Binary Clusters Research Articles

Binary colloidal clusters with quantum dots for nanoscopic device applications

Colloidal clusters have garnered significant interest for their ability to elucidate nanoscopic phenomena in atomic arrangements and to enable the fabrication of complex nanostructures for advanced photonic and electronic applications. This study introduces a novel approach using binary colloidal clusters composed of semiconducting quantum dots and conductive gold-coated latex microspheres, fabricated via evaporation-driven self-assembly within emulsion droplets. This configuration not only demonstrates the binary colloidal clusters' capability for self-organization but also highlights the distinct regions formed by the smaller quantum dots, crucial for the electrical functionality of these nanoscopic devices. We have observed diode-like rectification behavior in these binary colloidal clusters, demonstrating their potential as active nanoscopic devices. Our findings present groundbreaking methodologies for integrating semiconductive and conductive materials in a colloidal form, offering a scalable and versatile platform for the development of next-generation devices in photonics and nanoelectronics.

The carbonyl-sulfur chalcogen bonding interaction: Rotational spectroscopic study of the 2,2,4,4-tetrafluoro-1,3-dithietane···formaldehyde complex

The rotational spectrum of a binary molecular cluster consisting of 2,2,4,4-tetrafluoro-1,3-dithietane (C2S2F4) and formaldehyde (H2CO) was studied by means of high-resolution Fourier transform microwave spectroscopy in conjunction with quantum chemical calculations. One of the three isomers predicted at the B3LYP-D3(BJ)/def2-TZVP level of theory was successfully detected in the supersonic expansion. Theoretical analyses using the non-covalent interactions and natural bond orbital methods reveal that the observed isomer is primarily stabilized by one C=O⋯S chalcogen bond and two C−H⋯F hydrogen bonds. The distance between the oxygen atom of H2CO and the nearest sulfur atom of C2S2F4 within the observed isomer is 2.9260(1) Å and the angle ∠O⋯S−C is 161.83(1)°. The analysis utilizing the symmetry-adapted perturbation theory approach demonstrates that electrostatic interactions play a significant role in stabilizing the studied complex, with the contribution of dispersion interactions being comparable to that of electrostatic ones.

Dynamic Structural Fluxionality in a Planar Tetracoordinate Carbon Cluster Stabilized by Boron Ligands.

The design of boron-based molecular rotors stems from boron-carbon binary clusters containing multiple planar hypercoordinate carbons (phCs, such as C2B8). However, the design of boron-coordinated phCs is challenging due to boron's tendency to occupy hypercoordinate centers more than carbon. Although this challenge has been addressed, the designed clusters of interest have not exhibited dynamic fluxionality similar to that of the initial C2B8. To address this issue, we report a σ/π doubly aromatic CB2H5 + cluster, the first global minimum containing a boron-coordinated planar tetracoordinate carbon atom with dynamic fluxionality. Dynamics simulations show that two ligand H atoms exhibit alternate rotation, resulting in an intriguing dynamic fluxionality in this cluster. Electronic structure analysis reveals the flexible bonding positions of the ligand H atoms because they do not participate in π delocalized bonding nor bond to any other non-carbon atom, highlighting this rotational fluxionality. Unprecedentedly, the fluxional process involves not only the usual conversion of the number of bonding atoms, but also the type of bonding (3c π bonds ↔4c σ bonds), which is an uncommon fluxional mechanism. The cluster represents an effort to apply phC species to molecular machines.

Electronic shells regulate the geometric structures, stabilities and electronic properties of AlnCum (n = 10–15, m = 1–3) clusters

The properties of AlnCum (n = 10–15, m = 1–3) clusters are explored using genetic algorithm combined with density functional theory (GA-DFT). The geometric structures of Al-Cu binary clusters are spherical when the numbers of the valence electrons are around the magic number 40 predicted by Jellium model. The stabilities decrease as the number of doping Cu atom increases. The stabilities also relate to the electronic configurations. In Al13Cu-a cluster, the 3d orbitals of the central Cu atom interact strongly with the superatomic 1D orbitals and formed five bonding orbitals and five antibonding orbitals. The bonding orbitals are dominated by 3d orbitals of Cu, and antibonding orbitals are composed mainly of the superatomic 1D orbitals. The “50 valence electrons” (including 3d10 of Cu) form closed 1S21P63d101D102S21F142P6 shells, and this electronic configuration can be taken as the combination of 40-electron rule. The 3d electrons of Cu atom don’t affect the Jellium model of the cluster.

Infrared Spectroscopy of Neutral and Cationic Benzonitrile-Methanol Binary Clusters in Supersonic Jets.

The formation of nitrogen-containing organic interstellar molecules is of great importance to reveal chemical processes and the origin of life on Earth. Benzonitrile (BN) is one of the simplest nitrogen-containing aromatic molecules in the interstellar medium (ISM) that has been detected in recent years. Methanol (CH3OH) exists widely in interstellar space with high reactivity. Herein, we measured the infrared (IR) spectra of neutral and cationic BN-CH3OH clusters by vacuum ultraviolet (VUV) photoionization combined with time-of-flight mass spectrometry. Combining IR spectra with the density functional theory calculations, we reveal that the BN-CH3OH intends to form a cyclic H-bonded structure in neutral clusters. However, after the ionization of BN-CH3OH clusters, proton-shared N···H···O and N···H···C structures are confirmed to form between BN and CH3OH, with the minor coexistence of H-bond and O-π structures. The formation of the proton-shared structure expands our knowledge of the evolution of the life-related nitrogen-containing molecules in the universe and provides a possible pathway to the further study of biorelevant aromatic organic macromolecules.

A Suite of Classical Cepheids Tied to the Binary Cluster Berkeley 58 and NGC 7790

The classical Cepheids CE Cas A, CE Cas B, CF Cas, and CG Cas are likely members of the binary open cluster comprising NGC 7790 and Berkeley 58. The clusters are of comparable age and in close proximity, as deduced from differentially dereddened UuB P BVGR P photometry, and Cepheid period-age relations. Gaia DR3 astrometric and spectroscopic solutions for the clusters are likewise consistent. Conversely, the seemingly adjacent open cluster NGC 7788 is substantially younger and nearer.

Discovery and timing of ten new millisecond pulsars in the globular cluster Terzan 5

We report the discovery of ten new pulsars in the globular cluster Terzan 5 as part of the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We observed Terzan 5 at L-band (856–1712 MHz) with the MeerKAT radio telescope for four hours on two epochs, and performed acceleration searches of 45 out of 288 tied-array beams covering the core of the cluster. We obtained phase-connected timing solutions for all ten discoveries, covering nearly two decades of archival observations from the Green Bank Telescope for all but one. Highlights include PSR J1748−2446ao which is an eccentric (e = 0.32) wide-orbit (orbital period Pb = 57.55 d) system. We were able to measure the rate of advance of periastron (ω̇) for this system allowing us to determine a total mass of 3.17 ± 0.02 M⊙. With a minimum companion mass (Mc) of ∼0.8 M⊙, PSR J1748−2446ao is a candidate double neutron star (DNS) system. If confirmed to be a DNS, it would be the fastest spinning pulsar (P = 2.27 ms) and the longest orbital period measured for any known DNS system. PSR J1748−2446ap has the second highest eccentricity for any recycled pulsar (e ∼ 0.905) and for this system we can measure the total mass (1.997 ± 0.006 M⊙) and estimate the pulsar and companion masses, (1.700−0.045+0.015 M⊙ and 0.294−0.014+0.046 M⊙, respectively). PSR J1748−2446ar is an eclipsing redback (minimum Mc ∼ 0.34 M⊙) system whose properties confirm it to be the counterpart to a previously published source identified in radio and X-ray imaging. We were also able to detect ω̇ for PSR J1748−2446au leading to a total mass estimate of 1.82 ± 0.07 M⊙ and indicating that the system is likely the result of Case A Roche lobe overflow. With these discoveries, the total number of confirmed pulsars in Terzan 5 is 49, the highest for any globular cluster so far. These discoveries further enhance the rich set of pulsars known in Terzan 5 and provide scope for a deeper understanding of binary stellar evolution, cluster dynamics and ensemble population studies.

Investigating 56 High Galactic Latitude Open Cluster Candidates in Gaia DR3

Using Gaia DR3 data, we revisit 56 high Galactic latitude (∣b∣ ≥ 30°) open cluster (OC) candidates with poor shapes of color–magnitude diagrams (CMDs), including unclear and paired main sequences (MSs). We aim to confirm their physical reality and explore whether the special MS morphology is intrinsic to genuine OCs. Initially, we redetermine cluster memberships by integrating five outlier detection algorithms into pyUPMASK. However, this work fails to reproduce the 56 clusters. Instead, we find an alternative set of 56 clusters, six of which are non-duplicates. To ascertain whether the six clusters are real OCs, we build synthetic CMDs to derive reliable cluster properties, including fundamental parameters, binary fraction, and mass of the cluster. Subsequently, we investigate the structural parameters and the age–mass and mass–radius relations of the six candidate OCs. Finally, we utilize a multidimensional approach, incorporating cluster properties, spatial structure, kinematic attributes, and CMD verification, to assess their physical reality as genuine OCs further. Our results suggest that the six candidates should be physical OCs, exhibiting well-defined CMD characteristics. Moreover, we discover two of the six OCs as potential binary clusters.

Quantum Cluster Equilibrium Theory for Multicomponent Liquids.

In this work, we present a new theory to treat multicomponent liquids based on quantum-chemically calculated clusters. The starting point is the binary quantum cluster equilibrium theory, which is able to treat binary systems. The theory provides one equation with two unknowns. In order to obtain another linearly independent equation, the conservation of mass is used. However, increasing the number of components leads to more unknowns, and this requires linearly independent equations. We address this challenge by introducing a generalization of the conservation of arbitrary quantities accompanied by a comprehensive mathematical proof. Furthermore, a case study for the application of the new theory to ternary mixtures of chloroform, methanol, and water is presented. Calculated enthalpies of vaporization for the whole composition range are given, and the populations or weights of the different clusters are visualized.

Goodbye to Chi by Eye: A Bayesian Analysis of Photometric Binaries in Six Open Clusters

We present a robust methodology for identifying photometric binaries in star clusters. Using Gaia DR3, Pan-STARRS, and Two Micron All Sky Survey data, we self-consistently define the cluster parameters and binary demographics for the open clusters (OCs) NGC 2168 (M35), NGC 7789, NGC 6819, NGC 2682 (M67), NGC 188, and NGC 6791. These clusters span in age from ∼200 Myr (NGC 2168) to more than ∼8 Gyr (NGC 6791) and have all been extensively studied in the literature. We use the Bayesian Analysis of Stellar Evolution software suite to derive the age, distance, reddening, metallicity, binary fraction, and binary mass-ratio posterior distributions for each cluster. We perform a careful analysis of our completeness and also compare our results to previous spectroscopic surveys. For our sample of main-sequence stars with masses between 0.6 and 1 M ⊙, we find that these OCs have similar binary fractions that are also broadly consistent with the field multiplicity fraction. Within the clusters, the binary fraction increases dramatically toward the cluster centers, likely a result of mass segregation. Furthermore nearly all clusters show evidence of mass segregation within the single and binary populations. The OC binary fraction increases significantly with cluster age in our sample, possibly due to a combination of mass-segregation and cluster-dissolution processes. We also find a hint of an anticorrelation between binary fraction and cluster central density as well as total cluster mass, possibly due to an increasing frequency of higher-energy close stellar encounters that inhibit long-period binary survival and/or formation.

On the Particle Acceleration Mechanisms in a Double Radio Relic Galaxy Cluster, Abell 1240

We present a 368 ks deep Chandra observation of Abell 1240, a binary merging galaxy cluster at a redshift of 0.195 with two brightest cluster galaxies that may have passed each other 0.3 Gyr ago. Building upon previous investigations involving Giant Metrewave Radio Telescope, Very Large Array, and LOFAR data, our study focuses on two prominent extended radio relics at the northwest (NW) and southeast (SE) of the cluster core. By leveraging the high-resolution Chandra imaging, we have identified two distinct surface-brightness edges at ∼1 Mpc and 1.2 Mpc NW and SE of the cluster center, respectively, coinciding with the outer edges of both relics. Our temperature measurements suggest the edges to be shock front edges. The Mach numbers, derived from the gas density jumps, yield MSE = 1.49−0.24+0.22 for the SE shock and MNW = 1.41−0.19+0.17 for the NW shock. Our estimated Mach numbers are remarkably smaller compared to those derived from radio observations ( MSE = 2.3 and MNW = 2.4), highlighting the prevalence of a reacceleration scenario over direct acceleration of electrons from the thermal pool. Furthermore, we compare the observed temperature profiles across both shocks with those of predictions from collisional versus collisionless models. Both shocks favor the Coulomb collisional model, but we could not rule out a purely collisionless model due to pre-shock temperature uncertainties.

Time-resolved photoelectron spectroscopy of iodide-4-thiouracil cluster: The ππ* state as a doorway for electron attachment.

The photophysics of thiobases-nucleobases in which one or more oxygen atoms are replaced with sulfur atoms- vary greatly depending on the location of sulfonation. Not only are direct dynamics of a neutral thiobase impacted, but also the dynamics of excess electron accommodation. In this work, time-resolved photoelectron spectroscopy is used to measure binary anionic clusters of iodide and 4-thiouracil, I- · 4TU. We investigate charge transfer dynamics driven by excitation at 3.88eV, corresponding to the lowest ππ* transition of the thiouracil, and at 4.16eV, near the cluster vertical detachment energy. The photoexcited state dynamics are probed by photodetachment with 1.55 and 3.14eV pulses. Excitation at 3.88eV leads to a signal from a valence-bound ion only, indicating a charge accommodation mechanism that does not involve a dipole-bound anion as an intermediate. Excitation at 4.16eV rapidly gives rise to dipole-bound and valence-bound ion signals, with a second rise in the valence-bound signal corresponding to the decay of the dipole-bound signal. The dynamics associated with the low energy ππ* excitation of 4-thiouracil provide a clear experimental proof for the importance of localized excitation and electron backfilling in halide-nucleobase clusters.

Tracing the Origins of Mass Segregation in M35: Evidence for Primordially Segregated Binaries

M35 is a young open cluster and home to an extensive binary population. Using Gaia Data Release 3, Pan-STARRS, and Two Micron All Sky Survey photometry with the Bayesian statistical software, BASE-9, we derive precise cluster parameters, identify single and binary cluster members, and extract their masses. We identify 571 binaries down to Gaia G = 20.3 and a lower limit on the binary frequency of f b = 0.41 ± 0.02. We extend the binary demographics by many magnitudes faint-ward of previous (radial-velocity) studies of this cluster and further away from the cluster center (1.°78, roughly 10 core radii). We find the binary stars to be more centrally concentrated than the single stars in the cluster. Furthermore, we find strong evidence for mass segregation within the binary population itself, with progressively more-massive binary samples becoming more and more centrally concentrated. For the single stars, we find weaker evidence for mass segregation; only the most massive single stars (>2.5M ⊙) appear more centrally concentrated. Given the cluster age of ∼200 Myr, and our derived half-mass relaxation time for the cluster of 230 ± 84 Myr, we estimate ∼47% of the binary stars and ∼12% of single stars in the cluster have had time to become dynamically mass segregated. Importantly, when we investigate only stars with mass segregation timescales greater than the cluster age, we still find the binaries to be more centrally concentrated than the singles, suggesting the binaries may have formed with a primordially different spatial distribution from that of the single stars.

On assessing the carbon capture performance of graphynes with particle swarm optimization.

Tackling climate change is one of the greatest challenges of current times and therefore the development of efficient technologies to limit anthropogenic emissions is of utmost urgency. Recent research towards this goal has alluded to the use of carbon-based solid sorbents for carbon capture. Graphynes (GYs), an interesting class of porous carbon membranes, have recently proven their potential as excellent membranes for gas adsorption and separation. Herein, we explored the CO2 and N2 adsorption characteristics and CO2/N2 selectivities of a class of GYs, namely γ-GY-1, γ-GY-2 and γ-GY-4. We investigated the putative global minimum geometries of adsorbed unary (n = 2-10) and binary (n : m; n, m ∈ [1, 8]) clusters of CO2 and N2 by employing a stochastic global optimization method called particle swarm optimization in conjunction with empirical intermolecular force field formulations. The intervening interactions are modeled using various pairwise potentials, including Lennard-Jones potential, improved Lennard-Jones potential, Buckingham potential and Coulombic potential. The binding energies for both unary and binary clusters are highest for adsorption on γ-GY-1, followed by γ-GY-2. The putative global minimum geometries suggested that N2 molecules preferred binding over the pore centres while CO2 molecules showed higher clustering propensity than any binding site preference. The predicted interaction energies suggested higher selectivity for CO2 over N2 for all the three γ-GYs.

Searching for stable copper borozene complexes in CuB7- and CuB8.

Copper has been shown to be an important substrate for the growth of borophenes. Copper-boron binary clusters are ideal platforms to study the interactions between copper and boron, which may provide insight about the underlying growth mechanisms of borophene on copper substrates. Here we report a joint photoelectron spectroscopy and theoretical study on two copper-doped boron clusters, CuB7- and CuB8-. Well resolved photoelectron spectra are obtained for the two clusters at different wavelengths and are used to understand the structures and bonding properties of the two CuBn- clusters. We find that CuB8- is a highly stable borozene complex, which possesses a half-sandwich structure with a Cu+ species interacting with the doubly aromatic η8-B82- borozene. The CuB7- cluster is found to consist of a terminal copper atom bonded to a double-chain B7 motif, but it has a low-lying isomer composed of a half-sandwich structure with a Cu+ species interacting with an open-shell η7-B72- borozene. Both ionic and covalent interactions are found to be possible in the binary Cu-B clusters, resulting in different structures.

Directed assembly of small binary clusters of magnetizable ellipsoids.

We report the effect of shape anisotropy and material properties on the directed assembly of binary suspensions composed of magnetizable ellipsoids. In a Monte Carlo simulation, we implement the ellipsoid-dipole model to calculate the pairwise dipolar interaction energy as a function of position and orientation. The analysis explores dilute suspensions of paramagnetic and diamagnetic ellipsoids with different aspect ratios in a superparamagnetic medium. We analyze the local order of binary structures as a function of particle aspect ratio, medium permeability, and dipolar interaction strength. Our results show that local order and symmetry are tunable under the influence of a uniform magnetic field when one component of the structure is dilute with respect to the other. The simulation results match previously reported experiments on the directed assembly of binary suspension of spheres. Additionally, we report the conditions on particle aspect ratios and medium properties for various structures with rotational symmetries, as well as open and enclosed structures under the influence of a uniform magnetic field.

Revisit of 77 Clusters Candidates with Multiple Main Sequences using Gaia DR3

Gaia DR3 data provide the latest and full astrometric data for more than 1.5 billion sources, and these allow us to revisit the 77 special open cluster candidates collected from LISC star cluster catalog. According to their unclear color–magnitude-diagram (CMD) morphology, they are difficult to be ensured as real open clusters (OCs), and their cluster properties are still poorly known. We perform a cluster census by reidentification for these clusters using pyUPMASK based on the photometric and astrometric stellar information. We have redetected these 77 objects and they should be real OCs, of which five clusters are potential binary clusters. Their basic parameters are obtained by fitting isochrones to observed CMDs. Our results show that their CMDs display more clean main sequences (MSs) and less member stars lying on the right of lower MSs relative to most of clusters in our initial sample, but broad MSs have not changed significantly. We suggest that efficient clustering algorithm combined with precision data can only partly reduce some stars lying on the right of lower MSs, and a simple stellar population of binary and rotating stars can partly reproduce multiple MS phenomena, including split and broad MSs.

JGSED: An End-to-End Spectral Clustering Model for Joint Graph Construction, Spectral Embedding and Discretization

Most of the existing graph-based clustering models performed clustering by adopting a two-stage strategy which first completes the spectral embedding from a given fixed graph and then resorts to other clustering methods such as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k$</tex-math></inline-formula> means to achieve discrete cluster results. On one hand, such a discretization operation easily causes that the obtained results deviate far from the true solution. On the other hand, clustering performance heavily relies on the quality of graph; therefore, the fixed graph is usually not optimal enough. In addition, clustering by separated steps inevitably breaks the underlying connections among the graph construction, spectral embedding and discretization. To address these drawbacks, in this paper, we propose a new spectral clustering model termed JGSED which integrates the graph construction, spectral embedding and spectral rotation together into a unified objective. JGSED is an end-to-end framework to directly take data as input and output the final binary cluster indicator matrix. An efficient algorithm is proposed to optimize the model variables in JGSED, which can be co-evolved towards the optimum. Extensive experiments are conducted on both synthetic and real data sets and the results demonstrate that JGSED outperforms the other state-of-the-art spectral clustering models, indicating the effectiveness of joint optimization.

The synergistic nucleation of iodous acid and sulfuric acid: A vital mechanism in polluted marine regions

The new particle formation occurs frequently in polluted marine regions, which is related to urban pollutants such as sulfuric acid (H2SO4). However, current H2SO4-based nucleation mechanism can seldom explain the concentrations of particles in polluted marine regions. Iodous acid (HIO2) can stabilize iodic acid (HIO3) clusters through its basic property. Nevertheless, whether HIO2 could nucleate with H2SO4 and the corresponding mechanism are still unknown. Using theoretical calculations, we find that HIO2 and H2SO4 can form stable binary clusters through hydrogen bonds, halogen bonds and acid-base proton transfer. The formation pathways of HIO2–H2SO4 contribute over 73% to the total cluster formation rates (J). Moreover, the J of HIO2–H2SO4 is at least two orders of magnitude higher than that of HIO3–H2SO4 and comparable with the critical HIO2–HIO3 system. The HIO2–H2SO4 nucleation may explain some missing fluxes of new particles and expand the H2SO4-based nucleation mechanism in polluted marine areas.

Steady-state and transient photocurrents of As-S-Sb-Te amorphous thin films

In the present work some nanostructured quaternary chalcogenides of the As-S-Sb-Te system have been investigated by a photoelectric method. The spectral distribution of steadystate photocurrent Iph=(λ) and the relaxation curves of photocurrent Iph=(t) were registered at positive and negative polarity of the applied voltage to the top Al illuminated electrode. In the spectral distribution of steady-state photocurrent, for the amorphous thin films As1.17S2.7Sb0.83Te0.40, As1.04S2.4Sb0.96Te0.60, As0.63S2.7Sb1.37Te0.30, and As0.56S2.4Sb1.44Te0.60 in the wavelength range λ=0.50÷0.92 mm (2.48÷1.35 eV) some maxima were detected, which are the result of the presence of binary clusters As2S3, Sb2S3 and Sb2S3. The photovoltaic method was used to obtain the value of the band gap width, which was about Eg =1.41 eV.