| | | | | | | webmail : intra-extra| Accès VPN| Accès IST| Contact | Français

Headlines 2010

24-11-2010
C. Hrelescu, T. K. Sau, A. L. Rogach, F. Jäckel, G. Laurent, L. Douillard et F. Charra

In optics, the possibility to confine light below its natural wavelength is hampered by the longstanding barrier of the diffraction limit. Surface plasmons are electromagnetic surface waves coupled to free electrons at metal dielectric interfaces. They offer a unique opportunity for scaling down photonic devices to the nanometre range. Experiments carried out in the SPCSI have investigated the differences between the spatial and spectral signatures of metallic nano-objects whether they are observed in far field (observed with our eyes in a classic optical microscope) or in near-field (observed at subwavelength scale using a photoemission electron microscope PEEM). This investigation brings important fundamental results in the plasmonics research field for the scaling down of photonic devices to the nanometre range.

01-06-2010

(version française Version française)

The violation of J. Bell's inequalities with two spatially separated objects is often considered as the most prominent demonstration of the quantum nature of our world: the objects can be so intimately entangled that speaking of the state of each object loses its meaning even when they are far apart. The famous experiment by A. Aspect's team, in which the two objects were polarized light particles (photons), was a perfect demonstration of such a non local realism.

13-01-2010
P. Maillet*, C. Levard**, E. Larquet§, C. Mariet,* O. Spalla*, N. Menguy§, A. Masion**, E. Doelsch, J. Rose** et Antoine Thill*

Imogolites (OH)3Al2O3Si(OH) are natural minerals discovered in 1962 in Japanese volcanic soils. Their structure is similar to that of a carbon nanotube. They are made of a curved Gibbsite  sheet Al(OH)3  forming a nanotube of 2 nm in diameter. The tetrahedral silicon adsorbed inside the nanotube controls  its curvature. The diificulties to synthesized  large quantities of  this  mineral have indered the development of industrial applications. Recently a new synthetic process has allowed to circumvent this difficulty. Research are now performed  to better understand and control this new synthesis.

11-02-2010
S. Haessler, J. Caillat, W. Boutu, C. Giovanetti-Teixeira, T. Ruchon, T. Auguste, Z. Diveki, P. Breger, A. Maquet, B. Carré, R. Taïeb & P. Salières,

Visualizing the motion of electrons in matter requires both a spatial resolution at the Angstrom scale and a temporal resolution at the attosecond scale (1 as = 10-18 s). Such an "ultra-fast camera" opening a path towards "viewing the electrons" is demonstrated: it allows imaging molecular orbitals using the ultra-short attosecond emission from this orbital in an intense laser field. In a close collaboration, scientists from IRAMIS-SPAMLCPMR of the Univ. Paris 6 and from CNRS (UMR 7614) have shown, in experiments realized within the CEA-Saclay, the possibility of an "Attosecond-Angstrom" imaging in the case of the nitrogen molecule N2.

 

16-03-2010
J. Scheibert, C. Guerra, F. Célarié, D. Dalmas and D. Bonamy

Depending on their fracture mode, materials are traditionally gathered into three distinct classes:

  • (i) ductile materials that like metals deform plastically before their fracture
  • (ii) quasi-brittle materials such as rock or concrete, where "non-visible" damage starts to accumulate through microcracking, up to coalescence that yields to catastrophic failure.
  • (iii) brittle materials like oxide or polymer glasses... that deform elastically up to their fracture. This occurs through the successive breaking of atomic bonds at the crack tip. 

Experiments performed at IRAMIS-SPCSI show that a given material may, depending on the crack velocity, belong to two of these categories: Plexiglas®, archetype of brittle material, is found to damage through the nucleation of microcracks like quasi-brittle materials, beyond a well defined crack speed.


 

Retour en haut