Institut des
NanoSciences de Paris
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Research

Last updated 03-Jan-2020

Those research topics were developed in close collaborations with various groups worldwide : Yves J. Chabal (University of Texas at Dallas), Philippe Dollfus (Université Paris-Sud), Miquel Salmeron (University of California Berkeley), A-F Lamic-Humblot (chemistry department at UPMC), Sergii Snegir (Kyiv University), François Rochet (chemistry department at UPMC), Thomas Huhn (University of Konstanz, chemistry department), Elke Scheer (University of Konstanz, physics department), Bertrand Busson (University of Paris-Saclay), Anna Proust (Sorbonne Université), Florence Volatron (Sorbonne Université)


(1) Advanced plasmonics with switchable molecules

ANR project PlasmoChrom : collaborative research with Elke Scheer and Thomas Huhn, Germany

Gold nanoparticles exhibit unique optical properties related to their plasmon resonance (LSPR). LSPR under excitation by light, induces a strong resonance of the electrons inside the nanoparticles. We seek using this high-energy electrons (called hot electrons) for enhancing conductive properties of conjugated molecules. We are working in particular with switchable molecules such as diarylethene (Nobel Prize in chemistry 2016) whose morphology and electronic properties can be switched by illumination at the proper wavelength. These molecules can be switched from conductive to insulating molecular wire. The PlasmoChrom project is based on the expertise in three hot topics shared by the three partners of the project : the understanding of electrical transport through metal-molecule-metal junctions, the synthesis of tailored switching molecules, and advanced plasmonics related to the physics of photo-assisted transport.


(2) Chemical control of the electronic properties of gold nanoparticles

Gold nanoparticles can be viewed as extra-small electrodes and help understand how electronic currents can be controlled at the smallest scale at complex interfaces. The unrivalled advantage of gold over any other metals is to remain metallic at the nanoscale, without being modified by oxidation. We are currently investigating how the work function of gold is modified at the nanoscale, how the electric charging of single nanoparticle is controlled by its chemical functionalization.

For example, the number of charges stored by individual nanoparticles was measured in air with KPFM (Kelvin Probe Force Microscopy). Our group has recently purchased a state-of-the-art KPFM (2015). Currently we investigate how the nature of molecules capping gold nanoparticles modifies their electrical properties (work function, charge state).


(3) Functionalization of silicon surfaces with electrically active chemical species

Molecules are self-assembled into monolayers on silicon surfaces with an extreme control so that we can avoid any oxidation of silicon, even at room pressure. We have especially studied the case of Grafted Organic Monolayers (GOM) on oxide-free silicon and have developed a chemistry to graft gold nanoparticles or POM (polyoxometallate). This last aspect is a collaboration with Pr. A. Proust (Sorbonne Université). POM such as PM12O40, with M = W(+VI) or Mo(+VI) are investigated. These POMs can be oxidized or reduced without any geometrical change. In other words, they can store charges at an extremely high density without any changes and have huge application in molecular electronics.


(4) Nanoelectronics, single charge electronics with gold nanoparticles

Go-N-SEE project : Gold Nanoparticles for Single Electron Experiments

Gold nanoparticles serve as ultra-small electron dispensers and make possible the control of electric current with the accuracy of a single electron (Coulomb blockade). The challenge is to fabricate reproducible architectures where gold nanoparticles of diameters between 5 and 10 nm are deposited on top of a GOM molecular layer which plays the role of an insulating layer (tunnel barrier) and which is grafted on a silicon substrate. The experimental study is carried out in ultra-high vacuum with a STM (Scanning Tunnel Microscope).

Read a 3 page summary published in SPIE Newsroom. Gold nanoparticles to drive single-electron currents


(5) Adhesion of individual nanoparticles and its relation with electrical charging

Research in partnership with C. Grisolia (CEA) and F. Gensdarmes (IRSN)

Adhesion of nanoparticles and dust on surfaces is an intricate combination of Van der Waals forces, surface roughness, and electrostatic forces. By using an AFM, we are able to measure adhesion forces of spherical nano- and micro-particles. This fundamental understanding of fundamental interaction is crucial for how metallic dusts or pollutants are released in the atmosphere.


FORMER TOPICS


(6) Former topic : molecular reactivity of silicon surfaces in UHV

We have investigated the mechanism at play when a chemical bond is created between a silicon substrate and some organic molecules (see video 2 « Adsorption of the phenylacetylene », on the video page). This research was carried out in Ultra-High Vacuum (UHV) chambers. Thanks to a tight collaboration with Y. J Chabal at University of Texas at Dallas, we have developed the Grafted Organic Monolayers (GOM) where molecules are bound covalently directly to silicon without no oxide layer. This GOM offers unique electrical properties and has lead to the Go-N-SEE project above.


(7) Former topic : plasmonics, linear and nonlinear optical response of gold nanoparticles

I am interested in understanding how the optical properties due to the plasmon resonance can be used to enhance the sensitivity of nanoparticles to their molecular environment and make them ultra sensitive nano-sensors. The optical probe of the molecules was achieve with Sum Frequency Generation a nonlinear optical spectroscopy. This research was developped in close collaboration with B. Busson and C. Humbert at CLIO-LCP laboratory (University Paris-Saclay).


Highlights published on INSP website (in French) / Faits d’actualités publiés sur le site de l’INSP