Search results for "surface plasmon"

Protein-membrane interaction probed by single plasmonic nanoparticles.

2008

We present a nanosized and addressable sensor platform based on membrane coated plasmonic particles and show unequivocally the covering with lipid bilayers as well as the subsequent detection of streptavidin binding to biotinylated lipids. The binding is detected on membrane covered gold nanorods by monitoring the spectral shift by fast single particle spectroscopy (fastSPS) on many particles in parallel. Our approach allows for local analysis of protein interaction with biological membranes as a function of the lateral composition of phase separated membranes.

Reactive Surface Coatings Based on Polysilsesquioxanes: Controlled Functionalization for Specific Protein Immobilization

2009

The key designing in reliable biosensors is the preparation of thin films in which biomolecular functions may be immobilized and addressed in a controlled and reproducible manner. This requires the controlled preparation of specific binding sites on planar surfaces. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylates) (PMSSQ-PFPA) are promising materials to produce stable and adherent thin reactive coatings on various substrates. Those reactive surface coatings could be applied onto various materials, for example, gold, polycarbonate (PC), poly(tetrafluoroethylene) (PTFE), and glass. By dipping those substrates in a solution of a desired amine, specific binding sites for protein ads…

Disclosing of optical properties of metal/dielectric heterostructures by Spectroscopic Ellipsometry enhanced by Surface Plasmon Resonance

2013

Absence of mutual polariton scatterings for strongly coupled surface plasmon polaritons and dye molecules with large Stokes shift

2013

The understanding and control of the dynamics of hybrid modes consisting of strongly coupled surface plasmon polaritons and molecular excitations of dye molecules is of great timely interest, as it allows one to tailor interactions between optical signals as needed for active all-optical devices. Here we utilize dye molecules with an especially large Stokes shift to demonstrate the absence of mutual scatterings among the strongly coupled hybrid modes. We employ a quantum mechanical three-level model and show that the hybrid modes decay via dephasing and internal relaxation of the molecules to a fluorescing state of the dye, which can be used as a measure for the decay. Our results provide e…

Surface plasmon interference fringes in back-reflection

2010

We report the experimental observation of surface plasmon polariton (SPP) interference fringes with near-unity visibility and half-wavelength periodicity obtained in back reflection on a Bragg mirror. The presented method based on leakage radiation microscopy (LRM) represents an alternative solution to optical near-field analysis and opens new ways for the quantitative analysis of SPP fringes. With LRM we investigate various SPP interference patterns and analyze the high reflectivity of Bragg mirror in comparison with theoretical models.

Equilibrium coverage fluctuations: a new approach to quantify reversible adsorption of proteins.

2005

Cavités plasmoniques et nanosources optiques

2013

Optical microcavities exhibit high resonance quality, so that, they are of key interest for the design of low-threshold lasers or for achieving strong coupling regime. But, such systems support modes whose the volume remain diffraction limited.In this manuscript, we are interested in their plasmonic counterparts because they support confined modes at the sub-wavelength scale. First, we study an in-plane plasmonic cavity which is the transposition of 1D optical cavity to surface wave. We characterize the cavity by measuring the fluorescence lifetime of dye molecules deposited inside.Then, we are interested in 3-dimension mode confinement achieved by spherical metal nanoparticles. We discuss …

Study of the dynamics of biomolecules by high speed atomic force microscopy and surface enhanced Raman spectroscopy

2015

This thesis focuses on the coupling of High–Speed Atomic Force Microscopy (HS-AFM) and Surface Enhanced Raman Spectroscopy (SERS) for biomolecule analysis. We have designed a fabrication protocol to manufacture “SERS-active” substrates. The efficacy of gold, silver and gold-silver bimetallic crystalline nanoparticle substrates were evaluated. We have investigated the impact of optical and morphological features of the substrates on Raman signal intensity by analyzing well-known samples such as bipyridine ethylene and methylene blue molecules. We took an interest in three distinct biological problematics with HS-AFM and SERS analyses. First, we have detected the chemical signature of cytochr…

Optical near-field distributions of surface plasmon waveguide modes

2003

International audience; Thin gold stripes, featuring various widths in the micrometer range, were microfabricated to obtain surface-plasmon guides on a glass substrate. Each metal stripe (MS) was excited by an incident surface-plasmon polariton which was itself launched on an extended thin gold film by the total internal reflection of a focused beam coming through the substrate. The optical near-field distributions of the surface-plasmon (sp) modes sustained by the stripes were then recorded using a photon scanning tunneling microscope (PSTM). For a fixed frequency of the incident light, these field distributions are found to depend on the widths of the stripes. We first provide an experime…

Determination of the spatial extension of the surface-plasmon evanescent field of a silver film with a photon scanning tunneling microscope.

1993

A photon scanning tunneling microscope is employed to probe the surface-plasmon field in the evanes- cent region of a silver film for p (parallel to the plane of incidence) and s (perpendicular to the plane of incidence) polarizations of the light beam at several angles of incidence near the critical angle. The in- teraction between the field and the probe is measured and compared to theoretical calculations involving a single four-media model. A systematic analysis of images obtained for several positions of the optical fiber above the film is presented and it is shown that, for tip-to-sample distances smaller than half the wavelength of the incoming light, the collected intensity curves a…