosensors based on standard disks and drives. At first, a comprehensive experimental assessment of the analytical possibilities offered by DBS is presented. Then, the fabrication of arrays of diffractive protein networks on TED disks is investigated, with which sensitive analysis of antibodies in label-free conditions has been demonstrated, using adapted drives as scanners. This investigation provides important insights into cost-effective and industrially scalable functional materials and detection setups that exploit consumer electronics for label-free biosensing.Esta tesis explora nuevos avances en química analítica usando tecnologías de biosensado basadas en sistemas de disco compacto y comprende seis publicaciones científicas distribuidas a lo largo de cuatro capítulos. Los estudios se han centrado en la tecnología Thermochromic Etching Disks (TED) (Capítulo 1), el diseño racional de ensayos de bioreconocimiento en discos compactos (Capítulo 2), y la detección sin marcaje para realizar análisis in situ (Capítulos 3 y 4). Primero, enmarcado en una discusión del estado del arte y futuras tendencias en biosensado foto y termocrómico, se presenta un nuevo sistema (basado en discos y lectores TED) mediado por luz para el desarrollo de señales en ensayos de bioreconocimiento. Ésta constituye una estrategia novedosa para aprovechar el foto y termocromismo en biosensado, y presenta un gran potencial para simplificar los procesos de desarrollo de señal en sistemas bioanalíticos. A continuación, se aborda cómo transformar la tecnología TED en sistemas analíticos integrados basados en discos compactos. TED ha demostrado ser una herramienta muy versátil para analizar, de forma sensible, ensayos de bioreconocimiento usando plataformas y escáneres fácilmente obtenidos a partir de discos y lectores convencionales, respectivamente. Un único disco ha mostrado poder albergar varios ensayos biológicos importantes y de distinta naturaleza (micromatriz, cultivos celulares, inmunofiltración, turbidimetría, etc.), para ser analizados de forma sensible a través de imágenes En cuanto al diseño racional, se presenta un método teórico-experimental (INSEL), basado en modelos cinéticos y de transporte de masa, para optimizar ensayos de bioreconocimiento y explorar su comportamiento. INSEL se ha implementado como una herramienta in silico que permite caracterizar biointeracciones mediante mínima experimentación, realizar optimizaciones dirigidas a objetivos particulares definidos por el usuario, y computar el efecto de variables críticas de forma sencilla y sin experimentos adicionales. En otro estudio incluido en esta tesis, nanoestructuras en forma de surco obtenidas a partir de discos regrabables convencionales (CD-R y DVD-R) fueron recubiertas con plata y adaptadas para ser activas en SERS. Esta estrategia supone una alternativa, económicamente efectiva e industrialmente escalable, a los sustratos SERS típicamente usados en bioanálisis. Estos materiales han mostrado respuestas plasmónicas sintonizables, una amplificación Raman significativa, y han permitido analizar muestras biológicas complejas (como proteínas y exosomas) mediante SERS sin usar marcadores. Además de introducir sustratos SERS grandes y baratos, este trabajo también sugiere el desarrollo de escáneres Raman basados en lectores de disco. Otra aproximación presentada en esta tesis aborda la implementación de DBS (diffraction-based sensing) en tecnologías TED, con el fin de desarrollar biosensores para detección sin marcaje basados en discos y lectores convencionales. Primero, se presenta una amplia evaluación experimental de las posibilidades analíticas ofrecidas por DBS. A continuación, se investiga la fabricación de multitud de redes difractivas de proteínas sobre discos TED, con las que se ha demostrado la determinación sensible y sin marcaje de anticuerpos, usando lectores adaptados como escáneres analíticos. Esta investigación introduce avances importantes que apuntan al desarrollo de materiales funcionales y sistemas de detección, baratos e industrialmente escalables, que aprovechen las tecnologías de consumo para realizar biosensado sin marcaje.Aquesta tesi explora nous avanços en la química analítica usant tecnologies de biosensat basades en sistemes de disc compacte, i comprèn sis publicacions científiques distribuïdes en quatre capítols. Els estudis s'han centrat en la tecnologia Thermochromic Etching Disks (TED) (Capítol 1), el disseny racional d'assajos de bioreconeixement en discos compactes (Capítol 2), i la detecció sense marcatge per realitzar anàlisi in situ (Capítols 3 i 4). Primer, dins del marc d'una discussió de l'estat de l'art i tendències futures en biosensat foto i termocròmic, es presenta un nou sistema (basat en discos i lectors TED) per al desenvolupament de senyals mitjançant llum, en assajos de bioreconeixement. Aquesta constitueix una nova estratègia per aprofitar el foto i termocromisme en biosensat, mentre que també presenta una gran potencial per simplificar els processos de desenvolupament de senyal en sistemes bioanalítics. Tot seguit, s'aborda com transformar la tecnologia TED en sistemes analítics integrats basats en discos compactes. TED ha demostrat ser una eina molt versàtil per analitzar, de forma sensible, assajos de bioreconeixement usant plataformes i escàners fàcilment obtinguts a partir de discos i lectors convencionals, respectivament. Un únic disc ha mostrat poder albergar diversos assajos biològicament importants i de distinta naturalesa (micromatrius, cultius cel·lulars, immunofiltració, turbidimetria, etc.), per a ser analitzats de forma sensible a través d'imatges. Pel que fa al disseny racional, es presenta un mètode teòric-experimental (INSEL), basat en models cinètics i de transport de massa, per optimitzar assajos de bioreconeixement i explorar el seu comportament. INSEL s'ha implementat com a una eina in silico que permet caracteritzar biointeraccions amb mínima experimentació, realitzar optimitzacions dirigides cap a objectius particulars definits per l'usuari, i computar l'efecte de variables crítiques de forma senzilla i sense experiments addicionals. En un altre estudi inclòs en aquesta tesi, nanoestructures en forma de solc obtingudes a partir de discos compactes regravables convencionals (CD-R i DVD-R) van ser recobertes amb plata i adaptades per a ser actives en SERS. Aquesta estratègia suposa una alternativa, econòmicament efectiva i industrialment escalable, als substrats SERS típicament usats en bioanàlisi. Aquests materials han mostrat respostes plasmòniques sintonitzables, una amplificació Raman significativa, i han permès analitzar mostres biològiques complexes (com proteïnes i exosomes) mitjançant SERS sense usar marcadors. A més d'introduir substrats SERS grans i barats, aquest treball també suggereix el desenvolupament d'escàners Raman basats en lectors de disc. Una altra aproximació presentada en aquesta tesi aborda la implementació de DBS (diffraction-based sensing) en tecnologies TED, per tal de desenvolupar biosensors basats en discos i lectors convencionals que permeten detecció sense marcatge. Primer, es presenta una amplia avaluació experimental de les possibilitats analítiques que ofereix aquesta tècnica. A continuació, s'investiga la fabricació de multitud de xarxes difractives de proteïnes sobre discos TED, amb les quals s'ha demostrat la determinació sensible i sense marcatge d'anticossos, usant lectors adaptats com a escàners analítics. Aquesta investigació introdueix avanços importants que apunten cap al desenvolupament de materials funcionals i sistemes de detecció, barats i industrialment escalables, que aprofiten les tecnologies de consum per dur a terme bioanàlisi sense marcatge.Avellà Oliver, JM. (2017). Towards label-free biosensing in compact disk technologies f or point-of-need analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86128TESISCompendi

Mechanisms of Condensed Phase Reactions: The Role of Structure, Dynamics, and Environment in Photoisomerization and Photodissociation

Light-activated chemistry begins with the excitation of a ground-state molecule to a higher-lying excited state. Once in the excited state, the nuclei in the molecule respond by trying to minimize the energy of the system. The nuclear motions sometimes propagate along a pathway that facilitates a reaction, such as isomerization or dissociation. However, in the condensed phase, the environment impacts these fundamental dynamics, thereby changing the excitation process and altering the nuclear motions of the molecule. In order to investigate the kinetics and dynamics for a variety of light sensitive systems we use time-resolved pump-probe spectroscopy. Transient optical and x-ray absorption spectroscopy provide valuable insight into the different reactive pathways and fundamental chemistry in light-activated systems. First, we show how spatial confinement for a series of stilbene and azobenzene deivatives profoundly impacts the isomerization dynamics involving large amplitude structural rearrangements of a molecule. This work uses ultrafast spectroscopy to probe the effects of confinement for molecules encapsulated in a supramolecular host-guest complex. The supramolecular complex distorts the ground- and excited-state potential energy surfaces, including the conical intersection connecting those states, which results in hindered nuclear motions and different reactive pathways. For stilbene derivatives, the transient absorption measurements reveal broader excited-state absorption spectra, longer excited-state lifetimes, and reduced quantum yields for isomerization in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central C=C double bond in the excited-state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. Unlike stilbene, azobenzene derivatives also have an in-plane inversion pathway for isomerization, in additon to out-of-plane rotation around the N=N bond. The transient absorption spectroscopy of the encapsulated azobenzene derivative reveals formation of the cis isomer in the excited state after exciting the trans geometry, indicating a direct excited-state isomerization channel that is not observed in solution. The confined environment provides new mechanistic insight on the relative roles of inversion and rotation in the ultrafast photoisomerization of azobenzene derivatives. The solvent affects the photodissociation reactions of manganese tricarbonyl complexes. Interest in manganese tricarbonyl complexes stems from the possible use as earth abundant catalysts for CO2 reduction, but the complexes decompose under visible light. To investigate the photodecomposition of manganese tricarbonyl complexes, we use ultrafast transient absorption spectroscopy and time-resolved x-ray absorption spectroscopy. The optical transient absorption measurement probes the femtosecond relaxation of a metal-to-ligand charge transfer state via back-electron-transfer, which facilitates the loss of a CO ligand to form a 5-coordinate Mn species. The 5-coordinate species has two competing reaction pathways, the first is solvent coordination to form a stable 6-coordinate Mn species and the second pathway involves the 5-coordinate species reducing the starting Mn(I) complex to a Mn(0) species. In order to distinguish between the two pathways, we use a non-coordinating solvent which prevents the formation of the 6-coordinate complex and results in the survival of a 5-coordinate species in solution. Time-resolved x-ray absorption measurements provide structural information about the 5-coordinate and solvent-coordinated manganese species on the picosecond to nanosecond timescale. The combination of optical and x-ray techniques provides new insight into the photodecomposition pathway for manganese tricarbonyl complexes. Finally, we examine the excitation event directly for photochromic molecules in the plasmonic field of an array of gold nanorods. Incident laser light on a gold nanostructure creates an enhanced electric field capable of driving higher-order excitation processes. To investigate the spatial dependence and anisotropy of optical activation in the field surrounding gold nanorods, we use pulsed 800 nm laser light incident on a plasmonic array of gold nanorods to induce an oscillating plasmonic field that interacts with an overlaid film of photochromic molecules through nonlinear two-photon excitation. Following nonlinear excitation, the photochromic molecules isomerize. The enhanced electric field results in a larger fraction of molecules excited in the near-field in comparison with the photochromic molecules outside of the enhanced field. The conversion rate is greatest at the tips of the nanorod where the enhanced electric field is the strongest. However, the observed conversion rate depends on the difference in polarization vectors for the 800 nm and probe light near the nanoparticle surface. The excitation and probe fields have different alignment based on the wavelength-dependence of the plasmonic resonance. Using a simple simulation of the enhanced near-field, we model the conversion of molecules around a single gold nanorod

Low-Toxicity Diacetone Acrylamide-Based Photopolymer For applications in Holography

Photopolymers are fast becoming one of the most popular holographic recording media due to their suitability for a wide range of holographic applications, such as sensors, diffractive optics and data storage. The majority of the investigated water-soluble holographic photopolymers are Acrylamide (AA) based. However, the toxic and carcinogenic nature of AA is a growing concern. In order for photopolymer recording media to be a viable option for holographic applications, efforts must be made to remove any occupational and environmental hazards involved in large-scale material development and device fabrication. The main objective of the work presented here is the development and characterisation of an environmentally friendly photopolymer for holographic applications which uses the non-toxic, non-carcinogenic monomer Diacetone Acrylamide (DA) as a substitute for AA in the photopolymer composition. The new DA photopolymer has been shown to achieve diffraction efficiency values of up to 95 % in transmission mode with refractive index modulation values of 3.5×10-3, and diffraction efficiencies of up to 38 % in the reflection regime with the incorporation of a chain transfer agent and after UV post exposure. Parameters such as shrinkage of the photopolymer layer and rate of polymerisation during the recording process have been quantified. The effect of the incorporation of the additives, namely glycerol and zeolite nanoparticles, on the holographic recording properties of the DA-based material has been investigated. A cytotoxicity comparison between the DA and AA photopolymers has also been carried out. The ability of the new photopolymer material to act as a gas sensor has been demonstrated. For the first time, reflection gratings recorded in the photopolymer have been successfully used as pressure-sensing devices, producing a visible and quantifiable colour change under exposure to different pressures

Stimuli-responsive materials: developing integrated opto-molecular systems as sensors and actuators in micro-fluidic devices

Micro-fluidic platforms have been conferred with inherent optical sensing capabilities by coating the walls of micro-fluidic channels or micro-capillaries with stimuli-responsive materials. These adaptive materials respond optically to environmental stimuli, such as changes in pH, solvent polarity, the presence of certain metal ions and light. This approach confers sensing capabilities along the entire length of the coated micro-channel or micro-capillary. Adaptive coatings based on two types of materials are presented: 1. Conductive polymer polyaniline - The optical properties of these coatings respond to changes in the pH of the solution that is passing through the micro- channel or micro-capillary, and therefore can be used for dynamic pH monitoring (pH 2-8) or for aqueous ammonia sensing. 2. Photochromic spiropyrans - Photoswitchable coatings based on spiropyran are used to photo-detect solvents of different polarity when passing through the micro-capillary in continuous flow. This sensing behaviour can be switched on/off remotely using light. Finally, it is reported, for the first time, the potential of using spiropyran as a pH pump in fluidic channels for photo-activated chemopropulsion of organic droplets and the solvato-morphological control of self-assembled micro-structures based on spiropyran

Étude et réalisation de cristaux photoniques à base de polymère: Applications à l’optique non-linéaire et à l’optique quantique

We have investigated the optical properties of polymer-based photonic crystals and photonic quasicrystals. We have demonstrated a great interest of using quasi-periodic structures to obtain an isotropic photonic bandgap, with material possessing low refractive index. These photonic structures are very promising for different applications, for example, coupling to active particles to enhance the fluorescence or nonlinear signal.We have proposed and implemented new technologies for the fabrication of polymer-based sub-micrometer photonic structures. Two original techniques are successfully demonstrated : i) the multiple-exposure two-beam interference technique, and ii) the direct laser writing based on ultra-low one-photon absorption. Each technique has its own advantages, but they are all simple and low-cost, and allows to realize arbitrary structures in 1D, 2D, and 3D.Besides, we have investigated the linear/nonlinear optical properties of various polymers. In particular, two kinds of polymers, photochromic and azobenzene, with different forms (thin films or micro-structures) are studied in detail, showing different promising applications. The optical and magnetic properties of NV color centers in diamond (bulk or nanocrystal) are also investigated and demonstrated to be very useful. Indeed, it allows to realize a perfectly stable single photon source at room temperature. The optical manipulation of a single electron spin associated to an individual NV center is also demonstrated, showing promising applications such as ultrasensitive magnetic or electric sensor.Finally, we have demonstrated theoretically and experimentally a few techniques to overcome the diffraction limit barrier in an optical microscope, which are useful for super-resolution imaging and fabrication.Les propriétés des cristaux photoniques et quasi-cristaux photoniques sont étudiées théorique- ment et expérimentalement. Nous avons démontré l’intérêt des structures quasi-périodiques en vue de l’obtention d’une bande photonique interdite isotrope avec un matériau de faible indice de réfraction. Ces structures photoniques sont très prometteuses pour améliorer les propriétés optiques des particules actives via un couplage photonique.A cet effet, nous avons mis en œuvre de nouvelles technologies de fabrication pour réaliser des structures photoniques sub-micrométriques 1D, 2D, et 3D à base de matériaux polymères. Les deux techniques originales sont i) l’interférences de deux faisceaux laser avec une exposition multiple et ii) la gravure directe par absorption ultra-faible à un photon. Chaque technique présente ses avantages propres, mais elles sont toutes simples et à faible coût.Nous avons ensuite réalisé des études en optique linéaire et non-linéaire de matériaux poly- mères sous leurs différentes formes (couches minces ou structures), et mis en évidence un vaste choix d’applications intéressantes. Les propriétés optiques et magnétiques des centres colorés NV dans le diamant (massif ou nanocristal) sont également étudiées en détail. Ces centres peuvent déboucher sur plusieurs applications telles que la source de photons uniques à température ambiante, le capteur ultrasensible de champs magnétiques et électriques, ou encore l’informa- tion quantique. Les interactions entre ces matériaux actifs et les structures photoniques sont également étudiées.Finalement, nous avons mis au point théoriquement et expérimentalement quelques tech- niques pour surmonter le problème de la limite de diffraction dans un microscope optique, afin de réaliser une imagerie optique super-résolue