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1.
Adsorption of acetylene molecules by water clusters at T 230 K was studied by the method of molecular dynamics. Addition of already two C2H2 molecules to (H2O) n clusters (10 ≤ n ≤ 20) makes them thermodynamically unstable. With an increase in the acetylene concentration in the disperse aqueous system, the IR absorption by the cluster system in the frequency range 0 ≤ ω ≤ 1000 cm?1 increases. Depending on the number of C2H2 molecules per water cluster, the IR reflection by cluster systems can either increase or decrease. The power of the thermal radiation emitted by the clusters considerably increases after the adsorption of C2H2 molecules and grows with an increase in the acetylene concentration in the disperse aqueous system.  相似文献   

2.
The ground and low-lying excited states of H3O(H2O) k radicals are studied. The character of the unpaired electron localization in the systems is analyzed, and the relative probability of the radical dissociation onto a water cluster and atomic hydrogen is estimated. Reaction coordinates of the dissociation are constructed and conditions of metastable existence of an H3O radical are determined. Structures, in which H3O can spontaneously dissociate, are found. Lifetimes of H3O(H2O) k clusters before the hydrogen atom detachment at the initial conditions of two kinds, namely, upon the vertical attachment of an electron to H3O+(H2O) k cations and upon the vibrational excitation of metastable neutral H3O(H2O) k systems, are estimated.  相似文献   

3.
Absorption of ethane molecules by water clusters containing 10–20 molecules is studied by the molecular dynamics method. The (H2O) n (I), C2H6(H2O) n (II), and (C2H6)2(H2O) n (III) cluster systems are composed on the basis of specific statistical weights. Spectral characteristics of system and single clusters are determined in the frequency range of 0 ≤ ω ≤ 1000 cm?1. In this frequency range, both real and imaginary parts of dielectric permittivity decrease monotonically after the absorption of C2H6 molecules by an aqueous ultradispersed system. Integral coefficient of IR absorption increases, while average (over frequency) reflection coefficient decreases after the absorption of ethane molecules. The intensity of IR scattering by the systems of clusters containing C2H6 molecules lowers. Maximal values of radiation power for water clusters with various sizes are balanced with the capture of ethane molecules by the clusters, whereas oscillations in the size dependence of the density of electrons that are active with respect to IR radiation decrease.  相似文献   

4.
The stability and structure of water clusters absorbing nitrogen molecules or argon atoms was analyzed by molecular dynamics simulation at 233 K. The (?μ/?i)V, T derivative of the chemical potential, a value characterizing the stability of a cluster with respect to its size, depends linearly on the number of molecules i. According to this criterion, the clusters under study become stable near i = 40. The average length of H-bonds increases monotonically in the growing cluster of pure water and exhibits oscillatory behavior if the growing cluster contains N2 molecules or Ar atoms. The number of H-bonds per molecule oscillates between one and six as the cluster size changes. These oscillations are damped in pure water and sustained for clusters containing impurities, especially argon.  相似文献   

5.
IR absorption, reflection, and emission spectra of aqueous disperse systems that absorbed molecules of nitric oxide are calculated. In order to reveal the effect of the absorption of NO molecules on the dielectric properties of water clusters with different sizes, clusters are divided into two groups. The first group consists of clusters containing two to ten water molecules, while the second group contains from 11 to 20 H2O molecules. Six systems of clusters are studied, e.g., (H2O) n , and (NO)2(H2O) n with 2 ≤ n ≤ 10 and 11 ≤ n ≤ 20 ranges. An increase in the cluster size in each group leads to the amplification of absorption, reflection, and the power of emission of IR radiation. The doubling of the NO concentration in the disperse system results in weak changes in the absorption of IR radiation, reduces the reflection and decreases the number of electrons participating in the interaction with external IR radiation, as well as significantly lowers the power of thermal radiation emitted by the system.  相似文献   

6.
Spectral characteristics of (H2O) i , N2(H2O) i , and (N2)2(H2O) i cluster systems, where 10≤i≤50, are studied in the 0 ≤ ε ≤ 3500 cm?1 frequency range with the molecular dynamics method on the basis of a flexible molecule model. After nitrogen is captured by an aqueous disperse system, the absorption of the IR radiation by this system increases owing to the enhancement of intramolecular vibrations. In general, the reflection of the outer IR radiation by nitrated aqueous disperse systems is attenuated; however, when the nitrogen concentration increases twofold, there is a tendency toward an increase in the fraction of reflected radiation. As the nitrogen concentration in a system of water clusters rises, the power of radiation emitted by the system increases significantly and the number of electrons interacting with the outer IR radiation decreases.  相似文献   

7.
Novel supramolecular networks based on an anionic polymolybdophosphate cluster Sr10(H2O)12[Sr2P9HMo12O71] is hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, thermogravimetric analysis, infrared, ultraviolet spectroscopy, and cyclic voltammetry in an aqueous solution. It crystallizes in the orthorhombic space group Pnmm (No. 59) with a = 12.699(1) Å, b = 14.914(1) Å, c = 23.851(2) Å and Z = 2. The compound is made up of unusual shaped-cage [Sr2P9HMo12O71]20?. The strontium cations are divided in two kinds. The first occupy vacant sites in the [P9Mo12O 68]n– polyoxoanions unit and the second [Sr(H2O)6]2+, [Sr(H2O)4]2+, and [Sr(H2O)2]2+ serve to bridge together the adjacent polymolybdophosphate clusters to yield unprecedented three-dimensional pure inorganic assemblies of the shaped-cage polymolybdophosphate clusters.  相似文献   

8.
Spectral and thermochemical investigation of physicochemical properties of quinoline N-oxide crystallohydrates with H2O and D2O is carried out. Quinoline N-oxide is established to form with H2O a stable dihydrate where two water molecules are energetically not equal. Complete dehydration of quinoline N-oxide occurs when temperature reaches 150°C. With accounting for the obtained thermochenical data, quinoline N-oxide and its mono- and dihydrates are isolated in the individual state and their IR spectra are registered and considered. It is established that at boiling quinoline N-oxide in D2O proceeds chemical reaction affording isoindoline-1,3-dione (phthalimide). The product is identified by elemental analysis and 1H NMR and IR spectroscopy. The band assignment in the IR spectra of quinoline N-oxide, phthalimide and of the complex of the latter with D2O is based on the quantum-chemical DFT calculations.  相似文献   

9.
To contribute to the understanding of Eu(III) interaction preperties on hydrous alumina particles in the absence and presence of fulvic acid (FA), the complexation properties of Eu(III) with hydrous alumina, FA and FA-alumina hybrids are studied by batch and time-resolved laser fluorescence spectroscopy (TRLFS) techniques. The continuous increase in the fluorescence lifetime of Eu-alumina and Eu-FA with increasing pH indicates that the complexation is accompanied by decreasing number of hydration water in the first coordination sphere of Eu(III). Eu(III) is adsorbed onto alumina particles as outer-sphere surface complexes of ≡(Al?O)?Eu· (OH)· 7H2O and ≡(Al?O)?Eu· 6H2O at low pH values, and as inner-sphere surface complexes as ≡(Al?O)2?Eu+· 4H2O at high pH. In FA solution, Eu(III) forms complexes with FA as (COO)2Eu+(H2O) x and the hydration water number in the first coordination sphere decreases with pH increasing. The formation of ≡COO?Eu?(O?Al≡)· 4H2O is observed on FA-alumina hybrids, suggesting the formation of strong inner-sphere surface complexes in the presence of FA. The surface complexes are also characterized by their emission spectra [the ratio of emission intensities of 5 D 07 F 1 (λ=594 nm) and 5 D 07 F 2 (λ=619 nm) transitions] and their fluorescence lifetime. The findings is important to understand the contribution of FA in the complexation properties of Eu(III) on FA-alumina hybrids that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Eu(III), or its analogue trivalent lanthanide and actinide ions in natural environment.  相似文献   

10.
Observations on metastable peaks resulting from the unimolecular decomposition of ion clusters show that intensity variations as a function of cluster size can reveal the presence of stable cluster configurations. This technique has been used to confirm that (H2O)21H+ and (D2O)21D+ are stable ion clusters, and the method also provides evidence to suggest that Ar19+ is a particularly stable species.  相似文献   

11.
Structures of Na(H2O)n and Na+(H2O)n clusters with n = 1?6, 19, and 28 are determined in the second order of the Møller-Plesset perturbation theory with the use of extended atomic basis set 6–31++G**. It is found that when the number of molecules is sufficient for the formation of two solvation shells around sodium, a continuous hydrogen-bond network is formed in both neutral and charged clusters, and the orientation of each molecule is determined by the balance between interactions with the neighboring water molecules and with the field of the central particle. In the cations, this field is stronger, and up to the third solvation shell, molecules have a predominant orientation with respect to sodium. In the neutral clusters, with an increase in the number of water molecules, the maximum of the electron density distribution of the highest occupied molecular orbital becomes more distant from the sodium nucleus, being shifted toward the cluster surface. The energy of this orbital accordingly decreases in absolute value approaching 22 kcal/mol inmicroparticles. In the charged clusters, the distribution of the positive charge generally correlates with the character of the highest occupied orbital in the neutral systems, so that with an increase in the number of molecules, the atomic charge of sodium decreases and tends to zero as n → ∞. The ionization potential of sodium changes in inverse proportion to the linear size of the cluster, and should not exceed 1.1 eV in watermicroparticles.  相似文献   

12.
In the problem of the production silver nanoparticles, mass spectrometry allows one to identify nanoclusters as nuclei or intermediates in the synthesis of nanoparticles and to understand the mechanisms of their formation. Using low-temperature secondary emission mass spectrometry, we determined the cluster composition of a system formed in the microwave treatment of a solution of AgNO3 in ethylene glycol (M). Along with silver ion–ethylene glycol associates М m ? Ag+ (m = 1–5) and small silver clusters AgM n + (n = 1–9), unusual silver clusters with one hydrogen atom [Ag n H]+ (n = 2, 4) were observed. Possible pathways for the formation of silver nanoparticles taking into account hydrogen-containing cluster intermediates are discussed.  相似文献   

13.
The free energy and entropy of the dissociation of HCl molecule into ions in water vapor, HCl(H2O) n + mH2O → H3O + (H2O) n+m -1Cl?, were calculated. The dependences of various parameters on the interionic distance at 273 K and various vapor pressures were obtained. A detailed model taking into account unpaired covalent-type interactions, polarization interactions, charge transfer effect, and hydrogen bonds was applied. The numerical values of the parameters were reconstructed from the experimental data on the free energy and enthalpy of the first reactions of addition of vapor molecules to ions, and also from the results of quantum-chemical calculations of the energy and geometry of locally stable configurations of clusters HCl(H2O) n . Despite lower internal energy of the dissociated state, the molecular form is absolutely stable in clusters of water molecules. The dissociated state is relatively stable. Accumulation of unrecombined ion pairs in clusters is possible with a decrease in the temperature to 200 K.  相似文献   

14.
The vibrational (IR and Raman) and photoelectron spectral properties of hydrated iodine‐dimer radical‐anion clusters, I2.? ? n H2O (n=1–10), are presented. Several initial guess structures are considered for each size of cluster to locate the global minimum‐energy structure by applying a Monte Carlo simulated annealing procedure including spin–orbit interaction. In the Raman spectrum, hydration reduces the intensity of the I? I stretching band but enhances the intensity of the O? H stretching band of water. Raman spectra of more highly hydrated clusters appear to be simpler than the corresponding IR spectra. Vibrational bands due to simultaneous stretching vibrations of O? H bonds in a cyclic water network are observed for I2.? ? n H2O clusters with n≥3. The vertical detachment energy (VDE) profile shows stepwise saturation that indicates closing of the geometrical shell in the hydrated clusters on addition of every four water molecules. The calculated VDE of finite‐size small hydrated clusters is extrapolated to evaluate the bulk VDE value of I2.? in aqueous solution as 7.6 eV at the CCSD(T) level of theory. Structure and spectroscopic properties of these hydrated clusters are compared with those of hydrated clusters of Cl2.? and Br2.?.  相似文献   

15.
Autocorrelation functions of the total dipole moment of clusters composed of H2O and N2O molecules are calculated in terms of the molecular dynamics method. The IR absorption and reflection spectra of systems composed of (H2O)i, N2O(H2O)i, and (N2O)2(H2O)i clusters (2 ≤ i ≤ 20) are obtained on the basis of these functions. Frequency-dependent dielectric permittivity of clusters increases after the absorption of N2O molecules. The absorption coefficient of cluster systems with trapped N2O molecules increases at low frequencies and decays at frequencies ω > 500 cm?1. The inclusion of N2O molecules increases also reflection coefficient R and changes the pattern of R(ω) spectra. The absorption of IR radiation increases with the number of H2O molecules in clusters. Dielectric losses also increase with an increase in i number upon the absorption of N2O molecules. The number of electrons interacting with an incident electromagnetic wave increases upon the capture of N2O molecules.  相似文献   

16.
A novel layered supramolecular compound [Ni(L)(TPHA)]·8H2O, containing two-dimensional (2D) water clusters and terephthalato-bridged ligand, where L = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.16,9] octadecane, TPHA = terephthalate dianion, has been synthesized and structurally characterized by spectroscopy and X-ray crystallography. The complex is neutral, in which the nickel(II) ions are bridged by the TPHA to form a one-dimensional (1D) infinite chain structure, and containing the eight-member water cluster. The presence of octameric water clusters have effectively increased the 1D coordination polymer to a three-dimensional layered structure. Every water cluster is connected strongly by a O–H···O hydrogen bond (range of the bonds between 2.724 and 3.056 Å). The complex crystallizes in monoclinic, space group P21/c with a = 9.788(3), b = 13.030(4), c = 11.646(4) Å, and β = 104.551(5)°.  相似文献   

17.
The process of reduction of divalent copper ions with tert-butylamine borane in dilute aqueous solutions of poly(N-vinylpyrrolidone) is investigated. The influence of polymer molecular mass on properties of the resultant Cu2O sols is studied. It is shown that Cu2O nanoparticles with an average diameter of 6–8 nm independent of polymer molecular mass and a relatively narrow size distribution of particles are formed in the systems under study. The contour length of macromolecules and the hydrodynamic diameter of a poly(N-vinylpyrrolidone) macromolecular coil are compared with the diameter of Cu2O particles. Poly(N-vinylpyrrolidone) with M ≥ 1 × 104 can be used to produce Cu2O nanoparticles. Poly(N-vinylpyrrolidone) with M > 4 × 104 should be used for the formation of long-living Cu2O sols.  相似文献   

18.
A supramolecular adduct of gadolinium aqua nitrato complex and cucurbit[6]uril { [Gd(NO3)(H2O)7](C5H5N)@(C36H36N24O12)}(NO3)2·10H2O is obtained by slow diffusion of methanol into an aqueous solution containing gadolinium nitrate, pyridine, and cucurbit[6]uril. According to single crystal X-ray diffraction data, water molecules coordinated to metal atom make hydrogen bonds to polarized carbonyl groups of the macrocycle. The heptaaquanitratogadolinium(III) [Gd(NO3)(H2O)7]2+ cation is structurally characterized for the first time. Crystal system is triclinic, space group \(P\overline 1 \), a = 12.3137(4) Å, b = 14.2334(5) Å, c = 19.5629(6) Å; α = 80.850(1)°, β = 86.879(1)°, γ = 68.855(1)°; V = 3157.15(18) Å3, Z = 2. Oriented hydrogen-bonded chains of alternating cucurbit[6]uril molecules and gadolinium aqua cations form in the crystal structure.  相似文献   

19.
It was shown that the monomeric rhodium sulfate complexes [Rh(H2O)4(SO4)]+, trans-[Rh(H2O)2(SO4)2]?, cis-[Rh(H2O)2(SO4)2]?, and [Rh(SO4)3]3? were not predominant forms in aqueous solutions. The 103Rh NMR chemical shifts of the complexes were assigned, and the conditions for their formation in solutions, concentration parameters, and acidity at which the fraction of the monomers was maximal were determined. The constants of formation of the complexes and ion pair (IP) were estimated: K IP = 8 ± 3.5, K 1 ≈ 8, K 2trans ≈ 1, K 2cis ≈ 1, and K 3 ≈ 2.  相似文献   

20.
The trans(O)-cis(C)-bis(pyridine-2-carboxylato)dicyanocobaltate(III) ions, [Co(Pic)2(CN)2]?, crystallize from acid medium with three water molecules per two crystallographically nonequivalent complexes whose charge is compensated by protons. One of the water molecules forms an oxonium ion (H3O+) with a proton. The other two water molecules bound to each other through a short hydrogen bond O-H…O (2.403(2) Å) and thus forming (H5O2)+ cations is another proton site. The (H3O)(H5O2)[Co(Pic)2(CN)2]2 crystals are monoclinic: a = 10.7027(7) Å, b = 25.786(1) Å, c = 11.4865(8) Å, β = 91.411(9)°, Z = 4, space group P21/n.  相似文献   

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