Linear Geometry Research Articles

Supported or unsupported three-center two-electron bonds? A criterion based on Interference Energy Analysis.

The classification of three-center two-electron (3c2e) bonds into supported (closed) or unsupported (open) was proposed by Lipscomb in his work on boranes and extended to transition metal complexes by Bau and co-workers. The species in which the interactions of the terminal atoms are negligible are called "unsupported bonds." Examples of chemical species that are said to exhibit such bonds are Li2H+, Na2H+, B2H7 -, Al2(CH3)7 -, and [(μ2-H)Cr2(CO)10]- although the general criterion for distinguishing these types of bonds is somewhat qualitative. Besides providing a unifying view of the nature of the chemical bond, in terms of quantum interference among electronic states, the Generalized Product Function Energy Partitioning method through the Interference Energy Analysis (IEA) is also potentially capable of providing a rigorous ground to the concept of supported bonds by looking at the specific interference energies between the orbital pairs associated with the bond. The IEA was performed in the species Li2H+, Na2H+, B2H7 -, C2H7 -, Al2H7 -, and [(μ2-H)Cr2(CO)10]-, as well as along the reaction path Li2H+ → Li2 + + H. The results shown that in all studied A-B-C bonds, the A-C interactions are as important as the A-B/B-C ones, leading to the conclusion that all studied 3c2e bonds are "supported," in the sense that the A-C interaction is not negligible. The particularity of those species in preferring linear geometry is completely explained by quasi-classical effects, more specifically, by minimization of the electron-electron and nucleus-nucleus repulsions.

Bird Migration with Visual Avian Navigation & Nest Nidification: The Spatial Linear Geometries Georeferencing Functionality

Problem: Bird migration (eye): Georeferencing procedure with clues, rules, functionalities, and restrictions, for avian navigation and nest nidification.
 Literature Knowledge: Computer vision (sensor): Robot self-referencing with the Perspective-n- Point pose estimation technique.
 Aim: Hypothesis introduction and proving (“The birds also follow the same georeferencing procedure like robots in avian navigation and nest nidification”).
 Methodology: (a) Reference data, images, and photography acquisition and 4-means layering (eBird dataset, Flickr imagery, CORINE land covering, and Volunteered Geographic Information);
 (b) Image processing; and (c) GIS spatial overlay analysis.
 Results: Statistical spatial analysis using data of the GIS overlays (the 4 layers). Correlation matrix (Avian navigation and nest nidification in low-density urban areas as these are affected by spatial linear geometries and land cover types).
 Conclusion: A statistically satisfactory approach to the introduced hypothesis.
 Potential Applications: Human spatial cognition and movement behavior; Children’s motor control and coordination.

Dinuclear silver(I)‐ and gold(I)‐ N heterocyclic carbene complexes; Synthesis, structural characterizations, photoluminescence and theoretical studies

Herein, a new family of cationic Ag(I)- and Au(I)-, complexes ligated to a novel C∩N donor N- heterocyclic carbene (NHC) ligand 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolin-2-ylidene, (1) are described. Compound 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6) essentially serves as a carbene precursor that delivers the NHC carbene to Ag(I) and Au(I). The corresponding complex [{Ag(1)}{PF6}]2,(2), was prepared using mild base Ag2O and 3-methyl-1-(1-methyl-2-methylbenzoyl)imidazolium hexafluorophosphate (1.HPF6). Transmetallation method was capitalized to synthesize [{Au(1)}{PF6}]2,(3). All the novel compounds were characterized by elemental analysis, 1H NMR, 13C NMR, HR mass spectroscopic studies, and finally by single crystal X-ray studies. X-ray crystallographic studies revealed that the dinuclear complex 2 and 3 adopt linear geometry (Ccarbene-Ag/Au-Nimi) where strong Ag–Ag and Au–Au interaction present. The structural assignments were further supported by DFT calculations. TDDFT studies have been performed to inside into the electronic properties.

Silver(I) pyridinyl complexes with benzothiazole, thiophene, and furan moieties: DNA/protein-binding, antibacterial, antioxidant, and anticancer studies.

We have synthesized and characterized nine Ag(I) complexes of Schiff bases containing thiophene, furan, and pyridine moieties for in vitro antibacterial, antioxidant, anticancer activities, and DNA/bovine serum albumin(BSA) binding studies. Based on the analytical and spectral analyses, a linear geometry was proposed for all the Ag(I) complexes, except for one (with the furan moiety), which formed a distorted T-shaped geometry. UV-vis absorption studies on the interactions of calf thymus-DNA (CT-DNA) with the nine Ag(I) complexes pointed to an intercalative binding mode. With a binding constant Kb of 3.75 × 105 M-1 , the complex bearing a benzothiazole moiety (1) interacted stronger with CT-DNA than the rest of the complexes. Fluorescence spectroscopic data revealed that the complexes had a modest binding affinity for BSA through static quenching. The complexes displayed good antioxidant properties, especially those with a benzothiazole moiety. Notable antibacterial activities against methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae were observed for complexes with the furan and thiophene moieties. The in vitro anticancer studies of selected complexes against three cancer cell lines showed that the complexes were more effective against the inhibition of the growth of cervical cancer cells relative to cisplatin.

Influence of the Analytical Segment Length on the Tram Track Quality Assessment

In the track quality analysis, numerical values representing the relative condition of track geometry called track quality indices (TQIs) are calculated along a specific track segment. Segments are defined as linear track geometry datasets with the homogeneous characteristics of factors affecting geometry degradation. The 200m-long analytical segment is used most often on inter-city conventional and high-speed rail networks. However, in the case of the small urban rail networks, the homogeneity of track-geometry degradation influential factors is very low. This segment length is usually too long for efficient track maintenance or reconstruction with minimal disruption of the urban traffic. This paper explores the effect of reducing the analytical segment length in the condition assessment of the tram network in the City of Osijek, Croatia. The research had two main objectives: (1) to assess the narrow-gauge tram-track geometry quality through the application of the established synthesized TQIs, and (2) to analyze how a change in the analytical segment length affects this assessment. Two synthesized track quality indices—one based on a weighted value and the other on a standard deviation of measured track geometry parameters—were calculated for the 27.5 km of tracks on consecutive 200-, 100-, 50-, and 25 m long analytical segments. The comparative analysis of the TQIs’ calculation results showed that the reduction in the segment length increased the resolution of the track quality analysis in both cases, while the index based on a weighted value of geometry deviations proved less sensitive to this reduction. These results contribute to further segmentation process establishment and TQIs implementation on tram infrastructure.

Parametricism: Order or Chaos?

Parametricism is defined as a groundbreaking discovery in today’s digital world. It claims to be the single style for avant-garde architecture, spreading its domains into architecture, planning, and allied design genres such as product design. While parametric architecture looks aesthetically dynamic, it doesn’t follow straight-line geometries which are deemed so important by architects such as Le Corbusier. As Corbusier very clearly says in his book The City of Tomorrow, it is the man who follows the straight path, while it is the donkey who meanders; his idea of “order” clearly suggests linear arrangements to the fractal level. Parametricism, on the other hand, lays it down as one of its ground rules that it abstains itself from the usage of linear geometry. It disregards linearity as rigid and considers it its sincere responsibility to break through it. With such strong emotions against Corbusier’s idea of “order”, how, then, does Parametricism justify order within itself? Or is there no inherent order which is followed by this new style that considers itself the next big movement in architecture after modernism? The route to finding an answer to this question lies in the Theory of Chaos. One of the things that the theory says is that chaos doesn’t mean a lack of order; apparent randomness, generated as a result of mathematical expressions with various parameters, only seems random because it has an inherent order which is too complex to be comprehended by the human mind at a single glance. Hence, cases were taken up and studies were done accordingly, leading to the finding that every aspect of parametric design derives its form by virtue of some running parameters, which are fed into computational software, thus generating the form which then falls under the parametric style of architecture; and that no aspect governing the design is arbitrary. Hence, it is proved that parametricism does have a sense of inherent order as is existent in chaos, which, though radically complex and principally contrary to the idea of order that Corbusier had, still holds valid on the grounds of the Theory of Chaos.

Spectroscopic Properties of the Astrochemical Molecules [Al, O, Si] x (x = 0, +1)

Aluminum and silicon are present in large quantities in the interstellar medium, making the triatomic species consisting of both elements intriguing with regard to the foundations of astrochemistry. Spectroscopic parameters have been calculated via high-level ab initio methods to assist with laboratory and observational detection of [Al, O, Si] x (x = 0,+1). All [Al, O, Si] x (x = 0,+1) isomers exist in the linear geometry, with linear AlOSi (X 2Π) and linear AlOSi+ (X 1Δ) being the most stable neutral and cationic species, respectively. Formation of the neutral species most likely occurs via reaction of AlO/SiO on an Si/Al dust grain surface, respectively. The cation molecules may form via ion–neutral reaction or as a consequence of photoionization. The rotational frequencies of linear AlOSi (X 2Π) have been calculated using vibrationally corrected rotational constants and centrifugal distortion to lead experimental and observational radio detection. The rotational frequencies are discussed for three temperatures indicative of various astronomical environments: the central circumstellar envelope (CSE) (100 K), outer CSE (30 K), and the interstellar medium (3 K). At 100 K, the lines originating from J′ > 30 are the best candidates for detection via ground-based telescope. Anharmonic vibrational analysis revealed various Fermi resonances that may complicate the vibrational spectrum of linear AlOSi (X 2Π). Finally, electronic spectroscopy may be the best means for laboratory detection of linear AlOSi (X 2Π), due to the presence of two overlapping electronic transitions with large oscillator strengths occurring at approximately 250 nm.

A simple approximate solution for the H3+ ion

AbstractHere I derive analytical expressions for the total energy of the cation in its equilateral and linear geometries. The theoretical model consists of a simple variational trial wavefunction made of the sum of three 1S Gaussian functions, each centered on each nucleus. Detailed derivations are presented and the advantages and limitations of this simple model are discussed. The correctness of the results was verified independently via Monte Carlo integration. This simple model correctly predicts and rationalizes the preference of for the equilateral geometry rather than the linear configuration. Despite its simplicity, the calculated HH bond length (R = 0.9088 Å) and breathing vibrational frequency (ν1 = 3276.59 cm−1) for equilateral ion are in good agreement with high‐level ab initio methods and the experiment, respectively.

Cationic Nickel d9‐Metalloradicals [Ni(NHC)2]+

AbstractA series of five new homoleptic, linear nickel d9‐complexes of the type [NiI(NHC)2]+ is reported. Starting from the literature known Ni(0) complexes [Ni(Mes2Im)2] 1, [Ni(Mes2ImH2)2] 2, [Ni(Dipp2Im)2] 3, [Ni(Dipp2ImH2)2] 4 and [Ni(cAACMe)2] 5 (Mes2Im=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolin‐2‐ylidene, Mes2ImH2=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolidin‐2‐ylidene, Dipp2Im=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolin‐2‐ylidene, Dipp2ImH2=1,3‐bis(2,6‐diisopropylphenyl)‐imidazolidin‐2‐ylidene, cAACMe=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐yliden), their oxidized Ni(I) analogues [NiI(Mes2Im)2][BPh4] 1+, [NiI(Mes2ImH2)2][BPh4] 2+, [NiI(Dipp2Im)2][BPh4] 3+, [NiI(Dipp2ImH2)2][BPh4] 4+ and [NiI(cAACMe)2][BPh4] 5+ were synthesized by one‐electron oxidation with ferrocenium tetraphenyl‐borate. The complexes 1+–5+ were fully characterized including X‐ray structure analysis. The complex cations reveal linear geometries in the solid state and NMR spectra with extremely broad, paramagnetically shifted resonances. DFT calculations predicted an orbitally degenerate ground state leading to large magnetic anisotropy, which was verified by EPR measurements in solution and on solid samples. The magnetic anisotropy of the complexes is highly dependent from the steric protection of the metal atom, which results in a noticeable decrease of the g‐tensor anisotropy for the N‐Mes substituted complexes 1+ and 2+ in solution due to the formation of T‐shaped THF adducts.

Magnetophoretic Cell Sorting: Comparison of Different 3D-Printed Millifluidic Devices

Cell sorting is a highly applicable technology for multiple biological, biotechnological, and medical applications. Magnetic cell sorting can be realized with microfluidic and millifluidic flow cells. Additive manufacturing and 3D printing allow for fast prototyping and validating separation processes on this small scale. Therefore, our novel approach is to use this technology to print millifluidic channels and to directly evaluate them on their magnetic separation performance and their handling for cell manipulation. In this study, two different flow cells manufactured with a 3D printer are compared in regard to their use for the magnetic cell sorting of algae. One linear flow cell geometry and one spiraling flow cell geometry have been investigated with perpendicular magnetic fields. Iron oxide nanoparticles have been synthesized and characterized prior to their use as a magnetic label for algae cells. Particle uptake by algae are investigated by a phenanthroline assay, and the particle/algae mixtures are studied by microscopy, dynamic light scattering, zeta potential, and magnetophoretic mobility measurements. Depending on magnetic susceptibility, the cells undergo different magnetophoretic forces. Interestingly, the spiraling geometry leads to a better fractionation of algae cells in accordance with their iron oxide load.

Dieless drawing wire with a given end geometry by realizing temperature distribution evolution

Dieless drawing that has been widely used to produce metal tubes, wires, and rods has more potential for the future, especially in manufacturing high performance screws and nails with specific points. Because there are no dies but heating and cooling system along with drawing platform needed, it is highly flexible and meets the requirements of the steadily asked manufacturing on-demand. Under this trend, this study attempts to propose a heat transfer model that can achieve the required temperature evolution for dieless drawing a wire to form a specific end geometry as a nail point by obtaining the required evolution of heat transfer coefficient and the correspondingly approximated cooling fluid rate. After it is validated with tests on a dieless drawing platform implemented with a cooling system, whose cooling flow rate is controllable, the results show that for a linear end geometry of a stainless steel wire, there is no significant difference between the temperature distribution evolution required and obtained from the experiment. Furthermore, the end geometry of the drawn wire falls within the current industry standard tolerances as well.

Traveling waves for a quasilinear wave equation

We consider a 2+1 dimensional wave equation appearing in the context of polarized waves for the nonlinear Maxwell equations. The equation is quasilinear in the time derivatives and involves two material functions V and Γ. We prove the existence of traveling waves which are periodic in the direction of propagation and localized in the direction orthogonal to the propagation direction. Depending on the nature of the nonlinearity coefficient Γ we distinguish between two cases: (a) Γ∈L∞ being regular and (b) Γ=γδ0 being a multiple of the delta potential at zero. For both cases we use bifurcation theory to prove the existence of nontrivial small-amplitude solutions. One can regard our results as a persistence result which shows that guided modes known for linear wave-guide geometries survive in the presence of a nonlinear constitutive law. Our main theorems are derived under a set of conditions on the linear wave operator. They are subsidized by explicit examples for the coefficients V in front of the (linear) second time derivative for which our results hold.

Hierarchical Access Control in Cloud Computing

Access control is an essential security component of cloud computing, and hierarchical access management is of particular interest because different access privileges are granted in practice. As a solution to versatile and fine-grained hierarchical access control in cloud computing, this paper also presents a hierarchical key assignment scheme based on linear geometry. The encryption key of each class in the hierarchy is connected with a private vector and a public vector in our scheme, and the inner product of an ancestor class's private vector as well as the public variable of its decedent’s class could be used to deduce the encryption method of that descendant class. The proposed scheme is among the direct access strategies on hierarchical access control, which also means so each class at a higher level can straight derive this same encryption key of its decedent’s class without and need to iterate. In furthermore to this basic hierarchy key derivation, we propose a dynamic key management mechanism to handle possible changes in the hierarchy efficiently. Under the assumption of pseudo - random number functions, our scheme requires only light computations over a finite field by providing strong key in-distinguishability. Furthermore, the simulation demonstrates that our scheme maximises the trade-off among computation consumption as well as storage space.

Pyridine‐functionalized N‐heterocyclic carbene gold(I) binuclear complexes as molecular electrocatalysts for oxygen evolution reactions

N‐heterocyclic carbene (NHC) complexes of gold(I/III) attained immense interest in catalytic organic transformations and as anticancer agents against several types of human cancers; however, their potential as electrocatalysts is scarce. The electrocatalytic oxygen evolution reaction was performed for the first time using pyridine‐functionalized NHC gold(I) binuclear metallacycles (8 and 9) possessing aptly designed ligand field. Complexes were prepared by the transmetallation of corresponding silver(I) NHC complexes, which were prepared by in situ deprotonation of pyridine and aryl substituted 1,2,4‐triazolium hexafluorophosphate salts (6 and 7) with Ag2O under dark. Both triazolium salts and binuclear gold(I) metallacycles were thoroughly characterised by NMR and ATR‐IR spectral and elemental analyses. A bromide salt 4 and a binuclear gold complex 9 were elucidated for structure by single crystal X‐ray diffraction analysis. Complex 9 possesses distorted linear coordination geometry around the gold atoms by the coordination of carbene carbon and pyridine nitrogen atoms bearing close Au–Au interaction (3.251 Å). The binuclear gold complexes 8 and 9 (along with 10 wt% conductive mesoporous carbon) were investigated as molecular electrocatalysts in oxygen evolution reaction (OER), which evidenced an oxygen evolution overpotential of 2.422 and 2.370 V versus reversible hydrogen electrode (RHE), respectively, to attain a current density of 10 mA.cm−2. The Tafel slope values of 40.9 and 30.4 mV dec−1 for 8 and 9, respectively, indicate the reaction mechanism involved and the suitability of these complexes as apt electrocatalysts for OER. The stability of the prepared molecular electrocatalysts was investigated by cyclic voltammetry and chronoamperometry techniques.

Terahertz technology in diagnosis of glioma molecular markers

Gliomas are invasive brain tumors with high rates of recurrence and mortality. It has been shown that specific markers for glioma’s differential diagnostics are enantiomers of 2-hydroxyglutarate (L-2HG and D-2HG) in brain tissues and blood. These isomers have unique absorption peaks originating from vibrational and rotational transitions in their molecules. In particular, the peaks centered at 1.337 THz and 1.695 THz correspond to L-2HG and D-2HG isomers, respectively. The goal of this work is to develop highly efficient frequency-selective sensors for L-2HG and D-2HG isomers using the effect of nanoantenna-assisted plasmonic enhancement of THz absorption. Such an approach provides a noticeable increase in detection sensitivity versus direct non-resonant methods. In this paper, we present the numerical results of the design optimization for L-2HG and D-2HG sensors based on Si/SiO2-wafer-backed arrays of golden nanoantennas of linear geometry. The optimal structural parameters of the arrays found through integral averaging of the square of the surface electric field over an array unit cell are recommended for further nanolithographic fabrication of this kind of THz sensor.

Demonstration of Mechanics-Based Track Geometry Deterioration Models

The Transportation Technology Center, Inc. (TTCI) is working to build on and extend existing mechanics-based track geometry deterioration forecasting models to support improved safety and reliability of ballasted tracks. This paper demonstrates how the railway track lifecycle model (RTLM) ballast model performs against field data and makes recommendations for improvement. Overall, the demonstration showed the mechanics-based model matches the general field behavior and its variations well, and it also identified potential improvements. The field data reinforced ballast fouling index (BFI) as a key factor in track geometry degradation. Additional factors that can cause variation in the BFI–track geometry degradation relationship were also identified, along with proposed curves that are easier to fit with field data. Linear track geometry degradation, with reference to mid-chord offset measurement with tonnage, fits the field data better than a logarithmic curve, which, historically, has been used to fit settlement as a function of tonnage. Using these improvements to the model, future work will focus on making the model as flexible as possible. This means identifying and incorporating key variables, in addition to BFI, that affect track geometry deterioration and allowing the model to either give general projections in situations with little historical data or become site-specific to a particular track section by incorporating historic data.

Pairs, trimers, and BCS-BEC crossover near a flat band: Sawtooth lattice

We investigate pairing and superconductivity in the attractive Fermi Hubbard model on the one-dimensional sawtooth lattice, which exhibits a flat band by fine-tuning the hopping rates. We first solve the two-body problem, both analytically and numerically, to extract the binding energy and the effective mass of the pairs. Based on the DMRG method, we address the ground-state properties of the many-body system, assuming equal spin populations. We compare our results with those available for a linear chain, where the model is integrable by Bethe ansatz, and show that the multiband nature of the system substantially modifies the physics of the BCS-BEC crossover. Near a flat band, the chemical potential remains always close to its zero-density limit predicted by the two-body physics. In contrast, the pairing gap exhibits a remarkably strong density dependence and, differently from the pair binding energy, it is no longer peaked at the flat-band point. We show that these results can be interpreted in terms of polarization screening effects, due to an anomalous attraction between pairs in the medium and single fermions. Importantly, we unveil that three-body bound states (trimers) exist in the sawtooth lattice, in sharp contrast with the linear chain geometry, and we compute their binding energy. The nature of these states is investigated via a strong coupling variational approach, revealing that they originate from tunneling-induced exchange processes.

Cytotoxicity of asymmetric mononuclear silver(I)-N-heterocyclic carbene complexes against human cervical cancer: Synthesis, crystal structure, DFT calculations and effect of substituents

A new series of asymmetrical N,N’-disubstituted benzimidazolium derived N-heterocyclic carbene (NHC) ligands and their mononuclear silver(I)-NHC complexes are reported. The ligands were prepared from N-alkylation of 1-methylbenzimidazole with alkyl bromides (n = 10-18 in even parity), non-fluorinated or fluorinated benzyl bromides. In situ deprotonation of the ligands with silver oxide, followed by metathesis reaction with potassium hexafluorophosphate facilitated the formation of the mononuclear silver(I)-NHC complexes. Chemical structures of all the compounds were elucidated using Fourier transform infrared, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and CHN elemental microanalysis. The coordination mode of the Ag(I)-NHC complexes was confirmed by single crystal XRD analysis. Single crystal analysis of ortho-fluorinated benzyl-containing complex showed that each complex consisted of one Ag(I) ion coordinated with two NHC ligands in a linear geometry in the presence of one PF6− anion in the lattice. Cytotoxic effects of the NHC ligands and their silver(I) complexes against human cervical cancer cells (HeLa) and normal human skin fibroblasts (Hs27) were investigated using the MTT assay. Cytotoxicity of these compounds was dependent on the N-substituents in the benzimidazolium moiety and the presence of silver ions. Benzylated ligands were non-active whilst their dialkylated analogues showed weak to excellent cytotoxic effects on HeLa cells. The incorporation of silver ions and elongation of alkyl chains significantly enhanced cytotoxicity. Density functional theory revealed that Ag–C bond strength was insensitive to the NHC ligand design, and about one-third of the overall complex binding enthalpy was contributed by the non-covalent interaction between the long alkyl chains. Long-chain ligands (n = 16-18) and all silver(I)-NHC complexes exhibited superior cytotoxicity against HeLa cells (IC50 ranged between 1.18 µM–9.38 µM) as compared to that of the anticancer drug, Etoposide (IC50 = 25.67 µM).

Experimental investigation of current jumps in linear geometry hot cathode ionization gauges in strong magnetic fields

In magnetic confinement nuclear fusion, neutral gas in the plasma edge region plays an important role for plasma fuelling and plasma wall interaction and thus influences the overall plasma behaviour. The ASDEX pressure gauge is a diagnostic instrument designed to provide local and temporally highly resolved measurements of the neutral gas flux density within the strong magnetic fields of fusion devices. It is a hot cathode ionization gauge with a linear geometry. Its function principle relies on the measurement of an ion current, caused by oscillating electrons in the gauge which ionize the neutral gas. Anomalous jumps in the ion current of up to 30% have been observed during gauge operation in the tokamak ASDEX Upgrade and the stellarator Wendelstein 7-X, which introduces an error in the measurement. This paper describes for the first time the characterization of these jumps over the broad operational space. Parameter dependencies on pressure, electron current, electrode potentials and magnetic field angle are discussed. The appearance of electrostatic oscillations with frequencies in the range of 160MHz to 350MHz which are associated with the current jumps has been discovered. The frequency of these oscillations was found to scale with the oscillation frequency of the electron motion inside the gauge. Potential physical mechanisms to explain the jumps are discussed.

Probing the structures and bonding of Ag/H end-capping acetylene and polyyne, AgC2nH− (n = 1, 2), a combined photoelectron imaging and quantum chemical calculation study

The electronic structures of AgC2nH− (n = 1, 2) are reported by using photoelectron imaging and ab initio calculations. The results indicate that all the ground states of anion and neutral AgC2nH have a linear geometry. The electron affinities (EAs) are measured to be 1.123 and 1.379 eV for AgC2H and AgC4H, respectively. The NRT analysis shows that ionic character dominates the Ag–C chemical bond in these neutral species. The calculated static dipole polarizability (α) and second hyperpolarizability (γ) of the molecules indicate that the cap of Ag could enhance the nonlinear optical responses.