Field emission measure of the time response of individual semiconducting nanowires to laser excitation

International audienceA simple technique is explored to determine the temporal photo-response, s, of individual semiconducting SiC and Si nanowires (NWs), with a high time resolution. Laser-assisted field emission (LAFE) from the NWs is first shown to be highly sensitive to continuous laser illumination. Pulsed illumination is then combined with measurements of the total energy distributions to determine s which were rather large, 4-200 ls. The time response scaled roughly with the square of the NWs length and could be attributed to laser-induced heating. LAFE is thus a new tool for quantifying rapid thermo-optical effects in such nano-objects

An introduction to schoenberg's approximation

AbstractFor a given function B and a non-zero real number h, Schoenberg's approximation defines from some data (jh, yj)jϵZd the function ΣjϵZd yj B(•h − j). For people not used to this kind of approximation, this paper intends to do a summary of the main definitions, properties and utilizations of Schoenberg's approximation: we show that the main tool to handle Schoenberg's approximation is the Fourier transform of B and even more its modified version, the transfer function of B; we give conditions for convergence of ΣjϵZd f(jh) B(•h − j) when h tends to zero, and we give various ways to define various B as combinations of translates of some function ϕ (usually ϕ is either some radial function, or obtained by a tensor product of some radial function), depending on the properties we want for the associated Schoenberg's approximation. Last, we show how multi-resolution analysis, subdivision techniques, and wavelets techniques, are nicely connected to Schoenberg's approximation

Single-electron transistor made of multiwalled carbon nanotube using scanning probe manipulation

We positioned semiconducting multiwalled carbon nanotube, using an atomic force microscope, between two gold electrodes at SiO2 surface. Transport measurements exhibit single-electron effects with a charging energy of 24 K. Using the Coulomb staircase model, the capacitances and resistances between the tube and the electrodes can be characterized in detail.Peer reviewe

Structure and vibrational properties of single wall carbon nanotubes

We report on some Raman measurements of single wall carbon nanotubes (SWNT) prepared by laser ablation (LA) or electric arc discharge (EA). We correlate the Raman features with structural information and discuss the resonance behaviour of the Raman signal in terms of a distribution of tubes diameters and symmetries.Peer reviewe

Raman characterization of singlewalled carbon nanotubes and PMMA-nanotubes composites

The Raman spectroscopy have allowed us to perform studies on singlewalled nanotubes (SWNT's) produced by following methods: electric arc, laser ablation and solar energy. As this characterization method provides a great deal of informations, we will present a comparison between the nanotubes produced by all these processes and the influence of some synthesis parameters. By using spin casting, we have produced thin films of PMMA-SWNT's for different concentrations. Then, we have characterized these new materials by Raman spectroscopy. The aim of these investigations is to get information on the possible interactions between these two materials. In particular, we have studied the evolution of the composites films spectra as a function of the nanotubes concentration in the polymer.This work has been fully supported by the European Community through its Training and Mobility of Researcher program under network contract : NAMITECH, ERBFMRX- CT96-0067 @GlZ-MIHT) and by the tiench CNRS program : ULTIMATECH.Peer reviewe

Production of carbon nanotubes

International audienc

Etude comparative de la fiabilité et de la stabilité des régulateurs de débit pour perfusion par gravité

CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Rôle du médecin généraliste dans le diagnostic et le suivi des maladies rares (exemples des vascularites systémiques (étude rétrospective monocentrique))

CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

L'atelier de reliure et de restauration des Archives de la Drôme

Nathan Tilloy Michèle, Journet Catherine. L'atelier de reliure et de restauration des Archives de la Drôme. In: La Gazette des archives, n°155, 1991. Préservation et restauration des documents sur papier (actes de la journée d’études de l’AAF, Paris, 24 janvier 1991) pp. 321-327

Atomic layer deposition of stable 2D materials

International audienc