In this letter, the development of an electron momentum spectrometer, which is the first in China, has been described shortly, and using this spectrometer, the experimental results on the electron momentum spectroscopy of helium were reported.

The low-lying singlet and triplet states of HCB and HBC, and doublet states of HCB~- and HBC~- are examined using ab initio molecular orbital theory at the HF/TZP, FOCI/MCSCF level. For the neutral molecules, several new low-lying electroinc states are found, and the linear triplet structures are found to have the lowest energy. For the anions, the ~2∑~+ states are lower in energy than the ~2Π states. For HCB, the ~3Π state is 15.38 kcal·mol~(-1) more stable than the ~3∑~- state, and for HBC the ~3Π is 2.51 kcal·mol~(-1) below the ~3∑~- state at the first order configuration interaction (FOCI) level. The barriers of the conversion of HBC(~3Π) to HCB(~3Π), HBC(~1Δ(~1A_1)) to HCB(~1A′C_s) and HBC(~1Δ(~1A_2)) to HCB(~1A″C_s) are 23.21, 12.97 and 21.09 kcal·mol~(-1), respectively. The activation energies of the conversion of HBC~-(~2∑~+) to HCB(~2∑~+) and HCB~-(~2Π) to HBC~-(~2Π) are 18.13 and 25.88 kcal·mol~(-1), respectively. A symmetry breaking phenomenon is observed in several states. The harmonic vibrational frequencies of the neutral molecules and the anions are also reported to provide information for the possible experimental observation of these species.

This paper reports the thermodynamics of reversible oxygen binding to a dicobalt di(meso-tetraphenylporphyrin) linked by a diamido- aliphatic chain in N,N-dimethylformamide solution. Thermodynamic values(standard state 101325 Pa O_2): △G ~θ(298 K)=-3.1 kJ·mol~(-1), △H~θ (298 K)=-37.1 kJ·mol~(-1), △S~θ (298 K)=-114 J·mol~(-1)·K~(-1), Co:O_2=1:1. The ESR parameters of the dioxygen complex in DMF at 133 K are as follows: g_⊥=2.000, g_(||)=2.046, A~(C_0)_⊥=15G, A~(C_0)_(||)=22G, The pressure of dioxygen necessary for half-oxygenation of the system (P_(1/2)=42.7 kPa at 288 K) is comparable with that for cobalt substituted human hemoglobin at T state.

Using ab initio molecular orbital theory at the SOCI/MCSCF/HF/DH+d level, the equilibrium geometries, total energies, harmonic vibrational frequencies, zerro point vibrational energy and potential energy curves of the ground state and 8 excited states of Si_2 molecule were obtained. The relationship between the bond length and the electronic codriguration of the state was discussed. The results revealed that bond length and the harmonic vibrational frequency of the molecule strongly depended upon the number of π-electrons in the bonding MO's. The reported states ~3Π_g, ~5Σ~-_u, ~3Δ_u, ~3Σ~-_u have not been seen in literatures.

The microdisk electrode voltammetric behaviors of C_(60) are reported in this communication. This was accomplished by use of a mixed solvent system as Acetonotrile:Xylene=1:4 and a supporting electrolyte as 0.1 mol·L~(-1) Bu_4NPF_6. Au, Pt and Hg (Pt) were used as working electrode. In this new conditions, the successive six step reduction of C60 were obtained at below 15 ℃. It was found that the former five steps are all the single electron reversible reduction, but behaviors of the sixth steps are like EC' processes. Several electrochemical data were determined.

In this paper the changes of Mo species of Mo/Al_2O_3 and Mo/TiO_2-Al_2O_3 catalysts in reducing and sulfiding process have been studied by in situ LR spectroscopic technique. The results show: (1) The reducibility of various Mo species in Mo/Al_2O_3 is different.The bands of octahedral Mo species and their polymer at 215 and 971 cm~(-1) disappeared first at 100 ℃, and then crystalline MoO_3 at 820 cm~(-1) at below 300 ℃ in H_2. The bands of Al_2(MoO_4)_3 phase at 377 and 1003 cm~(-1) disappeared at 400 ℃. Polymer of octahedral Mo species at 961 cm~(-1) and crystalline MoO_3 at 289, 666, 816 and 994 cm~(-1) exist in Mo/TiO_2-Al_2O_3 catalysts. The former was reduced at lower temperatures than the latter. (2) When H_2S-H_2 flowed into sample cell at room temperature, the bands of oxidic Mo/Al_2O_3 disapeared, and simultaneously, the bands of MoS_2 at 377, 401 cm~(-1) and complicated molybdenum oxysulfide at 325, 348, 450, 540 cm~(-1) emerged. After sulfiding at 400 ℃, only MoS_2 phase exists. For Mo/TiO_2-Al_2O_3, the bands of Mo and TiO_2 disappeared upon sulfiding of a sample at room temperature, and the bands of MoS_2 at 375 and 398 cm~(-1) emerged. This reveals that modification of the Al_2O_3 surface by TiO_2 strongly enhances the sulfiding of Mo supported catalysts.

The O_(1s) binding energies of M , ZrO_2, TiO_2, Al_2O_3 and SiO_2 were determined by XPS. It is shown that the BSCCO-oxides interactions are predominately acid-base in nature, and the reactivity can be evaluated either by the acid-base parameter or by the core-level binding energy of oxygen of the oxide substrate materials.

The crystal structure of octadecyl hydrogen maleate was determined by Xray diffeaction method. C_(22)H_(40)O_4, Mr=368.56, triclinic, space group Pī, a=0.6833 (2), b=3.1662 (5), c=0.5392 (1) nm, α=90.63 (2), β=102.61 (2), γ=89.03 (2)°, V=1.1383 (5) nm. Z=2, Dc.=1.08 g·cm~(-3), F(000)=408, λ(Mo K_α) =0.071069 nm, μ(Mo K_α)=0.67 cm~(-1), final R=0.0465 for 1332 observations with I ≥3σ(I) and 240 variables. In the crystal OHM molecules form dimers via intermolecular hydrogen bonding between carboxyl groups. The long hydrocarbon chain of octadecyl is zigzag-like and the carbon atoms of this chain are basically coplanar. These dimers arrange along (101) plane to form a layer, then these layers stack along [010] to give the crystal structure. The van der Waals interaction intralayer is evidently larger than interlayer. On the base of the crystal structure some phenomena in the crystal growth of OHM were illustrated.

Cupric (Ⅱ) ion transfer across the water/nitrobenzene interface facilitated by 2,2'-biqulnoline was investigated by cyclic voltammtry. Transfer process was controlled by diffusion. At [BQ]_(NB)>>[Cu~(2+)]_W, transfer ion was found to be 1:2 Cu~(2+)-biquinoline complex. Kinetics of complex action was described. Diffusion coefficient of Cu(BQ)~(2+)_2 in water phase was estimated as 3.8×10~(-5) cm~2/s and rate constant k of this complex action was determined as 2.6×10~(-4) s~(-1). At [Cu~(2+)]_W>>[BQ]_(NB), no transfer peaks were observed and 1:1 Cu~(2+)-biquinoline complex was formed.

The thermal decomposition of acetylacetone has heen studied with MINDO/3 MO theory. The results obtained show that the enol forms are more stable than the tone forms; the activation energies of the reaction (1) and (2) are 210.250 and 225.501 kJ·mol~(-1), respectively.

Crystallization behavior of a series of newly synthesized poly (tetrahydrofuran-b-methyl methacrylate) diblock copolymer has been studied by differential scanning calorimetry (DSC) and X-ray scattering and diffraction techniques. The results show that the microphase separation and crystallization are very different from that of poly (ethylene oxid-b-styrene) diblock copolymer, the only one systematically investigated in literature. Our results suggeste that crystalline ability of the crystallizable block of such type of diblock copolymer is one of the important factors verning its microphase separation and crystallization.

At the level of 3-21G basis set, the transition states of the titled reactions have been optimized by using the energy gradient method with GAUSSIAN 80 program.On this basis, a vibrational analysis has been performed with GAUSSIAN 86 program to make the transition states further confirmed.
It has been found that the substitution of -F, -CN, -NH_2 and -CH_3 at α or β carbon leads to the change of the structures of the transition states of the titled reactions. The charge distribution of the transition states shows that all of them are polarized fourmember ring structures.
It is shown that the substitution of -F at α or β carbon leads to a rising of the reaction arrier height and the barrier of the former is higher than that of the later. However, the substitution of -CN at α and β carbons lead to a rising and a lowering of the reaction barrier respectively. As for the -NH_2 and -CH_3 cases, α substitution always increases the barrier height, while β substitution decreases it, and the substitution effect of -NH_2 is stronger than that of -CH_3. These results are in accord with the conclusions derived from experiments.

Four acrylic copolymers (MMA/BA/HEMA/AA) containing various amount of AA were prepared by solution polymerization. The soap-free water-solubilized colloidal dispersions were obtained by dispersing the copolymer in water through seif-emulsion of the partly neutralized AA in the copolymer. TEM showed that the particles of the colloidal dispersions are spherical and of monodispersion, and the particle size decreases with increasing AA content ranging from 30 nm to 90 nm. It was found by conductometric titration that most —COO~- locates on the particle surface and the surface —COO~- increases with increasing AA content, resulting in the enhancement of zeta-potential. All these results are consistent with the facts that the electrolyte-resistance (expressed as C.C.C. value) and the storage stability (expressed as apparent viscosity) of the colloidal dispersions increase with increasing AA content.

Simulated armealing is a promising new method for conformational analysis of flexible molecules. It differentiates from the conventional molecular mechanics optimization in that it not only accepts the changes that the energy decreases, but also accepts some uphin changes. so it is possible to make transitions out of the local minima and reach the global minimum of the system. The program SAPEP has been made using ECEPP/2 force field for conformational analysis of peptides. A set of linear peptides which was cyclized into the same cyclopentapeptide was analysed using SAPEP in order to explore the relationship between the conformation and yield of cyclization. The results show that relationship exists between the conformation and yield.

In this paper, the effects of hydroxylamine sulfate and hydrated hydrazine on the B-Z reaction are studied. Hydroxylamine sulfate and hydrated hydrazine can react with BrO~-_3 to produce Br~-. They show some analogies with vitamin C in their effects on B-Z reaction, that is, they sbolarly lengthen the induction period and oscillating period, and shorten the life-span of this oscillating reaction. From this reason the conjecture of reaction mechanism that is proposed by Zhao Xuezhuang et al can be confirmed.

The corrosion behavior of copper in 3% NaCl solutions has been investigated using AES. XPS and photoelectrochemical tectniques. The results show that Cl~- has remarkable influence on the corrosion behavior of copper. With the increasing immersion time, the photoresponse of copper electrode changes from p-type to n-type gradually, and the invasion degree of Cl~- ions on copper electrode increases. Finally, the band gap of the sedriconduct film formed on copper electrode surface is 1.7 eV.

The CMC and the aggregation number of Triton X-100 in mixtures of ethylene glycol and water have been measured by surface tension and static flucorescence decay methods. The discontinuity of the surface tension curve indicates that Triton X-100 forms micelles in ethylene glycol, though its CMC (0.05 mol·L~(-1), 20 ℃) is greater than that in water. From fluorescence decay the aggregation number of Trion X-100 in ethylene glycol is 25 (30 ℃) in comparison with 97 in water. The aggegation number is reduced by adding glycol into an aqueous solution of Trion X-100. These could be interpreted in terms of a more favourable interaction between molecules of glycol and Trion X-100 than between water and Trion X-100.

A correlation of free volume of saturated vapor with that of coexisting liquid phase is derived from the cell theory of flulds. Then this correlation is combined with a revised free volume model proposed by this author for viscosity and thermal conductivity, equations are derived which correlate the viscosities and thermal conductivities of coekisting vapors and liqueds with heat of vaporization and temperature. The literature data for 44 representative substances are used to test the equations and the results are satisfactory. It can be seen from this work that there might exist some relations between the transport properties of vapors and those of coexisting liquids.

There are four single phase regions in part of the phase diagram for Triton X-100-C_(10)H_(21)OH/H_2O system. These are O/W region, W/O region, lamellar liquid crystal region, and hexa nal liquid crystal region. In the O/W region, the maximum molecular ratio of Thiton X-100 to C10H21OH is about 2.4~2.5. The maximum solubilization of water in the W/O region is related to both the weight ratio of Triton X-100 to C_(10)H_(21)OH and the formation of lamellar liquid crystal. The interlayer spacing of lamellar liquld crystal at constant water content decreases with increasing weight ratio of C_(10)H_(21)OH/Triton X-100 which is related to the penetration of water in the lamellar phase.

The cause of Warburg impedance on the impedance spectra for copper electrode in low-conductivity solution has been studied. The slopes of Randles plots (Warburg coefficients) do not change with dissolved oxygen concentration and strring rate, but they increase with the increase of the pH of solution and driesion time. The experimental results show that the Warburg twedance at low frequencies is caused by the diffusion of copper ions from the inner side to the outer side of the oxide film on the surface of copper electrode.