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1.
We use a variation–perturbation method to calculate the electric polarizabilities and the electric dipole moment of the LiH molecule. We obtain 4.455 for the perpendicular polarizability and 4.001 (×10?24 cm3) for the parallel polarizability. Our result for the electric dipole moment at equilibrium nuclear distance is 5.866, which is in excellent agreement with the experimental value 5.828 debye units.  相似文献   

2.
We calculated the static and the dynamic dipole polarizabilities and the static quadrupole polarizability of the helium atom. The results are α = 0.2070 × 10?24 cm3 for the static dipole polarizability and γ4 = 0.1038 × 10?40 cm5 for the static quadrupole polarizability.  相似文献   

3.
The absorption spectrum of SiH4 from 32 to 400 cm?1 has revealed two sepasrate bonds,one linear in density and one quadratic.From the linear band,the electric dipole moment produced in the ground vibronic state by centrifugal distortion effects has been estimated to be 9.3 × 10?6 D in magnitude. From the quadratic band, the molecular octopole moment has been determined to be 3.0 × 10?34 esu cm3 in magnitude. The simplicity of the techniques used is stressed.  相似文献   

4.
A laser ion-molecule reaction interaction through both polarizability and dipole moment contribution leads to variation in the intersection point in potential energy surface crossings along the reaction path; the polarizability is maximum and the dipole changes its sign at s = 4 a.u., defining a virtual transition state. Using the gauge representation (electric field gauge) for a wave length λ = 20.6 μm, intensity I = 5×1012 W/cm2, I = 1×1013 W/cm2, I = 3×1013 W/cm2, we show here that we can create a laser-induced potential energy surface crossing along the reaction path (s = 7-8 a.u.). We illustrate such effects for the Li H + CH 3 + ? Li+ + CH4 reaction which takes the form of inverted Morse (without a barrier) using ab initio methods for calculating the reaction path and electric properties of the ion-molecule reaction.  相似文献   

5.
The changes in chemical shift induced by isomerization for all the ring protons of the Z- and E-5,5-dimethyl-2-cyclohexenylidene acetonitriles depend only on the through-space effects of the cyano group. The configurational assignments were made taking into consideration the anisotropic and electric field effects, either separately or together. In the first case, the total effects are ΔXCNT=?14.7×10?6cm3 mol?1 and bμCNT=14.7×10?30 cm3, respectively. The second approach allows the estimation of the values ΔXCN=?4.9 × 10?6 cm3 mol?1 and bμCN=9.8 × 10?3 cm3, reflecting the combined contributions of magnetic anisotropy and electric field to the total effect.  相似文献   

6.
Changes in light scattering induced by a strong laser beam, as predicted theoretically by Kielich, were measured for unfractionated yeast transfer ribonucleic acid (tRNA) solutions. The vertically polarized electric field of a strong laser pulse (λ = 1060nm) amounted to 4.5 × 103 esu cgs; its duration was 10 nsec. A weak incident laser beam (λ = 630nm) was also polarized vertically and the vertical and horizontal intensity components of the light scattered through 90° at the latter wavelength were measured. These measurements together with previous results from measurements of Rayleigh light scattering and light scattering in a magnetic field permitted evaluation of the tensor of third-order polarizability (c = 3 × 10?30 esu cgs, c = ?373 × 10?30 esu cgs) and the anisotropy of the third-order polarizability components with its sign (δc = +56 × 10?2, δc = +0.25 × 10?2 for tRNA monomer and aggregate, respectively). The new method described may be useful for studies of macromolecules and macromolecular complexes of biological importance.  相似文献   

7.
The hfs of205Pb in the 283.3-nm resonance line and its isotope shift (IS) have been measured in absorption with the use of dispersive spectroscopy. A new method for calibration and analysis, when internal standards are not available is described. The results are: hfs interaction constantsA=70.3(5)×10?3 cm?1,B=?0.6(1.1)×10?3 cm?1,205Pb-208Pb IS=?123.9(2.0)×10?3 cm?1. The derived nuclear magnetic dipole moment,μ=0.704(5)μ N is in good agreement with values calculated with a nuclear configuration mixing model.  相似文献   

8.
Abstract

The EPR spectra of single crystals of 63Cu(II) doped N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(sal)2en] and 7-methyl-N, N'-bis(salicylidene)ethylenediimine Ni(II), [Ni(7-me sal)2en] have been studied. The usual doublet spin-Hamiltonian parameters for the complexes have been found to be: Cu(II)[(sal)2en]; g z =2.192 ± 0.002; g x =2.046 ± 0.004; g y =2.049 ± 0.004; A z =201.0 × 10?4 cm?1; A x =29.3 × 10?4 cm?1; A y =31.3 × 10?4 cm?1; AN z =12.6 × 10?4 cm?1; A N x =14.5 × 10?4 cm?1; A N y =15.7 × 10?4 cm?1; A H z =6.3 × 10?4 cm?1; A H x =7.3 × 10?4 cm?1; A H y =7.9 × 10?4 cm?1; Cu(II)[(7-me sal)2en]; g z =2.189 ± 0.002; g x =2.037 ± 0.004; g y =2.046 ± 0.004; A z =203.0 × 10?4 cm?1; A x =36.9 × 10?4 cm?1; A y =22.7 × 10?4 cm?1; A N z =12.6 × 10?4 cm?1; A N x =13.3 × 10?4 cm?1; A N y =14.0 × 10?4 cm?1. Values of molecular orbital coefficients calculated for these complexes show that their bonding properties are similar to those of other compounds of this type. There is considerable covalency in the metal-ligand [sgrave]-bonds, and significant in-plane pi-bonding is present.  相似文献   

9.
The halide‐binding properties of N‐confused porphyrin (NCP, 1 ) and doubly N‐confused porphyrins (trans‐N2CP ( 2 ), cis‐N2CP ( 3 )) were examined in CH2Cl2. In the free‐base forms, cis‐N2CP ( 3 ) showed the highest affinity to each anion (Cl?, Br?, I?) with association constants Ka=7.8×103, 1.9×103, and 5.8×102 M ?1, respectively. As metal complexes, on the other hand, trans‐N2CP 2–Cu exhibited the highest affinity to Cl?, Br?, and I? with Ka=9.0×104, 2.7×104, and 1.9×103 M ?1, respectively. The corresponding Ka values for cis‐N2CP 3–Cu and NCP 1–Cu were about 1/10 and 1/2, respectively, of those of 2–Cu . With the help of density functional theory (DFT) calculations and complementary affinity measurements of a series of trisubstituted N‐confused porphyrins, the efficient anion binding of NCPs was attributed to strong hydrogen bonding at the highly polarized NH moieties owing to the electron‐deficient C6F5 groups at meso positions as well as the ideally oriented dipole moments and large molecular polarizability. The orientation and magnitude of the dipole moments in NCPs were suggested to be important factors in the differentiation of the affinity for anions.  相似文献   

10.
The reactions of CCl3 with O(3P) and O2 and those of CCl3O2 with NO have been studied at 295 K using discharge flow methods with helium as the bath gas. The rate coefficient for the reaction of CCl3 with O was found to be (4.2 ± 0.6) × 10?11 cm3/s and that for CCl3O2 with NO was (18.6 ± 2.8) × 10?12 cm3/s with both coefficients independent of [He]. For reaction between CCl3 and O2 the rate coefficient was found to increase from 1.51 7times; 10?14 cm3/s to 7.88 × 10?14 cm3/s as the [He] increased from 3.5 × 1016 cm?3 to 2.7 × 1017 cm?3. There was no evidence for a direct two-body reaction, and it is concluded that the only product of this reaction is CCl3O2. Examination of these results for CCl3 + O2 in terms of current simplified falloff treatment suggests that the high-pressure limit for this reaction is ~ 2.5 × 10?12 cm3/s, which may be compared with a direct measurement of the high-pressure limit of 5 × 10?12 cm3/s. A value of (5.8 ± 0.6) × 10?31 cm6/s has been obtained for k0, the coefficient in the low-pressure region. This value is compared with corresponding values found earlier for the (CH3, O2) and (CF3, O2) systems and with estimates based on unimolecular rate theory.  相似文献   

11.
The rate coefficients for the reaction OH + CH3CH2CH2OH → products (k1) and OH + CH3CH(OH)CH3 → products (k2) were measured by the pulsed‐laser photolysis–laser‐induced fluorescence technique between 237 and 376 K. Arrhenius expressions for k1 and k2 are as follows: k1 = (6.2 ± 0.8) × 10?12 exp[?(10 ± 30)/T] cm3 molecule?1 s?1, with k1(298 K) = (5.90 ± 0.56) × 10?12 cm3 molecule?1 s?1, and k2 = (3.2 ± 0.3) × 10?12 exp[(150 ± 20)/T] cm3 molecule?1 s?1, with k2(298) = (5.22 ± 0.46) × 10?12 cm3 molecule?1 s?1. The quoted uncertainties are at the 95% confidence level and include estimated systematic errors. The results are compared with those from previous measurements and rate coefficient expressions for atmospheric modeling are recommended. The absorption cross sections for n‐propanol and iso‐propanol at 184.9 nm were measured to be (8.89 ± 0.44) × 10?19 and (1.90 ± 0.10) × 10?18 cm2 molecule?1, respectively. The atmospheric implications of the degradation of n‐propanol and iso‐propanol are discussed. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 10–24, 2010  相似文献   

12.
The electrochemical redox properties of a surface‐confined thin solid film of nanostructured cobalt(II) tetracarboxyphthalocyanine integrated with multiwalled carbon nanotube (nanoCoTCPc/MWCNT) have been investigated. This novel nanoCoTCPc/MWCNT material was characterized using SEM, TEM, zeta analysis and electrochemical methods. The nanoCoTCPc/MWCNT nanohybrid material exhibited an extra‐ordinarily high conductivity (15 mS cm?1), which is more than an order of magnitude greater than that of the MWCNT‐SO3H (527 µS cm?1) and three orders of a magnitude greater than the nanoCoTCPc (4.33 µS cm?1). The heterogeneous electron transfer rate constant decreases as follows: nanoCoTCPc/MWCNT (kapp≈19.73×10?3 cm s?1)>MWCNT‐SO3H (kapp≈11.63×10?3 cm s?1)>nanoCoTCPc (kapp≈1.09×10?3 cm s?1). The energy‐storage capability was typical of pseudocapacitive behaviour; at a current density of 10 µA cm?2, the pseudocapacitance decreases as nanoCoTCPc/MWCNT (3.71×10?4 F cm?2)>nanoCoTCPc (2.57×10?4 F cm?2)>MWCNT‐SO3H (2.28×10?4 F cm?2). The new nanoCoTCPc/MWCNT nanohybrid material promises to serve as a potential material for the fabrication of thin film electrocatalysts or energy‐storage devices.  相似文献   

13.
Our earlier work on the formation of particulate NH4NO3 in the NH3? O3 reaction at 25°C is extended to include air as a diluent and H2O vapor as an additive. More extensive data at different values of [NH3]/[O3]0 were obtained also, where [O3]0 is the initial O3 concentration. In our earlier work we concluded that NH4NO3 vapor was dissociated to NH3 + HNO3 and that the HNO3 was removed by diffusion to the walls with a rate coefficient kdiff = 0.4 min?1 or by condensation on the suspended particles. Particles were nucleated by 8 NH3? HNO3 pairs when their concentration product reached 5.8 × 1027 molec2/cm6 with a rate coefficient knucl of 6.2 × 10?224 cm45/min and removed by coagulation with a rate coefficient kcoag of 1.3 × 10?7 cm3/min. A corrected calculation modifies the number of pairs required to 6–7 with a correspondingly changed value of knucl. With the more extensive data of the present study the indications are that the vapor-phase NH4NO3 monomer is not dissociated and that its diffusion constant for loss to the walls varies between 0.3 and 0.9 min?1 for different reaction conditions. Nucleation occurs when the NH4NO3 vapor concentration reaches 1.0 × 1012 molec/cm3 via. where r is 9 and the nucleation rate coefficient knucl is 3 × 10?108 cm24/min. With 5.0 or 9.5 torr of H2O vapor present, there is an excess of particles produced over that expected from this rate coefficient, indicating an additional nucleation step in which H2O vapor participates directly to produce a hydrated salt. The coagulation coefficient of (1.87 ± 0.14) × 10?7 cm3/min found here is in good agreement with that found previously.  相似文献   

14.
Using a relative rate technique, rate constants for the gas-phase reactions of the OH radical with a series of monoterpenes have been determined in one atmosphere of air at 294 ± 1 K. Relative to a rate constant for the reaction of OH radicals with 2,3-dimethyl-2-butene of 1.12 × 10?10 cm3 molecule?1 sec?1, the rate constants obtained were (in units of 10?11 cm3 molecule?1 sec?1): α-Pinene, 5.45 ± 0.32; β-pinene, 7.95 ± 0.52; Δ3-carene, 8.70 ± 0.43; d-limonene, 16.9 ± 0.5; α-terpinene, 36.0 ± 4.0; γ-terpinene, 17.6 ± 1.8; α-phellandrene, 31.0 ± 7.1; myrcene, 21.3 ± 1.6; and ocimene (acis-, trans-mixture), 25.0 ± 1.9. These are the first quantitative kinetic data reported for many of these monoterpenes. The rate constants obtained are compared with the available literature data and with a priori estimates based on the number and configuration of substituents around the double bond(s). The tropospheric lifetimes of these monoterpenes with OH radicals, NO3 radicals and O3 are estimated and compared. Atmospheric lifetimes with respect to reaction with the OH radical are calculated to range from ~0.75 hr for α-terpinene to ~5 hr for α-pinene.  相似文献   

15.
Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)2], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)2], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)2], gz =2.183 ± 0.003, gx =2.047 ± 0.004, gy =2.048 ± 0.004, Az =204.8 × 10?4cm?1, Ax =31.5 × 10?4cm?1, Ay =27.1 × 10?4 cm?1, AzN= 12.8 × 10?4 cm?1 and AxN =AyN =14.3 × 10?4 cm?1: Cu[en(tfacac)2], gz =2.192 ± 0.002, gx =2.048 ± 0.004, gy =2.046 ± 0.004, Az =200.8 × 10?4 cm?1, Ax =31.1 × 10?4 cm?1, Ay =28.3 × 10?4 cm?1, AzN =12.8 × 10?4 cm?1 and AxN =AyN =14.6 × 10?4 cm?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp2.  相似文献   

16.
Pyrolytic decay of carbon diselenide was monitored by ultraviolet absorption spectroscopy in reflected shock waves in the temperature range of 1600–2600°K. The temperature dependence of the absorption coefficient of CSe2 at 2308 Å was determined and was used to provide kinetic information along with a deconvolution procedure which accounted for and removed systematic distortions of the fast time-resolved absorbance profile. For temperatures of 1600–2600°K and argon densities of 1.5–7.0 × 10?5 mol/cm3 dilute (1.0–9.0 × 10?9 mol/cm3) CSe2 pyrolyzed with measured first-order decay rates in the range of log10 k1 (sec?1) = 3.0?5.7; at midrange (2100°K and 4.3 × 10?5 mol/cm3 in Ar) k1 ≈ 3 × 104 sec?1. The decay probably occurs via a unimolecular low-pressure process, first order in both CSe2 and Ar, for which k2 ± 109 cm3/mol·sec at 2100°K. The deconvoluted data yield Arrhenius activation energies of 53.2 kcal/mol under second-order treatment, but the activation energy is less reliable than the general magnitude of the rate constant. A comparison of CSe2 with other molecules which are isoelectronic in their valence shells (CO2, CS2, OCS, and N2O) is made.  相似文献   

17.
Rate constants for the gas-phase reactions of NO3 radicals with a series of alkynes, haloalkenes, and α,β-unsaturated aldehydes have been determined at 298 ± 2 K using a relative rate technique. Using rate constants for the reactions of NO3 radicals with ethene and propene of (1.1 ± 0.5) × 10?16 cm3 molecule?1 s?1 and (7.5 ± 1.6) × 10?15 cm3 molecule?1 s?1, respectively, the following rate constants (in units of 10?16 cm3 molecule?1 s?1) were obtained: acetylene, ≤0.23; propyne, 0.94 ± 0.44; vinyl chloride, 2.3 ± 1.1; 1,1-dichloroethene, 6.6 ± 3.1; cis-1,2-dichloroethene, 0.75 ± 0.35; trans-1,2-dichloroethene, 0.57 ± 0.27; trichloroethene, 1.5 ± 0.7; tetrachloroethene, <0.4; allyl chloride, 2.9 ± 1.3; acrolein, 5.9 ± 2.8; and crotonaldehyde, 41 ± 9. The atmospheric implications of these data are discussed.  相似文献   

18.
The thermal decomposition of cyanogen azide (NCN3) and the subsequent collision‐induced intersystem crossing (CIISC) process of cyanonitrene (NCN) have been investigated by monitoring excited electronic state 1NCN and ground state 3NCN radicals. NCN was generated by the pyrolysis of NCN3 behind shock waves and by the photolysis of NCN3 at room temperature. Falloff rate constants of the thermal unimolecular decomposition of NCN3 in argon have been extracted from 1NCN concentration–time profiles in the temperature range 617 K <T< 927 K and at two different total densities: k(ρ ≈ 3 × 10?6 mol/cm3)/s?1=4.9 × 109 × exp (?71±14 kJ mol?1/RT) (± 30%); k(ρ ≈ 6 × 10?6 mol/cm3)/s?1=7.5 × 109 × exp (‐71±14 kJ mol?1/RT) (± 30%). In addition, high‐temperature 1NCN absorption cross sections have been determined in the temperature range 618 K <T< 1231 K and can be expressed by σ /(cm2/mol)= 1.0 × 108 ?6.3 × 104 K?1 × T (± 50%). Rate constants for the CIISC process have been measured by monitoring 3NCN in the temperature range 701 K <T< 1256 K resulting in kCIISC (ρ ≈ 1.8 ×10?6 mol/cm3)/ s?1=2.6 × 106× exp (‐36±10 kJ mol?1/RT) (± 20%), kCIISC (ρ ≈ 3.5×10?6 mol/cm3)/ s?1 = 2.0 × 106 × exp (?31±10 kJ mol?1/RT) (± 20%), kCIISC (ρ ≈ 7.0×10?6 mol/cm3)/ s?1=1.4 × 106 × exp (?25±10 kJ mol?1/RT) (± 20%). These values are in good agreement with CIISC rate constants extracted from corresponding 1NCN measurements. The observed nonlinear pressure dependences reveal a pressure saturation effect of the CIISC process. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 30–40, 2013  相似文献   

19.
A high‐resolution IR diode laser in conjunction with a Herriot multiple reflection flow‐cell has been used to directly determine the rate coefficients for simple alkanes with Cl atoms at room temperature (298 K). The following results were obtained: k(Cl + n‐butane) = (1.91 ± 0.10) × 10?10 cm3 molecule?1 s?1, k(Cl + n‐pentane) = (2.46 ± 0.12) × 10?10 cm3 molecule?1 s?1, k(Cl + iso‐pentane) = (1.94 ± 0.10) × 10?10 cm3 molecule?1 s?1, k(Cl + neopentane) = (1.01 ± 0.05) × 10?10 cm3 molecule?1 s?1, k(Cl + n‐hexane) = (3.44 ± 0.17) × 10?10 cm3 molecule?1 s?1 where the error limits are ±1σ. These values have been used in conjunction with our own previous measurements on Cl + ethane and literature values on Cl + propane and Cl + iso‐butane to generate a structure activity relationship (SAR) for Cl atom abstraction reactions based on direct measurements. The resulting best fit parameters are kp = (2.61 ± 0.12) × 10?11 cm3 molecule?1 s?1, ks = (8.40 ± 0.60) × 10?11 cm3 molecule?1 s?1, kt = (5.90 ± 0.30) × 10?11 cm3 molecule?1 s?1, with f( ? CH2? ) = f (? CH2? ) = f (?C?) = f = 0.85 ± 0.06. Tests were carried out to investigate the potential interference from production of excited state HCl(v = 1) in the Cl + alkane reactions. There is some evidence for HCl(v = 1) production in the reaction of Cl with shape n‐hexane. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 34: 86–94, 2002  相似文献   

20.
Kinetics for the reactions of OBrO with NO, O3, OClO, and ClO at 240–350 K were investigated using the technique of discharge flow coupled with mass spectrometry. The Arrhenius expression for the OBrO reaction with NO was determined to be k1 = (2.37 ± 0.96) × 10?13 exp[(607 ± 63)/T] cm3 molecule?1 s?1. The reactions of OBrO with O3, OClO, and ClO are slow chemical processes at 240–350 K. Upper limit rate constants for the OBrO reactions with O3, OClO, and ClO at 240–350 K were estimated to be k2 < 5.0 × 10?15 cm3 molecule?1 s?1, k3 < 6.0 × 10?14 cm3 molecule?1 s?1, and k4 < 1.5 × 10?13 cm3 molecule?1 s?1, respectively. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 430–437, 2002  相似文献   

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