Exotic Molecules Research Articles

Electrochemical Control of Copper Intercalation into Nanoscale Bi2Se3.

Intercalation of exotic atoms or molecules into the layered materials remains an extensively investigated subject in current physics and chemistry. However, traditionally melt-growth and chemical interaction strategies are either limited by insufficiency of intercalant concentrations or destitute of accurate controllability. Here, we have developed a general electrochemical intercalation method to efficaciously regulate the concentration of zerovalent copper atoms into layered Bi2Se3, followed by comprehensive experimental characterization and analyses. Up to 57% copper atoms (Cu6.7Bi2Se3) can be intercalated with no disruption to the host lattice. Meanwhile the unconventional resistance dip accompanied by a hysteresis loop below 40 K, as well as the emergence of new Raman peak in CuxBi2Se3, is a distinct manifestation of the interplay between intercalated Cu atoms with Bi2Se3 host. Our work demonstrates a new methodology to study fundamentally new and unexpected physical behaviors in intercalated metastable materials.

Crafting markets for succinic acid

No one can say what the hardest task in industrial chemistry is, but developing a biobased route to an obscure chemical, running the process at large scale, and getting the exotic molecule to compete with entrenched petrochemicals is as good a guess as any. This is exactly what BioAmber is attempting. The company has a gleaming new plant in Sarnia, Ontario, that can crank out more succinic acid than any other facility in the world. It has real customers putting the building block chemical to use in a variety of specialty applications. Now BioAmber is aiming higher. The firm is beginning to cultivate a market for the chemical in polyester for beverage containers, an application that could gobble up all the succinic acid it can send from its loading docks. But it will be a tough business to break into. BioAmber is a relatively old hand in the new field

Heavy exotic molecules

We briefly review the formation of pion-mediated heavy-light exotic molecules with both charm and bottom, under the general structures of chiral and heavy quark symmetries. The charm isosinglet exotic molecules with [Formula: see text] binds, which we identify as the reported neutral [Formula: see text]. The bottom isotriplet exotic with [Formula: see text] binds, and is identified as a mixed state of the reported charged exotics [Formula: see text] and [Formula: see text]. The bound bottom isosinglet molecule with [Formula: see text] is a possible neutral [Formula: see text] to be observed.

Heavy-Light Exotics from QCD Laplace Sum Rule at N2LO in the chiral limit

These talks review and summarize our results in [1, 2] on XYZ-like spectra obtained from QCD Laplace Sum Rule in the chiral limit at next-to-next-leading order (N2LO) of perturbation theory (PT) and including leading order (LO) contributions of dimensions d≤6−8 non-perturbative condensates. We conclude that the observed XZ states are good candidates for 1+ and 0+ molecules or / and four-quark states while the predictions for 1− and 0− states are about 1.5 GeV above the Yc,b experimental candidates and hadronic thresholds. We (numerically) find that these exotic molecules couple weakly to the corresponding interpolating currents than ordinary D, B heavy-light mesons while we observe that these couplings decrease faster [1/mb3/2 (resp. 1/mb) for the 1+, 0+ (resp. 1−, 0−) states] than 1/mb1/2. results do not also confirm the existence of the X(5568) state in agreement with LHCb findings.

Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio.

Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio [Formula: see text] can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10-9 to 16 × 10-9 About 2 × 109 antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, [Formula: see text] was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10-10.

Exotic molecule tests fundamental symmetry

Physics Spectroscopy of exotic molecules can offer insight into fundamental physics. Hori et al. studied the transition frequencies of an unusual helium atom in which one of the two electrons was substituted by an antiproton, the negatively charged antiparticle partner of the proton (see the

Observation of pendular butterfly Rydberg molecules.

Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron–perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance.

Electrostatic-Charge- and Electric-Field-Induced Smart Gating for Water Transportation.

Regulating and controlling the transport of water across nanochannels is of great importance in both fundamental research and practical applications because it is difficult to externally control water flow through nanochannels as in biological channels. To date, only a few hydrophobic nanochannels controlling the transport of water have been reported, all of which use exotic hydrophobic molecules. However, the effect of electrostatic charges, which plays an indispensable role in membrane proteins and dominates the energetics of water permeation across aquaporins, has not gained enough attention to control water transport through a solid-state nanochannel/nanopore. Here, we report electrostatic-charge-induced water gating of a single ion track-etched sub-10 nm channel. This system can directly realize the gating transition between an open, conductive state and a closed, nonconductive state by regulating the surface charge density through a process that involves alternating capillary evaporation and capillary condensation. Compared to the introduction of exotic hydrophobic molecules, water gating controlled by electrostatic charges is simple, convenient, and effective. Such a system anticipates potential applications including desalination, controllable valves, and drug delivery systems.

Heavy exotic molecules with charm and bottom

We revisit the formation of pion-mediated heavy-light exotic molecules with both charm and bottom and their chiral partners under the general strictures of both heavy-quark and chiral symmetry. The chiral exotic partners with good parity formed using the $(0^+, 1^+)$ multiplet are about twice more bound than their primary exotic partners formed using the $(0^-,1^-)$ multiplet. The chiral couplings across the multiplets $(0^\pm, 1^\pm)$ cause the chiral exotic partners to unbind, and the primary exotic molecules to be about twice more bound, for $J\leq 1$. Our multi-channel coupling results show that only the charm isosinglet exotic molecules with $J^{PC}=1^{++}$ binds, which we identify as the reported neutral $X(3872)$. Also, the bottom isotriplet exotic with $J^{PC}=1^{+-}$ binds, which we identify as a mixture of the reported charged exotics $Z^+_b(10610)$ and $Z^+_b(10650)$. The bound isosinglet with $J^{PC}=1^{++}$ is suggested as a possible neutral $X_b(10532)$ not yet reported.

Ultracold molecular Rydberg physics in a high density environment

Sufficiently high densities in Bose–Einstein condensates provide favorable conditions for the production of ultralong-range polyatomic molecules consisting of one Rydberg atom and a number of neutral ground state atoms. The chemical binding properties and electronic wave functions of these exotic molecules are investigated analytically via hybridized diatomic states. The effects of the molecular geometry on the system’s properties are studied through comparisons of the adiabatic potential curves and electronic structures for both symmetric and randomly configured molecular geometries. General properties of these molecules with increasing numbers of constituent atoms and in different geometries are presented. These polyatomic states have spectral signatures that lead to non-Lorentzian line-profiles.

Three-body calculation of exotic molecules with negatively charged massive particle

SynopsisIf the gravitino mass is in the region from a few GeV to a few 10’s GeV, the scalar lepton X− such as stau is most likely the next lightest supersymmetry particle. The negatively charged and long-lived X− can form a Coulombic bound state, an exotic atom, with a nucleus. Energy levels and structures of exotic molecules consisting of two nuclei and X− are precisely calculated. We discuss stabilities of the exotic molecule and intramolecular nuclear reactions.

Efimov trimers imaged for the first time

The exotic molecules, though composed of three identical atoms, have an asymmetric structure.

One-dimensional water cages with repeat units of (H2O)24resembling pagodane trapped in a 3D coordination polymer: proton conduction and tunable luminescence emission by adsorption of anionic dyes

A 3D-coordination polymer was shown to trap one-dimensional polyhedral water cages consisting of repeat units of (H2O)24, the geometry of which resembles the exotic organic molecule pagodane.

ChemInform Abstract: Metallacyclocumulenes: A Theoretical Perspective on the Structure, Bonding, and Reactivity

AbstractReview: 45 refs.

Metallacyclocumulenes: a theoretical perspective on the structure, bonding, and reactivity.

Conspectus Transition metals help to stabilize highly strained organic fragments. Metallacycles, especially unsaturated ones, provide much variety in this area. We had a sustained interest in understanding new C-C bond formation reactions affected by binuclear transition metal fragments Cp2M. One such study led to the exploration of the bimetallic C-C cleavage and coupled complexes, where the acetylide ligands bridge two metal atoms. The underlying M-C interaction in these complexes inspired the synthesis of a five-membered cyclocumulene complex, which opened a new phase in organometallic chemistry. The metallacyclocumulene produces a variety of C-C cleavage and coupled products including a radialene complex. Group 4 metallocenes have thus unlocked a fascinating chemistry by stabilizing strained unsaturated C4 organic fragments in the form of five-membered metallacyclocumulenes, metallacyclopentynes, and metallacycloallenes. Over the years, we have carried out a comprehensive theoretical study to understand the unusual stability and reactivity of these metallacycles. The unique (M-Cβ) interaction of the internal carbon atoms with the metal atom is the reason for unusual stability of the metallacycles. We have also shown that there is a definite dependence of the C-C coupling and cleavage reactions on the metal of metallacyclocumulenes. It demonstrates unexpected reaction pathways for these reactions. Based on this understanding, we have predicted and unraveled the stabilization factors of an unusual four-membered metallacycloallene complex. Indeed, our prediction about a four-membered heterometallacycle has led to an interesting bonding situation, which is experimentally realized. This type of M-C bonding is intriguing from a fundamental perspective and has great relevance in synthesizing unusual structures with interesting properties. In this Account, we first give a short prologue of what led to the present study and describe the salient features of the structure and bonding of the metallacyclocumulenes. The unusual reaction pathway of this metallacycle is explored next. Similar features of the metallacyclopentynes and metallacycloallenes are briefly mentioned. Then, we discuss the exploitation of the unique M-C bonding to design some exotic molecules such as a four-membered metallacycloallene complex. Our efforts to build a conceptual framework to understand these metallacycles and to exploit their chemistry continue.

Search forJPC=1−+exotic state ine+e−annihilation

The charmed meson pair $(\frac{3}{2})^+$ and anti-$(\frac{1}{2})^-$, i.e. $D_1(2420)\bar D+c.c.$, $D_1(2420)\bar D^*+c.c.$, $D_2(2460)\bar D^*+c.c.$, can couple to states with vector quantum number $J^{PC}=1^{--}$ and exotic quantum number $J^{PC}=1^{-+}$ in a relative $S$ wave. Near threshold, the charmed meson pair may form hadronic molecules due to the strong $S$-wave coupling, and the mysterious vector state $Y(4260)$ could be such a state of the $D_1(2420)\bar D+c.c.$ molecule. This implies the possible existence of its exotic partner made of the same charmed mesons but with $J^{PC}=1^{-+}$. We evaluate the production rate of such exotic hadronic molecules and propose a direct experimental search for them in $e^+e^-$ annihilation. The confirmation of such exotic states in experiment will shed light on the spectrum in the heavy quark sector.

Automated Design of Realistic Organometallic Molecules from Fragments

A method for the automated generation of realistic, synthetically accessible transition metal and organometallic complexes is described. Computational tools were designed to generate molecular fragments, preferably harvested from libraries of existing, stable compounds, to be used as building blocks for the construction of new molecules. These fragments are enriched with information about the number and type of possible connections to other fragments and are stored in library files. When connecting fragments in the subsequent building process, compatibility matrices, which define the connection rules between fragments, are used to delineate organometallic fragment spaces from which molecules can be generated in an automated fashion. The approach is flexible and allows ample structural variation at the same time as the combination of known fragments is easily restrained to avoid generation of exotic and unrealistic substructures and molecules. The method was tested in the generation of ruthenium complexes, with a given coordination environment, which can serve as candidates in catalyst development. The results demonstrate that molecules generated with the described method do not contain exotic arrangements of atoms and are by far more realistic than those obtained by the application of valence rules alone.

Three milieux for interstellar chemistry: gas, dust, and ice

The interdisciplinary science of astrochemistry is 45 years of age, if we pinpoint its origin to have occurred when the first polyatomic molecules were detected in the interstellar gas. Since that time, the field has grown remarkably from an esoteric area of research to one that unites scientists around the globe. Almost 200 different molecules have been detected in the gas-phase of interstellar clouds, mainly by rotational spectroscopy, while dust particles and their icy mantles in colder regions can be probed by vibrational spectroscopy. Astrochemistry is exciting to scientists in a number of different fields. Astronomers are interested in molecular spectra from the heavens because such spectra are excellent probes of the physical conditions where molecules exist, while chemists are interested in the exotic molecules, their spectra, and the unusual chemical processes that produce and destroy them under conditions often very different from those on our home planet. Chemical simulations involving thousands of reactions are now used to calculate concentrations and spectra of interstellar molecules as functions of time. Even biologists share an interest in the subject, because the interstellar clouds of gas and dust, portions of which collapse to form stars and planetary systems, contain organic molecules that may become part of the initial inventory of new planets and may indeed be the precursors of life. An irresistible subject to its practitioners, astrochemistry is proving to be exciting to a much wider audience. In this perspective article, the field is first introduced, and the emphasis is then placed on the three environments in which chemistry occurs in the interstellar medium: the gas phase, the surfaces of bare dust particles, and the ice mantles that cover bare grains in cold dense interstellar clouds. What we do know and what we do not know is distinguished. The status of chemical simulations for a variety of interstellar sources having to do with stellar and planetary evolution is surveyed. An optimistic view of the future of astrochemistry ends the article.

Stability of the Ground and Low-Lying Vibrational States of the Ammonium Radical

The tetrahedral ammonium radicals NH4 and ND4 are exotic neutral molecules that can be produced by charge exchange (CE) neutralization of the ammonium cation. In the present study, the stability of these radicals was measured by translational spectroscopy on the NH3/ND3 + H/D fragments resulting from CE between NH4+/ND4+ and cesium. The vibrationally resolved spectrum reveals the energy of the 3s(2A1) ground state of the ammonium radical relative to ground-state NH3 + H dissociation products as well as the energies for the singly excited ν1 and ν2 modes of the NH4 isotopologues. Using these values, a lower limit for the heat of formation of NH4, ΔHf,0K° = (189.7 ± 0.4) kJ/mol has been determined, as well as an adiabatic ionization energy of (4.62 ± 0.01) eV for NH4, in good agreement with recent predictions.

Analytical matrix elements of the Uehling potential in three-body systems and applications to exotic molecules

Exact analytical expressions for the matrix elements of the Uehling potential in a basis of explicitly correlated exponential wave functions are presented. The obtained formulas are then used to compute with an improved accuracy the vacuum polarization correction to the binding energy of muonic and pionic molecules, both in a first-order perturbative treatment and in a nonperturbative approach. The first resonant states lying below the n=2 threshold are also studied, by means of the stabilization method with a real dilatation parameter.