Formation Of Multiplets Research Articles

Glass transition temperature of styrene‐based ionomer controlled over a very wide temperature range by nonpolar plasticizer content and ion content

AbstractThe plasticization effect by the addition of nonpolar bis(2‐ethylhexyl) phthalate (dioctyl phthalate) (DOP) on the glass transition temperatures (Tgs) of poly(styrene‐Na methacrylate) (PSMANa) ionomers was investigated. The matrix Tg (Tg,m) and cluster Tg (Tg,c) of the ionomers dropped linearly as the DOP content in the PSMANa ionomers enhanced, only when the phase separation of DOP did not occur. Since the Tg,m and Tg,c of the ionomer increased somewhat linearly with increasing ion content of the ionomer, simple equations were obtained to express the Tgs of the ionomers using the ion contents (x mol%) and the DOP contents (y wt%) of the ionomers; Tg,m (°C) = 121 + 3.0x + 2.8y and Tg,c (°C) = 171 + 6.3x + 2.6y. According to the x‐ray scattering results, for the ionomer containing 6.4 mol% of ions, the distance between scattering centers increased from 21 to 22 Å when ca. 40 wt% of DOP was added. This suggested that the DOP promoted the mobility of the styrene chains, enhancing the formation of multiplets. On the other hand, for the ionomer containing 22.4 mol% of ions, when ca. 40 wt% was added, the distance between multiplets widened from 18 to 21 Å.

Local multiplet formation around a single vacancy in graphene: An effective Anderson model analysis based on the block-Lanczos DMRG method

To better understand the electronic structure of a single vacancy in graphene, we study the ground state property of an effective Anderson model, consisting of three dangling $sp^2$ orbitals of the surrounding carbon atoms around the vacancy and the $\pi$ orbitals of carbon atoms that form the honeycomb lattice with a single vacancy. Employing the block-Lanczos density-matrix renormalization group method, we show that there are two phases in the relevant parameter space, i.e., a nonmagnetic phase in the weak coupling region and a free magnetic moment phase in the realistic parameter region. The systematic analysis finds that, in the free magnetic moment phase, local multiplets of the doubly degenerate irreducible representation of the $\mathcal{C}_3$ point group with spin 1 become dominant in the ground state, and approximately half of this local spin 1 is screened by electrons in the surrounding $\pi$ orbitals, indicating the emergence of the residual spin-1/2 free magnetic moment. Furthermore, we find that the emergence of the free magnetic moment is robust against carrier doping, which is in sharp contrast to the case of graphene with an adatom, thus explaining the qualitative difference observed experimentally in these two classes of systems. We also find the enhancement of the spin correlation function between $\pi$ electrons around the vacancy and those in the conduction band away from the vacancy in the undoped case, as compared to that in the doped case, while the spin correlation function between the $\sigma$ electrons in the $sp^2$ dangling orbitals around the vacancy and the $\pi$ electrons in the conduction band remains large in both undoped and doped cases. Our calculations thus support qualitatively the previous experiment that suggests the emergence of free magnetic moment with two distinct origins.

Associative Behavior of Lignosulphonates in Moderately Concentrated Water, Water-Salt, and Water-Alcoholic Media.

Industrial derivatives of lignin lignosulfonates are produced during sulfite delignification of wood. They are characterized by a wide molecular weight distribution, polyfunctionality, and lack of crystallinity. The presence of hydrophobic and hydrophilic domains in the lignosulfonate macromolecular system determines the amphiphilic and polyelectrolyte properties of this biopolymer. As a polyelectrolyte, lignosulfonates (LSs) show complex conformational and phase behavior, which can be controlled by a wide range of external factors (ionic strength, medium acidity, solvent polarity, etc.). Herein, we present the results of a study of the associative behavior of three lignosulfonate samples with different molecular weight distributions (Mw 9250-46 300) and structural and cationic (Na+, Ca2+) composition. The effects of the concentration of LS (0.2-200.0 g/dm3), temperature (293-353 K), ionic strength of the medium (KCl, 0.08-0.80 mol), and ethanol additives (0.6-73.0 vol %) on the bulk and surface properties of lignosulfonates have been revealed. It was assumed that the LS association in solutions is a consequence of the processes of counterionic condensation with the formation of ionic pairs and multiplets. The binding of counterions is facilitated by an increase in the ionic strength of the medium and ethyl alcohol additives.

Autoionizing Polaritons in Attosecond Atomic Ionization

Light-induced states and Autler-Townes splitting of laser-coupled states are common features in the photoionization spectra of laser-dressed atoms. The entangled light-matter character of metastable Autler-Townes multiplets, which makes them autoionizing polaritons, however, is still largely unexplored. Weemploy attosecond transient-absorption spectroscopy in argon to study the formation of polariton multiplets between the 3s^{-1}4p and several light-induced states. We measure a controllable stabilization of the polaritons against ionization, in excellent agreement with abinitio theory. Using an extension of the Jaynes-Cummings model to autoionizing states, we show that this stabilization is due to the destructive interference between the Auger decay and the radiative ionization of the polaritonic components. These results give new insights into the optical control of electronic structure in the continuum and unlock the door to applications of radiative stabilization in metastable polyelectronic systems.

Ongoing (2015‐) Magma Surge in the Upper Mantle Beneath the Island of Hawaiʻi

Abstract“Surges” in magma supply from the mantle can lead to significant changes in eruptive behavior, thus their early identification is critical to long‐term eruption forecasting. Here, we document and analyze two order‐of‐magnitude increases in seismicity in the upper mantle beneath southern Hawaiʻi between 2015 and 2020. We interpret the anomalous seismicity, which involved the rapid formation of new multiplets and a change in fault‐plane solution orientations relative to pre‐2015 events, as reflecting a substantial increase, or “surge” in mantle‐derived magma, and we suggest that the intruded magma has been driving concurrent unrest at Mauna Loa, Kīlauea, and Lōʻihi Volcanoes through mechanical stress transfer.

Ab initio calculation of the calorimetric electron-capture spectrum of Ho163 : Intra-atomic decay into bound states

The determination of the electron neutrino mass by electron capture in $^{163}$Ho relies on a precise understanding of the deexcitation of a core hole after an electron capture event. We here present an \textit{ab intio} calculation of the electron capture spectrum in $^{163}$Ho, including all intra-atomic decay channels into bound-states. We use theoretical methods developed for the calculation of core level spectroscopy on correlated electron compounds. Our comparison critically tests the reality of these theories. We find that relativistic interactions beyond the Dirac equation, i.e. quantum-electro dynamics, only lead to minor shifts of the spectral peaks. The electronic relaxation after an electron capture event due to the changed nuclear potential leads to a mixing of different edges, but due to conservation of angular momentum of each scattered electron, no additional structures emerge. Many-body Coulomb interactions lead to the formation of multiplets and to additional peaks with multiple core-holes due to Auger decay. Multiplets crucially change the appearance of the resonances on a Rydberg energy scale. The additional structures due to Auger decay are, although clearly visible, relatively weak compared to the one core hole states and accidentally far away from the end-point region of the spectrum. As the end-point of the spectrum is effected most by the neutrino mass these additional states do not influence the statistics for determining the neutrino mass directly. The multiplet broadening and Auger shake-up of the main core-level edges do change the apparent line-width and accompanying lifetime of these edges, thereby invalidating experimentally obtained lifetimes at the resonance for regions far away from the resonance.

Nonlinear Spectroscopy of Alkali Atoms in Cold Medium of Astrophysical Relevance

The time-dependent population dynamics of hyperfine (HF) sublevels of n 2 p 3 / 2 atomic states upon laser excitation in a cold medium of alkali atoms is examined. We demonstrate some peculiarities of the absorption HF multiplet formation in D2-line resulting from a long interaction time (∼200 μ s) interaction between light and Na ( n = 3 ) and Cs ( n = 6 ) atoms in a cold and slow sub-thermal ( T ∼ 1 K) beam. We analytically describe a number of D2-line-shape effects that are of interest in spectroscopic studies of cold dusty white dwarfs: broadening by optical pumping, intensity redistribution within components of D2-line HF multiplet for partially closed transitions and asymmetry of absorption lines induced by AC Stark shifts for cyclic transitions.

Bioinspired Design of a Robust Elastomer with Adaptive Recovery via Triazolinedione Click Chemistry.

It is a significant but challenging task to simultaneously reinforce and functionalize diene rubbers. Inspired by "sacrificial bonds", the authors engineer sacrificial hydrogen bonds formed by pendent urazole groups in crosslinked solution-polymerized styrene butadiene rubber (SSBR) via triazolinedione click chemistry. This post-crosslinking modification reveals the effects of the sacrificial bonds based on a consistent covalent network. The "cage effect" of the pre-crosslinked network facilitates the heterogeneous distribution of urazole groups, leading to the formation of hydrogen-bonded multiplets. These multiplets further aggregate into clusters with vicinal trapped polymer segments that form microphase separation from the SSBR matrix with a low content of urazole groups. The clusters based on hydrogen bonds, serving as sacrificial bonds, promote energy dissipation, significantly improving the mechanical properties of the modified SSBR, and enable an additional wide transition temperature region above room temperature, which endows the modified SSBR with promising triple-shape memory behavior.

Systematics of ground state multiplets of atomic nuclei in the delta-interaction approach

Pairing forces between nucleons in an atomic nucleus strongly influence its structure. One of the manifestations of pair interaction is the ground state multiplet (GSM) formation in the spectrum of low-lying excited states of even–even nuclei. The value of GSM splitting is determined by the value of pair interaction of nucleons; for each isotope, it can be estimated on the basis of experimental nuclear masses. The quality of this estimate is characterized by the degree of reproduction of GSM levels in the nucleus. The GSM systematics in even–even nuclei with a pair of identical nucleons in addition to the filled nuclear core is considered on the basis of delta interaction.

Moments of inertia and B(E2;01+→21+)s in the NpNn scheme

We examine the collective nuclear structure of light and medium mass (Z = 50–82, N = 82–126) even–even nuclei using valence nucleon pair product (NpNn). We discuss the role of proton–neutron interaction in light mass nuclei and illustrate the variation of observables of collectivity and deformation (i.e., ground band moment of inertia) and B(E2) values with N and NpNn). The plot of these observables against NpNn vividly displays the formation of isotonic multiplets in quadrant I, strong dependence on NpNn in quadrant II and weak constancy with Z in quadrant III is illustrated.

Ring-type multisoliton dynamics in shallow water.

The propagation, in a shallow water, of nonlinear ring waves in the form of multisolitons is investigated theoretically. This is done by solving both analytically and numerically the cylindrical (also referred to as concentric) Korteweg-de Vries equation (cKdVE). The latter describes the propagation of weakly nonlinear and weakly dispersive ring waves in an incompressible, inviscid, and irrotational fluid. The spatiotemporal evolution is determined for a cylindrically symmetric response to the free fall of an initially given multisoliton ring. Analytically, localized solutions in the form of tilted solitons are found. They can be thought as single- or multiring solitons formed on a conic-modulated water surface, with an oblique asymptote in arbitrary radial direction (tilted boundary condition). Conversely, the ring solitons obtained from numerical solutions are localized single- or multiring structures (standard solitons), whose wings vanish along all radial directions (standard boundary conditions). It is found that the wave dynamics of these standard ring-type localized structures differs substantially from that of the tilted structures. A detailed analysis is performed to determine the main features of both multiring localized structures, particularly their break-up, multiplet formation, overlapping of pulses, overcoming of one pulse by another, "amplitude-width" complementarity, etc., that are typically ascribed to a solitonlike behavior. For all the localized structures investigated, the solitonlike character of the rings is found to be preserved during (almost) entire temporal evolution. Due to their cylindrical character, each ring belonging to one of these multiring localized structures experiences the physiological decay of the peak and the physiological increase of the width, respectively, while propagating ("amplitude-width" complementarity). As in the planar geometry, i.e., planar Korteweg-de Vries equation (pKdVE), we show that, in the case of the tilted analytical solutions, the instantaneous product P=(maximumamplitude)×(width)(2) is rigorously constant during all the soliton spatiotemporal evolution. Nevertheless, in the case of the numerical solutions, we show that this product is not preserved; i.e., the instantaneous physiological variations of both peak and width of each ring do not compensate each other as in the tilted analytical case. In fact, the amplitude decay occurs faster than the width increase, so that P decreases in time. This is more evident in the early times than in the asymptotic ones (where actually cKdVE reduces to pKdVE). This is in contrast to previous investigations on the early-time localized solutions of the cKdVE.

5f Electron correlations and core level photoelectron spectra of Uranium compounds

AbstractMicroscopic model calculations for core‐level spectra of U compounds are presented. The consequences of strong intra‐atomic correlations within the 5f shell are analyzed. The formation of atomic multiplets leads to a re‐distribution of spectral weight. The results suggest that the orbital‐selective localization resulting from strongly anisotropic renormalization of the hybridization between 5f‐ and conduction electrons should be reflected in the line shapes.

Estimation of arrival-times in intense seismic sequences using a Master-Events methodology based on waveform similarity

SUMMARY Intense seismic sequences involve a large number of earthquakes densely clustered in space and time. Their detailed analysis is important for the geometry of the activated faults, which contributes to studies of the seismotectonic characteristics of an area. The sheer number of small events as well as their low energy content renders their processing problematic. In this work, we have developed and applied a methodology to automatically pick the arrival-times of P- and S-waves using a correlation detector. Event detection is performed using the waveform recordings of a reference station located close to the epicentral area of an intense seismic sequence such as aftershocks or swarms. Cross-correlation matrices are constructed, followed by nearest-neighbour clustering and the formation of multiplets. A Master-Event is chosen from each cluster and its arrival-times are picked manually. The automatic algorithm uses the P -o rS-wave of each Master-Event as a correlation detector, searches the waveforms of the other events of the same multiplet and imposes the corresponding arrival-time when the bestfit is achieved. The picks are characterized by observation weights, which derive from the quality of thefit, the type of the available waveform components and the consistency between multiple measurements. The proposed methodology was applied to an important seismic sequence that occurred between 2010 January 18 and 26 near the city of Efpalio, Greece. This procedure has the potential to increase 10-fold the amount of information and provide sufficient detail for a subsequent analysis of the spatiotemporal distribution of a seismic series.

Breakdown of Inverse Morphologies in Charged Diblock Copolymers

Brownian Dynamics simulations are carried out to understand the effect of temperature and dielectric constant of the medium on microphase separation of charged-neutral diblock copolymer systems. For different dielectric media, we focus on the effect of temperature on the morphology and dynamics of model charged diblock copolymers. In this study we examine in detail a system with a partially charged block copolymer consisting of 75% neutral blocks and 25% of charged blocks with 50% degree of ionization. Our investigations show that due to the presence of strong electrostatic interactions between the charged block and counterions, the block copolymer morphologies are rather different than those of their neutral counterpart at low dielectric constant, however at high dielectric constant the neutral diblock behaviors are observed. This article highlights the effect of dielectric constant of two different media on different thermodynamic and dynamic quantities. At low dielectric constant, the morphologies are a direct outcome of the ion-counterion multiplet formation. At high dielectric constant, these charged diblocks behavior resembles that of neutral and weakly charged polymers with sustainable long-range order. Similar behavior has been observed in chain swelling, albeit with small changes in swelling ratio for large changes in polarity of the medium. The results of our simulations agree with recent experimental results and are consistent with recent theoretical predictions of counterion adsorption on flexible polyelectrolytes.

Signatures of carrier multiplication in the frequency resolved fluorescence spectra from polaritons

Using the micro-cavity coupled to weakly confined excitons in quantum dots we investigated the signatures of carrier multiplication in the single and two-photon emitted frequency resolved fluorescence. Those are compared to the spectra provided by the conventional multi-photon induced fluorescence. The two processes are distinguished by the statistics of the initial polariton distribution. We argue that exciton emission spectra turned out to be CM insensitive, while the polaritons emission demonstrates strong spectral signatures of the CM. When the polaritonic effect dominates the confinement-boosted excitons' nonlinearities, increasing quantum yield leads to consecutive appearance of Rabi multiplets. The correlation spectra reveal the formation of more multiplets as compared to the single photon emission. When the confinement increases the multiplets start to overlap and their classification requires transient measurements of the spectral snapshots. These are based on the discrete Auger lifetimes of the multi-excitons.

Correlation between Morphology and Mechanical Properties in Zn‐Neutralized Sulfonated Polystyrene Ionomer/Poly(ethylene glycol) Blends: Contribution of EFTEM

AbstractRelationships between microstructure and mechanical properties in SPS‐Zn/PEG blends are investigated. Ion/dipole interactions induce the miscibility of both blend components for PEG content up to 10 wt.‐% as evidenced by DSC and TEM observations. Elemental mapping by EFTEM was used to investigate the ionic cluster microstructure and the phase structure in the blends. PEG chains do not hinder the formation of ionic multiplets but modify the microstructure of the clusters. Moreover, a PEG‐rich layer is observed in the vicinity of the aggregates surface. As a consequence, no cluster glass transition is observed in DMA experiments for these blend systems and besides, the absence of ionic plateau is assigned to the decrease in the ionic clusters' stability.magnified image

Self-Assembly of Structurally Persistent Micelles Is Controlled by Specific-Ion Effects and Hydrophobic Guests

A combined study using cryo-TEM experiments and molecular dynamics simulations reveals remarkable details of the factors that affect the self-organization of specifically designed T-shaped amphiphilic dendrimers upon treatment of an aqueous solution with ultrasound under a layer of hexane. This treatment leads to dodecameric, structured micelles rather than the heptameric ones observed without hexane. Three-dimensional reconstruction of the cryo-TEM images provides very detailed structures of the micelles, and molecular dynamics simulations suggest that approximately 36 hexane molecules are needed to stabilize the dodecameric micelles. Sodium counterions are found to exert a significant stabilizing effect that results in an apparent attraction between the highly negatively charged polycarboxylate headgroups. DFT calculations support the observation that the formation of ion multiplets is especially crucial for this stabilizing counterion effect, which reduces headgroup repulsion. This and the increased hydrophobic stabilization that results from the hexane-enlarged core of the micelle lead to stable dodecameric micelles. The specific effects found for sodium counterions are largely absent for potassium.

Self-organized vortex multiplets in swirling flow

The possibility of double vortex multiplet formation at the center of an intensively swirling cocurrent flow generated in a cylindrical container by its rotating lid is reported for the first time. The boundary of the transition to unsteady flow regimes, which arise as a result of the equilibrium rotation of self-organized vortex multiplets (triplet, double triplet, double doublet, and quadruplet), has been experimentally determined for cylinders with the aspect (height to radius) ratios in a wider interval than that studied previously.

Influence of ionic association on the nonisothermal crystallization kinetics of sodium sulfonate poly(butylene succinate) ionomers

AbstractWe evaluated the relationship between the ionic substituents and nonisothermal crystallization behavior in poly(butylene succinate) (PBS) ionomers, synthesized by the introduction of sulfonated dimethyl fumarate (SDMF) with sodium sulfonate. In addition, we investigated the effect of sodium ions on the molecular structure of the PBS backbone by solid‐state 23Na NMR analysis. Sodium ion aggregates (multiplets) was predominately created with the ionic group concentration, and melt rheology and dynamic melt analysis results showed that multiplet formation induced not only remarkable heterogeneity, but also a high degree of clustering in the PBS chains. At low ionic group concentration, well dispersed multiplets behaved as effective nuclei during the crystallization of the PBS ionomer and accelerated the rate of crystallization. As ionic group concentration grew higher, crystallization rates decreased due to hindered chain mobility by clusters consisting of numerous multiplets. A combined Ozawa and Avrami equation proved to be more effective than the Ozawa equation in describing the nonisothermal crystallization kinetics of PBS and its ionomers. The observed nucleation activity indicates that the nonisothermal crystallization rate is not directly proportional to the ionic group concentration. Superior nucleation activity was observed in PBS ionomer containing 1 mol % SDMF. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 925–937, 2008

Chiral symmetry and the string description of excited hadrons

A large symmetry group is perhaps experimentally observed in excited hadrons which includes the chiral group $U(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(2{)}_{R}$ as a subgroup. To possess this large symmetry a dynamical model for excited hadrons, presumably a string model, should explain formation of chiral multiplets and, at the same time, predict coinciding slopes of the angular and radial Regge trajectories. This is possible only if both the dynamics of the string and the chirality of the quarks at the ends of the string are considered together. We construct a model-independent unitary transformation from the relativistic chiral basis to the ${^{2S+1}L_{J}}$ basis, commonly used in hadronic phenomenology as well as in the string models, and demonstrate that a hadron belonging to the given chiral representation is a fixed superposition of the basis vectors with different $L$'s. Thus the description of highly excited hadron in terms of a fixed $L$ is not compatible with chiral symmetry and has to be disregarded in favor of the description in terms of the total hadron spin $J$. Therefore, dynamics of the string must deliver the principal quantum number $\ensuremath{\sim}n+J$, in order chiral multiplets with different spins to become degenerate, as required by the large symmetry group.