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1990 Volume 6 Issue 5
1990, 6(05): 513-516
doi: 10.3866/PKU.WHXB19900501
Abstract:
1990, 6(05): 517-518
doi: 10.3866/PKU.WHXB19900502
Abstract:
It was proposed that all carbon clusters with n>30 have geometrically closed cage structures. The mass spectrum of C_(92-151)~+ was observed on a self-built laser probe time-of-flight mass spectrometer. The spectrum showed that for cluster size less or equal to 126, only even-number cluster exists, which is consistant with a closed structure. The system was broken for cluster larger than 126. This observation indicates that the structural configuration changes with increase of the cluster size.
It was proposed that all carbon clusters with n>30 have geometrically closed cage structures. The mass spectrum of C_(92-151)~+ was observed on a self-built laser probe time-of-flight mass spectrometer. The spectrum showed that for cluster size less or equal to 126, only even-number cluster exists, which is consistant with a closed structure. The system was broken for cluster larger than 126. This observation indicates that the structural configuration changes with increase of the cluster size.
1990, 6(05): 519-522
doi: 10.3866/PKU.WHXB19900503
Abstract:
The effects of high valence cations M~(n+) (n≥4) doped on the phase formation and the structure stability have been investigated. In the crystal structure X_2Sr_2Ca_2Cu_3O_(10)(X = Bi_(1-x-y)Pb_xM_y), the high valence cations M~(n+), Bi~(3+), and Pb~(2+) were deter-mined to statistically distribute at the bismuth positions. The bismuth valence is raised and the positions of oxygen atoms in the (XO_2X) double layers are fully occupied. Conseqently, The structural stability is increased. The phase 2223 was found to form more rapidly by doping and the single phase with T_c(0)>110 K can be obtained more easily.
The effects of high valence cations M~(n+) (n≥4) doped on the phase formation and the structure stability have been investigated. In the crystal structure X_2Sr_2Ca_2Cu_3O_(10)(X = Bi_(1-x-y)Pb_xM_y), the high valence cations M~(n+), Bi~(3+), and Pb~(2+) were deter-mined to statistically distribute at the bismuth positions. The bismuth valence is raised and the positions of oxygen atoms in the (XO_2X) double layers are fully occupied. Conseqently, The structural stability is increased. The phase 2223 was found to form more rapidly by doping and the single phase with T_c(0)>110 K can be obtained more easily.
1990, 6(05): 523-527
doi: 10.3866/PKU.WHXB19900504
Abstract:
The electrochemical reduction of 3-nitro-benzoic acid (3-NBA) has been investi-gated on Pt electrode in DMSO media by cyclic voltammetry and controlled potential electrolysis, in combination with ESR spectroscopy. The results show that 3-nitro-ben-zoic acid is reduced through a three-electron process to a of species of nitroso group. Hyperfine structures of ESR spectrum of the free radical were observed. The ESR parameters of the simulation have been determined as a_1~N = 10.91G, a_2~H=1.12G, a_4~H=a_6~H=3.38G, a_5~H=3.96G. The rate constant of the decay of free radical was evaluated as k=k=4.814×10~(-2)s~(-1).
The electrochemical reduction of 3-nitro-benzoic acid (3-NBA) has been investi-gated on Pt electrode in DMSO media by cyclic voltammetry and controlled potential electrolysis, in combination with ESR spectroscopy. The results show that 3-nitro-ben-zoic acid is reduced through a three-electron process to a of species of nitroso group. Hyperfine structures of ESR spectrum of the free radical were observed. The ESR parameters of the simulation have been determined as a_1~N = 10.91G, a_2~H=1.12G, a_4~H=a_6~H=3.38G, a_5~H=3.96G. The rate constant of the decay of free radical was evaluated as k=k=4.814×10~(-2)s~(-1).
1990, 6(05): 528-533
doi: 10.3866/PKU.WHXB19900505
Abstract:
The dielectric isotherms and the dielectric absorption curves of M , CaO, Ca(OH)_2 and TiO_2 have been measured at frequency from 400 Hz to 5 MHz in the present of water vapour (p/p_0= 0 to 0.75). Based on the Maxwell-Wagner-Sillars' theory, the general relation between adsorption and dielectric constant of these systems has been discussed. The differences in dielectric properties were observed for these solid oxides mentioned above. In addition, X-ray analysis showed that after adsorption of water vapour, the calcium oxide changed into crystallite calcium hydroxide. However, the dielectric properties of this sort of calcium hydroxide are different from general Ca(OH)_2/H_2O system. The results were explained preliminarily. It is concluded that from the studies of dielectric properties the useful informations about surface state of adsorbents and interactions between adsorbent and adsorbate can be obtained.
The dielectric isotherms and the dielectric absorption curves of M , CaO, Ca(OH)_2 and TiO_2 have been measured at frequency from 400 Hz to 5 MHz in the present of water vapour (p/p_0= 0 to 0.75). Based on the Maxwell-Wagner-Sillars' theory, the general relation between adsorption and dielectric constant of these systems has been discussed. The differences in dielectric properties were observed for these solid oxides mentioned above. In addition, X-ray analysis showed that after adsorption of water vapour, the calcium oxide changed into crystallite calcium hydroxide. However, the dielectric properties of this sort of calcium hydroxide are different from general Ca(OH)_2/H_2O system. The results were explained preliminarily. It is concluded that from the studies of dielectric properties the useful informations about surface state of adsorbents and interactions between adsorbent and adsorbate can be obtained.
1990, 6(05): 534-540
doi: 10.3866/PKU.WHXB19900506
Abstract:
The energy transfer processes between ~(12)CO(A~1Π) and ~(13)CO(X ~1Σ~+) were studied at 77 K by using the technique of two-color resonance enhanced multiphoton ionization spectroscopy. In a static cell with a mixture of 0.92 ~(13)CO + 0.08 ~(12)CO, ~(12)CO molecules were populated to the A state by 2-photon excitation using an UV dye laser. The ~(13)CO(A) resulted from the collision E-E energy transfer were detected by CO(A)→CO(B)→CO~+(X) 2-step ionization using a visible dye laser. The energy transfer processes were found to be very fast with total cross sections of 1.14±0.42, 0.22±0.04, 0.17±0.06 nm for ~(12)CO(A)V=1,2,3 respectively. We found that for different vibrational channels, cross section decreases with increasing energy mismatch ΔE. Another interesting result is that, for the ∧ doublet, the production of П~+ is always larger than that of П~-. The formation of an intermediate exciplex [OCCO]* is proposed to explain the experimental results.
1990, 6(05): 541-548
doi: 10.3866/PKU.WHXB19900507
Abstract:
In this paper, FT-IR and Raman spectra of Lanthanide-Dibenzoylmethanate chelate compounds were reported. A normal coordinate treatment was made by using a single chelate ring model. The calulated frequencies were in od agreement with the observed ones. The force constants obtained from the calculation have a od transferable property. Some important bands were discussed in detail.
In this paper, FT-IR and Raman spectra of Lanthanide-Dibenzoylmethanate chelate compounds were reported. A normal coordinate treatment was made by using a single chelate ring model. The calulated frequencies were in od agreement with the observed ones. The force constants obtained from the calculation have a od transferable property. Some important bands were discussed in detail.
1990, 6(05): 549-555
doi: 10.3866/PKU.WHXB19900508
Abstract:
In this paper, the Pitzer equation (1973) and Pitzer-Li equation (1983) are used to correlate the activity coefficient data of di (2-ethyl-hexyl) phosphoric acid (D_2EHPA) in aqueous alkali chlorides (LiCl, NaCl, KCl, RbCl, CsCl and NH_4 Cl), which were determined by P~(32) radioisotope tracer technique. The calculated results show that the Pitzer-Li equation is better than the Pitzer equation, since the ion-solvent short range interaction energy and the ion-ion long range interaction energy are considered in the Pitzer-Li equation. The parameters thus regressed can reflect the sequence of the salting effect for alkali cation series and can explain the salting-out phenomenon for D_2EHPA. It also shows that the ion-water interaction energies are much greater than the ion-D_2EHPA interaction energies in th D_2EHPA-MCl-HCl-H_2O systems.
In this paper, the Pitzer equation (1973) and Pitzer-Li equation (1983) are used to correlate the activity coefficient data of di (2-ethyl-hexyl) phosphoric acid (D_2EHPA) in aqueous alkali chlorides (LiCl, NaCl, KCl, RbCl, CsCl and NH_4 Cl), which were determined by P~(32) radioisotope tracer technique. The calculated results show that the Pitzer-Li equation is better than the Pitzer equation, since the ion-solvent short range interaction energy and the ion-ion long range interaction energy are considered in the Pitzer-Li equation. The parameters thus regressed can reflect the sequence of the salting effect for alkali cation series and can explain the salting-out phenomenon for D_2EHPA. It also shows that the ion-water interaction energies are much greater than the ion-D_2EHPA interaction energies in th D_2EHPA-MCl-HCl-H_2O systems.
1990, 6(05): 556-561
doi: 10.3866/PKU.WHXB19900509
Abstract:
A new nickel (II) complex with bis-schiff bases from picolinaldehyde N-oxide and 1,2-propanediamine, [Ni (piopn) (H_2O)_2] (ClO_4)_2 has been synthesised and its crystal structure has been determined. The crystal belongs to monoclinic system, space group C_c, with cell dimensions: a=0.7397(3) nm, b=1.3187(7) nm, c=2.5502(14) nm, β=102.18(4)°, V=224.10 nm, D_c=1.71 g·cm~(-3), F(000)=1135.8, μ=11.65 cm~(-1). According to the semiempirical MO theory calculation, the relationships between IR frequency shifts of ν_(C=N) and ν_(N-O) bands and their characteristics of chemical bonds have been discussed.
A new nickel (II) complex with bis-schiff bases from picolinaldehyde N-oxide and 1,2-propanediamine, [Ni (piopn) (H_2O)_2] (ClO_4)_2 has been synthesised and its crystal structure has been determined. The crystal belongs to monoclinic system, space group C_c, with cell dimensions: a=0.7397(3) nm, b=1.3187(7) nm, c=2.5502(14) nm, β=102.18(4)°, V=224.10 nm, D_c=1.71 g·cm~(-3), F(000)=1135.8, μ=11.65 cm~(-1). According to the semiempirical MO theory calculation, the relationships between IR frequency shifts of ν_(C=N) and ν_(N-O) bands and their characteristics of chemical bonds have been discussed.
1990, 6(05): 562-567
doi: 10.3866/PKU.WHXB19900510
Abstract:
In this paper, the structure of the anti-lipolytic 14 peptides of Ginseng was studied. Based on the primary structure, the secondary structure was predicted to be mainly a helicity segment which linked a short coil region. We computed the relative conformational energy and the atomic coordinate of Ginseug polypeptide, simulated the optimizing process of conformational energy, obtained the possible energy-minimized conformation by means of molecular mechanics combined with the information from crystallographic database. We also built the corresponding three-dimension model of the Ginseng polypeptide. We also built the corresponding three-dimension model of the Ginseng polypeptide. The stereo structure of the model indicated that the result of the conformation analysis corresponded to the conclusion of the secondary structure prediction.
Ginseng is a renowned and precious medico-botanical which contains many ...
In this paper, the structure of the anti-lipolytic 14 peptides of Ginseng was studied. Based on the primary structure, the secondary structure was predicted to be mainly a helicity segment which linked a short coil region. We computed the relative conformational energy and the atomic coordinate of Ginseug polypeptide, simulated the optimizing process of conformational energy, obtained the possible energy-minimized conformation by means of molecular mechanics combined with the information from crystallographic database. We also built the corresponding three-dimension model of the Ginseng polypeptide. We also built the corresponding three-dimension model of the Ginseng polypeptide. The stereo structure of the model indicated that the result of the conformation analysis corresponded to the conclusion of the secondary structure prediction.
Ginseng is a renowned and precious medico-botanical which contains many ...
1990, 6(05): 568-574
doi: 10.3866/PKU.WHXB19900511
Abstract:
A model of dipole orientation distribution for solvate layer at electrode/solution interface was suggested, and based on this model a generalized monolayer adsorption isotherm was derived by using the method of statistical mechanics and assuming the equilibrium condition of thermodynamics. The solvent of the electrolyte studied may be single component or multic-components (mixture). The dependence of inner-layer differential capacity upon snrface charge density at mercury electrode in formamide, methanol and ethylene carbonate solutions was estimated by curve-fitting respectively. The present model is more suitable for aqueous and mixed-solvent systems will be expected.
A model of dipole orientation distribution for solvate layer at electrode/solution interface was suggested, and based on this model a generalized monolayer adsorption isotherm was derived by using the method of statistical mechanics and assuming the equilibrium condition of thermodynamics. The solvent of the electrolyte studied may be single component or multic-components (mixture). The dependence of inner-layer differential capacity upon snrface charge density at mercury electrode in formamide, methanol and ethylene carbonate solutions was estimated by curve-fitting respectively. The present model is more suitable for aqueous and mixed-solvent systems will be expected.
1990, 6(05): 575-579
doi: 10.3866/PKU.WHXB19900512
Abstract:
Based on the model presented in part I of this work, the inner capacity depen-dence on surface charge was estimated for Hg/aqueous solution interface at five different temperatures.The results show that the treatment used in our previous paper is suitable to aqueous systems. However, at the vicinity of freezing point (273 K) for aqueous solutions, the formation of ice-like structure due to the adsorbed water molecules associated with H-bond at the inner-layer may be occured, and local-order array will tend to random distribution as soon as the temperature being higher.
Based on the model presented in part I of this work, the inner capacity depen-dence on surface charge was estimated for Hg/aqueous solution interface at five different temperatures.The results show that the treatment used in our previous paper is suitable to aqueous systems. However, at the vicinity of freezing point (273 K) for aqueous solutions, the formation of ice-like structure due to the adsorbed water molecules associated with H-bond at the inner-layer may be occured, and local-order array will tend to random distribution as soon as the temperature being higher.
1990, 6(05): 580-588
doi: 10.3866/PKU.WHXB19900513
Abstract:
Based on Double Sphere Coordination Point Charge Field (DSCPCF) model, the coordination field perturbation energy levels of Eu~(3+) and Tb~(3+) ions doped in LnOX matrixes (Ln~(3+)= La~(3+), Gd~(3+), Y~(3+); X~- = Cl~-, Br~-, I~-) were calculated and the corresponding spectra at liquid nitrogen and liquid helium temperature were assigned. The result shows that 1) the DSCPCF perturbation energy levels agree well with the spectra observed, 2) the coordination field parameters B_m~k show an increasing trend with the increasing of the ionic radius and the electronegativity of both Ln~(3+) and X~- host ions, 3) the Nephelauxetic effect on RE ions and the orbital overlap between RE ion and its ligands are partly revealed by their characteristic parameters－－the effective nuclear charge Z_j~* and the bond charge q_j in DSCPCF model, and 4) by comparison with Point Charge Field (PCF) model, B_m~2 in DSCPCF model decrease slightly, while B_m~4 especially B_m~6 increase greatly. This correction may overcome the shortcoming of PCF model in certain degree.
Based on Double Sphere Coordination Point Charge Field (DSCPCF) model, the coordination field perturbation energy levels of Eu~(3+) and Tb~(3+) ions doped in LnOX matrixes (Ln~(3+)= La~(3+), Gd~(3+), Y~(3+); X~- = Cl~-, Br~-, I~-) were calculated and the corresponding spectra at liquid nitrogen and liquid helium temperature were assigned. The result shows that 1) the DSCPCF perturbation energy levels agree well with the spectra observed, 2) the coordination field parameters B_m~k show an increasing trend with the increasing of the ionic radius and the electronegativity of both Ln~(3+) and X~- host ions, 3) the Nephelauxetic effect on RE ions and the orbital overlap between RE ion and its ligands are partly revealed by their characteristic parameters－－the effective nuclear charge Z_j~* and the bond charge q_j in DSCPCF model, and 4) by comparison with Point Charge Field (PCF) model, B_m~2 in DSCPCF model decrease slightly, while B_m~4 especially B_m~6 increase greatly. This correction may overcome the shortcoming of PCF model in certain degree.
1990, 6(05): 589-593
doi: 10.3866/PKU.WHXB19900514
Abstract:
Based on the study of DC-conductivity of KAP gingle crystal along three axial directions, the conductivity mechnism have been studied by Positron Annihilation Technique (PAT) and related to the crystal structure. The temperature range investigated in this paper is with in the usable temperature range of this crystal.
Based on the study of DC-conductivity of KAP gingle crystal along three axial directions, the conductivity mechnism have been studied by Positron Annihilation Technique (PAT) and related to the crystal structure. The temperature range investigated in this paper is with in the usable temperature range of this crystal.
1990, 6(05): 594-600
doi: 10.3866/PKU.WHXB19900515
Abstract:
The kinetics of the reaction of MovO(TPP)Cl and DMSO has been studied with a stopped-flow spectrophotometer. The results show that the reaction is a complicate one which includes at least four elementary steps. The relaxation time (τ) varies linearly with the initial concentrations of DMSO. A reaction mechanism was suggested which can explain the experimental results satisfactorily.
The kinetics of the reaction of MovO(TPP)Cl and DMSO has been studied with a stopped-flow spectrophotometer. The results show that the reaction is a complicate one which includes at least four elementary steps. The relaxation time (τ) varies linearly with the initial concentrations of DMSO. A reaction mechanism was suggested which can explain the experimental results satisfactorily.
1990, 6(05): 601-604
doi: 10.3866/PKU.WHXB19900516
Abstract:
The transient processes of pyrene (Py) have been studied by measuring fluores-cence lifetime and nanosecond time-resolved transient absorption spectra in n-hexane, cyclohexane, acetone, and acetonitrile. The single exponential decay for pyrene-hexane and pyrene-oyclohexane systems were observed, yet the double exponential decay were shown for the pyrene-acetone and pyrene-acetonitrile systems (Table 1 of the Chinese text). In the transient absorption spectra, the absorbance of excited triplet pyrene was observed for the pyrene-acetonitrile system (Fig.2 of the Chinese text). This result clearly demonstrate that there are interaction between pyrene and acetonitrile and pyrene cation radical is formed by electron transfer from the excited singlet state of pyrene to acetonitrile. According to experimental results, the photophysical mechanism for the four systems was suggested.
The transient processes of pyrene (Py) have been studied by measuring fluores-cence lifetime and nanosecond time-resolved transient absorption spectra in n-hexane, cyclohexane, acetone, and acetonitrile. The single exponential decay for pyrene-hexane and pyrene-oyclohexane systems were observed, yet the double exponential decay were shown for the pyrene-acetone and pyrene-acetonitrile systems (Table 1 of the Chinese text). In the transient absorption spectra, the absorbance of excited triplet pyrene was observed for the pyrene-acetonitrile system (Fig.2 of the Chinese text). This result clearly demonstrate that there are interaction between pyrene and acetonitrile and pyrene cation radical is formed by electron transfer from the excited singlet state of pyrene to acetonitrile. According to experimental results, the photophysical mechanism for the four systems was suggested.
1990, 6(05): 605-608
doi: 10.3866/PKU.WHXB19900517
Abstract:
The velocity autocorrelation function and the spectral density of LiCL melt and LiCL glass have been calculated based on the phase orbit obtained from molecular dynamics simulation. The results showed that the spectral densities of both melt and glass can be described as a linear combination of those damped oscillation and Brownian motion. So the movement of ions in LiCL system can be regarded roughly as the superposition of the damped oscillatory motion and Brownian movement. The coulombian force existed in LiCL system made the oscillatory motion more stronger than that in other liquide. It is found through the calculation, the higher the temperature the intenser the Brownian motion and the lower the ω value of the peak of Ψ(ω).
The velocity autocorrelation function and the spectral density of LiCL melt and LiCL glass have been calculated based on the phase orbit obtained from molecular dynamics simulation. The results showed that the spectral densities of both melt and glass can be described as a linear combination of those damped oscillation and Brownian motion. So the movement of ions in LiCL system can be regarded roughly as the superposition of the damped oscillatory motion and Brownian movement. The coulombian force existed in LiCL system made the oscillatory motion more stronger than that in other liquide. It is found through the calculation, the higher the temperature the intenser the Brownian motion and the lower the ω value of the peak of Ψ(ω).
1990, 6(05): 609-612
doi: 10.3866/PKU.WHXB19900518
Abstract:
A new oscillating system of glucose(Glu)-BrO_3~--acetone(Act)-H_2SO_4-Mn~(2+) has been reported. In this homogeneous Belousov-Zhabotinsky (B-Z) type oscillation, saccharide was used as a organic substrate. The roles of glucose and acetone in this oscillation have been investigated. According to the reaction products and the effects of many factors on the oscillation, a mechanism for this oscillation has been proposed in which both Br_2 and Br~- are the contolling factors.
A new oscillating system of glucose(Glu)-BrO_3~--acetone(Act)-H_2SO_4-Mn~(2+) has been reported. In this homogeneous Belousov-Zhabotinsky (B-Z) type oscillation, saccharide was used as a organic substrate. The roles of glucose and acetone in this oscillation have been investigated. According to the reaction products and the effects of many factors on the oscillation, a mechanism for this oscillation has been proposed in which both Br_2 and Br~- are the contolling factors.
1990, 6(05): 613-617
doi: 10.3866/PKU.WHXB19900519
Abstract:
The changes in potentials and pH values of the solution gave rise to variations of colour and electronic absorption spectra of poly-o-methylaniline film. However, its colour did not change with potential and polymer lost its electrochemical activities in the solution of pH 4.13. The g-value was 2.0027 and was not affected by the kinds of doped anions and hydrolysis. The ΔH_(p-p) was 1.6G. It did not depend onthe kinds of doped anions, but was affected by hydrolysis. The magnetic suscepti-billity of poly-o-methylaniline was not measurable at 0.8 to 4 kG magnetic field.
The changes in potentials and pH values of the solution gave rise to variations of colour and electronic absorption spectra of poly-o-methylaniline film. However, its colour did not change with potential and polymer lost its electrochemical activities in the solution of pH 4.13. The g-value was 2.0027 and was not affected by the kinds of doped anions and hydrolysis. The ΔH_(p-p) was 1.6G. It did not depend onthe kinds of doped anions, but was affected by hydrolysis. The magnetic suscepti-billity of poly-o-methylaniline was not measurable at 0.8 to 4 kG magnetic field.
1990, 6(05): 618-621
doi: 10.3866/PKU.WHXB19900520
Abstract:
UV spectra, IR spectra, Electronic oxidation-reduction properties and XPS spectrum of the tetramolybdenum cluster Mo_4O_4Cl_2(μ_3-O) (o-CH_3C_6H_4COO)_6 has been studied, and the electronic structure of the cluster has been interpreted with semiempirical quantum chemical calculation based on EHMO.
UV spectra, IR spectra, Electronic oxidation-reduction properties and XPS spectrum of the tetramolybdenum cluster Mo_4O_4Cl_2(μ_3-O) (o-CH_3C_6H_4COO)_6 has been studied, and the electronic structure of the cluster has been interpreted with semiempirical quantum chemical calculation based on EHMO.
1990, 6(05): 622-628
doi: 10.3866/PKU.WHXB19900521
Abstract:
A gas-diffusion electrode of WC was made by active WC powder, PTFE with some additives. The influences of the electro-catalytic activity of Tungsten Carbide (WC) powder and the preparation of the electrode on its activity have been investigated. The results show that the activity of the waterproof gas-diffusion electrode of WC is directly related to the composition, the specific surface area of WC powder, the loading capacity of WC powder and PTFE content in the electrode. At η=250 mV, the appa-rent activation energies (kJ·mol~(-1).) of hydrogen ionisation reaction (HIR) for the electrode are 23.3 in 3.5 mol·L~(-1) HCl, 14.5 in 2.0 mol·L~(-1) H_2SO_4 and 13.7 in 85% H_3PO_4 respectively. When the electrode is polarized to 250 mV (vs. DHE) in 2.0 mol·L~(-1) H_2SO_4 at 60 ℃, the current dentity of HIR is 3020 mA·g~(-1) and the electrode has the highest activity.
A gas-diffusion electrode of WC was made by active WC powder, PTFE with some additives. The influences of the electro-catalytic activity of Tungsten Carbide (WC) powder and the preparation of the electrode on its activity have been investigated. The results show that the activity of the waterproof gas-diffusion electrode of WC is directly related to the composition, the specific surface area of WC powder, the loading capacity of WC powder and PTFE content in the electrode. At η=250 mV, the appa-rent activation energies (kJ·mol~(-1).) of hydrogen ionisation reaction (HIR) for the electrode are 23.3 in 3.5 mol·L~(-1) HCl, 14.5 in 2.0 mol·L~(-1) H_2SO_4 and 13.7 in 85% H_3PO_4 respectively. When the electrode is polarized to 250 mV (vs. DHE) in 2.0 mol·L~(-1) H_2SO_4 at 60 ℃, the current dentity of HIR is 3020 mA·g~(-1) and the electrode has the highest activity.
1990, 6(05): 629-632
doi: 10.3866/PKU.WHXB19900522
Abstract:
Several calcium orthophosphates (tricalcium phosphate, monocalcium dihydropho-sphate, dicalcium hydrophosphate, and hydroxyapatite) are characterized by XPS and IR method. The P2p electron binding energies follow the order Ca(H_2PO_4)_2>CaHPO_4>Ca_(10)(OH)_2(PO_4)_6>Ca_3(PO_4)_2. It is expounded that there is hydrogen bonding of (OH...OPO_3) between the OH~- ion and the neighbour oxygen of the phosphate in hydroxyapatite.
Several calcium orthophosphates (tricalcium phosphate, monocalcium dihydropho-sphate, dicalcium hydrophosphate, and hydroxyapatite) are characterized by XPS and IR method. The P2p electron binding energies follow the order Ca(H_2PO_4)_2>CaHPO_4>Ca_(10)(OH)_2(PO_4)_6>Ca_3(PO_4)_2. It is expounded that there is hydrogen bonding of (OH...OPO_3) between the OH~- ion and the neighbour oxygen of the phosphate in hydroxyapatite.
1990, 6(05): 633-637
doi: 10.3866/PKU.WHXB19900523
Abstract:
The activity coefficients and osmotic coefficients of Na_2WO_4 aqueous solution in the concentration range of 0.3--2.5 mol·kg~(-1) have been determined by the isopiestic method. The excess Gibbs free energies are evaluated with the correspording activity coefficientc and osmotic coefficients.
The activity coefficients and osmotic coefficients of Na_2WO_4 aqueous solution in the concentration range of 0.3--2.5 mol·kg~(-1) have been determined by the isopiestic method. The excess Gibbs free energies are evaluated with the correspording activity coefficientc and osmotic coefficients.
1990, 6(05): 638-640
doi: 10.3866/PKU.WHXB19900524
Abstract:
The transient ring currents of the RRDE n-InP semiconductor disk- ld ring irradiated with a light step from dark to 25 mW·cm~(-2) with the seven different rota-tion speeds between 590 and 7000 r. p. m. in 0.101 mol·L~(-1) K_4 Fe(CN)_6 have been studied Experimental data were fitted by the computer. The diffusion coefficient of [Fe(CN)_6]~(3-) ion found is D=3.3×10~(-6) em~2·s~(-1) and the theoratical collection efficiency calculated for thin-gap and thin-ring RRDE is N=0.20 these are in od agreement with the literature. The experimental value of ωτ_0 agree with the theoratical value.
The agreement between the experiment and the theory suggests that the electrode reaction on n-InP is a simple photoelectro-chemical reaction, i.e.
[Fe(CN)_6]~(4-)+h~+→[Fe(CO)_6]~(3-).
The transient ring currents of the RRDE n-InP semiconductor disk- ld ring irradiated with a light step from dark to 25 mW·cm~(-2) with the seven different rota-tion speeds between 590 and 7000 r. p. m. in 0.101 mol·L~(-1) K_4 Fe(CN)_6 have been studied Experimental data were fitted by the computer. The diffusion coefficient of [Fe(CN)_6]~(3-) ion found is D=3.3×10~(-6) em~2·s~(-1) and the theoratical collection efficiency calculated for thin-gap and thin-ring RRDE is N=0.20 these are in od agreement with the literature. The experimental value of ωτ_0 agree with the theoratical value.
The agreement between the experiment and the theory suggests that the electrode reaction on n-InP is a simple photoelectro-chemical reaction, i.e.
[Fe(CN)_6]~(4-)+h~+→[Fe(CO)_6]~(3-).
