Nowadays, the recovering of both thicknesses and optical properties of nanometric multilayers is still a challenge. We propose a method to recover the effective relative permittivities and the thicknesses of copper/copper oxide layers, from absorbance spectra measured in the visible spectra. The experimental data are fitted with a model of classical light-matter interaction and a combination of two Drude-Lorentz laws to calculate the relative permittivities over the spectrum. The Particle Swarm Optimization and the evolutionary methods are used for the least-square fitting. A two steps study reveals that the relative permittivities of bulk cannot be used to fit adequately the absorbance curves. However, a perturbation of these reference values improves their fitting. The method is applied to the absorption spectra of a set of three copper samples that are progressively oxidized by six successive heat treatments.

We study the intrinsic optical spectroscopy (UV-vis-NIR absorption, Raman and photoluminescence) signatures of single wall carbon nanotubes (SWNT) dispersed in degassed water without additives, so called ‘‘eau de nanotubes” (EdN). They are found to be very close to those of SWNT dispersed in aqueous suspensions stabilized with surfactants. Absorption peaks appear to be even slightly better resolved for EdN, suggesting sharper excitonic resonances, which is also supported by the Raman data. On the other hand, the photoluminescence signal is significantly weaker. These signatures suggest that SWNT are dispersed as individuals in degassed water, in a similar way single layer graphene was recently shown to be readily dispersable in degassed water [1-3].References[1]G. Bepete et al, Nat. Chem. 2016, DOI 10.1038/NCHEM2669[2]G. Bepete et al, J. Phys. Chem. C 2016, 120 (49), 28204–28214.[3]G. Bepte et al, Phys. Stat. Solidi 2016, 10 (12), 895-899.

We discuss the intrinsic optical spectroscopy (UV-vis-NIR absorption, Raman and photoluminescence)signatures of single layer graphene (SLG) and single wall carbon nanotubes (SWNT) dispersed indegassed water without additives, so called "eau de graphene" (EdN) [1-3] and ‘‘eau de nanotubes”(EdN) [4].The most characteristic signature of SLG in EdG is a narrow and symmetric 2D band with a widthdepending on processing conditions [2,3]. The position of the G and 2D bands indicate moderate biaxialcompressive strain and weak n doping. The intensity of the D band and the width of the G band arediscussed in terms of point-defect density and flake size. We show that point defects can be easily curedby preparing thin films from EdG and annealing at 800°C.The signatures of SWNT in EdN are found to be very close to those of SWNT dispersed in aqueoussuspensions stabilized with surfactants [4]. Absorption peaks appear to be even slightly better resolvedfor EdN, suggesting sharper excitonic resonances, which is also supported by the Raman data. Thesesignatures support that SWNT are dispersed as individuals in EdN, in a similar way SLG aredispersable in EdG [1-3].[1] G. Bepete et al, Nat. Chem. 2016, DOI 10.1038/NCHEM2669[2] G. Bepete et al, J. Phys. Chem. C 2016, 120 (49), 28204–28214.[3] G. Bepte et al, Phys. Stat. Solidi 2016, 10 (12), 895-899.[4] G. Bepete et al, to be published

Aqueous dispersions of graphene-derived monolayers form liquid crystal at rather low concentrations due to the high aspect ratio of these flakes [1,2]. If graphene oxide dispersions are easily obtained in water, reduced graphene oxide necessitates the use of surfactants [3]. Preparing organized materials and thin films from these dispersions then requires a good control of the liquid crystal ordering during the deposition and the drying of the films.The flakes easily align at high shear [4,5], which has allowed us to complete previous optical characterizations of the various graphene layers (birefringence and linear dichroism). However at low shear or under small dispalcements, thin films often show peculiar patterns (such as the periodic textures shown in Fig.1). We have shown how to create and stabilize large-sized periodic textures. The patterns have been characterized under optical and electronic microscopies. Their stability can be explained by the competition between the anchoring field of the substrate and the presence of a yield stress resulting from the peculiar elastic and rheological properties of the graphene oxide liquid crystals. Our results also clarify why long-standing hypotheses on the presence of exotic phases [1] at large concentrations are present in the literature.References[1] Z. Xu, C. Gao Nat Commun., 2, 571 (2011).[2] C. Zakri et al., Phil. Trans. A, 371, 20120499 (2013).[3] C. Zamora et al, J. Phys. Chem. Lett. 3, 2425 (2012).[4] P. Poulin et al, Proc Natl Acad Sci USA, 113, 11088 (2016).[5] S-H Honga, T.Z. Shena and J. K. Songa, Liquid Crystals, 42, 261 (2015)

Thin and ultrathin metal coatings are increasingly required by the electronics and optics industries onall types of substrates. However, the adhesion of noble metals is very poor on non-metallic substrates like glass,other oxide materials and polymers. By contrast, CVD graphene has a strong adhesion energy (~0.31-0.45 J.m-2depending on the number of layers) on glass [1]. On the other hand, graphene oxide (GO) was recently shown topromote adhesion of ZnO nanoparticles and subsequent ZnO films on glass or silicon substrates [2].In this work we use GO/Au nanoparticles (NP) composite thin films as bifunctional materials to bothpromote adhesion on glass and assist the deposition of copper in electroless wet industrial coating processes. Wediscuss the influence of the NP density, surface treatment and deposition parameters on the homogeneity andadhesion of the GO/Au NP and copper layers.[1] S. P. Koenig, N. G. Boddeti, M. L. Dunn, and J. S. Bunch, 2011, Nat. Nano. 6, 543‑546[2] Q. Ma, X. Zhu, D. Zhang, and S. Liu, 2014, J. Mater. Chem. C 22, 8956‑8961