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1992 Volume 8 Issue 4
1992, 8(04): 433-435
doi: 10.3866/PKU.WHXB19920401
Abstract:
1992, 8(04): 436-437
doi: 10.3866/PKU.WHXB19920402
Abstract:
Mass spectrum of negative cluster carbon ions with cluster size up to 100 was recorded on a self-built laser plasma source time-of-flight mass spectrometer. For cluster anious larger than or equal to 50, only clusters with even size were observed. This observation suggests that these cluster anions can also adopt the fullerene configuration and the configuration transition from planar ring to closed shell starts at n=50. Among these anions, C_(60)~- does not have special ion intensity.
Mass spectrum of negative cluster carbon ions with cluster size up to 100 was recorded on a self-built laser plasma source time-of-flight mass spectrometer. For cluster anious larger than or equal to 50, only clusters with even size were observed. This observation suggests that these cluster anions can also adopt the fullerene configuration and the configuration transition from planar ring to closed shell starts at n=50. Among these anions, C_(60)~- does not have special ion intensity.
1992, 8(04): 438-440
doi: 10.3866/PKU.WHXB19920403
Abstract:
By laser ablation of NaBH_4 on a home-made instrument, four series of borane anions B_nH_m~- with formular of n=3k+1, m=5k+4; n=3k+2, m=5k+1; n=3k+2, m=5k+5; n=3k+3, m=5k+6 (k=0,1,2…) were observed at first time on recorded time-of-flight mass spectra with different ion intensities. From analysis of the mass spectra and calculate their possible topologies, a dra n-like structure was suggested for these new type of borane anions.
By laser ablation of NaBH_4 on a home-made instrument, four series of borane anions B_nH_m~- with formular of n=3k+1, m=5k+4; n=3k+2, m=5k+1; n=3k+2, m=5k+5; n=3k+3, m=5k+6 (k=0,1,2…) were observed at first time on recorded time-of-flight mass spectra with different ion intensities. From analysis of the mass spectra and calculate their possible topologies, a dra n-like structure was suggested for these new type of borane anions.
1992, 8(04): 441-444
doi: 10.3866/PKU.WHXB19920404
Abstract:
MNDO and X_a methods have been used for the quantum chemical calculation of [Al_2O(OH)_6]~(2-) and Al(OH)_4~- ions existed in sodium aluminate solutions. The rotation barrier of the former is 10.08 kJ·mol~(-1) and its most stable configuration is C_s. The UV absorption peaks due to the electronic transition between HOMO and LUMO of these two ions have been estimated to be 266.6 nm and 234.4 nm respectively, which are in agreement with the experimental data 270.0 nm and 230.0 nm.
MNDO and X_a methods have been used for the quantum chemical calculation of [Al_2O(OH)_6]~(2-) and Al(OH)_4~- ions existed in sodium aluminate solutions. The rotation barrier of the former is 10.08 kJ·mol~(-1) and its most stable configuration is C_s. The UV absorption peaks due to the electronic transition between HOMO and LUMO of these two ions have been estimated to be 266.6 nm and 234.4 nm respectively, which are in agreement with the experimental data 270.0 nm and 230.0 nm.
1992, 8(04): 445-451
doi: 10.3866/PKU.WHXB19920405
Abstract:
We calculated the energy band structures of the double TI-O layer TI-Ba-Ca-CuO oxide superconductors by performing the tight-binding band structure calculation method on the basis of EHT approximation. The results show that the Fermi surfaces are closed on the a~*b~* plane. The increase of electronic state densities on the Fermi level is consistent with the raise of T_c in this system. The regular changing of the net charges of Cu and O indicates that the ionic states of Cu and O in Cu-O plane may influence the superconductivity of this system.
We calculated the energy band structures of the double TI-O layer TI-Ba-Ca-CuO oxide superconductors by performing the tight-binding band structure calculation method on the basis of EHT approximation. The results show that the Fermi surfaces are closed on the a~*b~* plane. The increase of electronic state densities on the Fermi level is consistent with the raise of T_c in this system. The regular changing of the net charges of Cu and O indicates that the ionic states of Cu and O in Cu-O plane may influence the superconductivity of this system.
1992, 8(04): 452-458
doi: 10.3866/PKU.WHXB19920406
Abstract:
The characteristic behavior of H_2 and O_2 over CeO_2 and Pt/CeO_2 was studied by means of TPR, TPD, FT-IR and TPEC. The reduction of CeO_2 by H_2 is greatly promoted by supported Pt and highly labile adsorbed species is resulted. The temperatures of sorption and liberation of H_2 on Pt/CeO_2 are lowered by as much as 300 ℃ than on CeO_2. The oxygen adsorbed on partially reduced CeO_2 exists as dioxygen species(O_2~-,O_2~(2-)) at room temperature. On Pt/CeO_2 the oxygen species is altered and the dissociated species is formed even at ambient condition. The adsorbed oxygen on cerium oxide catalysts desorbs partly while the temperature is elevated and the retained oxygen is transformed into lattice oxygen ion above 170 ℃.
The characteristic behavior of H_2 and O_2 over CeO_2 and Pt/CeO_2 was studied by means of TPR, TPD, FT-IR and TPEC. The reduction of CeO_2 by H_2 is greatly promoted by supported Pt and highly labile adsorbed species is resulted. The temperatures of sorption and liberation of H_2 on Pt/CeO_2 are lowered by as much as 300 ℃ than on CeO_2. The oxygen adsorbed on partially reduced CeO_2 exists as dioxygen species(O_2~-,O_2~(2-)) at room temperature. On Pt/CeO_2 the oxygen species is altered and the dissociated species is formed even at ambient condition. The adsorbed oxygen on cerium oxide catalysts desorbs partly while the temperature is elevated and the retained oxygen is transformed into lattice oxygen ion above 170 ℃.
1992, 8(04): 459-463
doi: 10.3866/PKU.WHXB19920407
Abstract:
The inhibition effects of tributylphosphate on the radiolysis of cyclohexane have been reported. Combintion of the inhibition effects of the radiolytical productshydrogen gas, cyclohexene, bicyclohexyl with results of excitation energy transfer, it was found that the inhibition effects of TBP are performed by two processes: a)excitation energy transfer, b) electron capture. We obtained that the yield of the geminate ion pairs of cyclohexane is 3.8, and the electron capture coefficient of TBP is 6.3 L·mol~(-1).
The inhibition effects of tributylphosphate on the radiolysis of cyclohexane have been reported. Combintion of the inhibition effects of the radiolytical productshydrogen gas, cyclohexene, bicyclohexyl with results of excitation energy transfer, it was found that the inhibition effects of TBP are performed by two processes: a)excitation energy transfer, b) electron capture. We obtained that the yield of the geminate ion pairs of cyclohexane is 3.8, and the electron capture coefficient of TBP is 6.3 L·mol~(-1).
1992, 8(04): 464-469
doi: 10.3866/PKU.WHXB19920408
Abstract:
The uptake of glycine by 001×7, a strong acid cation exchange resin and 201×7, a strong base anion exchange resin at low concentration as a function of the solution pH has been investigated in detail, The test of equivalence law for the uptake of glycine and the release of counter-ion from the ion exchange resin, and the in-frared spectroscopy of glycine adsorbed on the 001×7 resin were used to elucidere the mechanism of uptake of amino acid on ion exchange resin from aqueous solution. The uptake of glycine on styrene-divinybenzene copolymer has been examined too.
The uptakes of seven amino acids (Gly, Phe, Lys, Len, Ala, Thr, Glu) by the 001×7 resin in H form at low solution concentration as a function of pH have been determined too, and it was found that the maximum uptake of amino acids takes place in the pH range close to the isoelectric points, the heights of the maximum uptake of the neutral amino acids are related to the second macroscopic dissociation constants, and the height of the maximum uptake of phenylalanine is higher than that of glycine in 50%.
On the basis of experimental data it can be concluded that the uptake of amino acid by strong acid ...
The uptake of glycine by 001×7, a strong acid cation exchange resin and 201×7, a strong base anion exchange resin at low concentration as a function of the solution pH has been investigated in detail, The test of equivalence law for the uptake of glycine and the release of counter-ion from the ion exchange resin, and the in-frared spectroscopy of glycine adsorbed on the 001×7 resin were used to elucidere the mechanism of uptake of amino acid on ion exchange resin from aqueous solution. The uptake of glycine on styrene-divinybenzene copolymer has been examined too.
The uptakes of seven amino acids (Gly, Phe, Lys, Len, Ala, Thr, Glu) by the 001×7 resin in H form at low solution concentration as a function of pH have been determined too, and it was found that the maximum uptake of amino acids takes place in the pH range close to the isoelectric points, the heights of the maximum uptake of the neutral amino acids are related to the second macroscopic dissociation constants, and the height of the maximum uptake of phenylalanine is higher than that of glycine in 50%.
On the basis of experimental data it can be concluded that the uptake of amino acid by strong acid ...
1992, 8(04): 470-475
doi: 10.3866/PKU.WHXB19920409
Abstract:
A series of supported palladium catalysts were prepared with impregnating method. SO_4~(2-) was introduced by dipping Al_2O_3 into dilute H_2SO_4 solution for the preparation of Pd/Al_2O_3--SO_4 or impregnating Pd/Al_2O_3 with a series of K_2SO_4 solutions for Pd/SO_4~(2-)/Al_2O_3 as catalysts. X-ray photoelectron spectroscopy was employed to measure the states of sulfur and palladium before and after the catalysts were treated under different atmospheres. Temperature programmed desorption-mass spectroscopy (TPD-MS) was used to investigate the effect of different sulfur species and atmosphere on H_2 adsorption on the catalysts. The results showed as follows: The influence of sulfur species upon H_2 desorption declined in a order as S_2~(2-), S~(2-) and SO_4~(2-), and the effect of the former two was more distinct than SO_4~(2-). Their behaviors were in accord with the evaluation of the catalyst for H_2-O_2 reaction, which may be interpreted with the molecular orbital theory.
A series of supported palladium catalysts were prepared with impregnating method. SO_4~(2-) was introduced by dipping Al_2O_3 into dilute H_2SO_4 solution for the preparation of Pd/Al_2O_3--SO_4 or impregnating Pd/Al_2O_3 with a series of K_2SO_4 solutions for Pd/SO_4~(2-)/Al_2O_3 as catalysts. X-ray photoelectron spectroscopy was employed to measure the states of sulfur and palladium before and after the catalysts were treated under different atmospheres. Temperature programmed desorption-mass spectroscopy (TPD-MS) was used to investigate the effect of different sulfur species and atmosphere on H_2 adsorption on the catalysts. The results showed as follows: The influence of sulfur species upon H_2 desorption declined in a order as S_2~(2-), S~(2-) and SO_4~(2-), and the effect of the former two was more distinct than SO_4~(2-). Their behaviors were in accord with the evaluation of the catalyst for H_2-O_2 reaction, which may be interpreted with the molecular orbital theory.
1992, 8(04): 476-480
doi: 10.3866/PKU.WHXB19920410
Abstract:
The heterogeneous electron transfer kinetic parameters of Indi Carmine at tin dioxide optically transparent electrode are reported here in this study. Both spectroelectrochemical and electrochemical techniques were used. In the former case, kinetic parameters were calculated from the normalized absorbance which was measured by absorbance versus time transient curve after serveral overpotential steps. A compu-ter data treatment method instead of the working curve method usually reported in literature was used in the calculation. In the later case, kinetic parameters were determined by measuring the difference of peak potentials ΔE_p of cathodic and anodic reference curve. The results obtained with both techniques had od coincidence. Further investigation shows that the value of kinetic parameters are dependent on Indi Carmine concentration and solution pH values. It is considered as an important information for the electrochemical reduction mechanism of Indi Carmine.
The heterogeneous electron transfer kinetic parameters of Indi Carmine at tin dioxide optically transparent electrode are reported here in this study. Both spectroelectrochemical and electrochemical techniques were used. In the former case, kinetic parameters were calculated from the normalized absorbance which was measured by absorbance versus time transient curve after serveral overpotential steps. A compu-ter data treatment method instead of the working curve method usually reported in literature was used in the calculation. In the later case, kinetic parameters were determined by measuring the difference of peak potentials ΔE_p of cathodic and anodic reference curve. The results obtained with both techniques had od coincidence. Further investigation shows that the value of kinetic parameters are dependent on Indi Carmine concentration and solution pH values. It is considered as an important information for the electrochemical reduction mechanism of Indi Carmine.
1992, 8(04): 481-486
doi: 10.3866/PKU.WHXB19920411
Abstract:
Infrared spectra of binary mixtures of aniline or N-methylaniline with n-heptane, carbon tetrachloride, benzene or toluene have been measured at room temperatures with an IR spectrometer. The solvent effect on the NH group stretching vibration frequencies were discussed. Infrared spectra of several mixtures containing a nitro-genous Lewis base in CCl_4. were also determined and the involved cross-association contants were calculated. The results indicate that aniline is a stronger proton donor than N-methylaniline when they associate with pyridine in CCl_4, and the protonaccepting ability of several bases increase in the order: aniline ～N-methylaniline<tributylamine<pyridine<triethylamine when they associate with ethanol in CCl_4. Moreover, infrared spectra of ternary mixtures (ethanol+pyridine+chloroform) were briefly analysed in terms of the interactions between unlike molecules.
Infrared spectra of binary mixtures of aniline or N-methylaniline with n-heptane, carbon tetrachloride, benzene or toluene have been measured at room temperatures with an IR spectrometer. The solvent effect on the NH group stretching vibration frequencies were discussed. Infrared spectra of several mixtures containing a nitro-genous Lewis base in CCl_4. were also determined and the involved cross-association contants were calculated. The results indicate that aniline is a stronger proton donor than N-methylaniline when they associate with pyridine in CCl_4, and the protonaccepting ability of several bases increase in the order: aniline ～N-methylaniline<tributylamine<pyridine<triethylamine when they associate with ethanol in CCl_4. Moreover, infrared spectra of ternary mixtures (ethanol+pyridine+chloroform) were briefly analysed in terms of the interactions between unlike molecules.
1992, 8(04): 487-492
doi: 10.3866/PKU.WHXB19920412
Abstract:
In the form-space,the form-distribution for the ensemble of La(OH)_3-aggregation has been described. On the basis of this description, the size distribution of La(OH)_3-aggregation has been simulated, and the mechanism of the formation of La(OH)_3-aggregation has heen suggested.
In the form-space,the form-distribution for the ensemble of La(OH)_3-aggregation has been described. On the basis of this description, the size distribution of La(OH)_3-aggregation has been simulated, and the mechanism of the formation of La(OH)_3-aggregation has heen suggested.
1992, 8(04): 493-499
doi: 10.3866/PKU.WHXB19920413
Abstract:
The polysaccharide of pleuratu ostreatus was fractionated by repeated precipitation method. Modified Elias cloud-point titration method with an UV detecter was used to determine the cloud-point. It was found that water/acetone (83.5:16.5 by volume) is a θ-solvent for the polymer at 25 ℃. Number average molecular weights of all samples fractionated were characterized by rapid dynamic membrane osmometry and viscometry. The second virial coefficient A_2 decreases as the molecular weight in-creases. The relationship is A_2=2 slope (M_nRT)~(-1/2).
The intrinsic viscosities were determined by capillary viscometry in θ-solvent. Thus and thus a mondispersed [η]～M relationship has been obtained:
[η]_θ=0.124~(0.513)
The unperturbed dimension ...
The polysaccharide of pleuratu ostreatus was fractionated by repeated precipitation method. Modified Elias cloud-point titration method with an UV detecter was used to determine the cloud-point. It was found that water/acetone (83.5:16.5 by volume) is a θ-solvent for the polymer at 25 ℃. Number average molecular weights of all samples fractionated were characterized by rapid dynamic membrane osmometry and viscometry. The second virial coefficient A_2 decreases as the molecular weight in-creases. The relationship is A_2=2 slope (M_nRT)~(-1/2).
The intrinsic viscosities were determined by capillary viscometry in θ-solvent. Thus and thus a mondispersed [η]～M relationship has been obtained:
[η]_θ=0.124~(0.513)
The unperturbed dimension ...
1992, 8(04): 500-504
doi: 10.3866/PKU.WHXB19920414
Abstract:
The kinetics and mechanism of electron transfer from sodium tartrate to Ni(Ⅳ) periodate complex have been studied in aqueous alkaline medium using spectroscopic and stopped-flow method. The kinetics exhibits a pseudo first order for the disap-pearance of Ni(Ⅳ) periodate complex when substrate is present in excess. The order for the substrate found is not an integer. Additon of NaIO_4 and NaOH affects the reaction rates. Results are interpreted in terms of a mechanism involving two separated steps of one-electron transfer from the substrate to the species containing Ni(IV). The activation parameters of this reaction have been calculated.
The kinetics and mechanism of electron transfer from sodium tartrate to Ni(Ⅳ) periodate complex have been studied in aqueous alkaline medium using spectroscopic and stopped-flow method. The kinetics exhibits a pseudo first order for the disap-pearance of Ni(Ⅳ) periodate complex when substrate is present in excess. The order for the substrate found is not an integer. Additon of NaIO_4 and NaOH affects the reaction rates. Results are interpreted in terms of a mechanism involving two separated steps of one-electron transfer from the substrate to the species containing Ni(IV). The activation parameters of this reaction have been calculated.
1992, 8(04): 505-509
doi: 10.3866/PKU.WHXB19920415
Abstract:
In this paper, the spectra of absorption, fluorescence excitation and fluorescence emission for the ethanol solutions of sodium fluorescein at various pH values were observed and their fluorescence lifetimes were also measured. From these results, the existence of different modifications of sodium fluorescein in the ethanol solution and their protolytic reactions were discussed.
In this paper, the spectra of absorption, fluorescence excitation and fluorescence emission for the ethanol solutions of sodium fluorescein at various pH values were observed and their fluorescence lifetimes were also measured. From these results, the existence of different modifications of sodium fluorescein in the ethanol solution and their protolytic reactions were discussed.
1992, 8(04): 510-514
doi: 10.3866/PKU.WHXB19920416
Abstract:
The presence of pre-exsisting foreign particles will strongly affect the formation, morphology and even the crystal types of colloidal particles formed by the hydrolysis of concerned salts at elevated temperature, depending on the shape, size, surface charge and number concentration of pre-exsisting particles. The nucleation of new materials usally varies in different ways: (1) independent nucleation; (2) local nucleation on the active sites of pre-exsiting particles; (3) nucleation on the full surfaces of pre-exsisting particles. Our new finding is that the morphology, chemical compostion and even crystal types of new precipitation change with the number concentration of pre-exsisting particles. For example, the aging solution for preparing β-FeOOH, a mixture of β-FeOOH and hematite in the presence of pre-exsisting spherical or spindle hematite will be obtained. Accompanying with the presence of the foreigners, the content of hematite obviously. When the number of foreign particles is equal to or more than that of β-FeOOH formed without foreigners, the product is pure hematite. It indicates that the saturated concentration of the components may be redueed by foreign particles.
The presence of pre-exsisting foreign particles will strongly affect the formation, morphology and even the crystal types of colloidal particles formed by the hydrolysis of concerned salts at elevated temperature, depending on the shape, size, surface charge and number concentration of pre-exsisting particles. The nucleation of new materials usally varies in different ways: (1) independent nucleation; (2) local nucleation on the active sites of pre-exsiting particles; (3) nucleation on the full surfaces of pre-exsisting particles. Our new finding is that the morphology, chemical compostion and even crystal types of new precipitation change with the number concentration of pre-exsisting particles. For example, the aging solution for preparing β-FeOOH, a mixture of β-FeOOH and hematite in the presence of pre-exsisting spherical or spindle hematite will be obtained. Accompanying with the presence of the foreigners, the content of hematite obviously. When the number of foreign particles is equal to or more than that of β-FeOOH formed without foreigners, the product is pure hematite. It indicates that the saturated concentration of the components may be redueed by foreign particles.
1992, 8(04): 515-518
doi: 10.3866/PKU.WHXB19920417
Abstract:
Poly(aniline) (PAn) was synthesized by chemical oxidation with (NH_4)_2S_2O_8 as oxidant, and the interface between PAn and an improved PEO-LiClO_4 complex was investigated using ac impedance technique. In the interface a salt-rich passiva-tion film arising from the self-diffusion of ClO_4~- anions exists. During film formation the thickness of the film may be expressed in terms of L=Kt~(0.14) where K is a constant related to the intrinsic properties of the film. The passivation film has an ionic conductivity of 2.2×10~(-6) S·cm~(-1) at 15 ℃, suggesting that it causes no unfavorable effect on the electrochemical reversibility of the PAn. The constancy of R_pC_p values with time implies that the storage time does not affect the structure or components of the passivation film during the thickening of the film. The relationship of temperature-conductivity, silimar to that observed in other amorphous PEO-MX complexes, can be described by VTF equation.
Poly(aniline) (PAn) was synthesized by chemical oxidation with (NH_4)_2S_2O_8 as oxidant, and the interface between PAn and an improved PEO-LiClO_4 complex was investigated using ac impedance technique. In the interface a salt-rich passiva-tion film arising from the self-diffusion of ClO_4~- anions exists. During film formation the thickness of the film may be expressed in terms of L=Kt~(0.14) where K is a constant related to the intrinsic properties of the film. The passivation film has an ionic conductivity of 2.2×10~(-6) S·cm~(-1) at 15 ℃, suggesting that it causes no unfavorable effect on the electrochemical reversibility of the PAn. The constancy of R_pC_p values with time implies that the storage time does not affect the structure or components of the passivation film during the thickening of the film. The relationship of temperature-conductivity, silimar to that observed in other amorphous PEO-MX complexes, can be described by VTF equation.
1992, 8(04): 519-522
doi: 10.3866/PKU.WHXB19920418
Abstract:
Palladium oxide electrodes were prepared by decomposition of Pd(NO_3)_2 or thermal oxidation of Pd, their voltammetric characteristics were found to be dependent on preparation methods. XPS analysis showed that these electrodes had different compo-sitions. The impedance behavour of the electrodes can be presented with a simple eguivalent circuit containing a constant phase-angle element, indicating the microin-homogeneity of the oxide layers. The pH-sensing properties of the electrodes were measured and the pH response mechanism was discussed.
Palladium oxide electrodes were prepared by decomposition of Pd(NO_3)_2 or thermal oxidation of Pd, their voltammetric characteristics were found to be dependent on preparation methods. XPS analysis showed that these electrodes had different compo-sitions. The impedance behavour of the electrodes can be presented with a simple eguivalent circuit containing a constant phase-angle element, indicating the microin-homogeneity of the oxide layers. The pH-sensing properties of the electrodes were measured and the pH response mechanism was discussed.
1992, 8(04): 523-526
doi: 10.3866/PKU.WHXB19920419
Abstract:
In this paper the antibody of HCG was immobilzed on the cellulose acetate membrane. The membrane potentials varied with the electrolyte concentrations of the two aqueous phases. The charge density of the membrane phase was lowered as the immunochemical reaction of HCG with HCG antibody proceeded on the membrane surface. When c_1/c_2=8.0, the antibody-bound membrane potentials shifted to posi-tive values with the increase of HCG concentrations. The membrane immunosensor for the measurement HCG in the solution was constructed according to the change of the membrane potential. A linearity between Δφ and lg HCG can be obtained in the concentration range of 50—2500 mlU·ml~(-1) HCG.
In this paper the antibody of HCG was immobilzed on the cellulose acetate membrane. The membrane potentials varied with the electrolyte concentrations of the two aqueous phases. The charge density of the membrane phase was lowered as the immunochemical reaction of HCG with HCG antibody proceeded on the membrane surface. When c_1/c_2=8.0, the antibody-bound membrane potentials shifted to posi-tive values with the increase of HCG concentrations. The membrane immunosensor for the measurement HCG in the solution was constructed according to the change of the membrane potential. A linearity between Δφ and lg HCG can be obtained in the concentration range of 50—2500 mlU·ml~(-1) HCG.
1992, 8(04): 527-529
doi: 10.3866/PKU.WHXB19920420
Abstract:
The influence of added elements on the solidification process of Al-Si alloys was systematially investigated by DTA and thermal analysis. It was obtained that Na, Sr in the melt can raise the temperature of eutectic solidification. Our work indicates that the traditional retard nucleation theory of modification may have some shortcomings.
The influence of added elements on the solidification process of Al-Si alloys was systematially investigated by DTA and thermal analysis. It was obtained that Na, Sr in the melt can raise the temperature of eutectic solidification. Our work indicates that the traditional retard nucleation theory of modification may have some shortcomings.
1992, 8(04): 530-535
doi: 10.3866/PKU.WHXB19920421
Abstract:
The Raman and infrared spectra of dicarbonyl (acetylacetonato) rhodium have been measured form 4000 to 80 cm~(-1). A normal coordinate analysis was performed for all modes by using Simplified General Valence Force Field. 38 force constants were used during the calculation process. Some new assignments of bands have been made and they were supported by some proofs. The reliabilty of result was discussed.
The Raman and infrared spectra of dicarbonyl (acetylacetonato) rhodium have been measured form 4000 to 80 cm~(-1). A normal coordinate analysis was performed for all modes by using Simplified General Valence Force Field. 38 force constants were used during the calculation process. Some new assignments of bands have been made and they were supported by some proofs. The reliabilty of result was discussed.
1992, 8(04): 536-539
doi: 10.3866/PKU.WHXB19920422
Abstract:
MPI spectrum of Si(CH_3)_4 has been measured in the wavelength range of 410—370 nm. Most of the peaks with strong background were assigned to (2+1) ionization of Si atoms initiated from their ground state 3~3P_J and the first singlet state 3~1D_2. TOF mass spectra showed that Si~+, C_2~+ were the major products at lower laser energy, whereas more ions Si(CH_3)_n~+ (n=1—4), even silicon carbide ion C_3Si~+, appeared at higher energy.
MPI spectrum of Si(CH_3)_4 has been measured in the wavelength range of 410—370 nm. Most of the peaks with strong background were assigned to (2+1) ionization of Si atoms initiated from their ground state 3~3P_J and the first singlet state 3~1D_2. TOF mass spectra showed that Si~+, C_2~+ were the major products at lower laser energy, whereas more ions Si(CH_3)_n~+ (n=1—4), even silicon carbide ion C_3Si~+, appeared at higher energy.
1992, 8(04): 540-544
doi: 10.3866/PKU.WHXB19920423
Abstract:
The merocyanine dye 3-ethyl-5-(2-(3-ethyl-2-benzothiazolinylidene)-ethylidene)-rhodanine (BTER) known as Agfa-10 has been found to have a od photoconductivity as solution cast film. In this paper iodine-doped BTER was obtained by doping with iodine vapor. Its structure was investigated with the following characteristies.
1 The doped iodine had been excited as I_3~- anion.
2 Because the electron located on the sulphur atom was transferred to iodine, the charge transfer complex of (BTER-I_3) formed.
3 During the iodine doping process, BTER changed from α-form to β-modification. These had been identified by X-ray diffraction, VIS-absorption spectra and SEM picture.
4 From the volt-Ampere curve obtained from sandwich cell, when E≤2.2×10~(-1) V·cm~(-1), the room temperature electrical conductivity of BTER and BTER-I_3 were found to be 2.22×10~(-10) s·cm~(-1) and 2.6×10~(-7) S·cm~(-1), respectively.
The merocyanine dye 3-ethyl-5-(2-(3-ethyl-2-benzothiazolinylidene)-ethylidene)-rhodanine (BTER) known as Agfa-10 has been found to have a od photoconductivity as solution cast film. In this paper iodine-doped BTER was obtained by doping with iodine vapor. Its structure was investigated with the following characteristies.
1 The doped iodine had been excited as I_3~- anion.
2 Because the electron located on the sulphur atom was transferred to iodine, the charge transfer complex of (BTER-I_3) formed.
3 During the iodine doping process, BTER changed from α-form to β-modification. These had been identified by X-ray diffraction, VIS-absorption spectra and SEM picture.
4 From the volt-Ampere curve obtained from sandwich cell, when E≤2.2×10~(-1) V·cm~(-1), the room temperature electrical conductivity of BTER and BTER-I_3 were found to be 2.22×10~(-10) s·cm~(-1) and 2.6×10~(-7) S·cm~(-1), respectively.
1992, 8(04): 545-549
doi: 10.3866/PKU.WHXB19920424
Abstract:
The crystal structures of 1,2-dimethyl-3-indolylmethylidene succinic fulgide anhydride (1) and 1,2-dimethyl-3-indolylethylidene succinic fulgide anhydride(2) were determined by singe crystal X-ray diffraction analysis. The crystal data are C_(18)H_(17)NO_3(1), ortho nal space group Pbca, with a=1.0084(3) nm, b=1.3966(4) nm, c=2.0945(6) nm, V=2.9498(15) nm, Z=8; C_(19)H_(19)NO_3 (2), ortho nal space group Pbca, with a=0.7988(3) nm, b=2.5782(10) nm, c=1.5664(5) nm, V=3.2259(22) nm, Z=8. R values are 0. 047 for (1) and 0.059 for (2) respectively.
The photochemical properties of (1) and (2) were reported. Compound (1) is nonphotochromic, compound (2) changed from pale yellow to blue or green on irradiation at 365 nm or on exposure to indoor UV light either in crystal state or in solution (liquid or rigid plastic matrix).
The differences in photochromic properties of compound (1) and (2) were discussed.
The crystal structures of 1,2-dimethyl-3-indolylmethylidene succinic fulgide anhydride (1) and 1,2-dimethyl-3-indolylethylidene succinic fulgide anhydride(2) were determined by singe crystal X-ray diffraction analysis. The crystal data are C_(18)H_(17)NO_3(1), ortho nal space group Pbca, with a=1.0084(3) nm, b=1.3966(4) nm, c=2.0945(6) nm, V=2.9498(15) nm, Z=8; C_(19)H_(19)NO_3 (2), ortho nal space group Pbca, with a=0.7988(3) nm, b=2.5782(10) nm, c=1.5664(5) nm, V=3.2259(22) nm, Z=8. R values are 0. 047 for (1) and 0.059 for (2) respectively.
The photochemical properties of (1) and (2) were reported. Compound (1) is nonphotochromic, compound (2) changed from pale yellow to blue or green on irradiation at 365 nm or on exposure to indoor UV light either in crystal state or in solution (liquid or rigid plastic matrix).
The differences in photochromic properties of compound (1) and (2) were discussed.
1992, 8(04): 550-554
doi: 10.3866/PKU.WHXB19920425
Abstract:
In the research on metallic glass, there are arguments against the "rigid band charge transfer", model which assumes a charge transfer from metalloid atoms to transition metal atoms to explain the experimental evidence of linear reduction of average atomic magnetic moment with the increasing concentration of metalloid atoms, but they could not explain the experimental relation of the reduction. In the present work, spin-polarized SCC-DV-X_a calculation for atomic clusters for metallic glass Co-B has been empoloyed to investigate the local electronic structure and magnetic property of the metallic glass. As opposed to the "rigid band charge transfer" model, calculation in the present work indicates that charge transfers from Co4s to both B and Co3d. It is found that there is Co3d4s-B2p hybird bonding in Co-B, which leads to the linear reduction of average atomic magnetic moment. Thus the explanation removes the above controversy.
In the research on metallic glass, there are arguments against the "rigid band charge transfer", model which assumes a charge transfer from metalloid atoms to transition metal atoms to explain the experimental evidence of linear reduction of average atomic magnetic moment with the increasing concentration of metalloid atoms, but they could not explain the experimental relation of the reduction. In the present work, spin-polarized SCC-DV-X_a calculation for atomic clusters for metallic glass Co-B has been empoloyed to investigate the local electronic structure and magnetic property of the metallic glass. As opposed to the "rigid band charge transfer" model, calculation in the present work indicates that charge transfers from Co4s to both B and Co3d. It is found that there is Co3d4s-B2p hybird bonding in Co-B, which leads to the linear reduction of average atomic magnetic moment. Thus the explanation removes the above controversy.
1992, 8(04): 555-557
doi: 10.3866/PKU.WHXB19920426
Abstract:
The electrochemical intercalation reaction of lithium cell was investigated by photoelectrochemical technique. The experimental results show that the lithium ions inserting into the orystal lattice of the cathode, act as a donor impurities and change the semiconductor properties of the cathode matrix. From the change of photovoltage of the cathode during the discharging process of the lithium cell, the intercalation process of lithium ions could be studied in-situ.
The electrochemical intercalation reaction of lithium cell was investigated by photoelectrochemical technique. The experimental results show that the lithium ions inserting into the orystal lattice of the cathode, act as a donor impurities and change the semiconductor properties of the cathode matrix. From the change of photovoltage of the cathode during the discharging process of the lithium cell, the intercalation process of lithium ions could be studied in-situ.
1992, 8(04): 558-562
doi: 10.3866/PKU.WHXB19920427
Abstract:
The p—C—T curves of three kinds of hydrogen-storage alloys were examined by solid-gas phase hydrogen absorbing-desorbing and electrochemical method, the thermodynamic characteristics of each alloy were calculated by Van't Hoff equation. There is small difference between the results of the two methods at low temperatures but at high temperatures the difference is relatively large.
The p—C—T curves of three kinds of hydrogen-storage alloys were examined by solid-gas phase hydrogen absorbing-desorbing and electrochemical method, the thermodynamic characteristics of each alloy were calculated by Van't Hoff equation. There is small difference between the results of the two methods at low temperatures but at high temperatures the difference is relatively large.
1992, 8(04): 563-566
doi: 10.3866/PKU.WHXB19920428
Abstract:
Specific surface area of solid is an important physico-chemical parameter. This kind of information is frequently required in describing the interactions between liquid and solid or gas and solid. In this paper, two equations which can be used to calculate the surface area of solid powder directly from the adsorptions enthalpy of liquid on solid are derived from the liquid solid surface state equations. Surface areas of eight metallic oxides have been calculated from the adsorption enthalpies measured by means of LKB-2107 Microadsorption Flow Calorimeter. For comparision, these surface areas have also been measured by using traditonal BET (N_2 adsorption) method. The results obtained by using these two methods agree quite well.
Specific surface area of solid is an important physico-chemical parameter. This kind of information is frequently required in describing the interactions between liquid and solid or gas and solid. In this paper, two equations which can be used to calculate the surface area of solid powder directly from the adsorptions enthalpy of liquid on solid are derived from the liquid solid surface state equations. Surface areas of eight metallic oxides have been calculated from the adsorption enthalpies measured by means of LKB-2107 Microadsorption Flow Calorimeter. For comparision, these surface areas have also been measured by using traditonal BET (N_2 adsorption) method. The results obtained by using these two methods agree quite well.
1992, 8(04): 567-570
doi: 10.3866/PKU.WHXB19920429
Abstract:
α-layered zirconium phosphate was obtained by direct precipitation method. Composites formed by α-zirconium phosphate and fumed silica were prepared by dispersing predetermined molar ratios of polycrystalline α-zirconium phosphate and fumed silica in water. Admittance measurement of the samples was made in a sealed cell connected to a Hewlett Packard 4192A impedance analyzer in the frequency range from 5 Hz to 1 MHz. All of the samples with varing molar ratios of α-zirconium phosphate to silica at 60%, 40% relative humiditites have the same approximate Arrhenius activation energies, around 48 kJ·mol~(-1), that means the charge transport mechanism was maintained after mixing fumed silica into α-layered zirconium phosphate.
α-layered zirconium phosphate was obtained by direct precipitation method. Composites formed by α-zirconium phosphate and fumed silica were prepared by dispersing predetermined molar ratios of polycrystalline α-zirconium phosphate and fumed silica in water. Admittance measurement of the samples was made in a sealed cell connected to a Hewlett Packard 4192A impedance analyzer in the frequency range from 5 Hz to 1 MHz. All of the samples with varing molar ratios of α-zirconium phosphate to silica at 60%, 40% relative humiditites have the same approximate Arrhenius activation energies, around 48 kJ·mol~(-1), that means the charge transport mechanism was maintained after mixing fumed silica into α-layered zirconium phosphate.
1992, 8(04): 571-574
doi: 10.3866/PKU.WHXB19920430
Abstract:
Electrodeposition process of metallic Cr from chromic acid solution was investigated with techniques of AC impedance, polarization curve, AES and XPS. The Nyquist plots and polarization curves of Fe electrode in the chromic acid solution containing sulfuric acid at potentials at which Cr can be deposited all show phenomena characterizing the formation of a surface film. AES and XPS tests also prove the existance of a surface film and reveal the composition of the film being composed of oxide and hydroxide of trivalent chromium, chromate and a small amount of sulfate. It is suggested that the surface film is essential for the depositon of Cr and that sulfuric acid plays a key role in the formation of the surface film. It is likely that sulfuric acid catalyses the reduction of Cr_2O_7~(2-) to Cr~(3+), causing the Cr~(3+) concentration and pH value of solution in the vicinity of the cathode surface to increase and leading to the formation of a film on the cathode surface. This film changes the state and nature of the cathode surface, forces the potential of the cathode to shift to more negative values, and ultimately promotes the reduction reaction of chromate ions to metallic chromium.
Electrodeposition process of metallic Cr from chromic acid solution was investigated with techniques of AC impedance, polarization curve, AES and XPS. The Nyquist plots and polarization curves of Fe electrode in the chromic acid solution containing sulfuric acid at potentials at which Cr can be deposited all show phenomena characterizing the formation of a surface film. AES and XPS tests also prove the existance of a surface film and reveal the composition of the film being composed of oxide and hydroxide of trivalent chromium, chromate and a small amount of sulfate. It is suggested that the surface film is essential for the depositon of Cr and that sulfuric acid plays a key role in the formation of the surface film. It is likely that sulfuric acid catalyses the reduction of Cr_2O_7~(2-) to Cr~(3+), causing the Cr~(3+) concentration and pH value of solution in the vicinity of the cathode surface to increase and leading to the formation of a film on the cathode surface. This film changes the state and nature of the cathode surface, forces the potential of the cathode to shift to more negative values, and ultimately promotes the reduction reaction of chromate ions to metallic chromium.
1992, 8(04): 575-576
doi: 10.3866/PKU.WHXB1992431
Abstract:
