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1988 Volume 4 Issue 4
1988, 4(04): 337-339
doi: 10.3866/PKU.WHXB19880401
Abstract:
Using microcalorimetric method, we have determined the metabolic output power of Mouse Mammary Adenocarcinoma cell (MA 782/5S-8101) at the culture medium, the average value is 35.1 pW/cell. As cross reference, using the same method the output power of this cancer cell was determined at medium which contain inhibitor, the results show clearly that the output power was inhibited obviously, the correspondent average value is 23,2pW/cell.
Using microcalorimetric method, we have determined the metabolic output power of Mouse Mammary Adenocarcinoma cell (MA 782/5S-8101) at the culture medium, the average value is 35.1 pW/cell. As cross reference, using the same method the output power of this cancer cell was determined at medium which contain inhibitor, the results show clearly that the output power was inhibited obviously, the correspondent average value is 23,2pW/cell.
1988, 4(04): 340-343
doi: 10.3866/PKU.WHXB19880402
Abstract:
Using MS 80 standard microcalorimeter and specific measuring tube, we have obstained the normal growth thermal graphs of Hela cell and Human Andenocarcinoma Gastic cell (SGc 7901), the thermal graph of Hela cells synchronized in M phase of cell-cycle at the start and the themal graph of Gc cells in culture medium containing anticancer medicine, determined the relationships of the number of cells, the peak height of themal graph and the specific heat output power. In addition, our work has shown the prospects of microcalormetic method in cytological study.
Using MS 80 standard microcalorimeter and specific measuring tube, we have obstained the normal growth thermal graphs of Hela cell and Human Andenocarcinoma Gastic cell (SGc 7901), the thermal graph of Hela cells synchronized in M phase of cell-cycle at the start and the themal graph of Gc cells in culture medium containing anticancer medicine, determined the relationships of the number of cells, the peak height of themal graph and the specific heat output power. In addition, our work has shown the prospects of microcalormetic method in cytological study.
1988, 4(04): 344-346
doi: 10.3866/PKU.WHXB19880403
Abstract:
Coadsorption in electrochemistry is a complex phenomenon involving several interactions of two or more than two species with the electrode surface. It is dif- ficult to investigate coadsorption with conventional electrochemical techniques that inevitably measure the sum of all the processes at the electrode/solution interfaces. In this article surface enhanced Raman spectroscopy (SERS)~[1-3] has been used to characterize the nature of the coadsorption process as the SER signals of these coadsorbed species can be detected simultaneously~[4]. By analysing relations of the SER spectra and the electro-chemical parameters, it is possible to classify coadsorption as two aspects: parallel coadsorption and induced coadsorption. Moreover, the latter can be further divided into two groups: induced chemical coadsorption and induced physical coadsorption.
Coadsorption in electrochemistry is a complex phenomenon involving several interactions of two or more than two species with the electrode surface. It is dif- ficult to investigate coadsorption with conventional electrochemical techniques that inevitably measure the sum of all the processes at the electrode/solution interfaces. In this article surface enhanced Raman spectroscopy (SERS)~[1-3] has been used to characterize the nature of the coadsorption process as the SER signals of these coadsorbed species can be detected simultaneously~[4]. By analysing relations of the SER spectra and the electro-chemical parameters, it is possible to classify coadsorption as two aspects: parallel coadsorption and induced coadsorption. Moreover, the latter can be further divided into two groups: induced chemical coadsorption and induced physical coadsorption.
1988, 4(04): 347-348
doi: 10.3866/PKU.WHXB19880404
Abstract:
We have investigated the electronic structure and potential energy curve of molecule Mo_2 using ECP ab initio method at SCF and CI levels. Relativistic effective core potential have been used for molybdenum. It is found that the ground state of Mo_2 is
~1Σ_g~+: 1σ_g~2 1π_u~4 1δ_g~4 2σ_g~2.
It is predicted that the bond length are 1.75 and 2.01 at SCF and SCF+CI, respectively, and dissociation energy are 10.3 eV and 5.2 eV. As bond length increase, the correlation energy increase rapidly, and t a reasonable dissociation procedure at SCF+Cl level.
We have investigated the electronic structure and potential energy curve of molecule Mo_2 using ECP ab initio method at SCF and CI levels. Relativistic effective core potential have been used for molybdenum. It is found that the ground state of Mo_2 is
~1Σ_g~+: 1σ_g~2 1π_u~4 1δ_g~4 2σ_g~2.
It is predicted that the bond length are 1.75 and 2.01 at SCF and SCF+CI, respectively, and dissociation energy are 10.3 eV and 5.2 eV. As bond length increase, the correlation energy increase rapidly, and t a reasonable dissociation procedure at SCF+Cl level.
1988, 4(04): 349-355
doi: 10.3866/PKU.WHXB19880405
Abstract:
The kinetics of oxidative dehydrogenation of butene-2 over Fe-Zn-My-Cr spinel catalyst has been investigated in a flow-recirculation glass reactor. The kinetics of oxidative dehydrogenation of butene-2 obeyed the Redox mechanism of three steps. The reduction step of catalyst with butene-2 and reoxidation step of reduced catalyst with oxygen were investigated by the pulse method. The heat of adsoption of butene-2 was determined by the pulse method. The kinetics of deep oxidation of butene-2 and butadiene obeyed the empirical rate equation. The values of parameters of kinetic equations were estimated by the method of ortho nal design. It has be shown that the rate of oxidative dehydrogenation of butene-2 was faster than the rate of butene-1.
The kinetics of oxidative dehydrogenation of butene-2 over Fe-Zn-My-Cr spinel catalyst has been investigated in a flow-recirculation glass reactor. The kinetics of oxidative dehydrogenation of butene-2 obeyed the Redox mechanism of three steps. The reduction step of catalyst with butene-2 and reoxidation step of reduced catalyst with oxygen were investigated by the pulse method. The heat of adsoption of butene-2 was determined by the pulse method. The kinetics of deep oxidation of butene-2 and butadiene obeyed the empirical rate equation. The values of parameters of kinetic equations were estimated by the method of ortho nal design. It has be shown that the rate of oxidative dehydrogenation of butene-2 was faster than the rate of butene-1.
1988, 4(04): 356-360
doi: 10.3866/PKU.WHXB19880406
Abstract:
The molecular structure of 4-NH_2-2-OH-cytosine (for short, Lactim) has been optimized by MINDO/3. The Lactam is more stable than Lactim by ΔE=36.79 kJ mol~(-1). The geometric parameters of the transition state of the tautomeric reaction has been optimized by Powell's procedure which is contained in the MINDO/3 program. The reaction pathway of the Lactam <=> Lactim has been studied by Fukui's IRC theory. The activation energy of the forward reaction is 204.08 kJ mol~(-1) while it is 167.30 kJ mol~(-1) for the backward reaction.
The molecular structure of 4-NH_2-2-OH-cytosine (for short, Lactim) has been optimized by MINDO/3. The Lactam is more stable than Lactim by ΔE=36.79 kJ mol~(-1). The geometric parameters of the transition state of the tautomeric reaction has been optimized by Powell's procedure which is contained in the MINDO/3 program. The reaction pathway of the Lactam <=> Lactim has been studied by Fukui's IRC theory. The activation energy of the forward reaction is 204.08 kJ mol~(-1) while it is 167.30 kJ mol~(-1) for the backward reaction.
1988, 4(04): 361-365
doi: 10.3866/PKU.WHXB19880407
Abstract:
In the present paper the surface reaction mechanism with that the CO hydrogenation will proceed to ethanol is investigated by the transient response method using a quadrupole mass spectrometer under atmospheric CO-H_2 over Rh/Al_2O_3 and K doped Rh/Al_2O_3 catalysts.
According to the experimental results, it is found that: 1. the presence of K causes a marked increase in the steadystate rate and selectivity for ethanol synthesis; 2. the formation of ethanol depends on the surface adjacent intermediates and is independent of the concentration of CO or H_2 in the gas phase, i.e. the results favor the condensation mechanism to the insertion mechanism.
A mechanism of ethanol synthesis on the modified Rh/Al_2O_3 has been proposed and a set of rate constants of all elementary steps are calculated by Marquardt nonlinear optimization technique and Rung-Kutta-Gill numerical value integration method.
In the present paper the surface reaction mechanism with that the CO hydrogenation will proceed to ethanol is investigated by the transient response method using a quadrupole mass spectrometer under atmospheric CO-H_2 over Rh/Al_2O_3 and K doped Rh/Al_2O_3 catalysts.
According to the experimental results, it is found that: 1. the presence of K causes a marked increase in the steadystate rate and selectivity for ethanol synthesis; 2. the formation of ethanol depends on the surface adjacent intermediates and is independent of the concentration of CO or H_2 in the gas phase, i.e. the results favor the condensation mechanism to the insertion mechanism.
A mechanism of ethanol synthesis on the modified Rh/Al_2O_3 has been proposed and a set of rate constants of all elementary steps are calculated by Marquardt nonlinear optimization technique and Rung-Kutta-Gill numerical value integration method.
1988, 4(04): 366-369
doi: 10.3866/PKU.WHXB19880408
Abstract:
The second virial coefficients of ring-shaped polystyrene in cyclohexane were determined at different temperature using low angle laser light scattering photometer (LALLS). The temperature obtained at which the second virial coefficient equals zero is 30 ℃. That is the θ temperature of ring-shaped polystyrene in cyclohexane solution. It is 4.5 ℃ lower than that of linear polystyrene (34.5 ℃). The Mark-Houwink equation of ringshaped polystyrene in cyclohexane at 30 ℃ and 35 ℃ were determined. They are
[η]=5.10×10~(-2) M_W~(0.508), cm~3 g~(-1) [η]=2.70×10~(-2) M_W~(0.576), cm~3 g~(-1)
respectively.
The second virial coefficients of ring-shaped polystyrene in cyclohexane were determined at different temperature using low angle laser light scattering photometer (LALLS). The temperature obtained at which the second virial coefficient equals zero is 30 ℃. That is the θ temperature of ring-shaped polystyrene in cyclohexane solution. It is 4.5 ℃ lower than that of linear polystyrene (34.5 ℃). The Mark-Houwink equation of ringshaped polystyrene in cyclohexane at 30 ℃ and 35 ℃ were determined. They are
[η]=5.10×10~(-2) M_W~(0.508), cm~3 g~(-1) [η]=2.70×10~(-2) M_W~(0.576), cm~3 g~(-1)
respectively.
1988, 4(04): 370-375
doi: 10.3866/PKU.WHXB19880409
Abstract:
The solubility of ethylene in cuprous aluminium tetrachloride-toluene solutions was measured. A thermodynamic model in which phase and complex equilibrium are considered simultaneously was presented. The simplified Scatchard-Hildebrand equation is employed for estimation of activity coefficents of each component. The corresponding computer program was compiled and conveniently used for the correlation of experimental solubility data. The comparison between calculated and experimental values of ethylene solubility gives od agreement.
---------------
** China Textile University
The solubility of ethylene in cuprous aluminium tetrachloride-toluene solutions was measured. A thermodynamic model in which phase and complex equilibrium are considered simultaneously was presented. The simplified Scatchard-Hildebrand equation is employed for estimation of activity coefficents of each component. The corresponding computer program was compiled and conveniently used for the correlation of experimental solubility data. The comparison between calculated and experimental values of ethylene solubility gives od agreement.
---------------
** China Textile University
1988, 4(04): 376-381
doi: 10.3866/PKU.WHXB19880410
Abstract:
The systems of CrO_3/SiO_2 and CrO_3/γ-Al_2O_3 have been studied by X-ray diffraction (XRD). The CrO_3/SiO_2 (or CrO_3/γ-Al_2O_3) samples with various amounts of CrO_3 were prepared by mixing CrO_3 and SiO_2 (or γ-Al_2O_3) in dry atmosphere, and by calcining at temperatures below the melting point of CrO_3 (196 ℃) for 24 hrs. In order to protect the samples from moisture in the XRD measurement, a special sample holder (see Fig.1) was used. The maximum dispersion amounts (dispersion threshold)of CrO_3 on SiO_2 at various temperatures (101 to 170 ℃) have been obtained from the XRD quantitative phase analysis (see Fig.3). It has been shown that the dispersion thresholds change with calcination temperatures. For CrO_3/SiO_2 system, as temperature changes from 101 to 170 ℃, the threshold increases from 0.27 to 0.38 g CrO_3/g SiO_2 (see Fig.4). For CrO_3/γ-Al_2O_3 system, as temperature changes from 120 to 171 ℃, the threshold changes from 0.22 to 0.42 g CrO_3/g γ-Al_2O_3 (see Fig.5). The specific surfaces of the SiO_2 and γ-Al_2O_3 are CrO_3 on SiO_2 and for CrO_3 on γ-Al_2O_3 at 150 ℃ are 0.096 and 0.191 g CrO_3/100 m~2 respectively. According to a closepacked monolayer model, the monolayer capacity of CrO_3 on a support should be 0.081 g CrO_3/100 m~2. The experimental results indicate that CrO_3 dispersed on SiO_2 or γ-Al_2O_3 are not monolayer. They are quite different from those systems we reported before. In thoe systems the active components could disperse spontaneously onto the carrier surface to form a monolayer or submonolayer and have definitive dispersion thresholds. The dispersion thresholds of CrO_3 on SiO_2 or γ-Al_2O_3 increase with calcination temperature, and can exceed their monolayer capacities. These behaviours can be attributed to the polymerization of CrO_3. We suggested that heating at a lower temperature CrO_3 reacted with SiO_2 to form surface compound and heating at a higher temperature CrO_3 formed homopoly-acid-radical.
The systems of CrO_3/SiO_2 and CrO_3/γ-Al_2O_3 have been studied by X-ray diffraction (XRD). The CrO_3/SiO_2 (or CrO_3/γ-Al_2O_3) samples with various amounts of CrO_3 were prepared by mixing CrO_3 and SiO_2 (or γ-Al_2O_3) in dry atmosphere, and by calcining at temperatures below the melting point of CrO_3 (196 ℃) for 24 hrs. In order to protect the samples from moisture in the XRD measurement, a special sample holder (see Fig.1) was used. The maximum dispersion amounts (dispersion threshold)of CrO_3 on SiO_2 at various temperatures (101 to 170 ℃) have been obtained from the XRD quantitative phase analysis (see Fig.3). It has been shown that the dispersion thresholds change with calcination temperatures. For CrO_3/SiO_2 system, as temperature changes from 101 to 170 ℃, the threshold increases from 0.27 to 0.38 g CrO_3/g SiO_2 (see Fig.4). For CrO_3/γ-Al_2O_3 system, as temperature changes from 120 to 171 ℃, the threshold changes from 0.22 to 0.42 g CrO_3/g γ-Al_2O_3 (see Fig.5). The specific surfaces of the SiO_2 and γ-Al_2O_3 are CrO_3 on SiO_2 and for CrO_3 on γ-Al_2O_3 at 150 ℃ are 0.096 and 0.191 g CrO_3/100 m~2 respectively. According to a closepacked monolayer model, the monolayer capacity of CrO_3 on a support should be 0.081 g CrO_3/100 m~2. The experimental results indicate that CrO_3 dispersed on SiO_2 or γ-Al_2O_3 are not monolayer. They are quite different from those systems we reported before. In thoe systems the active components could disperse spontaneously onto the carrier surface to form a monolayer or submonolayer and have definitive dispersion thresholds. The dispersion thresholds of CrO_3 on SiO_2 or γ-Al_2O_3 increase with calcination temperature, and can exceed their monolayer capacities. These behaviours can be attributed to the polymerization of CrO_3. We suggested that heating at a lower temperature CrO_3 reacted with SiO_2 to form surface compound and heating at a higher temperature CrO_3 formed homopoly-acid-radical.
1988, 4(04): 382-386
doi: 10.3866/PKU.WHXB19880411
Abstract:
The coulombs of cathodic reduction can be measured when the high pure iron electrode passivated first in 0.5 mol L~(-1) H_2SO_4 for ten minutes was swept towards the cathodic direction. It is mainly due to the reduction of oxide film on the surface. A very small amount of Cl~- can obviously decrease the reduction current. The primary effect of Cl~- is its arreting the formation of passive film and reducing the stability of the passive film.
The coulombs of cathodic reduction can be measured when the high pure iron electrode passivated first in 0.5 mol L~(-1) H_2SO_4 for ten minutes was swept towards the cathodic direction. It is mainly due to the reduction of oxide film on the surface. A very small amount of Cl~- can obviously decrease the reduction current. The primary effect of Cl~- is its arreting the formation of passive film and reducing the stability of the passive film.
1988, 4(04): 387-392
doi: 10.3866/PKU.WHXB19880412
Abstract:
The chemiluminescent reactions of Ba+Cl_2, Br_2 were carried out in a beamgas apparatus and the CL spectra have been observed. The continuum in the visible region of the CL spectrum has been asigned as the emission of BaCl_2~*, but there is a discrepancy about the mechanism of formation of BaCl_2~*. The observed quadratic dependences of the BaCl_2~* intensity on Cl_2 pressure (Fig.1), the Ba intensity upon the Ba atom number density (Fig.3) and the independence of the BaCl_2~* emission upon the Ba atom number density in the high density region (Fig.2) imply that the two body recombination radiation or the dimmer Ba_2 exchange reaction Ba_2+Cl_2 should be neglected. No enhancement but a slight drop of the BaCl_2~* intensity with increasing N_2 mixed with Cl_2 indicates that the three body stabilization route can be excluded as well.
The fact that the BaCl_2~* intensity increases along the Ba beam axis from the entrance as measured by OMA (Fig.5) is an evidence against the rule of single collision reaction radiation in a beam-gas regime. From the above consideration the following reaction processes for the formation of BaCl_2~* are proposed:
Ba+Cl_2 ~(k_1)—— BaCl~≠+Cl (1)
BaCl~≠+Cl_2 ~（k_2)—— BaCl_2~*+Cl (2)
BaCl~≠+Ba ~(k_3)—— BaCl+Ba~* (3)
BaCl_2~* ~(k_4)—— BaCl_2+hν′ (4)
Ba~* (k_5)—— Ba+hν′ (5)
where the superscripts≠and * denote the vibrationally highly excited ground state and electronically excited state respectively.
The kinetic analysis shows that the two step reaction mechanism for the formation of BaCl_2~* represented by the above elementary processes is reasonable. The computer simulations. as shown in Figures 1, 2 and 5, are well in agreement with the experimental observations.
The same experiments and discussion have been done ofr the reaction Ba+Br_2. The dynamics of the reaction Ba+Br_2 is similar to that of Ba+Cl_2. We have found that the CL intensity of BaBr_2~* is weaker but spreader than that of BaCl_2~* (Fig.6). A discussion about the CL spreading and an argument on the life time of the emitter BaCl_2~* are presented.
The chemiluminescent reactions of Ba+Cl_2, Br_2 were carried out in a beamgas apparatus and the CL spectra have been observed. The continuum in the visible region of the CL spectrum has been asigned as the emission of BaCl_2~*, but there is a discrepancy about the mechanism of formation of BaCl_2~*. The observed quadratic dependences of the BaCl_2~* intensity on Cl_2 pressure (Fig.1), the Ba intensity upon the Ba atom number density (Fig.3) and the independence of the BaCl_2~* emission upon the Ba atom number density in the high density region (Fig.2) imply that the two body recombination radiation or the dimmer Ba_2 exchange reaction Ba_2+Cl_2 should be neglected. No enhancement but a slight drop of the BaCl_2~* intensity with increasing N_2 mixed with Cl_2 indicates that the three body stabilization route can be excluded as well.
The fact that the BaCl_2~* intensity increases along the Ba beam axis from the entrance as measured by OMA (Fig.5) is an evidence against the rule of single collision reaction radiation in a beam-gas regime. From the above consideration the following reaction processes for the formation of BaCl_2~* are proposed:
Ba+Cl_2 ~(k_1)—— BaCl~≠+Cl (1)
BaCl~≠+Cl_2 ~（k_2)—— BaCl_2~*+Cl (2)
BaCl~≠+Ba ~(k_3)—— BaCl+Ba~* (3)
BaCl_2~* ~(k_4)—— BaCl_2+hν′ (4)
Ba~* (k_5)—— Ba+hν′ (5)
where the superscripts≠and * denote the vibrationally highly excited ground state and electronically excited state respectively.
The kinetic analysis shows that the two step reaction mechanism for the formation of BaCl_2~* represented by the above elementary processes is reasonable. The computer simulations. as shown in Figures 1, 2 and 5, are well in agreement with the experimental observations.
The same experiments and discussion have been done ofr the reaction Ba+Br_2. The dynamics of the reaction Ba+Br_2 is similar to that of Ba+Cl_2. We have found that the CL intensity of BaBr_2~* is weaker but spreader than that of BaCl_2~* (Fig.6). A discussion about the CL spreading and an argument on the life time of the emitter BaCl_2~* are presented.
1988, 4(04): 393-400
doi: 10.3866/PKU.WHXB19880413
Abstract:
The Hückel eigenvalues of three-dimensional rectangular clusters of arbitary size are explored on concerning not only the nearest but also those second and third neighboring interactions. For better specifying these interactions, three sets of parameters namely (β_1,β_2,β_3), (η_1,η_2,η_3) and ζ are introduced which can be illustrated schematically by 4_~.
Based on the well-known solution of the linear Hückel chain verned by a tri-dia nal matrix A~((1)) and the commutability between matrices A~((1))'s of equal dimension, we efficently derive the genera solutions for the planar and rectangular clusters respectively which are expressed by Eqs.(11) and (16).
The three-dimensional solution can be reduced to various special cases previously obtained by Messmer~[2] and Bilek & Skala~[3] but that for the face center rectangular lattice is new due to the introduction of parameters (η_1, η_2, η_3). The energy levels spread symmetricaly around α in terms of parameters (β_1, β_2, β_3) and ζ but the antibonding partners would be increased depending on the magnitude of η′s as indicated by 7_~. This means that the second neighbors play a role of destabilization in more or less extent much like the Madelung contribution in ionic crystals. As a consequence, the face-center (fc) lattice would be less favorable than the body-center (bc) one for alkali crystals, which seems really the case that most alkali metals are of be lattice except for lithium which is of either lattice form.
What is the minimum size of a cluster behaving like a crystal? In other words, when does the discrete energy levels change into continuous bands? By dint of the present results, we try to propose a criterion of maximum energy level separation, 0.02 eV that a finite cluster might behave approximately as a crystal. In order to illustrate the estimation, numerical calculation are given in Table 2.
The Hückel eigenvalues of three-dimensional rectangular clusters of arbitary size are explored on concerning not only the nearest but also those second and third neighboring interactions. For better specifying these interactions, three sets of parameters namely (β_1,β_2,β_3), (η_1,η_2,η_3) and ζ are introduced which can be illustrated schematically by 4_~.
Based on the well-known solution of the linear Hückel chain verned by a tri-dia nal matrix A~((1)) and the commutability between matrices A~((1))'s of equal dimension, we efficently derive the genera solutions for the planar and rectangular clusters respectively which are expressed by Eqs.(11) and (16).
The three-dimensional solution can be reduced to various special cases previously obtained by Messmer~[2] and Bilek & Skala~[3] but that for the face center rectangular lattice is new due to the introduction of parameters (η_1, η_2, η_3). The energy levels spread symmetricaly around α in terms of parameters (β_1, β_2, β_3) and ζ but the antibonding partners would be increased depending on the magnitude of η′s as indicated by 7_~. This means that the second neighbors play a role of destabilization in more or less extent much like the Madelung contribution in ionic crystals. As a consequence, the face-center (fc) lattice would be less favorable than the body-center (bc) one for alkali crystals, which seems really the case that most alkali metals are of be lattice except for lithium which is of either lattice form.
What is the minimum size of a cluster behaving like a crystal? In other words, when does the discrete energy levels change into continuous bands? By dint of the present results, we try to propose a criterion of maximum energy level separation, 0.02 eV that a finite cluster might behave approximately as a crystal. In order to illustrate the estimation, numerical calculation are given in Table 2.
1988, 4(04): 400-400
doi: 10.3866/PKU.WHXB19880414
Abstract:
1988, 4(04): 401-405
doi: 10.3866/PKU.WHXB19880415
Abstract:
In this work the internal energy angular distributions of the products produced in the atom-diatomic molecule reactive collisions have been calculated using quasiclassical theory. And the vibrational branching ratios were derived from this calculation.
The reactions F+H_2(D_2)→HF(DF)+H(D)were studied with Monte Carlo calaulation of quasiclasscal trajectory method. A potential energy surface of LEPS form was used. A comparison of the results with the experimental data from molecular beam studies shows a fairly od agreement.
In this work the internal energy angular distributions of the products produced in the atom-diatomic molecule reactive collisions have been calculated using quasiclassical theory. And the vibrational branching ratios were derived from this calculation.
The reactions F+H_2(D_2)→HF(DF)+H(D)were studied with Monte Carlo calaulation of quasiclasscal trajectory method. A potential energy surface of LEPS form was used. A comparison of the results with the experimental data from molecular beam studies shows a fairly od agreement.
1988, 4(04): 406-410
doi: 10.3866/PKU.WHXB19880416
Abstract:
The relaxation rates of the V_(l0),v_(11),3v_(l6) and v_4 eight single vibrational levels of benzene have been studied by using IR-UV double resonance technique for the first time. The relaxation processes for these eight vibrational levels all exhibit a feature of two exponential decay, which correspond to the V-V and V-T energy ralaxation process respectively. As an example the values of κ_(V-V) and κ_(V-T) for 16_1 10_1 level are 0.59±0.05 μs~(-1)Torr~(-1) and 0.023±0.003 μs~(-1) Torr~(-1) respectively.
The relaxation rates of the V_(l0),v_(11),3v_(l6) and v_4 eight single vibrational levels of benzene have been studied by using IR-UV double resonance technique for the first time. The relaxation processes for these eight vibrational levels all exhibit a feature of two exponential decay, which correspond to the V-V and V-T energy ralaxation process respectively. As an example the values of κ_(V-V) and κ_(V-T) for 16_1 10_1 level are 0.59±0.05 μs~(-1)Torr~(-1) and 0.023±0.003 μs~(-1) Torr~(-1) respectively.
1988, 4(04): 411-414
doi: 10.3866/PKU.WHXB19880417
Abstract:
Excess enthalpies of partially miscible system 4-methyl-2-pentanol and water were measured with LKB-2107 Flow Microcalorimeter at 293.15 K, 298.15 K, 303.15 K under normal pressure. The results obtained were fitted with Redlich-Kister equation.
The NRTL parameters correlated from the H~E data measured on rich alcohol region were used to predict the vapor-liquid equilibrium under normal pressure with mean deviations of vapor composition and bubble point of 0.02 mole fraction and 1.03 K from the values in literature respectively.
Excess enthalpies of partially miscible system 4-methyl-2-pentanol and water were measured with LKB-2107 Flow Microcalorimeter at 293.15 K, 298.15 K, 303.15 K under normal pressure. The results obtained were fitted with Redlich-Kister equation.
The NRTL parameters correlated from the H~E data measured on rich alcohol region were used to predict the vapor-liquid equilibrium under normal pressure with mean deviations of vapor composition and bubble point of 0.02 mole fraction and 1.03 K from the values in literature respectively.
1988, 4(04): 415-418
doi: 10.3866/PKU.WHXB19880418
Abstract:
Infrared spectra of SF_6 trapped in cryogenic matrix of ar n have been measured. Five peaks are observed at the frequencies of 938.51, 938.05, 937.55, 939.82 and 936.22 cm~(-1) for the v_3 mode. Varying the concentration of SF_6 in ar n matrix and diffusion studies indicate that the 937.55 cm~(-1) peak is due to SF_6 aggregate and the others arise from monomer. The changes in relative intensities with annealing show that there are at least three different trapping sites for monomeric SF_6 in ar n lattice. The result that the increase in intensity of the peak at 938.03 cm~(-1) parallels the decrease in that of the peak at 938.51 cm~(-1) implies a temperature-induced-change in the site population.
Infrared spectra of SF_6 trapped in cryogenic matrix of ar n have been measured. Five peaks are observed at the frequencies of 938.51, 938.05, 937.55, 939.82 and 936.22 cm~(-1) for the v_3 mode. Varying the concentration of SF_6 in ar n matrix and diffusion studies indicate that the 937.55 cm~(-1) peak is due to SF_6 aggregate and the others arise from monomer. The changes in relative intensities with annealing show that there are at least three different trapping sites for monomeric SF_6 in ar n lattice. The result that the increase in intensity of the peak at 938.03 cm~(-1) parallels the decrease in that of the peak at 938.51 cm~(-1) implies a temperature-induced-change in the site population.
1988, 4(04): 419-423
doi: 10.3866/PKU.WHXB19880419
Abstract:
In order to get a better insight into the structural features of the benzo-12-crown-4 molecule, the determination of its crystal structure has been undertaken, while the electronic structure was calculated. The crystal belongs to monoclinic with space group p2_1/a and cell dimensions a=0.8011(2), b=3.3560(2), c=0.8435(7) nm, β=91.06(2)°, V=2.2674 nm, z=8 and D_C=1.31 g cm~(-3). Full matrix leastsquares refinement with isotropic thermal parameters for H and anisotropic for the other atoms converged at R=0.062 and R_W=0.050. There are two molecules in an asymmetric unit. In comparison with 12-crown-4, the molecule has an entirely different conformation, having the carbon atom C(110) twisted to the center of the 12-membered ring. The MINDO/3-SCF calculation has been carried out on an M-340 computer, and the geometrical and electronic structure features of the molecule were discussed.
In order to get a better insight into the structural features of the benzo-12-crown-4 molecule, the determination of its crystal structure has been undertaken, while the electronic structure was calculated. The crystal belongs to monoclinic with space group p2_1/a and cell dimensions a=0.8011(2), b=3.3560(2), c=0.8435(7) nm, β=91.06(2)°, V=2.2674 nm, z=8 and D_C=1.31 g cm~(-3). Full matrix leastsquares refinement with isotropic thermal parameters for H and anisotropic for the other atoms converged at R=0.062 and R_W=0.050. There are two molecules in an asymmetric unit. In comparison with 12-crown-4, the molecule has an entirely different conformation, having the carbon atom C(110) twisted to the center of the 12-membered ring. The MINDO/3-SCF calculation has been carried out on an M-340 computer, and the geometrical and electronic structure features of the molecule were discussed.
1988, 4(04): 424-427
doi: 10.3866/PKU.WHXB19880420
Abstract:
A thermostatic method for reversible reactions is derived in this paper. The method is suitable to reactions in which two reactants are ligand and univalent cation. This method has been used to study complex reaction of Dibenzo-18-Crown-6 and Na~+. The values of ΔH and K~(°-) calculated with this method are in agreement with those in literature.
A thermostatic method for reversible reactions is derived in this paper. The method is suitable to reactions in which two reactants are ligand and univalent cation. This method has been used to study complex reaction of Dibenzo-18-Crown-6 and Na~+. The values of ΔH and K~(°-) calculated with this method are in agreement with those in literature.
1988, 4(04): 428-431
doi: 10.3866/PKU.WHXB19880421
Abstract:
The cluster (C_6H_5CO_2CH_2C)_2Co_2(CO)_6 has been synthesized and characterized by element analysis, IR, ~1H NMR etc. Its crystal structure has been determined by X-ray diffraction analysis with R=0.060. The crystal is triclinic, space group P_1 with a=0.8933(3) nm, b=1.1830(6) nm, c=1.3199(3) nm, α=65.64(3)°, β=84.55(3)°, γ=72.03(4)°, z=2, D_x=1.584 g cm~(-1) The C≡C and Co-Co form a tetrahedron with appoximate C_(2V) symmetry. The Co-Co bond is metl singal bond. The hybrid state of carbon atoms in the acetylene is between sp and sp~2.
The cluster (C_6H_5CO_2CH_2C)_2Co_2(CO)_6 has been synthesized and characterized by element analysis, IR, ~1H NMR etc. Its crystal structure has been determined by X-ray diffraction analysis with R=0.060. The crystal is triclinic, space group P_1 with a=0.8933(3) nm, b=1.1830(6) nm, c=1.3199(3) nm, α=65.64(3)°, β=84.55(3)°, γ=72.03(4)°, z=2, D_x=1.584 g cm~(-1) The C≡C and Co-Co form a tetrahedron with appoximate C_(2V) symmetry. The Co-Co bond is metl singal bond. The hybrid state of carbon atoms in the acetylene is between sp and sp~2.
1988, 4(04): 432-435
doi: 10.3866/PKU.WHXB19880422
Abstract:
The kinetics of oxidation of glycol and propanediol-1,2 by potassium diperiodatocuprate(Ⅲ) has been studied spectrophotometrically in alkaline medium at 25 ℃. The order with respect to Cu(Ⅲ) is found to be unity and that in α-diol to be about 1,7. The rate decreases with the increase of periodate concertration and increases with the increase of [OH~-]. The linear relationships between [a-diol]/κ′ and 1/[α-diol] and between 1/κ′ and [IO_4~-] are observed in our experiment, where κ′ is pesudo first-order rate constant. There is a negative ionic strength effect and under the protection of nitrogen gas, the reaction system can induce polymerization of acrylamide. The active species is assumed and a plausible mechanish involing free radical has been proposed. All the experimental phenomena can be explained by the rate equation derived from the mechanism. The second-order rate constants κ of rate-controlling steps fro glycol and propanediol-1, 2 are 0.42 and 1.60 mol~(-1)·L·s~(-1) respectively at 25 ℃.
The kinetics of oxidation of glycol and propanediol-1,2 by potassium diperiodatocuprate(Ⅲ) has been studied spectrophotometrically in alkaline medium at 25 ℃. The order with respect to Cu(Ⅲ) is found to be unity and that in α-diol to be about 1,7. The rate decreases with the increase of periodate concertration and increases with the increase of [OH~-]. The linear relationships between [a-diol]/κ′ and 1/[α-diol] and between 1/κ′ and [IO_4~-] are observed in our experiment, where κ′ is pesudo first-order rate constant. There is a negative ionic strength effect and under the protection of nitrogen gas, the reaction system can induce polymerization of acrylamide. The active species is assumed and a plausible mechanish involing free radical has been proposed. All the experimental phenomena can be explained by the rate equation derived from the mechanism. The second-order rate constants κ of rate-controlling steps fro glycol and propanediol-1, 2 are 0.42 and 1.60 mol~(-1)·L·s~(-1) respectively at 25 ℃.
1988, 4(04): 436-440
doi: 10.3866/PKU.WHXB19880423
Abstract:
Propylene oxide catalytically dissociates at the silver wire. The first-step product of this reaction is not acetone, but propyl aldehyde. According to the new assumptions suggested, the reaction probability per encounter has been simulated by
p_m=∫~∞_(E_0) 1/(kT) e~(-E/kT)dE/∫~∞_(E_d) 1/(kT)e~(-E/kT)dE
and a satisfactory result has been achieved in both qualitative and quantitative aspects. The energy transfer efficiency at gas-solid surface and the essence of catalytic action have also been reviewed concisely.
Propylene oxide catalytically dissociates at the silver wire. The first-step product of this reaction is not acetone, but propyl aldehyde. According to the new assumptions suggested, the reaction probability per encounter has been simulated by
p_m=∫~∞_(E_0) 1/(kT) e~(-E/kT)dE/∫~∞_(E_d) 1/(kT)e~(-E/kT)dE
and a satisfactory result has been achieved in both qualitative and quantitative aspects. The energy transfer efficiency at gas-solid surface and the essence of catalytic action have also been reviewed concisely.
1988, 4(04): 441-444
doi: 10.3866/PKU.WHXB19880424
Abstract:
In this paper, the structure of ZnO-SiO_2 prepared by precipitation method has been studied by XRD, XPS and surface acidity measurement. The results show that ZnO is dispersed on the surface of SiO_2 as a monolayer and has its utmost dispersion capacity (threshold) for this series of samples as well as for the reported ZnO/SiO_2 which were prepared by impregnation. And there are some stronger surface bonding between ZnO and SiO_2 for these two series of samples.
In the light of this view, the trend of chang of the density of surface acidic sites and the results of XRD for ZnO-SiO_2 reported by Sumiyoshi, Tanabe et al~[2] can be also interpreted satisfactorily.
In addition, authors proposed some comments on “the model structure of binary oxides” in the light of bond valence theory.
In this paper, the structure of ZnO-SiO_2 prepared by precipitation method has been studied by XRD, XPS and surface acidity measurement. The results show that ZnO is dispersed on the surface of SiO_2 as a monolayer and has its utmost dispersion capacity (threshold) for this series of samples as well as for the reported ZnO/SiO_2 which were prepared by impregnation. And there are some stronger surface bonding between ZnO and SiO_2 for these two series of samples.
In the light of this view, the trend of chang of the density of surface acidic sites and the results of XRD for ZnO-SiO_2 reported by Sumiyoshi, Tanabe et al~[2] can be also interpreted satisfactorily.
In addition, authors proposed some comments on “the model structure of binary oxides” in the light of bond valence theory.
1988, 4(04): 445-448
doi: 10.3866/PKU.WHXB19880425
Abstract:
The behaviour of the Nickel(Ⅱ) ion in the presence of dimethyl-glyoxime (DMG) on the hanging mercury drop electrode in NH_3/NH_4Cl media was investigated with different electrochemical techniques. It was found that: (1) the reactant was Ni(Ⅱ) complex with DMG, Ni(Ⅱ)A_2, adsorbed on the electrode surface; (2) the intermediate was Ni(Ⅰ)A_2 and (3) the product was metal amalgam Ni(0)(Hg). Two electrons were transferred in the overall reaction and the transfer coefficient was 1.8 which was measured experimentally. From experimental results, it was obvious that the reaction orders with respect to Ni(Ⅱ), DMG and H~+ were 1,2, and 1, respectively. A new compound, X, was detected. The reaction scheme could be written as follows
Ni(Ⅱ)A_2+Hg<=>Ni(Ⅱ)A_2(ads)(Hg)
Ni(Ⅱ)A_2(ads)(Hg)+e~-<=>Ni(Ⅰ)A_2(ads)(Hg)
Ni(Ⅰ)A_2(ads)(Hg)+H~++e~-→Ni(0)(Hg)+HA(des)+A~-(des)
→X+Hg
The behaviour of the Nickel(Ⅱ) ion in the presence of dimethyl-glyoxime (DMG) on the hanging mercury drop electrode in NH_3/NH_4Cl media was investigated with different electrochemical techniques. It was found that: (1) the reactant was Ni(Ⅱ) complex with DMG, Ni(Ⅱ)A_2, adsorbed on the electrode surface; (2) the intermediate was Ni(Ⅰ)A_2 and (3) the product was metal amalgam Ni(0)(Hg). Two electrons were transferred in the overall reaction and the transfer coefficient was 1.8 which was measured experimentally. From experimental results, it was obvious that the reaction orders with respect to Ni(Ⅱ), DMG and H~+ were 1,2, and 1, respectively. A new compound, X, was detected. The reaction scheme could be written as follows
Ni(Ⅱ)A_2+Hg<=>Ni(Ⅱ)A_2(ads)(Hg)
Ni(Ⅱ)A_2(ads)(Hg)+e~-<=>Ni(Ⅰ)A_2(ads)(Hg)
Ni(Ⅰ)A_2(ads)(Hg)+H~++e~-→Ni(0)(Hg)+HA(des)+A~-(des)
→X+Hg
