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https://www.readbyqxmd.com/read/29219566/dynamical-engineering-of-interactions-in-qudit-ensembles
#1
Soonwon Choi, Norman Y Yao, Mikhail D Lukin
We propose and analyze a method to engineer effective interactions in an ensemble of d-level systems (qudits) driven by global control fields. In particular, we present (i) a necessary and sufficient condition under which a given interaction can be decoupled, (ii) the existence of a universal sequence that decouples any (cancelable) interaction, and (iii) an efficient algorithm to engineer a target Hamiltonian from an initial Hamiltonian (if possible). We illustrate the potential of this method with two examples...
November 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29219561/long-range-order-in-the-dipolar-xy-antiferromagnet-er_-2-sn_-2-o_-7
#2
S Petit, E Lhotel, F Damay, P Boutrouille, A Forget, D Colson
Er_{2}Sn_{2}O_{7} remains a puzzling case among the extensively studied frustrated compounds of the rare-earth pyrochlore family. Indeed, while a first-order transition towards a long-range antiferromagnetic state with the so-called Palmer-Chalker structure is theoretically predicted, it has not yet been observed, leaving the issue as to whether it is a spin-liquid candidate open. We report on neutron scattering and magnetization measurements which evidence a second-order transition towards this Palmer-Chalker ordered state around 108 mK...
November 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29219540/noncollinear-magnetic-structure-and-multipolar-order-in-eu_-2-ir_-2-o_-7
#3
Yilin Wang, Hongming Weng, Liang Fu, Xi Dai
The magnetic properties of the pyrochlore iridate material Eu_{2}Ir_{2}O_{7} (5d^{5}) have been studied based on first principles calculations, where the crystal field splitting Δ, spin-orbit coupling (SOC) λ, and Coulomb interaction U within Ir 5d orbitals all play significant roles. The ground state phase diagram has been obtained with respect to the strength of SOC and Coulomb interaction U, where a stable antiferromagnetic ground state with all-in-all-out (AIAO) spin structure has been found. In addition, another antiferromagnetic state with energy close to AIAO has also been found to be stable...
November 3, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29219392/superfluid-filaments-of-dipolar-bosons-in-free-space
#4
Fabio Cinti, Alberto Cappellaro, Luca Salasnich, Tommaso Macrì
We systematically investigate the zero temperature phase diagram of bosons interacting via dipolar interactions in three dimensions in free space via path integral Monte Carlo simulations with a few hundreds of particles and periodic boundary conditions based on the worm algorithm. Upon increasing the strength of the dipolar interaction and at sufficiently high densities we find a wide region where filaments are stabilized along the direction of the external field. Most interestingly by computing the superfluid fraction we conclude that the superfluidity is anisotropic and is greatly suppressed along the orthogonal plane...
November 24, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29210429/probing-magnetic-coupling-between-lnpc2-ln-tb-er-molecules-and-the-graphene-ni-111-substrate-with-and-without-au-intercalation-role-of-the-dipolar-field
#5
V Corradini, A Candini, D Klar, R Biagi, V De Renzi, A Lodi Rizzini, N Cavani, U Del Pennino, S Klyatskaya, M Ruben, E Velez-Fort, K Kummer, N B Brookes, P Gargiani, H Wende, M Affronte
Lanthanides (Ln) bis-phthalocyanine (Pc), the so-called LnPc2double decker, are a promising class of molecules with a well-defined magnetic anisotropy. In this work, we investigate the magnetic properties of LnPc2 molecules UHV-deposited on a graphene/Ni(111) substrate and how they modify when an Au layer is intercalated between Ni and graphene. X-ray absorption spectroscopy (XAS), and linear and magnetic circular dichroism (XLD and XMCD) were used to characterize the systems and probe the magnetic coupling between LnPc2 molecules and the Ni substrate through graphene, both gold-intercalated and not...
December 6, 2017: Nanoscale
https://www.readbyqxmd.com/read/29185756/supramolecular-polymerization-of-n-n-n-n-tetra-tetradecyl-1-3-6-8-pyrenetetracarboxamide-a-computational-study
#6
Divya Bharathi Korlepara, Karteek K Bejagam, Sundaram Balasubramanian
The role of molecular dipole orientations and intermolecular interactions in a derivative of pyrene on its supramolecular self assembly in solution has been investigated using quantum chemical and force field based computational approaches. Five possible dipole configurations of the molecule have been examined, among which the one in which adjacent dipole vectors are antiparallel to each other is determined to be the ground state, on electrostatic grounds. Self-assembly of this molecule under realistic conditions has been studied using MD simu- lations...
November 29, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29166039/segmental-dynamics-of-polyethylene-alt-propylene-studied-by-nmr-spin-echo-techniques
#7
A Lozovoi, C Mattea, M Hofmann, K Saalwaechter, N Fatkullin, S Stapf
Segmental dynamics of a highly entangled melt of linear polyethylene-alt-propylene with a molecular weight of 200 kDa was studied with a novel proton nuclear magnetic resonance (NMR) approach based upon (1)H → (2)H isotope dilution as applied to a solid-echo build-up function I(SE)(t), which is constructed from the NMR spin echo signals arising from the Hahn echo (HE) and two variations of the solid-echo pulse sequence. The isotope dilution enables the separation of inter- and intramolecular contributions to this function and allows one to extract the segmental mean-squared displacements in the millisecond time range, which is hardly accessible by other experimental methods...
June 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29160229/improved-localized-surface-plasmon-resonance-index-sensitivity-based-on-chemically-synthesized-gold-nanoparticles-on-indium-tin-oxide-surfaces
#8
Jin Zhu, Xiaolong Li, Wei Zheng, Biao Wang, Yubo Tian
The results of this reported work indicated that gold nanoparticles (Au NPs) arrays self-assembled on Indium Tin Oxide (ITO) glasses can obtain broader localized surface plasmon resonance (LSPR) wavelength range and higher sensitivity than the bare quartz. The results of surface electric field calculated using Finite Difference Time Domain (FDTD) showed that the electric field of nanoparticles on ITO glasses is enhanced and the repulsive forces within each particle is weakened. According to the dipolar interaction mechanism, a weakened repulsive forces within each particle lead to a lower resonance frequency and a strong redshift of the LSPR spectra...
November 21, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29155822/heavy-atom-effect-on-optically-excited-triplet-state-kinetics
#9
Christian Hintze, Tobias O Morgen, Malte Drescher
In several fields of research, like e.g. photosensitization, photovoltaics, organic electroluminescent devices, dynamic nuclear polarization, or pulsed dipolar electron paramagnetic resonance spectroscopy, triplet state kinetics play an important role. It is therefore desirable to tailor the kinetics of photoexcited triplet states, e.g. by exploiting the intramolecular heavy-atom effect, and to determine the respective kinetic parameters. In this work, we set out to systematically investigate the photoexcited triplet state kinetics of a series of haloanthracenes by time-resolved electron paramagnetic resonance spectroscopy in combination with synchronized laser excitation...
2017: PloS One
https://www.readbyqxmd.com/read/29151204/afterglow-solid-state-nmr-spectroscopy
#10
Gili Abramov, Nathaniel J Traaseth
Biomolecular solid-state NMR experiments have traditionally been collected through detection of (13)C or (15)N nuclei. Since these nuclei have relatively low sensitivity stemming from their smaller gyromagnetic ratios relative to (1)H, the time required to collect multi-dimensional datasets serves as a limitation to resonance assignment and structure determination. One improvement in the field has been to employ simultaneous or parallel acquisition techniques with the goal of acquiring more than one dataset at a time and therefore speeding up the overall data collection process...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29148788/temperature-dependent-empirical-parameters-for-polarity-in-choline-chloride-based-deep-eutectic-solvents
#11
Arun Valvi, Jyoti Dutta, Shraeddha Tiwari
Deep eutectic solvents have emerged as a promising and economically viable alternative to address our need for environmentally benign media. Efficient utilization of deep eutectic solvents in various fields will require adequate knowledge about their physicochemical properties. In this work, independent polarity scales pertaining to solvent polarizability, dipolarity, acidity and basicity have been determined for some commonly used deep eutectic solvents based on choline chloride. The three eutectic mixtures selected for the study include reline (1:2 mixture of choline chloride and urea), ethaline (1:2 mixture of choline chloride and ethylene glycol) and glyceline (1:2 mixture of choline chloride and glycerol)...
November 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/29148715/ultrafast-long-range-charge-separation-in-nonfullerene-organic-solar-cells
#12
Yasunari Tamai, Yeli Fan, Vincent O Kim, Kostiantyn Ziabrev, Akshay Rao, Stephen Barlow, Seth R Marder, Richard H Friend, S Matthew Menke
Rapid, long-range charge separation in polymer-fullerene organic solar cells (OSCs) enables electrons and holes to move beyond their Coulomb capture radius and overcome geminate recombination. Understanding the nature of charge generation and recombination mechanisms in efficient, nonfullerene-acceptor-based OSCs are critical to further improve device performance. Here we report charge dynamics in an OSC using a perylene diimide (PDI) dimer acceptor. We use transient absorption spectroscopy to track the time evolution of electroabsorption caused by the dipolar electric field generated between electron-hole pairs as they separate after ionization at the donor-acceptor interface...
November 17, 2017: ACS Nano
https://www.readbyqxmd.com/read/29145080/comparing-the-efficacy-of-solid-and-magic-echo-refocusing-sequences-applications-to-1-h-nmr-echo-spectroscopy-of-shale-rock
#13
Gregory S Boutis, Ravinath Kausik
Quantitative evaluation of the solid and viscous components of unconventional shale rock, namely kerogen and bitumen, is important for understanding reservoir quality. Short transverse coherence times, due to strong (1)H-(1)H dipolar interactions, motivates the application of solid state refocusing pulse sequences that allow for investigating components of the free-induction decay that are otherwise obscured by instrumental effects such as probe ringdown. This work reports on static, wide-line (1)H spectroscopy of shale rock and their extracted components, which include kerogen and bitumen, by the application of solid echo and magic echo pulse sequences...
November 3, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/29141439/double-cross-polarization-for-the-indirect-detection-of-nitrogen-14-nuclei-in-magic-angle-spinning-nmr-spectroscopy
#14
Diego Carnevale, Xiao Ji, Geoffrey Bodenhausen
Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer (1)H → (14)N →(1)H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for (14)N quadrupolar couplings up to 4 MHz...
November 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29139285/subradiant-dipolar-interactions-in-plasmonic-nanoring-resonator-array-for-integrated-label-free-biosensing
#15
Yuzhang Liang, Hui Zhang, Wenqi Zhu, Amit Agrawal, Henri J Lezec, Lixia Li, Wei Peng, Yi Zou, Yan-Qing Lu, Ting Xu
With the development of advanced nanofabrication technologies over the last decade, plasmonic nanostructures have attracted wide attention for their potential in label-free biosensing applications. However, the sensing performance of nanostructured plasmonic sensors is primarily limited by the broad-linewidth features with low peak-to-dip signal ratio in the extinction spectra that result from strong radiative damping. Here, we propose and systematically investigate the in-plane and out-of-plane dipolar interactions in an array of plasmonic nanoring resonators that are from the spatial combination of classic nanohole and nanodisk structures...
November 15, 2017: ACS Sensors
https://www.readbyqxmd.com/read/29121512/composite-pulse-and-partially-dipolar-dephased-multicp-for-improved-quantitative-solid-state-13-c-nmr
#16
Pu Duan, Klaus Schmidt-Rohr
Improved multiple cross polarization (multiCP) pulse sequences for quickly acquiring quantitative (13)C NMR spectra of organic solids are presented. Loss of (13)C magnetization due to imperfect read-out and storage pulses in multiCP has been identified as a significant mechanism limiting polarization enhancement for (13)C sites with weak couplings to (1)H. This problem can be greatly reduced by composite 90° pulses with non-orthogonal phases that flip the magnetization onto the spin-lock field and back to the longitudinal direction for the (1)H repolarization period; the observed loss is <3% for over ±10 kHz resonance offset and up to 20% flip-angle error...
November 6, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29119518/cyclotron-phase-coherent-ion-spatial-dispersion-in-a-non-quadratic-trapping-potential-is-responsible-for-ft-icr-ms-at-the-cyclotron-frequency
#17
Konstantin O Nagornov, Anton N Kozhinov, Yury O Tsybin
Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) at the cyclotron frequency instead of the reduced cyclotron frequency has been experimentally demonstrated using narrow aperture detection electrode (NADEL) ICR cells. Here, based on the results of SIMION simulations, we provide the initial mechanistic insights into the cyclotron frequency regime generation in FT-ICR MS. The reason for cyclotron frequency regime is found to be a new type of a collective motion of ions with a certain dispersion in the initial characteristics, such as pre-excitation ion velocities, in a highly non-quadratic trapping potential as realized in NADEL ICR cells...
November 8, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/29116139/integrated-plasmon-enhanced-raman-scattering-ipers-spectroscopy
#18
Hailong Wang, Haibo Li, Shuping Xu, Bing Zhao, Weiqing Xu
A new strategy named integrated plasmon-enhanced Raman scattering (iPERS) spectroscopy that features a configuration of evanescent field excitation and inverted collection is presented, which well unites the local field enhancement and far field emission, couples localized and propagating surface plasmons, integrates the SERS substrates and Raman spectrometers via a self-designed aplanatic solid immersion lens. A metallic nanoparticle-on-a film (NOF) system was adopted in this configuration because it improves the amplification of the incidence light field in near field by 10 orders of magnitude due to the simultaneous excitation of quadrupolar and dipolar resonance modes...
November 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29113079/synthesis-of-ferrofluids-made-of-iron-oxide-nanoflowers-interplay-between-carrier-fluid-and-magnetic-properties
#19
Federico Spizzo, Paolo Sgarbossa, Elisabetta Sieni, Alessandra Semenzato, Fabrizio Dughiero, Michele Forzan, Roberta Bertani, Lucia Del Bianco
Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III) chloride hexahydrate (FeCl₃·6H₂O) in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG)...
November 5, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29106809/an-active-approach-to-colloidal-self-assembly
#20
Stewart A Mallory, Chantal Valeriani, Angelo Cacciuto
In this review, we discuss recent advances in the self-assembly of selfpropelled colloidal particles and highlight some of the most exciting results in this field, with a specific focus on dry active matter. We explore this phenomenology through the lens of the complexity of the colloidal building blocks. We begin by considering the behavior of isotropic spherical particles. We then discuss the case of amphiphilic and dipolar Janus particles. Finally, we show how the geometry of the colloids and/or the directionality of their interactions can be used to control the physical properties of the assembled active aggregates, and we suggest possible strategies for how to exploit activity as a tunable driving force for self-assembly...
November 6, 2017: Annual Review of Physical Chemistry
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