6. Le témoignage d’une organisation d’ouvriers rebelles durant la Révolution culturelle

En juin 1967, alors que la Révolution culturelle battait son plein, Mao Zedong déclarait : « Le contingent des ouvriers à Shanghai est plutôt bon, c’est pourquoi le comité central du Parti ne se fait pas d’inquiétude quant à la situation de la ville. » Si le président Mao pouvait tenir de tels propos, c’est parce que les ouvriers de Shanghai étaient alors représentés par le Quartier général des ouvriers révolutionnaires-rebelles de Shanghai (Shanghai gongren geming zaofan zong siling bu 上海工人革..

Synthesis and electrical properties of fullerene-based molecular junctions on silicon substrate

We report the synthesis and the electrical properties of fullerene-based molecular junctions on silicon substrate in which the highly \pi-conjugated molecule C60 (\pi quantum well) is isolated from the electrodes by alkyl chains (\sigma tunnel barriers). Initially, the Si/SiO2/\sigmaC60 architecture was prepared either by sequential synthesis (3 different routes) or by direct grafting of the presynthesized C60-\sigma-Si(OEt)3 molecule. We described the chemical synthesis of these routes and the physico-chemical properties of the molecular monolayers. Then, the second \sigma tunnel barrier was added on the Si/SiO2/\sigma C60 junction by applying a hanging mercury drop electrode thiolated with an alkanethiol monolayer. We compared the electronic transport properties of the Si/SiO2/\sigma C60//Hg and Si/SiO2/\sigma C60//\sigmaHg molecular junctions, and we demonstrated by transition voltage spectroscopy that the fullerene LUMO - metal Fermi energy offset can be tailored from ~ 0.2 eV to ~ 1 eV by changing the length of the alkyl chain between the C60 core and the Hg metal electrode (i. e. from direct C60//Hg contact to 14 carbon atoms tunnel barrier).Comment: Single pdf file including: main text, figures, tables and supporting information

Fullerene triplet state production and decay: R2PI probes of CGO and in a supersonic beam

Lifetimes of the lowest triplet state of the two most stable fullerenes, Csa and &a, were measured in a supersonic beam by twocolor resonant two-photon ionization. When prepared by intersystem crossing from the singlet manifold, excited at 4.03 eV, these triplet states were found to have lifetimes of 42 and 41 us, respectively. The energies of these triplet states (1.7 and 1.6 eV, respectively) were measured by photoelectron spectroscopy of the corresponding negative ions

Confined Quantum Molecular Degrees of Freedom

Motivated by recent experimental measurements of the degeneracy lifting of the rotational ground state of molecular ortho-H2 con ned inside the fullerene cage C60 and, more generally, motivated by the physics of con ned quantum molecular degree of freedom. By using exact diagonalization we performed a detailed study on the coupled translational and rotational motion of H2 based on the Van der Waals interaction model. We found that degeneracy lifting is caused by a symmetry reduction from Ih to C3i symmetry of C60 in its solid state. The origin of the degeneracy lifting is found to mainly arise from the interaction between H2 and its C60 cage instead of the interaction between the H2@C60 molecule and its neighbouring molecules. The size of the splitting is extremely sensitive to the cage geometry while sitting in a relatively large linear regime. The zero point motion e ect of carbon atoms does not change the size of the splitting. The analytical study also was preformed by using multipole expansion on Lennard-Jones potential in order to gain a more physical perspective on con ned quantum molecular degree of freedom

From hydrocarbons to carbon Nanostructures: a theoretical analysis of surface-catalysed cyclodehydrogenation

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica de la Materia Condensada. Fecha de lectura: 16-12-201

Laserinduzierte NO Desorption von C60 und Graphitoberflächen

In dieser Dissertation wird die NO Desorption von Fullerenoberflächen und Graphitoberflächen untersucht. Die desorbierenden Moleküle werden mit vollständiger Energieauflösung mittels 1+1 REMPI detektiert. Die Desorption von der untersuchten Fullerenoberfläche erfolgt in zwei Kanälen mit unterschiedlichen Geschwindigkeitsverteilungen. Der schnelle Kanal zeigt eine heiße Rotationsverteilung bei sehr niedriger Vibrationsanregung. Im langsamen Kanal weist eine breite Geschwindigkeitsverteilung bei langen Verzögerungszeiten zwischen Desorptions- und Nachweislaser auf eine verspätete Desorption hin. Die Lebensdauer dieser Anregung kann zu etwa 0,125 ms abgeschätzt werden und wird auf langlebige exzitonische Zustände im Fulleren zurückgeführt. Die Desorption von Graphit erfolgt mit einem femtosekunden Laser bei Photonenenergien bis 57 eV. Bei diesem Halbmetall wird sowohl eine heiße Rotationsverteilung als auch eine heiße Vibrationsverteilung der desorbierenden Moleküle beobachtet

Machine learning at the nanoscale

Although scanning probe microscopy (SPM) techniques have allowed researchers to interact with the nanoscale for decades now, little improvement has been made to the incredibly manual, time consuming process of setting up, running, and analysing the results of these experiments, often arising due to the constantly varying shape of the probe apex. Unlike traditional computing methods, machine learning methods (with neural networks in particular) are considerably more capable of automating subjective tasks such as these, and we are only just beginning to explore the potential applications of this technology in SPM. In this thesis we explore a number of areas where machine learning could potentially massively change the way we go about SPM experimentation. We begin by discussing the history, theory, and experimental concepts of scanning tunnelling microscopy (STM), atomic force microscopy (AFM), and normal-incidence-x-ray standing wave (NIXSW). We then explore the makeup of a neural network and demonstrate how they can be applied to a variety of use-cases in SPM, including classification and policy prediction. Moving to the experimental chapters, we first discuss how we can successfully distinguish between STM tip states of the H:Si(100), Au(111) and Cu(111) surfaces. We also show that by adapting this network to work in real time, we improve performance while requiring on the order of 100x less data. We next discuss our attempts to combine these networks with expert examples to intelligently maintain tip apex sharpness during experimentation, envisioning an end-to-end automatic experiment. Because one of the main difficulties in applying machine learning is the frequent need to manually label data, we then show how we can use Monte Carlo simulations of self-organised AFM nanostructures to automatically label training data for a network, and then combine it with classical statistics and preprocessing to find specific structures in a mixed, messy dataset of real, experimental AFM images. As part of this, we also build a network to denoise experimental images. Finally, we present NIXSW results from an investigation into the temperature dependence of H20@C60, discussing the potential to use unsupervised clustering techniques to distinguish between noisy human-indistinguishable spectra to overcome limitations in data collection

ELECTROLYTE- GATED THIN FILM TRANSISTORS WITH SOLUTION- PROCESSED SEMICONDUCTORS

The work in this thesis is concentrated on studies of improving the functionality of electrolyte- gated thin film transistors with solution- processed semiconductors in order to provide a promising platform in particular for sensor as transducers and introduce sensitizer layer on the top of the devices to improve their response to specific analytes. Calixarenes, a family of organic macrocycles, were used to bind selectively to waterborne cations, making them an attractive sensitizer option for such species. Here, it is found that calixarenes deposited over the surface of semiconductors using the Langmuir trough also show a positive impact on the performance of TFTs in terms of reducing unwanted electrochemical doping, which often competes with field effect. Also, electron- transporting and electrolyte- gated thin film transistors were demonstrated using precursor- route zinc- oxide (ZnO) semiconductors with hydrophobic surface modifications. This avoids the well- known problem of electron trapping in organic semiconductors. ZnO also shows ambipolar behavior when gated by an ionic liquid (IL) at high applied voltages. Moreover, it is found some organic solvents may act as EDL gate media for TFTs, thus establishing a new family of gate media, in addition to the previously known options (water, ILs, solid electrolytes). This ability is a property of the solvent, not the semiconductor, and a criterion is identified to qualify an organic solvent to act as EDL gate medium. The organic nano- wire (NW) morphology is attractive for sensor applications, due to the high surface area of NWs. Here, both p- type and n- type organic NW films were gated by water. NW TFTs of the hole- transporting polymer P3HT, grown via different solution- based routes, showed lower drain currents, but also lower thresholds, compared to conventional P3HT film TFTs. Water- gated electron- transporting organic TFTs were demonstrated using nano- belts of the n- type organic semiconductor BBL. Performance was improved significantly when using an aprotic organic solvent as EDL gate medium for BBL nano- belt films

Conférences chinoises de la rue d’Ulm

La référence à la Chine devient de plus en plus fondamentale dans le paysage mondial des sciences humaines et sociales. La construction de ponts reliant les cher­cheurs français à une société et un espace intellectuels trop longtemps réservés à une poignée de sinologues est devenue une exi­gence du moment à laquelle l’université Fudan et le labex TransferS ont souhaité répondre en organisant une série de confé­rences, la première rue d’Ulm, qui présente des regards de chercheurs chinois sur l’histoire, la philosophie, les études religieuses, la littérature, etc. Les professeurs Dai Yan, Ge Zhaoguang, Huang Bei, Huang Yang, Jin Guangyao, Li Hongtu, Li Tiangang, Mo Weimin, Sun Xiangchen, Benoît Vermander, Yu Xin ont accepté de délivrer aux auditeurs de l’Ecole normale supérieure (qui accueille maintenant chercheurs et étudiants chinois) un enseignement conçu non comme une in­troduction à la culture chinoise, mais plutôt comme l’ouverture à un indispensable débat sur des questions communes, un dialogue dont ces conférences se sont voulues le point de départ

Self-Healing Thermoplastic Polyurethane Linked via Host-Guest Interactions

High toughness with self-healing ability has become the ultimate goal in materials research. Herein, thermoplastic polyurethane (TPU) was linked via host-guest (HG) interactions to increase its mechanical properties and self-healing ability. TPU linked via HG interactions was prepared by the step-growth bulk polymerization of hexamethylene diisocyanate (HDI), tetraethylene glycol (TEG), and HG interactions between permethylated amino βCD (PMeAmβCD) and adamantane amine (AdAm). TPU linked with 10 mol% of HG interactions (HG(10)) showed the highest rupture stress and fracture energy (GF) of 11 MPa and 25 MJ·m−3, which are almost 40-fold and 1500-fold, respectively, higher than those of non-functionalized TEG-based TPU (PU). Additionally, damaged HG(10) shows 87% recovery after heated for 7 min at 80 °C, and completely cut HG(10) shows 80% recovery after 60 min of reattachment at same temperature. The HG interactions in TPU are an important factor in stress dispersion, increasing both its mechanical and self-healing properties. The TPU linked via HG interactions has great promise for use in industrial materials in the near future