Soft Report - Dipartimento di Fisica - Sapienza

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Self Assembly, Clustering, Structural arrestBiopolymer-Vescicle Interactions 85Polyelectrolyte-Liposome Complexes: Evidence of Equilibrium Multi-Compartment Aggregates 86Dielectric Properties of Polyelectrolyte Aqueous Solutions: the Scaling Approach 87Aging of aqueous Laponite suspensions studied by 23 Na Triple-Quantum NMR spectroscopy 88Clustering and Cooperative Dynamics in Reactive Mixtures 89Role of metal ions in protein aggregation processes 90Role of water around biomolecules and surfactants 91Multi-Scale Simulations of Macromolecular Systems 92Investigation of the Relation Between Local Inherent Structures Properties and the Diffusivity 93Coil-Globule Transition of DNA Molecules Induced by Cationic Surfactants 94Multi-Scale Coarse-Graining of Diblock Copolymer Self-Assembly 95Bernal Spiral Clusters in Colloid-Polymer Mixtures 96Molecular Clustering by High Resolution NMR 97Non-invasive 1 H-NMR in porous materials of artistic interest 98Elastic and anelastic scattering of neutrons and X-raysIon Density Fluctuations in Liquid Gallium 99Femtosecond dynamics in Ferromagnetic Metals 100Soft Resonant X-ray Scattering 101Picosecond-Timescale Fluctuations of Proteins in Glassy Matrices: The Role of Viscosity 102Neutron inelastic scattering on liquid CD 4 : a probe of the dynamics in simple molecular liquids 103The Dynamics of Dilute H 2 Enabling New Calibration Methods in Neutron Spectroscopy 104Effect of Solvent and of Confinement on the Dynamics of Hydrated Proteins 105Dynamics in Model Membranes, Membrane-Protein and Membrane-DNA Interactions 106Dynamics of Hydrated Saccharides and Saccharide Gels 10749SOFT Scientific Report 2004-06
Scientific Report – Non Equilibrium Dynamics and ComplexityLight and ComplexityIn a nutshell, a random laser is a disorderedamplifying optical cavity emitting coherent radiation.The system can be realized by artificial nanostructuredoptical devices, or can be a self-organizeddispersion of particles in the multi-scattering regime.In both cases, optical gain can be obtained with theaddition of some active materials, like dyes orquantum dots. Random laser emission is stronglyaffected by the structure and the history of thematerial, hence it is an original and multidisciplinaryapproach for the investigation of soft-matter.Additionally, this kind of lasers strikingly displaysthose ingredients which are typical of the physics ofcomplexity: randomness and nonlinearity.In Refs. [1], it has been shown that theory ofrandom laser can be reformulated as mean field spinglass theory and a series of new physical processes,including for example a “glassy behaviour of light,”have been predicted. Such an approach open newopportunities for testing the modern theory ofcomplexity, and conceiving new experiments on theglass transition which should enable to investigatenew previously un-accessible regimes, due to theintrinsically fast dynamics of a “photon glass.”Specifically, a random optical cavity is characterizedby N resonant modes with angular frequencies ω nand complex amplitudes a n, (n=1…N); such that theenergy stored into each mode is ω n|a n| 2 . Laser theorysays that the moduli of the a n are slowly varying withrespect to the phases ϕ n, hence the former can betaken as quenched variables while the latter are therelevant dynamic variables and take the role ofspherical spins. The Hamiltonian is:∑H = cos( ϕ + ϕ −ϕ−ϕ)J spqrspqwhere the random coupling constants J aredetermined by the spatial overlap of the resonantmodes. The replica method is applied for determiningthe energy landscape of the model and the existenceof a one-step replica symmetry breaking (1RSB), orglass-transition. The role of the inverse temperatureis played by the ratio between the squared averageenergy stored into each mode and the amount ofnoise due to spontaneous emission. There exist acritical value of this effective temperature for theexistence of an exponentially large number of metastablestates, each corresponding to a differentrFig. 2: Ab initio 3D+1 computation of specklepatterns at 532nm obtained when light propagatesin high concentration colloidal materials, whosestructure is determined by molecular dynamicsimulations. These numerical techniques providenew opportunities for the investigation of softmaterialproperties, as they may enrich theinformation that can be extracted by experiments inthe multiple-scattering regime.mode-locking process of the random laser. In thisway the complexity (i.e. the configurational entropy)of light in random lasers can be calculated, and thecritical temperature is expressed in term ofexperimentally accessible quantities.Complex dynamics of light is also found, theoreticallyand experimentally, when focused laser beamspropagated in soft-matter like liquid crystals. [2] Inthis case, disorder and nonlinearity contribute to thegeneration of multiple light filaments whosedynamics can be described by the same paradigmsof the physics of soft-matter. Understanding theseprocesses is relevant for various applications, fromall optical digital devices to laser surgery.Photonics in disordered or structured systems,(“complex photonics”) is a very active andmultidisciplinary research field, to which we are alsocontributing by developing new computationalapproaches (figure 1), and designing novel opticaldevices [3] (as e.g. “photonic crystals”) which can beinfiltrated by soft-materials, and provideopportunities for femtoliter substance analysis.References[1] L. Angelani, C. Conti, G. Ruocco, F. Zamponi,Phys. Rev. Lett. 96, 065702 (2006); Condmat/0511427;L. Angelani, C. Conti, G. Ruocco, F.Zamponi, cond-mat/0604242, submitted to Phys.Rev. B[2] C. Conti, Phys. Rev. 72, 066620 (2005); C.Conti, M. Peccianti, G. Assanto, Opt. Lett. (2006),submitted.[3] A. Di Falco, C. Conti, G. Assanto, Appl. Phys. B81, 415 (2005); A. Di Falco C. Conti, G. Assanto,Opt. Lett. 31, 250 (2006); A. Di Falco C. Conti, G.Assanto, Opt. Lett. (2006), submittedFig. 1: Relevant overlap of the spin glass theoryof random lasers and complexity Vs the effectivetemperature (from Ref. 1)AuthorsL. Angelani (a), C. Conti (b,c), G. Ruocco (c) , F.Zamponi (d), G. Assanto (e), M. Peccianti (e)(a) SMC INFM-CNR (b) Research Center EnricoFermi (c) SOFT INFM-CNR (d) Ecole NormalSuperiore (e) University Roma Tre.SOFT Scientific Report 2004-0650
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Page 6 and 7: ContentsIntroduction 7Scientific Mi
Page 8 and 9: IntroductionSOFT is a CRS (Centro d
Page 10 and 11: Scientific MissionThe scientific wo
Page 13 and 14: Missioncolloids and soft colloidal
Page 15 and 16: PersonnelManagement, Personnel and
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Page 19 and 20: FacilitiesX-ray Diffraction Laborat
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Page 31 and 32: LSFSOFT Scientific Report 2004-0630
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Page 35 and 36: LSFBRISP first spectraLeft panel: e
Page 37 and 38: LSFNeutron guideMonochromator cryst
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Page 43 and 44: LSFExperiments at LSFYear 2004Elett
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DisseminationSOFT Scientific Report
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