Nouveauté : Toutes les publications par laboratoires de l’UFR de chimie regroupées
dans la collection hal.sorbonne-universite.fr/CHIMIE-SU
Vibrational Spectra and Structures of Ti-N2O and OTi-N2: A Combined IR Matrix Isolation and Theoretical Study
Abstract: The reaction of atomic titanium with nitrous oxide has been reinvestigated using matrix isolation in solid neon coupled to infrared spectroscopy and by quantum chemical methods. Our technique of sublimation of Ti atoms from a filament heated at about 1500 °C allowed the formation of three species: one Ti–N2O pair of van der Waals (vdW) type characterized by small red shift with respect to N2O monomer, and two isomers of OTi–N2 pair where N2 is in interaction with the OTi moiety either with end-on or side-on structure...
Synthesis of Silver Nanoparticles Using Different Silver Phosphine Precursors: Formation Mechanism and Size Control
Abstract: Silver nanoparticles (AgNPs) ranging from 2.5 to 7.1 nm in diameter with a narrow size distribution are prepared by reducing different silver phosphine precursors RAg(PPh3)n (R = Cl, Br, or NO3 and n = 1 or 3) with tert-butylamine borane (TBAB) in the presence of dodecanethiols (C12) at a temperature between 100 and 160 °C. The study of the formation process of AgNPs by UV–vis and IR spectroscopy reveals that the phosphine (PPh3) derived from the metal precursor and thiols coat the NPs surface...
Structural and Dynamic Properties of a Hydrogen Bond from the Study of the CH3Cl-HCl Complex and Isotopic Species
Abstract: The microwave (4–20 GHz range) and infrared (HCl and DCl stretch ranges) spectra of six isotopic species of the CH3Cl–HCl hydrogen bond complex have been recorded for the first time and analyzed with the support of high level ab initio calculations (MP2 and CCSD(T) levels)...
Simultaneous Interfacial and Precipitated Supracrystals of Au Nanocrystals: Experiments and Simulations
Abstract: Under solvent saturation, a precipitation of full-grown supracrystals on the one hand and the formation of well-defined supracrystalline films at the air–liquid interface on the other hand were previously observed for the first time (J. Am. Chem. Soc.2012, 134, 3714–3719)....
Stability of Self-Ordered Thiol-Coated Silver Nanoparticles: Oxidative Environment Effects
Abstract: Here, we study the stability of the 2D organization of thiol-coated silver nanoparticles (NPs) by transmission electron microscopy. Whatever the alkyl chain length and the nature of the silver precursor, we show the rapid corrosion (over a few days) of the NPs by O2 from laboratory air whereas they remain stable for several weeks under a nitrogen atmosphere. We show that this phenomenon is amplified by the humidity in the air and by thiols trapped in the NP monolayers. We obtain evidence of these thiols in excess by infrared and energy-dispersive spectroscopies...
Synthesis of Silver Nanoparticles Using Different Silver Phosphine Precursors: Formation Mechanism and Size Control.
Abstract: Silver nanoparticles (AgNPs) ranging from 2.5 to 7.1 nm in diameter with a narrow size distribution are prepared by reducing different silver phosphine precursors RAg(PPh3)n (R = Cl, Br, or NO3 and n = 1 or 3) with tert-butylamine borane (TBAB) in the presence of dodecanethiols (C12) at a temperature between 100 and 160 °C. The study of the formation process of AgNPs by UV–vis and IR spectroscopy reveals that the phosphine (PPh3) derived from the metal precursor and thiols coat the NPs surface...
Self-assembly of nano-alloys in Nanoalloys: From Fundamentals to Emergent Applications
Abstract: Here, 11 nm γ-Fe2O3 nanocrystals characterized by a low size distribution of 5% and dispersed in chloroform are deposited onto a substrate as well-defined films. The film thickness is controlled by the initial concentration of the colloidal solution. After drying, the film shows a network of well-defined cracks. It is demonstrated using scanning electron microscopy and small-angle X-ray diffraction that the nanocrystals within the film are self-assembled in ordered lattices.
Crack patterns in superlattices made of maghemite nanocrystals
Abstract: Here, 11 nm γ-Fe2O3 nanocrystals characterized by a low size distribution of 5% and dispersed in chloroform are deposited onto a substrate as well-defined films. The film thickness is controlled by the initial concentration of the colloidal solution. After drying, the film shows a network of well-defined cracks. It is demonstrated using scanning electron microscopy and small-angle X-ray diffraction that the nanocrystals within the film are self-assembled in ordered lattices...
Unusual effect of an electron beam on the formation of core/shell Co/CoO nanoparticles differing by their crystalline structures
Abstract: In this study, an unusual effect of the electron beam in transmission electron microscopy (TEM) on the formation of Co/CoO core/shell structures is developed through careful in situ TEM/scanning TEM (STEM) analysis. By feature of the nanoscale precision of this approach, the electron beam-irradiated Co nanoparticles reveals remarkable resistance to oxidation compared to those without irradiation treatment. Moreover, the irradiated hcp single domain Co nanocrystals result in Co/CoO core/shell nanoparticles after oxidation, instead of the CoO hollow nanoparticles without irradiation treatment...
Tunable gold-chitosan nanocomposites by local field engineering
Abstract: A method to control the permittivity and tunability in composite materials formed by conductive nanoparticles embedded in a flexible nonlinear dielectric matrix is proposed. The local field distributions in composite structures were determined and the field-induced permittivity was estimated for different volume fraction of conductive particles...