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1989 Volume 5 Issue 1
Resonance Enhance Multiphoton Ionization Spectra of OCS Molecule in the 277-285 nm Wavelength Region
1989, 5(01): 1-2
doi: 10.3866/PKU.WHXB19890101
Abstract:
The first observation of the REMPI spectra of OCS molecule in the region of 277—285 nm is reported. The laser source is the pulse laser of Nd: YAG pumped tunable dye laser. The total ionization electric charges of OCS gas in the static cell is collected with the parallel electrodes connected to a boxcar averager. The power dependence shows the REMPI is resulted from the two photon resonant, three photon ionization. Comparing with the VUV absorption spectra, the main spectral lines in the REMPI spectra has been assigned preliminarily. The abnormal spectral line at 279.07 nm may be due to the MPI of oxygen atom produced from the photodissociation of OCS molecules.
The first observation of the REMPI spectra of OCS molecule in the region of 277—285 nm is reported. The laser source is the pulse laser of Nd: YAG pumped tunable dye laser. The total ionization electric charges of OCS gas in the static cell is collected with the parallel electrodes connected to a boxcar averager. The power dependence shows the REMPI is resulted from the two photon resonant, three photon ionization. Comparing with the VUV absorption spectra, the main spectral lines in the REMPI spectra has been assigned preliminarily. The abnormal spectral line at 279.07 nm may be due to the MPI of oxygen atom produced from the photodissociation of OCS molecules.
1989, 5(01): 3-6
doi: 10.3866/PKU.WHXB19890102
Abstract:
The scanning tunneling microscope (STM)is a powerful instrument which provide surface topographic images down to the atomic scale and spectroscopic information on the surface density of electronic states. A computerized system based on the IBM Personal Computer Model XT or AT for STM control, data acquisition and display is presented. The high resolution digital-to-analog converter card and analog-to-digital converter card are used for the computer to generate the voltages applied to the STM piezoelectric elements and to measure the tunneling current. A high resolution graphics controller card is used for real-time display of the STM “images”. The software that performs the control, data acquisition and display of the STM has been written in FORTRAN and linded with some ASSEMBLER subroutines for the critical tasks in order to get a fast and compact executable module which works under DOS Version 3.2. Some images anaysis and display tool are included for a posterior image processing.
The scanning tunneling microscope (STM)is a powerful instrument which provide surface topographic images down to the atomic scale and spectroscopic information on the surface density of electronic states. A computerized system based on the IBM Personal Computer Model XT or AT for STM control, data acquisition and display is presented. The high resolution digital-to-analog converter card and analog-to-digital converter card are used for the computer to generate the voltages applied to the STM piezoelectric elements and to measure the tunneling current. A high resolution graphics controller card is used for real-time display of the STM “images”. The software that performs the control, data acquisition and display of the STM has been written in FORTRAN and linded with some ASSEMBLER subroutines for the critical tasks in order to get a fast and compact executable module which works under DOS Version 3.2. Some images anaysis and display tool are included for a posterior image processing.
1989, 5(01): 7-9
doi: 10.3866/PKU.WHXB19890103
Abstract:
Li_(0.025)Na_(0.975)NbO_3 under es a ferroelectric-ferroelectric phase transition at 180K (on cooling) or 260 K (on heating). The structure determinations of both phases have been carried out by single crystal diffraction analysis. The ferroelectric room-temperature phase is orthorhombic, with space group Pc2_1b; the cell parameters are a=0.5508(3), b=1.5521(6), c=0.5568(2) nm. The structure is same with Li_(0.02)Na_(0.98)NbO_3. The ferroelectric low-temperature phase is also orthorhomhie, a=0.5497(7), b=0.7913(18), c=0.5565(10) nm, V=0.2421 nm, Z=4. There is disordernal position distribution of O(2) atomes in the low-temperature phase. Its “apparent space group” is P2/n2/n2/n. The relation of the ferroelectric properties to the low-temperature phase structure is discussed.
Li_(0.025)Na_(0.975)NbO_3 under es a ferroelectric-ferroelectric phase transition at 180K (on cooling) or 260 K (on heating). The structure determinations of both phases have been carried out by single crystal diffraction analysis. The ferroelectric room-temperature phase is orthorhombic, with space group Pc2_1b; the cell parameters are a=0.5508(3), b=1.5521(6), c=0.5568(2) nm. The structure is same with Li_(0.02)Na_(0.98)NbO_3. The ferroelectric low-temperature phase is also orthorhomhie, a=0.5497(7), b=0.7913(18), c=0.5565(10) nm, V=0.2421 nm, Z=4. There is disordernal position distribution of O(2) atomes in the low-temperature phase. Its “apparent space group” is P2/n2/n2/n. The relation of the ferroelectric properties to the low-temperature phase structure is discussed.
1989, 5(01): 10-14
doi: 10.3866/PKU.WHXB19890104
Abstract:
~(13)C relaxation parameters of morphine in solution were measured at 90.1 and 62.9 MHz. An axially symmetric rotational model was applied to calculate the ro- tational rates.The calculated rotational rates are 8.6×10~9 revolution s~(-1) about the principal X-axis and 6.1×10~9 revolution s~(-1) about Y-axis.The N-CH_3 methyl internal rotation rate is 5.7×10~9 revolution s~(-1) and the internal rotation barrier is 4.59 kcal mo1~(-1).
~(13)C relaxation parameters of morphine in solution were measured at 90.1 and 62.9 MHz. An axially symmetric rotational model was applied to calculate the ro- tational rates.The calculated rotational rates are 8.6×10~9 revolution s~(-1) about the principal X-axis and 6.1×10~9 revolution s~(-1) about Y-axis.The N-CH_3 methyl internal rotation rate is 5.7×10~9 revolution s~(-1) and the internal rotation barrier is 4.59 kcal mo1~(-1).
1989, 5(01): 15-19
doi: 10.3866/PKU.WHXB19890105
Abstract:
The molecular and crystal structure of the new compound [Co(H_2O)_4(NCS)_2]_2. (18-Crown-6) has been reported in a preiours paper by one of us. The electronic structure of the same compound has been calculated using CNDO/2 method, and the results are reported in this paper. Some interesting results have been obtained. Calculated atomic net charge, Mulliken bond order, total and local density of states (TDOS and LDOS) for isolated and interacted systems have been given. It is shown that a coordinate unit is bonded to a 18-crown-6 molecule by four hydrogen bonds which have different strengthes. These results are in agreement with the experimental measurements. It is concluded that the hydrogen bond interaction in the coordinated units is of primary importance for the explanation of the stability of this coordination compound.
The molecular and crystal structure of the new compound [Co(H_2O)_4(NCS)_2]_2. (18-Crown-6) has been reported in a preiours paper by one of us. The electronic structure of the same compound has been calculated using CNDO/2 method, and the results are reported in this paper. Some interesting results have been obtained. Calculated atomic net charge, Mulliken bond order, total and local density of states (TDOS and LDOS) for isolated and interacted systems have been given. It is shown that a coordinate unit is bonded to a 18-crown-6 molecule by four hydrogen bonds which have different strengthes. These results are in agreement with the experimental measurements. It is concluded that the hydrogen bond interaction in the coordinated units is of primary importance for the explanation of the stability of this coordination compound.
1989, 5(01): 20-26
doi: 10.3866/PKU.WHXB19890106
Abstract:
A synergistic extracted complex of bis-(1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5) mono (1,10-phenanthroline) eobalt(Ⅱ) has been synthesized and studied by solubility, conduetometric method, magnetometry, IR, far-IR, thermo analysis as well as single crystal X-ray diffractometry.
The crystal and molecular structure of the complex was determined by single crystal X-ray diffraction analysis and refined by full-matrix least square to a value of R 0.0716. The complex crystallizes in space group P2_1/c with a=1.0422(3) nm, b=1.6462(2) nm, c=2.0678(3) nm, β=75.86(1)°, V=3.4402(1.6) nm, Z=4, F(000)=1580, d_(calc)=1.50 g cm~(-3), d_(exp.)=1.492 g cm~(-3).
The metal atoms occupy general position in crystal. The crystal is composed of mononuclear complexes containing a six-coordinate cobalt (II) ions. Each PMTFP group coordinates to the central ion through two oxygen atoms bidentately. The phen molecule coordinates through its two nitrogen atoms bond lengths are 0.203, 0.204, 0.205, 0.210 nm for cotalt-oxygen, and 0.212 0.216 nm for cotalt-nitrogen.
A synergistic extracted complex of bis-(1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5) mono (1,10-phenanthroline) eobalt(Ⅱ) has been synthesized and studied by solubility, conduetometric method, magnetometry, IR, far-IR, thermo analysis as well as single crystal X-ray diffractometry.
The crystal and molecular structure of the complex was determined by single crystal X-ray diffraction analysis and refined by full-matrix least square to a value of R 0.0716. The complex crystallizes in space group P2_1/c with a=1.0422(3) nm, b=1.6462(2) nm, c=2.0678(3) nm, β=75.86(1)°, V=3.4402(1.6) nm, Z=4, F(000)=1580, d_(calc)=1.50 g cm~(-3), d_(exp.)=1.492 g cm~(-3).
The metal atoms occupy general position in crystal. The crystal is composed of mononuclear complexes containing a six-coordinate cobalt (II) ions. Each PMTFP group coordinates to the central ion through two oxygen atoms bidentately. The phen molecule coordinates through its two nitrogen atoms bond lengths are 0.203, 0.204, 0.205, 0.210 nm for cotalt-oxygen, and 0.212 0.216 nm for cotalt-nitrogen.
1989, 5(01): 27-32
doi: 10.3866/PKU.WHXB19890107
Abstract:
The title compound is synthesized and crystallized in the monoclinic system; space group P1, a=1.0761(2), b=1.3930(4), c=1.5117(2) nm; α=114.74(2)°, β=101.82(2)°, γ=95.85(2)°; Z=1. The final R factor is 0.076 based on 2083 reflections with I≥3σ(I). In the title compound, coppcr(II) ions are bridged in pairs by four acetate groups with two DMF molecules occupying the terminal positions. The copper(II) ions are 0.020 nm out of the plane of the four oxygen atoms. The distance between the two copper(II) ions is 0.2635 nm which is only slightly greater than 0.255 nm, the interatomic distance in metal copper. A weak bonding existed between the two atoms.
SCC-EHMO calculation...
The title compound is synthesized and crystallized in the monoclinic system; space group P1, a=1.0761(2), b=1.3930(4), c=1.5117(2) nm; α=114.74(2)°, β=101.82(2)°, γ=95.85(2)°; Z=1. The final R factor is 0.076 based on 2083 reflections with I≥3σ(I). In the title compound, coppcr(II) ions are bridged in pairs by four acetate groups with two DMF molecules occupying the terminal positions. The copper(II) ions are 0.020 nm out of the plane of the four oxygen atoms. The distance between the two copper(II) ions is 0.2635 nm which is only slightly greater than 0.255 nm, the interatomic distance in metal copper. A weak bonding existed between the two atoms.
SCC-EHMO calculation...
Investigation of Microstructure at Iron Tetraphenylporphyrin Modified Glassy Carbon Electroed by XPS
1989, 5(01): 33-37
doi: 10.3866/PKU.WHXB19890108
Abstract:
Microstructure of the glassy carbon surface modified with iron tetraphenyfporphyrin (FeTPP) by heat treatment has been studied by XPS,, DTA and TG. XPS spectra of Fe 2P_32 level in FeTPP and iron tetraphenylporphyriu/glassy carbon (FeTPP/GC) have shown that a bond can be formed between the glassy carbon surface and both the central metal iron ion and the macrocyclic, ligand, which loses its four phenyl groups during the beat treatment. The relationship between the surface mierostructure of FeTPP/GC and the stability of electrode for catalysis of dioxygen reduction bas been elucidated. Valence band spectra of FeTP/GC by heat treatment at various temperatures have shown the role of 3d electrons of Fe ion in electrocatalytic activity of electrode.
Microstructure of the glassy carbon surface modified with iron tetraphenyfporphyrin (FeTPP) by heat treatment has been studied by XPS,, DTA and TG. XPS spectra of Fe 2P_32 level in FeTPP and iron tetraphenylporphyriu/glassy carbon (FeTPP/GC) have shown that a bond can be formed between the glassy carbon surface and both the central metal iron ion and the macrocyclic, ligand, which loses its four phenyl groups during the beat treatment. The relationship between the surface mierostructure of FeTPP/GC and the stability of electrode for catalysis of dioxygen reduction bas been elucidated. Valence band spectra of FeTP/GC by heat treatment at various temperatures have shown the role of 3d electrons of Fe ion in electrocatalytic activity of electrode.
1989, 5(01): 38-43
doi: 10.3866/PKU.WHXB19890109
Abstract:
Several supported palladium catalysts were prepared and thier effects on the kinetic behaviors in the selective hydrogenation of cyclopentadiene were studied. Experiments show that cyclopentadiene inhibits the hydrogenation of cyelopentene. Data based on kinetic analysis indicate that the coordination of cyclopentadiene is much stronger than that of eyclopentene which should be the main factor of this inhibition reaction. Catalyst carriers via thier ligand effects can influence the ratio of the coordination equilibrium constants K_D/K_E and the rate constants k_2/k_4, which in turn change the selectivities and activites of catalysts.
Several supported palladium catalysts were prepared and thier effects on the kinetic behaviors in the selective hydrogenation of cyclopentadiene were studied. Experiments show that cyclopentadiene inhibits the hydrogenation of cyelopentene. Data based on kinetic analysis indicate that the coordination of cyclopentadiene is much stronger than that of eyclopentene which should be the main factor of this inhibition reaction. Catalyst carriers via thier ligand effects can influence the ratio of the coordination equilibrium constants K_D/K_E and the rate constants k_2/k_4, which in turn change the selectivities and activites of catalysts.
1989, 5(01): 44-49
doi: 10.3866/PKU.WHXB19890110
Abstract:
The effects of stirring on the oscillations of the ferrion-catalyzed and ceriumcatalyzed B-Z reactions are investigated in the stirred batch reactor. The experimental results show that the oscillatory behavours (period, amplitude etc.) are sensitive to the rate of stirring even in the nitrogen atmosphere and the stirring effects are different for ferrion-catalyzed and cerium-catalyzed reactions. We believe that such stirring effects reflect the interference between chemical reactions and transport processes. The inert salt which does not take part in the reaction may also effect the oscillations.
Some shortcomings in present ....
The effects of stirring on the oscillations of the ferrion-catalyzed and ceriumcatalyzed B-Z reactions are investigated in the stirred batch reactor. The experimental results show that the oscillatory behavours (period, amplitude etc.) are sensitive to the rate of stirring even in the nitrogen atmosphere and the stirring effects are different for ferrion-catalyzed and cerium-catalyzed reactions. We believe that such stirring effects reflect the interference between chemical reactions and transport processes. The inert salt which does not take part in the reaction may also effect the oscillations.
Some shortcomings in present ....
1989, 5(01): 50-55
doi: 10.3866/PKU.WHXB19890111
Abstract:
The band structures of two isomeric complexes 1-N-Mci TCNQ_2 and 2-N-Mci TCNQ_2 are calculated with the tight-binding approximation based on the extended Hckle method. The negative charges of TCNQ species in both complexes are estimated by calculating harmonic oscillator stabilization energy with using their geometry directly. The results show that the donor N-Mci has no effect on the front orhitals of band structure in one-dimensional systems. The geometry of 1-N-Mci is different from 2-N-Mci, which concerns with the crystal packing energy and effects on the arrangement of TCNQ species. Consequently, there are the different packing modes of TCNQ species and the different band structures. In 1-N-Mci TCNQ_2 complexe the .....
The band structures of two isomeric complexes 1-N-Mci TCNQ_2 and 2-N-Mci TCNQ_2 are calculated with the tight-binding approximation based on the extended Hckle method. The negative charges of TCNQ species in both complexes are estimated by calculating harmonic oscillator stabilization energy with using their geometry directly. The results show that the donor N-Mci has no effect on the front orhitals of band structure in one-dimensional systems. The geometry of 1-N-Mci is different from 2-N-Mci, which concerns with the crystal packing energy and effects on the arrangement of TCNQ species. Consequently, there are the different packing modes of TCNQ species and the different band structures. In 1-N-Mci TCNQ_2 complexe the .....
1989, 5(01): 56-61
doi: 10.3866/PKU.WHXB19890112
Abstract:
The molecular mechanics calculations (Allinger's MM2 program) was used to study the steric effect of substituents on extraction of metals (Ni, Co, RE) by acidic phosphorus esters. Some parameters for phosphorus which were not included in MM2 were estimated and used to reproduce the known structure of some phosphorus compounds with satisfactory results.
For the evaluation of steric effect of substituents, dialkyl t-butyIphosphate or phosphinate (Ⅱ) was proposed as a model structure for the simulation of the simulation of the steric environment of complexes. The optimum geometry of (II) and phosphorus ester (I) were determined by molecular mechanics program. It was found that the difference of the local steric energy of hydroxyl oxygen in I and II is closely correlated with the degree of the size of substituents and can thus be used as a measurement of the steric effect of the substituents (E_(s,ex)). A series of E_(s,ex) of alkyl and alkoxyl were estimated and used in the multiple regression of extraction data.
The molecular mechanics calculations (Allinger's MM2 program) was used to study the steric effect of substituents on extraction of metals (Ni, Co, RE) by acidic phosphorus esters. Some parameters for phosphorus which were not included in MM2 were estimated and used to reproduce the known structure of some phosphorus compounds with satisfactory results.
For the evaluation of steric effect of substituents, dialkyl t-butyIphosphate or phosphinate (Ⅱ) was proposed as a model structure for the simulation of the simulation of the steric environment of complexes. The optimum geometry of (II) and phosphorus ester (I) were determined by molecular mechanics program. It was found that the difference of the local steric energy of hydroxyl oxygen in I and II is closely correlated with the degree of the size of substituents and can thus be used as a measurement of the steric effect of the substituents (E_(s,ex)). A series of E_(s,ex) of alkyl and alkoxyl were estimated and used in the multiple regression of extraction data.
1989, 5(01): 62-66
doi: 10.3866/PKU.WHXB19890113
Abstract:
The phase transitions of N-(p-n-heptyloxybenzylidene)-p'-aminobenzonitrile (H_pBAB) were studied at various rates within the range 260—380K by DSC. It was revealed by the DSC experiments that the thermotropic nematogen H_pBAB obtained by the repeated recrystallization from absolute ethanol was the glassy crystal at room temperature in addition to the known stable and metastable crystal modifications K(Ⅰ) and K(Ⅱ). This is the first example of glassy crystal among the mesogens in so far as author's knowledge. The temperature and the heat capacity step of the glass transition of H_PBAB are 327.05±0.41 K and 310±27 J K~(-1) mol~(-1), respectively. Its melting temperature and enthalpy and entropy of fusion are 341.16±0.14 K, 32.78±0.22 kJ mol~(-1), 96.07±0.66 J K~(-1) mol~(-1) fro the crystal-I; 332.65±0.25 K, 22.66±0.99 kJ mol~(-1) for the metastable crystal-II, ....
The phase transitions of N-(p-n-heptyloxybenzylidene)-p'-aminobenzonitrile (H_pBAB) were studied at various rates within the range 260—380K by DSC. It was revealed by the DSC experiments that the thermotropic nematogen H_pBAB obtained by the repeated recrystallization from absolute ethanol was the glassy crystal at room temperature in addition to the known stable and metastable crystal modifications K(Ⅰ) and K(Ⅱ). This is the first example of glassy crystal among the mesogens in so far as author's knowledge. The temperature and the heat capacity step of the glass transition of H_PBAB are 327.05±0.41 K and 310±27 J K~(-1) mol~(-1), respectively. Its melting temperature and enthalpy and entropy of fusion are 341.16±0.14 K, 32.78±0.22 kJ mol~(-1), 96.07±0.66 J K~(-1) mol~(-1) fro the crystal-I; 332.65±0.25 K, 22.66±0.99 kJ mol~(-1) for the metastable crystal-II, ....
1989, 5(01): 67-71
doi: 10.3866/PKU.WHXB19890114
Abstract:
TEA CO_2 laser induced Si-SF_6 and W-SF_8 interactions have been studied and the surface reaction yields have been determined as a function of the laser frequency. The results show that the reaction yields depend strongly on the laser frequency and there is a maximum at the frequency of 942.4 cm~(-1), For Si-SF_6 system, the reaction yield also depends on the different planes of silicon single crystals and it shows that the Si(100) is more active than the Si(111) under the same experimental conditions. For W-SF_6 system, the reaction yields have been determined as a function of laser fluence and number of laser pulses. The results show that the reaction threshold is 1 J cm~(-2) at the laser frequency of 942.4 cm~(-1) and the reaction rate is of first order in SF_6 pressure. These results impies that the infrared laser irradiation plays and important role in these gas-surface reactions and the main step might be the interaction between the vibrationally excited SF_6 molecules and laser stimulated solid surfaces.
TEA CO_2 laser induced Si-SF_6 and W-SF_8 interactions have been studied and the surface reaction yields have been determined as a function of the laser frequency. The results show that the reaction yields depend strongly on the laser frequency and there is a maximum at the frequency of 942.4 cm~(-1), For Si-SF_6 system, the reaction yield also depends on the different planes of silicon single crystals and it shows that the Si(100) is more active than the Si(111) under the same experimental conditions. For W-SF_6 system, the reaction yields have been determined as a function of laser fluence and number of laser pulses. The results show that the reaction threshold is 1 J cm~(-2) at the laser frequency of 942.4 cm~(-1) and the reaction rate is of first order in SF_6 pressure. These results impies that the infrared laser irradiation plays and important role in these gas-surface reactions and the main step might be the interaction between the vibrationally excited SF_6 molecules and laser stimulated solid surfaces.
1989, 5(01): 72-75
doi: 10.3866/PKU.WHXB19890115
Abstract:
In this paper, the solubilities, viscosities, densities and vapor-liquid equilibrium were studied for the ternary system Li_2SO_4-EtOH-H_2O at 25 ℃. The equilibrium solid phases, which were determined by wet-residue method, were all Li_2SO_4·H_2O in the whole concentration. The solubilities and densities were correlated by using empirical formula In(y/y_0) =K_1x+K_2x~2+K_3x~3 and the od results were obtained. After lithium sulfate was added to the solvent, it was showed that the figure of viscosity, compared with that for the pure solvent system of ethanolwater, make a change because of the action of static electricity of salt ions on the solvent. According to Jaques' pseudobinary model, NRTL and WILSON equations were used to correlate the vapor-liquid equilibrium data of the system. It was obtained that ethanol is a salting out component and water is a salting in component.
In this paper, the solubilities, viscosities, densities and vapor-liquid equilibrium were studied for the ternary system Li_2SO_4-EtOH-H_2O at 25 ℃. The equilibrium solid phases, which were determined by wet-residue method, were all Li_2SO_4·H_2O in the whole concentration. The solubilities and densities were correlated by using empirical formula In(y/y_0) =K_1x+K_2x~2+K_3x~3 and the od results were obtained. After lithium sulfate was added to the solvent, it was showed that the figure of viscosity, compared with that for the pure solvent system of ethanolwater, make a change because of the action of static electricity of salt ions on the solvent. According to Jaques' pseudobinary model, NRTL and WILSON equations were used to correlate the vapor-liquid equilibrium data of the system. It was obtained that ethanol is a salting out component and water is a salting in component.
1989, 5(01): 76-80
doi: 10.3866/PKU.WHXB19890116
Abstract:
The system trial and error method (STEM) for crystal structure determination is a systematical method. It is different from other current direct methods that derive reflection phases individually from several known reflections. According to size of the molecular, intensity and extensity of relations between reflections, STEM derides reflections into many small solvable systems, so that of each reflection satisfy the probability requirement for phase determination in each of these systems. And on basis of Sayre equation, set up system's over-determined equation. Then, by means of trial and error method, find out the optimization to satisfy the system equation, thus the system's reflection phases be solved all at the same time.
A routine for crystal structure....
The system trial and error method (STEM) for crystal structure determination is a systematical method. It is different from other current direct methods that derive reflection phases individually from several known reflections. According to size of the molecular, intensity and extensity of relations between reflections, STEM derides reflections into many small solvable systems, so that of each reflection satisfy the probability requirement for phase determination in each of these systems. And on basis of Sayre equation, set up system's over-determined equation. Then, by means of trial and error method, find out the optimization to satisfy the system equation, thus the system's reflection phases be solved all at the same time.
A routine for crystal structure....
1989, 5(01): 81-86
doi: 10.3866/PKU.WHXB19890117
Abstract:
An isothermal equation for ion exchange-adsorption is derived by mass action law. The equation can be used to sum up empirical and semiempirical formnlas of exchangeadsorption, such as Gapon Equation, Sips Formula, Langmuir Equation and Freundlich Formula.
In this paper, by adopting the ion exchange reaction to act as the determining step of the ion exchange adsorption kinetics, an exchange-adsorption kinetics equation is derived. It is verified by the results of a series of experiments in which uranium is extracted form enriched sea-water and natural sea-water with hydrous titanium oxide (titanic gel). This equation can be used to explain not only the results of tests which have been applied to prove fast....
An isothermal equation for ion exchange-adsorption is derived by mass action law. The equation can be used to sum up empirical and semiempirical formnlas of exchangeadsorption, such as Gapon Equation, Sips Formula, Langmuir Equation and Freundlich Formula.
In this paper, by adopting the ion exchange reaction to act as the determining step of the ion exchange adsorption kinetics, an exchange-adsorption kinetics equation is derived. It is verified by the results of a series of experiments in which uranium is extracted form enriched sea-water and natural sea-water with hydrous titanium oxide (titanic gel). This equation can be used to explain not only the results of tests which have been applied to prove fast....
1989, 5(01): 87-90
doi: 10.3866/PKU.WHXB19890118
Abstract:
The morphology, size distribution and crystallography of supported nickel on ZSM-5 zeolites have been studied by electron microscopy. The obtained results are in agree with that given by X-ray diffraction. It was shown by bright and dark field microscopy, selected area diffraction that nickel particles aggregate as approximately spherical in shape having normal crystal structure of the bulk metal (f.e.c.) on the surface of carriers.
Some of the factors which have been found to affect the size distribution and the stability of the metal particles are: the type of support, the content of nickel, and the preparation method. etc.
For the impregnation type sample, the...
The morphology, size distribution and crystallography of supported nickel on ZSM-5 zeolites have been studied by electron microscopy. The obtained results are in agree with that given by X-ray diffraction. It was shown by bright and dark field microscopy, selected area diffraction that nickel particles aggregate as approximately spherical in shape having normal crystal structure of the bulk metal (f.e.c.) on the surface of carriers.
Some of the factors which have been found to affect the size distribution and the stability of the metal particles are: the type of support, the content of nickel, and the preparation method. etc.
For the impregnation type sample, the...
1989, 5(01): 91-94
doi: 10.3866/PKU.WHXB19890119
Abstract:
This paper presented the Mid-IR photoacoustic spectra of polyphenylene sulfide (PPS) which was first measured by us and the group theoretical analyses. By treating the chemical unit, C_6H_4S_2, as the characteristic unit for PPS chains, the group classifications and the normal mode constructions by the internal coordinates and projection operator technique were carried out successfully, also, the correlation analysis between PPS and benzene moleeule was performed to further aid the spectral assignments. This work was the basis upon which further studies of the PPS composites may proceed.
This paper presented the Mid-IR photoacoustic spectra of polyphenylene sulfide (PPS) which was first measured by us and the group theoretical analyses. By treating the chemical unit, C_6H_4S_2, as the characteristic unit for PPS chains, the group classifications and the normal mode constructions by the internal coordinates and projection operator technique were carried out successfully, also, the correlation analysis between PPS and benzene moleeule was performed to further aid the spectral assignments. This work was the basis upon which further studies of the PPS composites may proceed.
1989, 5(01): 95-98
doi: 10.3866/PKU.WHXB19890120
Abstract:
Using a precision static oxygen-bomb calorimeter, the standard energies of combustion at 298.15K of tetra-(p-nitrophenyl)-porphyrin, tetra-(3-pyridinyl)porphyrin were determined to be -27.412±0.012, -32.749±0.011 kJg~(-1), and the corresponding standard enthalpies of formation at 298.15 K were calculated to be 751.0±11.0, 811.8±8.6 kJ mol~(-1), respectively. The uncertainties of the results are given as twice of the final over-all standard deviation of the main.
Using a precision static oxygen-bomb calorimeter, the standard energies of combustion at 298.15K of tetra-(p-nitrophenyl)-porphyrin, tetra-(3-pyridinyl)porphyrin were determined to be -27.412±0.012, -32.749±0.011 kJg~(-1), and the corresponding standard enthalpies of formation at 298.15 K were calculated to be 751.0±11.0, 811.8±8.6 kJ mol~(-1), respectively. The uncertainties of the results are given as twice of the final over-all standard deviation of the main.
1989, 5(01): 99-102
doi: 10.3866/PKU.WHXB19890121
Abstract:
The adsorption properties of molecules with different polarizabilities, benzene, cyclohexane, n-hexane and water, on aluminophosphate molecular sieve AlPO_4-11 have been investigated by gravimetric method, and compared with those on zeolites NaX and ZSM-5 having high Si/Al ratio.
From adsorption data we have calculated the isosteric heat of adsorption and the differential molar adsorption work and entropy of benzene and cyclohexane on AlPO_4-11. The adsorption isotherms can be described by the theory of volume filling of micropores. The results show that the heat of adsorption of hydrocarbons on AlPO_4-11 mainly depends on the surface energy of dispersion.
AIPO_4-11 favourably...
The adsorption properties of molecules with different polarizabilities, benzene, cyclohexane, n-hexane and water, on aluminophosphate molecular sieve AlPO_4-11 have been investigated by gravimetric method, and compared with those on zeolites NaX and ZSM-5 having high Si/Al ratio.
From adsorption data we have calculated the isosteric heat of adsorption and the differential molar adsorption work and entropy of benzene and cyclohexane on AlPO_4-11. The adsorption isotherms can be described by the theory of volume filling of micropores. The results show that the heat of adsorption of hydrocarbons on AlPO_4-11 mainly depends on the surface energy of dispersion.
AIPO_4-11 favourably...
1989, 5(01): 103-106
doi: 10.3866/PKU.WHXB19890122
Abstract:
The characteristics of Mg electrodeposition on Pt in DMF have been investigated by means of cyclic voltammetry and rotating ring-disk electrode technique, The current-potential curves of Mg electrodeposition indicate that this electro deposition process is irreversible. The order of reaction for Mg~(2+) was found to beunity. A rate constant k of 10~(-7) cm s~(-1) was obtained for this electrodeposition process.
The characteristics of Mg electrodeposition on Pt in DMF have been investigated by means of cyclic voltammetry and rotating ring-disk electrode technique, The current-potential curves of Mg electrodeposition indicate that this electro deposition process is irreversible. The order of reaction for Mg~(2+) was found to beunity. A rate constant k of 10~(-7) cm s~(-1) was obtained for this electrodeposition process.
1989, 5(01): 107-109
doi: 10.3866/PKU.WHXB19890123
Abstract:
For non-centrosymmetric crystal structures, it is usually uses as many specila refletions as possible to define origin and enantiamorph. But in some cases, special reflections may be not enough or may be not in od quality to specify origin and enantiamorph so questions about specifying origin and enantiamorph with general reflections are discussed in this paper. Origin definition reflections of any space groups are differentiated into absolute freedoms and relative freedoms so that the problem of assigning values to the general refection phases for specifying origin is able to be solved. The concept of freedom is also used in enantiamorph specification. Two cases about enantiamorph specification relection related to or not related to origin definition refections are disecussed respectively. In both cases enantiamorph specification can be realized through two steps: (1) Chosing the signs of a certain number of structurral invariants (2) On the basis of step one, making restrictins to the amplitudes and phase signs of the invariant's component reflections.
For non-centrosymmetric crystal structures, it is usually uses as many specila refletions as possible to define origin and enantiamorph. But in some cases, special reflections may be not enough or may be not in od quality to specify origin and enantiamorph so questions about specifying origin and enantiamorph with general reflections are discussed in this paper. Origin definition reflections of any space groups are differentiated into absolute freedoms and relative freedoms so that the problem of assigning values to the general refection phases for specifying origin is able to be solved. The concept of freedom is also used in enantiamorph specification. Two cases about enantiamorph specification relection related to or not related to origin definition refections are disecussed respectively. In both cases enantiamorph specification can be realized through two steps: (1) Chosing the signs of a certain number of structurral invariants (2) On the basis of step one, making restrictins to the amplitudes and phase signs of the invariant's component reflections.
