Cl2 Molecules Research Articles

Tunneling Ionization of Aligned CH3X (X=I, Br, Cl) Molecules in Intense Femtosecond Laser Fields

SynopsisWe perform an experimental investigation on tunneling ionization of CH3X (X=I, Br, Cl) molecules in intense femtosecond laser fields (1013 to 1015 W/cm2). The angular distribution of the parent and fragment ions from the well aligned molecular targets has been measured. Compared with theoretical calculation, the results show some new insights into the ionization mechanism of these molecules in intense laser fields.

Edge effects in second-harmonic generation in nanoscale layers of transition-metal dichalcogenides

The results of studying the optical properties of nanoscale single crystals of MoS2:Cl2 and WS2:Br2 semiconductor compounds are presented. In microscopic images obtained at the wavelength of the second (400 nm), edge effects are detected, which consist in enhancement or reduction in the second-harmonic signal intensity. Unlike previously proposed interference mechanisms of edge effects, non-interference mechanisms are considered. The occurrence of edge effects is associated with either an increased Cl2 and Br2 halogen molecule concentration or with an electrically induced second harmonic caused by band bending at the edges of individual crystal layers.

Examining the Critical Roles of Protons in Facilitating Oxidation of Chloride Ions by Permanganates: A Cluster Model Study.

The oxidation power of permanganates (MnO4(-)) is known to be strongly dependent on pH values, and is greatly enhanced in acidic solutions, in which, for example, MnO4(-) can even oxidize Cl(-) ions to produce Cl2 molecules. Although such dependence has been ascribed due to the different reduced states of Mn affordable in different pH media, a molecular level understanding and characterization of initial redox pair complexes available in different pH solutions is very limited. Herein, we report a comparative study of [MnO4](-) and [MnO4·Sol](-) (Sol = H2O, KCl, and HCl) anion clusters by negative ion photoelectron spectroscopy (NIPES) and theoretical computations to probe chemical bonding and electronic structures of [MnO4·Sol](-) clusters, aimed to obtain a microscopic understanding of how MnO4(-) interacts with surrounding molecules. Our study shows that H2O behaves as a solvent molecule, KCl is a spectator bound by pure electrostatic interactions, both of which do not influence the MnO4(-) identity in their respective clusters. In contrast, in [MnO4·HCl](-), the proton is found to interact with both MnO4(-) and Cl(-) with appreciable covalent characters, and the frontier MOs of the cluster are comprised of contributions from both MnO4(-) and Cl(-) moieties. Therefore, the proton serves as a chemical bridge, bringing two negatively charged redox species together to form an intimate redox pair. By adding more H(+) to MnO4(-), the oxygen atom can be taken away in the form of a water molecule, leaving MnO4(-) as an electron deficient MnO3(+) species, which can subsequently oxidize Cl(-) ions.

Ground state analytical ab initio intermolecular potential for the Cl(2)-water system.

The chlorine/water interface is of crucial importance in the context of atmospheric chemistry. Modeling the structure and dynamics at this interface requires an accurate description of the interaction potential energy surfaces. We propose here an analytical intermolecular potential that reproduces the interaction between the Cl2 molecule and a water molecule. Our functional form is fitted to a set of high level ab initio data using the coupled-cluster single double (triple)/aug-cc-p-VTZ level of electronic structure theory for the Cl2 - H2O complex. The potential fitted to reproduce the three minima structures of 1:1 complex is validated by the comparison of ab initio results of Cl2 interacting with an increasing number of water molecules. Finally, the model potential is used to study the physisorption of Cl2 on a perfectly ordered hexagonal ice slab. The calculated adsorption energy, in the range 0.27 eV, shows a good agreement with previous experimental results.

Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

Abstract Molecular and electronic structure changes during successive reduction of a Fe-tetraphenylporphyrin chloride [Fe(III)(TPP):Cl] complex are reported on the basis of Mössbauer spectroscopy and DFT calculations. It is established that the attachment of additional electrons to a neutral Fe(III)(TPP):Cl molecule leads to significant shortening of Fe-N distances at the first stage of the reduction Fe(III)(TPP):Cl → Fe(II)(TPP) and lengthening of these bonds at the second stage Fe(II)(TPP) → Fe(I)(TPP). Changes of other bond lengths of the porphyrin ring also appear but in less degree. Interaction of Fe(II) and Fe(I)(TPP) with tetrahydrofuran (THF) solvent is considered. Electron configuration of Fe(II)(TPP) corresponds to intermediate-spin (S = 1) state and in the case of Fe(I)(TPP) low-spin state (S = ½) is observed. Electron density distribution in Fe(II)- and Fe(I)(TPP) complexes, in association with Mössbauer data, is analyzed. Good correlation between experimental and theoretical results was obtained.

Theoretical investigation of the halogen bonded complexes between carbonyl bases and molecular chlorine.

The halogen bonded complexes between six carbonyl bases and molecular chlorine are investigated theoretically. The interaction energies calculated at the CCSD(T)/aug-cc-pVTZ level range between -1.61 and -3.50 kcal mol(-1). These energies are related to the ionization potential, proton affinity, and also to the most negative values (V(s,min)) on the electrostatic potential surface of the carbonyl bases. A symmetry adapted perturbation theory decomposition of the energies has been performed. The interaction results in an elongation of the Cl-Cl bond and a contraction of the CF and CH bonds accompanied by a blue shift of the ν(CH) vibrations. The properties of the Cl2 molecules are discussed as a function of the σ*(Cl-Cl) occupation, the hybridization, and the occupation of the Rydberg orbitals of the two chlorine atoms. Our calculations predict a large enhancement of the infrared and Raman intensities of the ν(Cl-Cl) vibration on going from isolated to complexed Cl2.

The process of dissociation of Cl2 molecule on the Ge(0 0 1)-p(1 × 2) surface

In this paper, we analyze theoretically four possible reaction paths during dissociative adsorption of chlorine molecule at the germanium surface. We have calculated the temporary atomic structures, local density of states and spatial distributions of charge density during the processes of dissociation and adsorption. Depending on the reaction path the properties of the system in the process can differ significantly from the final state.

N-nitroimidoyl chlorides: synthesis and structure

A new method was developed for the synthesis of N-nitroimidoyl chlorides O2N—N=C(R)Cl (R = SMe, Phth; Phth is phthalimide) by the reaction of O2N—N=C(R)SMe with SO2Cl2. The reaction of O2N—N=C(SMe)Cl with potassium phthalimide leads to the replacement of the Cl atom by the phthalimide moiety. The compounds O2N—N=C(Phth)Cl and O2N—N=C(Phth)SMe were studied by X-ray diffraction and quantum chemical methods. The C=N—N and NO2 groups in the O2N—N=C(Phth)Cl molecule were found to be completely orthogonal to each other. The explanation of this fact was proposed.

Gas-phase reaction of two unsaturated ketones with atomic Cl and O3: kinetics and products.

The rate constants and products for the reactions of atomic Cl and O3 molecule with 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332) were determined in a 100 L Teflon chamber at 293 ± 1 K and atmospheric pressure. For MBO332 and MPO332, the rate constants measured with atomic Cl were (2.38 ± 0.26) × 10(-10) and (3.00 ± 0.34) × 10(-10) cm(3) molecule(-1) s(-1) using the relative rate method. Using the absolute rate method, the rate constants with O3 measured were (1.18 ± 0.21) × 10(-17) and (4.07 ± 0.45) × 10(-17) cm(3) molecule(-1) s(-1). The products of these reactions were investigated by the proton-transfer-reaction mass spectrum (PTR-MS). The results indicated that the major products observed in the atomic Cl reaction were formaldehyde together with chloroacetone for MBO332, and acetaldehyde and CH3C(O)C(O)Cl for MPO332. For O3 reactions, butanedione and formaldehyde were the main products of MBO332, while butanedione and acetaldehyde were the main products of MPO332. Possible reaction mechanisms were proposed and discussed and the atmospheric implications of these reactions were also discussed.

A NOVEL SYNTHESIS METHOD FOR SILVER NANOPARTICLES USING MOLTEN ε-CAPROLACTAM AS SOLVENT AND REDUCING AGENT

A precipitation–reduction synthesis method for silver nanoparticles ( Ag NPs) was developed. Molten ε-caprolactam (CL) was used not only as solvent but also as reducing agent and stabilizer. At first, Ag 2 O NPs was prepared by precipitation reaction of silver nitrate ( AgNO 3) and sodium hydroxide ( NaOH ) using molten CL as solvent at 100°C. Then, Ag 2 O NPs was in situ reduced into Ag NPs by molten CL at 120°C. Techniques of X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to monitor the synthesis process. With the increase of reduction time, monodispersed Ag 2 O NPs (ca. 3.7 nm) were integrated and larger Ag NPs (10–90 nm) were formed. Fourier transform infrared (FT-IR) results showed that the surface of Ag NPs was capped with about 0.9 wt.% of CL molecules. Surface enhanced Raman scattering (SERS) effect of Ag NPs was investigated using Rhodamine 6G as a probe molecule.

Dual-frequency capacitively coupled chlorine discharge

The effect of the control parameters of both high and low frequency sources on a dual-frequency capacitively coupled chlorine discharge is systematically investigated using a hybrid approach, which consists of a particle-in-cell/Monte Carlo simulation and a volume-averaged global model. The high frequency current density is varied from 20 to 80 A m−2, the driving high frequency is varied from 27.12 to 100 MHz, and the driving low frequency is varied from 1 to 13.56 MHz, while the low frequency current density is kept at 1 A m−2. The discharge pressure is maintained at 10 mTorr. Key plasma parameters (including the electron heating rate, the electron energy probability function, the ion flux, the ion energy, and angular distributions) are explored and their variations with the control parameters are analyzed and compared with other discharge chemistries. As the high frequency current increases, the electron heating is enhanced in the sheath region and is diminished in the bulk region, showing a transition of the electron heating from the drift-ambipolar mode to the α mode. The fluxes of ions and high-energy Cl2 molecules reaching the surface decrease with an increase in the driving high frequency, and the average sheath potential is approximately inversely proportional to the driving high frequency. The electron heating rate, the fluxes of and Cl+ ions reaching the surface, and the average sheath potential show little dependence on the driving low frequency, while the profile of the ion energy distribution evolves from a broad bimodal profile to a narrow single-peak profile as the driving low frequency increases, which corresponds to the transition of the discharge from the intermediate frequency regime to the high frequency regime.

Theoretical study on the bifunctional substitution reactions between gold(III) dithiocarbamate derivative Au(DMDT)Cl2 (DMDT = N,N-dimethyldithiocarbamate) and target molecules

The complex Au(DMDT)Cl2 (DMDT=N,N-dimethyldithiocarbamate) is one of the most potential anticancer drugs with the strong cytotoxicity. However, the mechanisms of its monofunctional adducts as the active species for the formation of bifunctional adducts have not been established, thus substitution reactions between hydrated [Au(DMDT)(H2O)Cys(S, N)]2+, [Au(DMDT)(H2O)Cys(N, O)]2+, and [Au(DMDT)(H2O)G]2+ and target molecules were studied by our laboratory at the DFT level using B3LYP hybrid functional and IEF-PCM solvation model. Firstly, the reactant complex (RC) via similar trigonal bipyramidal transition state (TS) structure generates product complex (PC), and with the structural analysis towards RC, PC and TS, we know the hydrogen bond (H-bond) playing an indispensable role in the stabilization of these complexes for the bifunctional substitutions. In addition, it is worth noting that there is competition of intrinsic kinetic among different active sites of cysteine. In the bifunctional substitution reactions, the result appears to be that the N7 of guanine is the strongest site and superior to active sites (S, N) of cysteine. The soft metal center Au prefers S site of cysteine over N site interactions with hydrated [Au(DMDT)(H2O)Cys]2+ complexes and the O site of cysteine is the weakest for all reactions in the aqueous solution. Besides, the [Au(DMDT)GG]2+ head-to-head path has the lowest free energy of activation at 3.7kcal/mol and its head-to-tail path at 6.2kcal/mol, while the [Au(DMDT)GA]2+ head-to-head path has the lowest barrier of 13.3kcal/mol, and then the following head-to-tail path at 18.9kcal/mol. There was something else: the calculations show the TS for amino group acts as the attacking group to be more stable than that for sulphydryl, when the monofunctional adduct [Au(DMDT)G(H2O)]2+ acts as the reactant. A favorable reaction pathway of bifunctional substitution process is proposed by our theoretical computation.

Accurate calculation of the ionization energies of the chlorine lone pairs in 1,1,1-trifluoro-2-chloroethane (HCFC-133a).

The vertical ionization energies of the chlorine lone pairs in HCFC-133a have been calculated at the SCF (via Koopmans' theorem and including orbital relaxation) and correlated (ROMP2, OVGF, and ROCCSD(T)) levels. Dunning aug-cc-pVXZ (X = D, T, and Q) basis sets were employed, and the ROMP2 and ROCCSD(T) results were extrapolated to the complete basis set (CBS) limit. Our highest-level results (obtained at the ROCCSD(T)/CBS level) were 11.99 and 12.08 eV for the Cl lone pairs of A″ and A' symmetry, respectively. The values obtained at the computationally much less demanding ROMP2/CBS level were just 0.10 and 0.13 eV higher than the highest-level ones. Using the Cl lone-pair band of the photoelectron spectrum of the HCF(2)Cl and CF(3)Cl molecules as a guide, it is considered very unlikely that these two lone pairs can be discriminated in the photoelectron spectrum of the title molecule. The use of the calculated IPs to estimate the energies of the Rydberg states of HCFC-133a is also discussed.

Singlet–triplet separation induced by the Pseudo Jahn–Teller effect examples: The CX2 and NX2+ (X = H, Cl) molecules

A theoretical investigation with high-level multireference methods is performed to reveal the Jahn–Teller origin of the triplet and singlet bent structures for CH2, CCl2, NH2+, and NCl2+ molecules and rationalize the relative energy ordering of the lowest singlet and triplet states. At the highest-symmetry linear configurations of these triatomic systems, the Pseudo Jahn–Teller effect (PJTE) between the ground state 3Σg- and excited state 3Πu upon the bending mode, denoted as (3Σg-+3Πu)⊗πu, is the reason of producing triplet 3B1 bent structures, and the combined PJTE of (1Δg+1Πu)⊗πu and Renner–Teller effect (RTE) of 1Δg state result in the formations of singlet 1A1 and 1B1 minima. The PJTE of “Δ–Π” plays a dominant role for the instability of degenerate Delta state which is subject to RTE. The spin-crossover induced by PJTE is responsible for the reversed order of singlet and triplet ground states in CH2/NH2+ and CCl2/NCl2+. The different singlet–triplet energy separations of those molecules can be rationalized from different Jahn–Teller vibronic coupling intensity at linear configurations.

Alignment dependence of ionization probability of Cl2, Br2 and S2 molecules by intense femto-second laser pulse

The role of molecular orientation in ionization of Cl2, Br2 and S2 molecules is studied by laser pulses at intensities 5×1014–5×1016Wcm−2. A numerical method for studying the ionization mechanism is implemented by RQCISD level with DGDZVP full-electron basic set and time-dependent density functional theory (TDDFT) in the Gaussian03. The results show that the angular distribution for Br2 is isotropic in comparison to S2 and Cl2 molecules. For a better insight into the importance of the electronic structure, a compression of alignment-dependent ionization yields between XeF and Cl2 molecules is achieved. It is found at intensity of 1016Wcm−2, the maximum ionization probabilities are about 12.5%, 8% and 12% for S2, Cl2 and Br2 molecules at 0°; however, it is 10% around 10° for anisotropic XeF molecule. In this mechanism, time evolution of dipole moment and its dependence to the laser intensity and molecular bond length are investigated. It is noticed that at the intensity of 5×1016Wcm−2, dipole moment of molecules reach to their maximum values of 23.62, 19.68 and 18.50 (atomic unit) for Br2, S2 and Cl2 molecules, respectively.

Revised Bismuth Chloroselenite System: Evidence of a Noncentrosymmmetric Structure with a Giant Unit Cell

The reactions between PbO, Bi2O3 (or BiOCl), and SeO2 by the chemical vapor transport method using HCl as a transporting agent afforded three novel bismuth/lead chloroselenites, namely, β-BiSeO3Cl (1), Bi6(SeO3)4Cl10 (2), and PbBi10(SeO3)12Cl8 (3). Compound 1 is noncentrosymmetric (space group Cc, SHG active) and has a giant unit cell (V = 19792(2) A3). In the context of the complex BiSeO3Cl phase diagram reported by Oppermann et al., it was assigned to the undescribed β-form on the basis of its IR spectra and powder X-ray diffraction pattern. The comparison between the α-, β-, and γ-forms suggests their formation via the condensation of volatile Bi(SeO3)Cl molecules. Analysis of the structures of the α-, β-, and γ-forms indicates that the α → β → γ phase transitions are associated with a dramatic fluctuation of structural complexity together with the transitional character of the β phase. Compounds 1 and 3 are layered compounds with identical ([M8Cl16]8+ and [M14(SeO3)24]6−) layers, where M stands for Bi...

NLO‐X (X = I–III): New Gaussian basis sets for prediction of linear and nonlinear electric properties

New adjusted Gaussian basis sets are proposed for first and second rows elements (H, B, C, N, O, F, Si, P, S, and Cl) with the purpose of calculating linear and mainly nonlinear optical (L–NLO) properties for molecules. These basis sets are new generation of Thakkar‐DZ basis sets, which were recontracted and augmented with diffuse and polarization extrabasis functions. Atomic energy and polarizability were used as reference data for fitting the basis sets, which were further applied for prediction of L–NLO properties of diatomic, H2, N2, F2, Cl2, BH, BF, BCl, HF, HCl, CO, CS, SiO, PN, and polyatomic, CH4, SiH4, H2O, H2S, NH3, PH3, OCS, NNO, and HCN molecules. The results are satisfactory for all electric properties tested; dipole moment (µ), polarizability (α), and first hyperpolarizability (β), with an affordable computational cost. Three new basis sets are presented and called as NLO‐I (ADZP), NLO‐II (DZP), and NLO‐III (VDZP). The NLO‐III is the best choice to predict L–NLO properties of large molecular systems, because it presents a balance between computational cost and accuracy. The average errors for β at B3LYP/NLO‐III level were of 8% for diatomic molecules and 14% for polyatomic molecules that are within the experimental uncertainty. © 2014 Wiley Periodicals, Inc.

Total cross sections for electron scattering with halocarbon molecules

A theoretical study on electron collision with chlorinated methanes: CH2Cl2 and CHCl3, brominated methanes: CH2Br2, CHBr3 and CBr4 and some mono chloroalkanes: CnH2n+1Cl (n=2–4) molecules in gaseous ground state is undertaken to report elastic, inelastic and total cross sections in the 20–5000eV energy range. The target molecule is represented as a sum of various scattering centres, which are assumed to scatter electrons independently. The spherical complex optical potential (SCOP) is formulated to represent the interaction dynamics between the electron and the constituent scattering centres. Using SCOP, the quantum mechanical scattering problem is solved through partial wave analysis. The results obtained for CH2Cl2 and CHCl3 are compared with the available experimental and theoretical values. The elastic cross section for CBr4 shows satisfactory agreement with the previous available data. The cross sections for CH2Br2, CHBr3, and CnH2n+1Cl (n=2–4) molecules presented in this work are reported for the first time.

Short-wavelength nanosecond-barrier-discharge-pumped emitter operating on lines of argon chloride (175 nm) and chlorine (258 nm) molecules

The emission characteristics of a pulsed-periodic nanosecond-barrier-discharge-pumped source of ultraviolet and vacuum ultraviolet radiation are presented. The source emits into a set of electronic-vibrational bands with maxima at λ = 175 nm ArCl(B→X) and λ = 258 nm Cl2(D′→A′). The emission intensity of ArCl and Cl2 molecules is optimized for the pressure and composition of an argon-freon vapor (CCl4) mixture and also for excitation conditions.

Ligand mediated valence fluctuation of copper in new hybrid materials constructed from decavanadate and a Cu(1,10-phenanthroline) complex

Two new organic hybrid materials [H4V10O28][CuCl(H2O)2(1,10-phenanthroline)]2·4H2O (V10O28-CuCl-phen) and [H4V10O28][Cu(H2O)3(1,10-phenanthroline)]2·4H2O (V10O28-CuO-phen) were synthesized at room temperature. The effect of the presence and absence of AlCl3 on the single crystal growth of the two compounds was studied. The compounds were characterized using single crystal X-ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, infra-red spectroscopy and thermogravimetric analysis. XRD studies on selected single crystals suggest that the compounds consist of supramolecular 3D layer structures constructed from a tetra-protonated [V10O28] unit and the organometallic complex Cu(1,10-phen) with Cl and 2H2O molecules in the presence of AlCl3 in V10O28-CuCl-phen and with 3H2O molecules in V10O28-CuO-phen which was confirmed by TGA studies. Both compounds crystallize in the triclinic space group P1[combining macron]: a = 8.3886(3) Å, b = 10.4266(4) Å, c = 13.5860(5) Å, α = 92.440(2)°, β = 92.315(2)°, γ = 98.160(2)° for V10O28-CuCl-phen and a = 8.3733(5) Å, b = 10.4132(6) Å, c = 13.5904(8) Å, α = 92.295(4)°, β = 92.331(2)°, γ = 98.086(4)° for V10O28-CuO-phen. Magnetic measurements suggest that Cu exists in magnetic +2 oxidation state in V10O28-CuCl-phen and non-magnetic +1 oxidation state in V10O28-CuO-phen.