Publications

2015

• Thermally activated delayed fluorescence evidence in non-bonding transition electron donor-acceptor molecules
  
  • Marghad Ikbal
  • Clochard M.
  • Ollier N.
  • Wade Travis
  • Aymes-Chodur C.
  • Renaud Cédric
  • Zissis Georges
  , 2015, pp.956629. The exhibition of thermally activated delayed fluorescence on triazine derivative by the introduction of a nonbonding part is demonstrated. Two molecules containing triazine core as acceptor and carbazole part as donor has been synthesized and characterized. One of these molecules bears an additional nonbonding part by the means of a phenoxy group. The results indicated that the molecule bearing the nonbonding molecular part (phenoxy) exhibit thermally activated delayed fluorescence while not on molecule free of non-bonding group. The results are supported by, photoluminescence, spectral analysis time-resolved fluorescence and time-dependent density functional estimation. (10.1117/12.2186802)
  DOI : 10.1117/12.2186802
• Quasiparticle dynamics in high-temperature superconductors far from equilibrium: An indication of pairing amplitude without phase coherence
  
  • Piovera C.
  • Zhang Zhongkai
  • d'Astuto M.
  • Taleb-Ibrahimi A.
  • Papalazarou E.
  • Marsi M.
  • Li Z.
  • Raffy H.
  • Perfetti L.
  Physical Review B, American Physical Society, 2015, 91 (22), pp.224509. We perform time-resolved photoelectron spectroscopy measurements of optimally doped $Bi_2Sr_2CaCu_2O_{8+δ}$ (Bi-2212) and $Bi_2Sr_{2−x}La_xCuO_{6+δ}$ (Bi-2201). The electron dynamics shows that inelastic scattering by nodal quasiparticles decreases when the temperature is lowered below the critical value of the superconducting phase transition. This drop in electronic dissipation is astonishingly robust and survives to photoexcitation densities much larger than the value sustained by long-range superconductivity. The unconventional behavior of quasiparticle scattering is ascribed to superconducting correlations extending on a length scale comparable to the inelastic path. Our measurements indicate that strongly driven superconductors enter in a regime without phase coherence but finite pairing amplitude. The latter vanishes near to the critical temperature and has no evident link to the pseudogap observed by angle-resolved photoelectron spectroscopy. (10.1103/PhysRevB.91.224509)
  DOI : 10.1103/PhysRevB.91.224509