Catégorie : Collaborations

Abstract : The behavior of shear-oscillated amorphous materials is studied using a coarse-grained model. Samples are prepared at different degrees of annealing and then subjected to athermal and quasi-static oscillatory deformations at various fixed amplitudes. The steady-state reached after several oscillations is fully determined by the initial preparation and the oscillation amplitude, as seen from stroboscopic stress and energy measurements. Under small oscillations, poorly annealed materials display shear-annealing, while ultra-stabilized materials are insensitive to them. Yet, beyond a critical oscillation amplitude, both kinds of materials display a discontinuous transition to the same mixed state composed of a fluid shear-band embedded in a marginal solid. Quantitative relations between uniform shear and the steady-state reached with this protocol are established. The transient regime characterizing the growth and the motion of the shear band is also studied.

Chen Liu 1 Ezequiel Ferrero 2 Eduardo Jagla 2 Kirsten Martens 3 Alberto Rosso 4 Laurent Talon 5
1 LPTENS – Laboratoire de Physique Théorique de l’ENS [École Normale Supérieure]
2 Centro Atómico Bariloche [Argentine]
3 LIPhy – Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères]
4 LPTMS – Laboratoire de Physique Théorique et Modèles Statistiques
5 FAST – Fluides, automatique, systèmes thermiques

Abstract : We study a chain of spinless fermions with a multimer hopping term which kinematically favors the formation of multimers and competes with single-particle hopping. We argue that this model generically stabilizes two different multimer phases, as well as intermediate phases where the free-fermion and multimer fluids coexist and do not spatially separate. Using density-matrix renormalization group techniques, we establish the phase diagram of the model in the case of trimers. For one of the intermediate phases, hybridization between the fermions and trimers liquids does occur and the onset of their correlations is well captured by a generalized BCS-like ansatz. The case of tetramers is finally addressed.

Auteurs

Lorenzo Gotta 1 Leonardo Mazza 1 Pascal Simon 2 Guillaume Roux 1

1 LPTMS – Laboratoire de Physique Théorique et Modèles Statistiques

2 LPS – Laboratoire de Physique des Solides

Abstract : We have studied the formation of ultracold RbSr molecules with laser pulses. After discussing the advantages of the Mott insulator phase for the control with pulses, we present two classes of strategies. The first class involves two electronic states. Two extensions of stimulated Raman adiabatic passage (STIRAP) for multilevel transitions are used: alternating STIRAP (A-STIRAP) and straddle STIRAP (S-STIRAP). Both transfer dynamics are modeled and compared. The second class of strategies involves only the electronic ground state and uses infrared (IR) and terahertz (THz) pulses. The molecular bond is first created by the application of a THz chirped pulse or π-pulse. Subsequently, the molecules are transferred to their rovibrational ground level using IR pulses. For this last step, different optimized pulse sequences that were obtained through optimal control techniques have been studied. The relative merits of these strategies in terms of efficiency and robustness are discussed with respect to the experimental feasibility based on present laser technologies.

Adrien Devolder 1 Michèle Desouter-Lecomte 2 Osman Atabek 3 Eliane Luc-Koenig 1 Olivier Dulieu 1
1 LAC – Laboratoire Aimé Cotton
2 ICP – Institut de Chimie Physique
3 ISMO – Institut des Sciences Moléculaires d’Orsay

R. Hahn A. Trimeche 1 Colin Lopez 2 D. Comparat 1 Y. Picard
1 LAC – Laboratoire Aimé Cotton
2 LuMIn – Laboratoire Lumière, Matière et Interfaces

Abstract : Drug nanocarriers (NCs) with sizes usually below 200 nm are gaining increasing interest in the treatment of severe diseases such as cancer and infections. Characterization methods to investigate the morphology and physicochemical properties of multifunctional NCs are key in their optimization and in the study of their in vitro and in vivo fate. Whereas a variety of methods has been developed to characterize “bulk” NCs in suspension, the scope of this review is to describe the different approaches for the NC characterization on an individual basis, for which fewer techniques are available. The accent is put on methods devoid of labelling, which could lead to artefacts. For each characterization method, the principles and approaches to analyze the data are presented in an accessible manner. Aspects related to sample preparation to avoid artefacts are indicated, and emphasis is put on examples of applications. NC characterization on an individual basis allows gaining invaluable information in terms of quality control, on: i) NC localization and fate in biological samples; ii) NC morphology and crystallinity; iii) distribution of the NC components (drugs, shells), and iv) quantification of NCs’ chemical composition. The individual characterization approaches are expected to gain increasing interest in the near future.

Maeva Chaupard 1, 2 Marta de Frutos 1 Ruxandra Gref 2
1 LPS – Laboratoire de Physique des Solides
2 ISMO – Institut des Sciences Moléculaires d’Orsay

Abstract : Recently developed, nanoscale metal-organic frameworks (nanoMOFs) functionalized with versatile coatings are drawing special attention in the nanomedicine field. Here we show the preparation of core–shell MIL-100(Al) nanoMOFs for the delivery of the anticancer drug doxorubicin (DOX). DOX was efficiently incorporated in the MOFs and was released in a progressive manner, depending on the initial loading. Besides, the coatings were made of biodegradable γ-cyclodextrincitrate oligomers (CD-CO) with affinity for both DOX and the MOF cores. DOX was incorporated and released faster due to its affinity for the coating material. A set of complementary solid state nuclear magnetic resonance (ssNMR) experiments including1H-1H and13C-27Al two-dimensional NMR, was used to gain a deep understanding on the multiple interactions involved in the MIL-100(Al) core–shell system. To do so,13C-labelled shells were synthesized. This study paves the way towards a methodology to assess the nanoMOF component localization at a molecular scale and to investigate the nanoMOF physicochemical properties, which play a main role on their biological applications.

Xue Li 1 Marianna Porcino 2 Jingwen Qiu 1 Doru Constantin 3 Charlotte Martineau-Corcos 4, 2, * Ruxandra Gref 1, *
* Auteur correspondant
1 ISMO – Institut des Sciences Moléculaires d’Orsay
2 CEMHTI – Conditions Extrêmes et Matériaux : Haute Température et Irradiation
3 LPS – Laboratoire de Physique des Solides
4 ILV – Institut Lavoisier de Versailles

bstract : In recent years, Metal-Organic Frameworks (MOFs) have attracted a growing interest for biomedical applications. The design of MOFs should take into consideration the subtle balance between stability and biodegradability. However, only few studies have focused on the MOFs’ stability in physiological media and their degradation mechanism. Here, we investigate the degradation of mesoporous iron (III) carboxylate MOFs, which are among the most employed MOFs for drug delivery, by a set of complementary methods. In situ AFM allowed monitoring with nanoscale resolution the morphological, dimensional, and mechanical properties of a series of MOFs in phosphate buffer saline and in real time. Depending on the synthetic route, the external surface presented either well-defined crystalline planes or initial defects, which influenced the degradation mechanism of the particles. Moreover, MOF stability was investigated under different pH conditions, from acidic to neutral. Interestingly, despite pronounced erosion, especially at neutral pH, the dimensions of the crystals were unchanged. It was revealed that the external surfaces of MOF crystals rapidly respond to in situ changes of the composition of the media they are in contact with. These observations are of a crucial importance for the design of nanosized MOFs for drug delivery applications.

Ioanna Christodoulou 1 Tom Bourguignon 1 Xue Li 1 Gilles Patriarche 2 Christian Serre 3 Christian Marlière 4 Ruxandra Gref 1
1 ISMO – Institut des Sciences Moléculaires d’Orsay
2 C2N – Centre de Nanosciences et de Nanotechnologies
3 IMAP – Institut des Matériaux Poreux de Paris
4 LPS – Laboratoire de Physique des Solides

Abstract : Noble metal nanoparticles exhibit localized plasmon resonance modes that span the visible and near-infrared spectral ranges and have many applications. Modifying the size, shape, and composition of the nanoparticles changes the number of modes and their properties. The characteristics of these modes are transiently affected when illuminating the nano-objects with ultrashort laser pulses. Here, we synthesize core-shell gold-silver nanocuboids and measure their spectral signature in the stationary and ultrafast transient regimes. Their dipolar transverse mode vanishes with increasing Ag-shell thickness, while higher-order modes grow in the near-ultraviolet range where no plasmon resonance can be generated with single noble metal nanoparticles. These higher-energy modes are associated with sharp spectral variations of the ultrafast transient light extinction by the bimetallic nanocuboids. By carrying out a theoretical investigation, we break down the different contributions to this response.

Tadele Orbula Otomalo 1 Lorenzo Di Mario 2 Cyrille Hamon 3 Doru Constantin 3 Khanh-Van Do 1 Patrick O’Keeffe 2 Daniele Catone 2 Alessandra Paladini 2 Bruno Palpant 1
1 LuMIn – Laboratoire Lumière, Matière et Interfaces
2 CNR-ISM – Istituto di Struttura della Materia
3 LPS – Laboratoire de Physique des Solides

Abstract : Quasi two-dimensional hybrid organic-inorganic perovskites (HOIPs) have been rediscovered recently for photovoltaics due to a higher stability than other HOIPs. We focus here on the electronic structure of the 2D perovskite (C6H5C2H4NH3)2PbI4. We perform an experimental k-resolved determination of the valence and conduction bands by angle-resolved photoemission spectroscopy (ARPES) and inverse photoemission spectroscopy (IPES). The experimental and theoretical dispersions are compared. The valence band width is in agreement with that of renormalized theoretical bands, while no significative renormalization is observed for the conduction band. The effect of the spin-orbit coupling in the conduction band is also experimentally observed.

Min-I Lee 1 Saleem Ayaz Khan 2 Hela Mrezguia 3 Ana Barragán 1 Maya N Nair 1, 4 Hamza Khelidj 3 Younal Ksari 3 Luca Giovanelli 3 Jean-Marc Themlin 3 Ferdinand Lédée 5 Gaëlle Trippé-Allard 5 Emmanuelle Deleporte 5 Amina Taleb-Ibrahimi 4 Ján Minár 2 Antonio Tejeda 1
1 LPS – Laboratoire de Physique des Solides
2 University of West Bohemia [Plzeň ]
3 IM2NP – Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
4 SSOLEIL – Synchrotron SOLEIL
5 LuMIn – Laboratoire Lumière, Matière et Interfaces