Anna Ritcey

Université Laval | ULAVAL · Department of Chemistry

Polydimethylsiloxane (PDMS)/iron oxide magnetic nanoparticle (NP) composites with tailored mechanical properties are prepared for use in magnetically actuated soft devices based on their controlled deformation by the application of an external magnetic field. This investigation reports the synthesis and functionalization of iron oxide NPs, the prep...

We report the development of a new family of deformable mirrors using soft polymeric membranes with embedded magnetic nanoparticles. We measure the performance metrics of such membranes under the influence of voice coil actuators.

Steady state and time-resolved optical properties of alloyed core/doped shell MNxZn1−xSe/ZnSe:Mn²⁺ nanocrystals with x between 0.2 and 1 were studied. The emission from Mn²⁺ ions at ∼580 nm is predominant for higher MnSe mole fractions in the core (higher x). At lower fractions, the ZnSe excitonic emission is also present while the Mn²⁺ emission sh...

The synthesis of AgInTe2 nanocrystals emitting between 1095 nm and 1160 nm is presented. Evolution of the Ag:In:Te ratio shows progressive incorporation of In3+ in Ag2Te, leading to the formation of orthorhombic AgInTe2. When zinc is added to the synthesis, the photoluminescence quantum yield reaches 3.4 %. Electronic supplementary material The on...

Low-polydispersity europium-doped (H3O)Y3F10·xH2O single-crystal nanoparticles can be prepared via a simple reverse microemulsion method. The doping level of the particles can be varied by changing the relative concentration of europium to yttrium in the initial precursor mixture. Doping levels of up to 14 ± 2 at% can be attained without loss of th...

The synthesis of AgInTe 2 nanocrystals emitting between 1095 nm and 1160 nm is presented. Evolution of the Ag:In:Te ratio shows progressive incorporation of In 3+ in Ag 2 Te, leading to the formation of orthorhombic AgInTe 2. When zinc is added to the synthesis, the photoluminescence quantum yield reaches 3.4 %.

Gold nanoparticles (NPs) coated with thiol-terminated polystyrene chains of varying molar mass were added to polystyrene-b-polymethylmethacrylate (PS-b-PMMA) block copolymer monolayers at the air–water interface. Composite films were transferred to solid substrates by the Langmuir–Blodgett technique. For most of the investigated systems, TEM microg...

Near-Infrared (NIR) wavelengths are interesting for many applications such as biological imaging, solar cells and telecommunications. Inorganic semiconductor nanocrystals (NCs) can be used for absorption and emission in the NIR range. These materials are increasingly investigated due to their good photostability and robustness compared to organic f...

We present the synthesis of air-stable AgInSe2 nanocrystals via thermolysis of an Ag-In-thiolate complex followed by an anion exchange reaction. Evolution of the Ag:In:Se ratio with the reaction time demonstrates progressive incorporation of In3+ in β-Ag2Se seeds. While their lattice stays in the metastable orthorhombic crystal structure, the final...

The combination of multinuclear solid-state NMR spectroscopy and powder X-ray diffraction has been applied to characterize the octahedron-shaped crystalline nanoparticle products resulting from an inverse micelle synthesis. Rietveld refinements of the powder X-ray diffraction data from the nanoparticles revealed their general formula to be (H3O)Y3F...

Near-field plasmon coupling between neighboring gold nanoparticles, measured by polarized optical waveguide lightmode spectroscopy, is employed to study the surface self-assembly of alcanethiol-capped gold nanoparticles during solvent evaporation. The waveguide used is a monomode optical fiber half-coupler. The sample is deposited on the surface of...

We discuss here different strategies for making arrays of Au nanoparticles using copolymer templates. Top-down and bottom-up routes are considered and the optical properties of as-prepared Au nanoparticles are discussed and compared to numerical simulations. Potential for applications such as biosensors or strain sensors is also assessed.

The organization of organic-capped gold nanoparticles in PS-b-PMMA monolayers is investigated. The preferred location of the particles within the block copolymer template is found to depend on both nanoparticle size and the length of the aliphatic capping agent. In the case of relatively short ligands, the particles behave as hard spheres and their...

There is provided a process for the preparation of a suspension of magnetic particles in a polar carrier liquid. The process includes the step of: coating the surface of the magnetic particles with an organic ligand having a hydrophilic chain prior to the suspension. For preparing a magnetically deformable mirror, the suspension of magnetic particl...

The investigation of the Localized Surface Plasmon Resonance for plasmonic nanoparticles has opened new perspectives for optical nanosensors. Today, an issue in plasmonics is the development of large scale and low cost devices. We focus here on the Langmuir-Blodgett technique to self-organize gold nanoparticles (~ 7 nm) into rings (~ 60 nm) via pol...

Our investigations of silver selenide colloidal quantum dots, emitting in the biologically important near-infrared region, demonstrate the size-dependence of their optical properties. Ag2Se nanocrystals were prepared in the orthorhombic phase with their average radius varying from 0.95 to 4.7 nm as observed by transmission electron microscopy. The...

We describe the influence of two fluorinated surfactant dopants on the electro-optical modulation of light scattering by near infrared sensitive polymer dispersed liquid crystals, based on multifunctional acrylates. The molecular configuration and droplet morphology of the obtained samples are found to be bipolar. It is shown that the addition of f...

Polystyrene nanoparticles doped with a luminescent europium complex, Eu(tta)(3)phen, are prepared by miniemulsion polymerization. The influence of the complex on the miniemulsion polymerization is investigated by the systematic variation of the initial concentration of Eu(tta)(3)phen from 2 to 7 wt% relatively to styrene. A maximum doping level of...

This article reports an investigation of the mechanism of YF(3) nanoparticle formation in two variants of the reverse microemulsion precipitation method. These two variants involve the addition of F(-), either as a microemulsion or directly as an aqueous solution, to Y(3+) dispersed in nonionic reverse micelles. The two methods yield amorphous and...

Fulgide Aberchrome 670-doped polymer films were studied. Two approaches were considered: photochemical characterization and holographic recording. In PMMA matrix, the closed form presents a maximum of absorption centered at 525 nm upon irradiation at 365 nm. We have determined the photoreaction rate constants kUV and kVIS respectively for the colo...

The apparent circular dichroism arising from the selective reflection of circularly polarized light by cholesteric films of (hydroxypropyl)cellulose is extremely sensitive to residual linear orientation. The introduction of a uniaxially oriented film in the spectropolarimeter beam in front of a liquid crystalline sample may change both the intensit...

The (1)H NMR spectrum of IgepalCO520 in ternary mixtures containing water and cyclohexane shows a complex dependence on water content. This is in part because of rapid exchange between surfactant molecules within the micelles and free surfactant dissolved in the continuous phase. The analysis of this two-state system is further complicated by the f...

This article describes the development of a magnetically deformable mirror composed of a reflective monolayer of silver nanoparticles deposited at the surface of a ferrofluid. In order to be commercially competitive, this mirror must surpass existing technologies with respect to optical performance. Several important characteristics of the mirror,...

This paper reports the use of dynamic light scattering (DLS) to study reverse micelles formed by the water/Igepal CO-520/cyclohexane system over a large range of global compositions. A novel approach for data analysis is presented, based on the realization that micelles of a given size must be in equilibrium with free surfactant of a fixed concentr...

Glass-deposited monolayers of polystyrene-coated gold nanoparticles with controlled interparticle distance have been prepared. Normal incidence extinction spectra show a progressive red shift of the plasmon resonance wavelength as the interparticle gap within the film is reduced. Polarized extinction spectra were measured at in-plane incidence usin...

We present a novel ferrofluid mirror design which will result in an inexpensive adaptive optics element with large stroke for use in ophthalmic imaging.

Ferrofluids can be used to make deformable mirrors having highly interesting characteristics (e.g., extremely large strokes and low costs). Until recently, such mirrors were thought to be restricted to corrections of frequencies lower than 10 Hz , thus limiting their usefulness. We present counterintuitive results that demonstrate that the limiting...

We discuss a new technology that promises large, inexpensive mirrors. We argue that it should be possible to tilt a rotating viscous liquid by perhaps as much as a few tens of degrees. The tilted liquid parabolic surface is used as the support for a thin reflecting metallic film. It may also be possible to use it to support an ultrathin glass mirro...

Stable ferrofluids composed of positively charged magnetic iron oxide nanoparticles coated with 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MOEEAA) are prepared in ethylene glycol. These new ferrofluids exhibit a magnetic response that is equivalent to that found for corresponding citrate stabilized particles. Unlike the uncoated positively charged p...

We report the preparation of metal liquid-like films (MELLFs) of silver nanoparticles stabilized by thiolate surface ligands. These surface films, composed of particles with diameters of about 100 nm, are highly reflective and can be employed in the fabrication of liquid mirrors. A number of different thiols are considered as stabilizing ligands, i...

We present the research status of a deformable mirror made of a magnetic liquid whose surface is actuated by a triangular array of small current carrying coils. We demonstrate that the mirror can correct a 11 microns low order aberrated wavefront to a residual RMS wavefront error 0.05 microns. Recent developments show that these deformable mirrors...

Isotherms of monolayers of poly(ethylene oxide) (PEO) and polystyrene (PS) triblock copolymers spread at the air/water interface were obtained by film balance technique. In a low concentration regime, the PEO segments surrounding the PS cores behave the same way as in monolayers of PEO homopolymers. Langmuir-Blodgett (LB) films prepared by transfer...

Context.We give a progress report on tiltable, nanoengineered, rotating liquid mirrors, which were discussed in previous papers.Aims.We want to develop the technology, improve reflectivities and user-friendliness. The ultimate goal is to demonstrate high-quality liquid mirrors that can be tilted by a few tens of degrees.Methods.We coated hydrophili...

Ferrofluidic mirrors can be used to improve images of structures at the rear of the eye and may be an effective, low cost solution for adaptive optics, perhaps allowing it to become widespread in clinical settings. We use a Hartmann-Shack wavefront reconstruction technique to study the static and dynamic responses of a ferrofluidic mirror. The disp...

Ferrofluid mirrors have the potential to be an inexpensive adaptive optical element which can be used to improve images of structures at the rear of the eye. Their low cost could allow adaptive optics technology to find widespread use in clinical settings. As discussed elsewhere1, their stroke and speed are suitable for correcting the aberrations o...

Ferrofluid mirrors have the potential to be an inexpensive adaptive optical element which can be used to improve images of structures at the rear of the eye. Their low cost could allow adaptive optics technology to find widespread use in clinical settings. As discussed elsewhere1, their stroke and speed are suitable for correcting the aberrations o...

Thiol end-functionalized polystyrene chains have been introduced onto the surface of gold nanoparticles via a two-step grafting-to method. This simple grafting procedure is demonstrated to be efficient for gold nanoparticles of different sizes and for particles initially dispersed in either aqueous or organic media. The method has been applied succ...

The massive amplification of fluorescence signal observed upon hybridization of as few as five DNA molecules into self-assembled structures formed between a cationic polymer and DNA oligonucleotides is investigated. These superlighting polymer-DNA aggregates were studied by fluorescence spectroscopy, static and dynamic light scattering, and zeta po...

We present a new class of magnetically shaped deformable liquid mirrors made of a magnetic liquid (ferrofluid). Deformable liquid mirrors offer advantages with respect to deformable solid mirrors: large deformations, low costs and the possibility of very large mirrors with added aberration control. They have some disadvantages (e.g. slower response...

Gold nanoparticles with shapes which varied from spheres to multipods and polygons were prepared with a seedless approach in water/methanol mixtures in the presence of polyvinyl alcohol using sodium ascorbate as the reducing agent. The shape of Au nanoparticles is critically affected by the water/methanol ratio, as well as by the ratio of hydrogen...

We give a progress report on an application of a new class of versatile optical elements pioneered by our laboratory: By coating liquids we create reflective surfaces that can be shaped by rotation into a parabolic mirror. Coated ferrofluids can also be shaped with magnetic fields. Low cost is what makes rotating mercury LM Telescopes interesting....

We give a progress report on a new class of versatile optical elements pioneered by our laboratory. By coating ferromagnetic liquids we create reflective surfaces that can be shaped with magnetic fields, allowing us to make complex wavefronts that can vary rapidly in time. This new technology is capable of achieving complex surfaces that cannot be...

A magnetic liquid mirror based on ferrofluids was demonstrated. Magnetic liquid mirrors represent a major departure from solid mirror technology. They present both advantages and disadvantages with respect to established technologies. Stroke (from a fraction of a wave to several hundreds of micrometers), cost (a few dollars per actuator), and scala...

Surface films of organically coated silver nanoparticles, when supported by a liquid substrate, exhibit properties of interest for the fabrication of a new class of liquid mirrors. The development of such mirrors clearly requires the optimization of film reflectivity and stability. The present article reports the dependence of film reflectivity on...

Optical aberrations reduce the imaging quality of the human eye. In addition to degrading vision, this limits our ability to illuminate small points of the retina for therapeutic, surgical or diagnostic purposes. When viewing the rear of the eye, aberrations cause structures in the fundus to appear blurred, limiting the resolution of ophthalmoscope...

Yttrium fluoride nanoparticles of varying crystallinity, shape, and size are prepared by precipitation in reverse microemulsions of water in cyclohexane stabilized with polyoxyethylene isooctylphenyl ether. YF 3 particles obtained by the classical microemulsion method are found to be monodisperse amorphous spheres, with controllable diameters betwe...

We discuss a new type of deformable mirror made from nanoengineered reflective layers deposited onto liquids. The surfaces are shaped by heating with a laser. The response times of the deformed surfaces are slow (>1 s). Simplicity and low cost appear to be the main advantages of thermally deformable liquid mirrors.

In this work, the temperature and pressure dependent growth of domains in DMPC/DSPC monolayers at various molar ratios was studied by Brewster angle microscopy. Upon compression, roughly discoidal domains with some branching are formed. Further compression leads to an increase in both the number and the average size of the domains, which range betw...

The trend towards ever larger telescopes and more advanced adaptive optics systems such as multi-conjugate adaptive optics is driving the need for deformable mirrors with a large number of low cost actuators. Other applications require strokes larger than those readily available from conventional mirrors. Magnetically deformable liquid mirrors are...

The trend towards ever larger telescopes and more advanced adaptive optics systems such as multi-conjugate adaptive optics is driving the need for deformable mirrors with a large number of low cost actuators. Other applications require strokes larger than those readily available from conventional mirrors. Magnetically deformable liquid mirrors are...

Langmuir-Blodgett films of a series of cellulose ethers are investigated by X-ray and neutron reflectometry. Two types of samples are considered: simple alkyl ethers of cellulose and derivatives obtained by the alkylation of (2-hydroxypropyl)cellulose (HPC). All of the cellulose ethers form stable monolayers at the air-water interface. Significant...

Polyion complexes formed by monolayers of quaternary ammonium amphiphiles containing the 4-nitro-4'-alkoxy azobenzene chromophore spread at the surface of aqueous solutions of a number of anionic polyelectrolytes were investigated. In general, pi-A isotherms were found to depend on the nature of the polyion present in the subphase, with monolayers...

Polyion complex formation at the air−water interface between carboxymethylcellulose and a series of triethylammonium-functionalized amphiphiles containing the 4-nitro-4‘-alkoxy azobenzene chromophore has been investigated. Surface pressure−area isotherms are found to exhibit a systematic dependence on subphase concentration up to a certain critical...

We describe a new technology for the fabrication of inexpensive high-quality mirrors. We begin by chemically producing a large number of metallic nanoparticles coated with organic ligands. The particles are then spread on a liquid substrate where they self-assemble to give optical quality reflective surfaces. Since liquid surfaces can be modified b...

We describe a technology for the fabrication of inexpensive and versatile mirrors through the use of a new type of nanoengineered optical material composed by the spreading of a self-assembling reflective colloidal film spread at the surface of a liquid. These new reflecting liquids offer interesting possibilities for astronomical instrumentation....

In this paper we present preliminary results on a new type of optical material. By combining a thin reflective colloidal film with a superparamagnetic liquid known as a ferrofluid, it is possible to produce an optical quality surface that can be shaped by the application of a magnetic field. Ferrofluids are colloidal suspensions of nanometer-sized...

The trend towards ever larger telescopes and more advanced adaptive optics systems is driving the need for deformable mirrors with a large number of low cost actuators. Liquid mirrors have long been recognized a potential low cost alternative to conventional solid mirrors. By using a water or oil based ferrofluid we are able to benefit from a stron...

Fulgide Aberchrome 670-doped polymer films are studied. The closed form of this chromophore presents a maximum of absorption centered at about 525 nm and is formed upon irradiation of its colorless open form at 365 nm. We have determined the photoreaction rate constants, kUV and kVIS, respectively, for the coloring and bleaching processes. It was f...

We present optical alignment studies of pure nematic liquid crystals using photoisomerisable Langmuir-Blodgett (LB) alignment layer. Monolayers of azobenzene-containing molecules exhibiting long lifetime for cis isomer are transferred on glass substrates using the Langmuir-Blodgett deposition technique. The anchoring produces homeotropic texture an...

Photochemical characterization and holographic recording of fulgide Aberchrome 670 and 540-doped polymethyl methacrylate (PMMA) were investigated. Upon UV and visible exposure, closed-form absorbency followed first-order kinetic. The real time holographic recording in fulgides doped PMMA films were studied. The effect of dye concentration, thicknes...

The photoexcitation, relaxation, and optical erasure regimes of spiropyran- (SP-) doped polymer films were studied. Cellulose acetate, poly(vinyl acetate), and poly(methyl methacrylate) (PMMA) were used as host polymer matrices. We studied the character of the photoreaction for both coloring and bleaching processes. Reversible holographic recording...

The behavior of Langmuir monolayers of octadecyl-substituted preformed polyimide molecules exhibits a strong dependence on temperature when the isotherms are measured using a Wilhelmy balance. This suggests a change in structure with temperature, though isotherms measured with a Langmuir balance change only modestly with temperature. Brewster angle...

The photo excitations of Spiropyran-doped polymer films were studied. Cellulose acetate (CA), commercial ploy(methyl methacrylate) (PMMA) and PMMA prepared by radical polymerisation of MMA, were used as host polymer matrices. The open form of SP presents a maximum of absorption cantered at about 600 nm upon UV irradiation. We have determined the ph...

The monolayer-forming capabilities of a tertiary amine-capped dialkyloxy biphenyl mesogen at the air-water interface were studied. It was found that stable monolayers are obtained in the presence of a water-soluble polymer in the subphase, notably the sodium salt of carboxymethylcellulose. Furthermore, the formation of a surface-adsorbed polymer la...

Spread monolayers of cellulose derivatives containing side chain carbazole chromophores are investigated. Structural parameters, such as side chain length and the degree of carbazole substitution, are systematically varied. At lower carbazole content, surface pressure-area isotherms exhibit a liquid analogous phase at molecular areas similar to tho...

Mercury liquid mirror telescopes work. This ia by now a well-established fact. However they suffer from a major limitation: they cannot be tilted. We have recently proposed that liquid mirrors can be tilted by several tens of degrees, provided one can develop a high-viscosity liquid having a high coefficient of reflectivity. The technology promises...

Mercury liquid mirror telescopes work. This ia by now a well-established fact. However they suffer from a major limitation: they cannot be tilted. We have recently proposed that liquid mirrors can be tilted by several tens of degrees, provided one can develop a high-viscosity liquid having a high coefficient of reflectivity. The technology promises...

The photoinduced reversible color change and in-situ recording of fulgide Aberchrome 670 doped polymethyl methacrylate (PMMA), cellulose acetate (CA) and polystyrene (PS) were investigated. Upon UV and visible exposure, closed-form absorbency followed first-order kinetic. The rate constants KUV and KVIS for respectively the coloring and bleaching p...

Cellulose ethers containing alkyl side chains of varying length were prepared from (2-hydroxypropyl)cellulose and alkyl bromides. Two different synthetic methods were employed. The average degree of alkyl substitution of the product polymers ranges from 1.8 to 2.8, as determined from 1H NMR spectroscopy. Surface pressure−area isotherms recorded for...

Cellulose derivatives containing long hydrocarbon side chains and the carbazole chromophore are prepared. N-4′-Bromobutylcarbazole is first synthesized from carbazole and 1,4-dibromobutane. Alkylated carbazole is then reacted with cellulose acetate in dimethyl sulfoxide solution to produce cellulose ethers containing the desired chromophore. Polyme...

Brewster angle microscopy, interfacial stress rheometry, and Π−A isotherm measurements are employed to characterize spread monolayers of two new cellulose derivatives, one containing octadecyl side chains, the other p-nitroaniline substituents. Similar monolayer phase behavior is found in both cases. At high surface area, a liquid phase is observed...

Cellulose acetate films doped with the azo dye Disperse Red 1 were prepared by dip coating. This matrix provides holograms of comparable efficiency for gratings recorded by intensity and polarization modulations. We used this matrix to store and successfully reconstruct the polarization state of an elliptically polarized object beam. A single plane...

We discuss a new technology that promises large inexpensive mirrors. We argue that it should be possible to tilt a rotating viscous liquid by perhaps as much as a few tens of degrees. The tilted liquid parabolic surface is used as the support for a thin reflecting metallic film. We demonstrate two critical steps: that a viscous liquid mirror can be...

One method for determining the nonlinear characteristics of materials consists of the study of Langmuir-Blodgett (LB) films prepared by the deposition of oriented monolayers on a glass substrate. When a powerful laser beam illuminates the substrate, two beams of second harmonic signal are generated, one originating from each of the substrate surfac...

Molding and direct-polymerization techniques are used for the fabrication of holographic materials based on dye-doped poly(methyl methacrylate). The thickness of the samples obtained ranges from several micrometers to several millimeters. Pump-signal cross modulation is studied experimentally, and photophysical mechanisms responsible for refractive...

Dynamic holography and cross modulation techniques are used to study a new photosensitive polymeric material, cellulose acetate doped with the azo-dye DR1. This allowed the identification of the principal photophysical mechanisms involved in the resonant photoexcitation processes. Angular hole burning and reorientation mechanisms are used to write...

Spread monolayers of a cellulose alkyl ether (HPC-C16) have been investigated at the air/water interface by polarisation modulation infrared reflection–absorption spectroscopy (PM-IRRAS). Infrared spectra exhibit bands associated with the symmetric and anti-symmetric methylene stretching vibrations, as well as with the methylene scissoring vibratio...

Infrared external reflectance spectra of a Langmuir−Blodgett film of cadmium arachidate deposited on a glass substrate were recorded for s- and p-polarized radiations at different angles of incidence from 20 to 80°. The peak intensity of the asymmetric CH2 and COO- stretching bands was measured on the difference (ΔR) and the normalized (ΔR/R) spect...

Aliphatic ethers of cellulose are found to form stable monolayers when spread from dilute chloroform solution at the air−water interface. Monolayer pressure−area isotherms exhibit a liquid analogous phase followed by a transition region of relatively high compression at constant pressure. Limiting molecular areas are found to depend on side-chain l...

Polarization-modulated reflection−absorption spectroscopy (PM-IRRAS) is employed to record infrared spectra of a monolayer of (dodecyl)cellulose spread at the air−water interface. Methylene symmetric and antisymmetric stretches of the alkyl side chains are clearly visible in the monolayer spectra as positive peaks at 2852 and 2922 cm-1. It is thus...

Fluorescence emission spectra are recorded for Langmuir-Blodgett (LB) films prepared from cellulose derivatives containing carbazole as a sidechain substituent. Three samples of differing carbazole content are considered. At low carbazole content, only the fluorescence characteristic of monomeric carbazole emission is observed. Clear excimer emissi...

The method of variable angle x-ray photoelectron spectroscopy has been applied to transferred monolayers of a new cellulose derivative. The results support a model for the monolayer in which the cellulose backbone lies flat on the substrate and the sidechains extend perpendicular to the surface. Furthermore, a significant portion of the substrate s...

Highly substituted cellulose ethers containing the carbazole moiety as a side chain substituent were prepared from cellulose acetate, alkyl bromides and N-(bromoalkyl) carbazoles in NaOH/DMSO. Two specific samples are discussed. The first is designated as (dodecyl)2.3(N-4-carbazolylbutyl)0.7 cellulose, where the subscripts correspond to the average...