Ref HAL: hal-01279551_v1
DOI: 10.1039/C5CP02742J
WoS: 000372229700039
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4 Citations
Résumé:

In this work, we develop the concept of evaporation-induced self-structuring as a novel approach forproducing organised films by exploiting cooperative physical and chemical interactions under far-fromequilibriumconditions (spin-coating), using sol–gel precursors with multiple functional groups. Thin filmsof self-structured silsesquioxane nanohybrids have been deposited by spin coating through the sol–gelhydrolysis and condensation of a bridged organosilane bearing self-assembling urea groups. The resultingnanostructure, investigated by FTIR, AFM and SEM, is shown to be highly dependent on the catalyst used(nucleophilic or acidic), and can be further modulated by varying the spinning rate. FTIR studies revealed thepresence of highly organised structures under acidic catalysis due to strong hydrogen bonding between ureagroups and hydrophobic interactions between long alkylene chains. The preferential orientation of the ureacross-links parallel to the substrate is shown using polarized FTIR experiments.

Ref HAL: hal-01271919_v1
Ref Arxiv: 1511.08175
DOI: 10.1103/PhysRevB.93.024305
WoS: 000369218500005
Ref. & Cit.: NASA ADS
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48 Citations
Résumé:

We analyze the impact of electric field and magnetic field fluctuations in the decoherence of the electronic spin associated with a single nitrogen-vacancy (NV) defect in diamond by engineering spin eigenstates protected either against magnetic noise or against electric noise. The competition between these noise sources is analyzed quantitatively by changing their relative strength through modifications of the environment. This study provides significant insights into the decoherence of the NV electronic spin, which is valuable for quantum metrology and sensing applications.

Commentaires: 8 pages, 4 figures, including supplementary informations. Réf Journal: Phys. Rev. B 93, 024305 (2016)

DOI: 10.1103/PhysRevB.93.035207
WoS: 000369221000004
43 Citations
Résumé:

We report photoluminescence experiments bringing the evidence for intervalley scattering in bulk hexagonal boron nitride. From a quantitative analysis of the defect-related emission band, we demonstrate that transverse optical phonons at the K point of the Brillouin zone assist inter-K valley scattering, which becomes observable because stacking faults in bulk hexagonal boron nitride provide a density of final electronic states. Time-resolved experiments highlight the different recombination dynamics of the phonon replicas implying either virtual excitonic states or real electronic states in the structural defects.

Commentaires: Editors' suggestion: The authors have conducted an experimental study of hexagonal boron nitride using steady-state and time-resolved photoluminescence. The assignment of previously observed lines of unknown origin is made convincingly to indirect excitons assisted by acoustic and optical phonons and to defect-assisted transitions. This is further evidence for h-BN being an indirect band-gap semiconductor.

Ref HAL: hal-01264155_v1
Ref Arxiv: 1512.03406
DOI: 10.1016/j.nuclphysbps.2016.02.021
WoS: WOS:000375626800021
Ref. & Cit.: NASA ADS
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Résumé:

Our renormalization group consistent variant of optimized perturbation, RGOPT, is used to calculate the nonperturbative QCD spectral density of the Dirac operator and the related chiral quark condensate $\langle \bar q q \rangle$, for $n_f=2$ and $n_f=3$ massless quarks. Sequences of approximations at two-, three-, and four-loop orders are very stable and give $\langle \bar q q \rangle^{1/3}_{n_f=2}(2\, {\rm GeV}) = -(0.833-0.845) \bar\Lambda_2 $, and $ \langle \bar q q \rangle^{1/3}_{n_f=3}(2\, {\rm GeV}) = -(0.814-0.838) \bar\Lambda_3 $ where the range is our estimated theoretical error and $\bar\Lambda_{n_f}$ the basic QCD scale in the $\rm \bar{MS}$-scheme. We compare those results with other recent determinations (from lattice calculations and spectral sum rules).

Commentaires: 5 pages, talk given at 18th International Conference in Quantum Chromodynamics (QCD 15) Montpellier, published in the proceedings

PMID 26573173
DOI: 10.1039/c5sm01952d
WoS: 000369747900007
18 Citations
Résumé:

The accumulation of colloidal particles to build dense structures from dilute suspensions may follow distinct routes. The mechanical, structural and geometrical properties of these structures depend on local hydrodynamics and colloidal interactions. Using model suspensions flowing into microfabricated porous obstacles, we investigate this interplay by tuning both the flow pattern and the ionic strength. We observe the formation of a large diversity of shapes, and demonstrate that growing structures in turn influence the local velocity pattern, favouring particle deposition either locally or over a wide front. We also show that these structures are labile, stabilised by the flow pushing on them, in low ionic strength conditions, or cohesive, in a gel-like state, at higher ionic strength. The interplay between aggregate cohesion and erosion thus selects preferential growth modes and therefore dictates the final shape of the structure.[on SciFinder (R)]

Ref HAL: hal-01250756_v1
Ref Arxiv: 1512.03811
DOI: 10.1063/1.4943294
WoS: 000374013800005
Ref. & Cit.: NASA ADS
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Résumé:

We recall the relation between Zeta function representation of groups and two-dimensional topological Yang-Mills theory through Mednikh formula. We prove various generalisations of Mednikh formulas and define generalization of Zeta functions representations of groups. We compute some of these functions in the case of the finite group $GL(2, {\mathbb F}_q)$ and $PGL(2,{\mathbb F}_q).$ We recall the table characters of these groups for any $q$, compute the Frobenius-Schur indicator of their irreducible representations and give the explicit structure of their fusion rings

Ref HAL: hal-01332698_v1
PMID 26835961
Ref Arxiv: 1511.04257
DOI: 10.1364/AO.55.0000A8
WoS: WOS:000369055100003
Ref. & Cit.: NASA ADS
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8 Citations
Résumé:

Heterodyne holography is a variant of phase shifting holography in which reference and signal arms are controlled by acousto optic modulators. In this review paper, we will briefy describe the method and its properties, and we will illustrate its advantages in experimental applications.

Commentaires: . Réf Journal: Appl. Opt. 55, A8-A16 (2016)