Search results for "Phenomenological model"
showing 10 items of 68 documents
Effect of structure relaxation on the holographic recording in amorphous As2S3 films
1997
Abstract Results of the experimental studies of holographic recording in a-As 2 S 3 films, such as exposure and intensity dependences, spatial frequency dependence, are reported. Several peculiarities are found including recording intensity threshold, nonmonotonical intensity dependences, nonlinear exposure curves, the change of the spatial frequency response due to film aging. These peculiarities are explained in terms of the phenomenological model which is based on the simultaneous action of the photostructural changes and the relaxational structural changes.
From Seeds to Islands: Growth of Oxidized Graphene by Two-Photon Oxidation
2016
The mechanism of two-photon induced oxidation of single-layer graphene on Si/SiO2 substrates is studied by atomic force microscopy (AFM) and Raman microspectroscopy and imaging. AFM imaging of areas oxidized by using a tightly focused femtosecond laser beam shows that oxidation is not homogeneous but oxidized and nonoxidized graphene segregate into separate domains over the whole irradiated area. The oxidation process starts from point-like “seeds” which grow into islands finally coalescing together. The size of islands before coalescence is 30–40 nm, and the density of the islands is on the order of 1011 cm–2. Raman spectroscopy reveals growth of the D/G band ratio along the oxidation. Sha…
Device variability and circuit redundancy in signal processing based on nanoswitches
2009
Signal processing based on molecular switches whose conductance can be tuned by an external stimulus between two (on and off) states has been proposed recently (Cervera et al 2008 J. Appl. Phys. 104 084317). The basic building block is a metal nanoparticle linked to two electrodes by an organic ligand and a nanoswitch. The net charge delivered by this nanostructure exhibits a sharp resonance when the alternating potential applied between the electrodes has the same frequency as the periodic variation between the on and off conductance states induced on the nanoswitch. This resonance can be used to process an external signal by selectively extracting the weight of the different harmonics. Ho…
Linearly polarized gluons and axial charge fluctuations in the glasma
2018
We calculate of the one- and two-point correlation functions of the energy density and the divergence of the Chern-Simons current in the nonequilibrium Glasma state formed in a high-energy nuclear collision. We show that the latter depends on the difference of the total and linearly polarized gluon transverse momentum distributions. Since the divergence of the Chern-Simons current provides the source of axial charge, we infer information about the statistical properties of axial charge production at early times. We further develop a simple phenomenological model to characterize axial charge distributions in terms of distributions of the energy density.
Phenomenological Model for Gold-Copper Electrodeposition: Application to Thick Coatings
2016
Pure gold-copper alloys are known to be difficult to electrodeposit because of a strong variation in composition after a few microns have been deposited. Commissariat al’Energie Atomique (CEA) stud...
Hidden-charm and bottom tetra- and pentaquarks with strangeness in the hadro-quarkonium and compact tetraquark models
2020
In two recent papers, we used the hadro-quarkonium model to study the properties of hidden-charm and bottom tetraquarks and pentaquarks. Here, we extend the previous results and calculate the masses of heavy-quarkonium-kaon/hyperon systems. We also compute the spectrum of hidden-charm and bottom tetraquarks with strangeness in the compact tetraquark (diquark-antidiquark) model. If heavy-light exotic systems with non-null strangeness content were to be observed experimentally, it might be possible to distinguish among the large variety of available theoretical pictures for tetra- and pentaquark states and, possibly, rule out those which are not compatible with the data. peerReviewed
Double parton correlations and constituent quark models: a light front approach to the valence sector
2014
An explicit evaluation of the double parton distribution functions (dPDFs), within a relativistic Light-Front approach to constituent quark models, is presented. dPDFs encode information on the correlations between two partons inside a target and represent the non-perturbative QCD ingredient for the description of double parton scattering in proton-proton collisions, a crucial issue in the search of new Physics at the LHC. Valence dPDFs are evaluated at the low scale of the model and the perturbative scale of the experiments is reached by means of QCD evolution. The present results show that the strong correlation effects present at the scale of the model are still sizable, in the valence r…
Beam-Helicity Asymmetries in Double-Charged-Pion Photoproduction on the Proton
2005
Beam-helicity asymmetries for the two-pion-photoproduction reaction gamma + p --> p pi+ pi- have been studied for the first time in the resonance region for center-of-mass energies between 1.35 GeV and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these…
Optical study of GeO2–PbO–PbF2 oxyfluoride glass singly doped with Pr3+, Nd3+, Sm3+ and Eu3+
2005
Abstract Glasses with composition 50GeO 2 –(50 − x )PbO–5PbF 2 – x LnF 3 (Ln = Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ ) were synthesised in the bulk form. The content of PbF 2 was constant and amounted to 5 mol% whereas, the concentration of luminescent ions was 0.2 and 2 mol%. Spectroscopic properties (absorption, emission) of optically active ions were studied at room temperature. Oscillator strengths have been used to calculate phenomenological intensity parameters Ω 2,4,6 . Radiative transition probabilities as well as branching ratios and radiative lifetimes of luminescent levels were estimated. Lifetimes and the fluorescence dynamics were studied as a function of concentration. The Judd–Ofelt…
Quantum non-Markovianity induced by Anderson localization
2017
As discovered by P. W. Anderson, excitations do not propagate freely in a disordered lattice, but, due to destructive interference, they localise. As a consequence when an atom interacts with a disordered lattice one indeed observes, a non-trivial excitation exchange between atom and lattice. Such non-trivial atomic dynamics will in general be characterised also by a non-trivial quantum information backflow, a clear signature of non-Markovian dynamics. To investigate the above scenario we consider a quantum emitter, or atom, weakly coupled to a uniform coupled-cavity array (CCA). If initially excited, in the absence of disorder, the emitter undergoes a Markovian spontaneous emission by rele…