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1987 Volume 3 Issue 2
1987, 3(02): 113-115
doi: 10.3866/PKU.WHXB19870201
Abstract:
In this paper, firstly, we have been studied the multiplication curves of E. coli at exponential phase of growth at 37 ℃ using microcalorimeter, LKB 2277 Bioactivity Monitor, and calculated the multiplication rate constant of E.coli using computer, which is k=0.0397±0.0025 min~(-1). Generation time, G=17.47 minutes, has been obtained from formula G=ln2/k, which is in close agreement with liter- ature value, G=17 minutes. Secondiy, using above method, rate constants of E. coli at different temperatures at exponential of growth have been determined. Finally, according to Arrhenius equation, the activation energy of E. coli multiplication has been obtained, which is 53.09 kJ mol~(-1).
In this paper, firstly, we have been studied the multiplication curves of E. coli at exponential phase of growth at 37 ℃ using microcalorimeter, LKB 2277 Bioactivity Monitor, and calculated the multiplication rate constant of E.coli using computer, which is k=0.0397±0.0025 min~(-1). Generation time, G=17.47 minutes, has been obtained from formula G=ln2/k, which is in close agreement with liter- ature value, G=17 minutes. Secondiy, using above method, rate constants of E. coli at different temperatures at exponential of growth have been determined. Finally, according to Arrhenius equation, the activation energy of E. coli multiplication has been obtained, which is 53.09 kJ mol~(-1).
1987, 3(02): 116-118
doi: 10.3866/PKU.WHXB19870202
Abstract:
According to Watson′s DSC principle, a new design of electric circuit of DSC was proposed, Referring to the instrument constraction of DSC of Perkin-Elmer corporation, a new instrument construction of DSC was designed.This new electric circuit and this new instrument construction can overcome the shortcomings in de- sign of DSC of Perkin-Elmer corporation, Figure 1 is a schematic diagram of the new electric circuit. The temperatures and enthalpies of phase transitions of stan- dard materials were measured by using the new DSC. The experimental results are shown in table 1.
According to Watson′s DSC principle, a new design of electric circuit of DSC was proposed, Referring to the instrument constraction of DSC of Perkin-Elmer corporation, a new instrument construction of DSC was designed.This new electric circuit and this new instrument construction can overcome the shortcomings in de- sign of DSC of Perkin-Elmer corporation, Figure 1 is a schematic diagram of the new electric circuit. The temperatures and enthalpies of phase transitions of stan- dard materials were measured by using the new DSC. The experimental results are shown in table 1.
1987, 3(02): 119-122
doi: 10.3866/PKU.WHXB19870203
Abstract:
The in-situ, highly spatial resolution, two-dimensional distribution of OH(X) species in a premixed liquified petroleum gas/air flame is reported. The measure- ment was performed by the saturated laser induced fluorescence method with the tran- sitions of OH (A~(2∑~+), v′=0←→X~(2Π), v″=0). The intensities of the broadband emission reflected the local concent ations of OH(X) in the flame.
The result showed that OH(X) populated at the rim of the visual flame.
State-to-state reactions related to OH(X) radical in flame condition are discussed. OH(X) was produced from the oxidation of small hydrogen-containing radicals. The consumption of OH(X) seemed via reaction (10) and (11). The population of OH(A) species is also discussed.
The in-situ, highly spatial resolution, two-dimensional distribution of OH(X) species in a premixed liquified petroleum gas/air flame is reported. The measure- ment was performed by the saturated laser induced fluorescence method with the tran- sitions of OH (A~(2∑~+), v′=0←→X~(2Π), v″=0). The intensities of the broadband emission reflected the local concent ations of OH(X) in the flame.
The result showed that OH(X) populated at the rim of the visual flame.
State-to-state reactions related to OH(X) radical in flame condition are discussed. OH(X) was produced from the oxidation of small hydrogen-containing radicals. The consumption of OH(X) seemed via reaction (10) and (11). The population of OH(A) species is also discussed.
1987, 3(02): 123-128
doi: 10.3866/PKU.WHXB19870204
Abstract:
This paper reports the results of a study devoted to the hydrogen production from liquid water on Co_3O_4/SrTiO_3 powders under UV irradiation. The results indi- cated that the photocatalysts behave rather actively in alkali solution. A strong con- centration dependence of OH~- for the rate of H_2 formation was observed. Reduction pretreatment of the photocatalysts by H_2 is unfavourable for the H_2 production, but an oxidation pretreatment by O_2 may improve remarkably the catalytic effi- ciency. By using SPV technique and ESR, it is found that near and above valence band of SrTiO_3 the photocatalysts have band-gap surface states, which may associate with surface cobalt ions. We believe that the surface states play a key role in the charge separation and transfer processes. Finally, a mechanism model is proposed.
This paper reports the results of a study devoted to the hydrogen production from liquid water on Co_3O_4/SrTiO_3 powders under UV irradiation. The results indi- cated that the photocatalysts behave rather actively in alkali solution. A strong con- centration dependence of OH~- for the rate of H_2 formation was observed. Reduction pretreatment of the photocatalysts by H_2 is unfavourable for the H_2 production, but an oxidation pretreatment by O_2 may improve remarkably the catalytic effi- ciency. By using SPV technique and ESR, it is found that near and above valence band of SrTiO_3 the photocatalysts have band-gap surface states, which may associate with surface cobalt ions. We believe that the surface states play a key role in the charge separation and transfer processes. Finally, a mechanism model is proposed.
1987, 3(02): 129-135
doi: 10.3866/PKU.WHXB19870205
Abstract:
Viscosity measurements havebeen made to determine the specificity of some counterions to induce the growth of micelles. From the intrinsic viscosity values abtained several basic micellar parameters including the thermodynamic parameter K, verning the sphere-to-rod transition in the micelle growth process, and the weight average aggregation number of polydisperse micelles, n_w, were calculated based on a thermodynamic model for micellization developed by Missel et al. The elongation of tetradecylpyridinium bromide micelles in aqueous solutions are induced by the monovalent anions Br~-, NO_3~-, ClO_3~-, the efficiency is ClO_3~->NO_3~->Br~-. In both 0.5 mol L~(-1) NaBr and KNO_3 Solutions a constancy of K was observed over a suitable range of ampnipnile concentrations. The parameter K as well as the parameter n_w calculated as a function of amphiphile concentrations are in od agreement with those obtained by static and dynamic light scattering techniques. In 0.5 mol L~(-1) KClO_3 solution, the parameter K becomes remarkably concentration-dependent and an obvious discrepancy in the determined parameter n_w between the two methods is observed, which demonstrates the invalidity of the model.
Viscosity measurements havebeen made to determine the specificity of some counterions to induce the growth of micelles. From the intrinsic viscosity values abtained several basic micellar parameters including the thermodynamic parameter K, verning the sphere-to-rod transition in the micelle growth process, and the weight average aggregation number of polydisperse micelles, n_w, were calculated based on a thermodynamic model for micellization developed by Missel et al. The elongation of tetradecylpyridinium bromide micelles in aqueous solutions are induced by the monovalent anions Br~-, NO_3~-, ClO_3~-, the efficiency is ClO_3~->NO_3~->Br~-. In both 0.5 mol L~(-1) NaBr and KNO_3 Solutions a constancy of K was observed over a suitable range of ampnipnile concentrations. The parameter K as well as the parameter n_w calculated as a function of amphiphile concentrations are in od agreement with those obtained by static and dynamic light scattering techniques. In 0.5 mol L~(-1) KClO_3 solution, the parameter K becomes remarkably concentration-dependent and an obvious discrepancy in the determined parameter n_w between the two methods is observed, which demonstrates the invalidity of the model.
1987, 3(02): 136-140
doi: 10.3866/PKU.WHXB19870206
Abstract:
Using laser induced fluorescence technique and shifting the position of the burner, two-dimensional concentration distribution diagrams of C_2(X) and CH(X) radicals in a part premixed, rich LPG/air flame were first obtained. The excita- tion and the detection bands were (0, 0) and (0, 1) of C_2(A~(3Π)←→X~(3Π)) transitions respectively, while for CH(X) species, the transition of B~(2∑), v′=0←X~(2Π), v″=0 was excited and the followed process A~(2Δ), v′=0→X~(2Π), v″=0 was detec- ted.
Both C_2(X) and CH(X) radicals concentrated in the thin layer of the inner cone of the flame and in an ellipsoid beyond the cone. C_2 was generated via pyrolysis and then agglomerated to form carbon particles. CH was produced from the reaction of small hydrocarbon radicals with oxygen and/or oxides in flame.
Using laser induced fluorescence technique and shifting the position of the burner, two-dimensional concentration distribution diagrams of C_2(X) and CH(X) radicals in a part premixed, rich LPG/air flame were first obtained. The excita- tion and the detection bands were (0, 0) and (0, 1) of C_2(A~(3Π)←→X~(3Π)) transitions respectively, while for CH(X) species, the transition of B~(2∑), v′=0←X~(2Π), v″=0 was excited and the followed process A~(2Δ), v′=0→X~(2Π), v″=0 was detec- ted.
Both C_2(X) and CH(X) radicals concentrated in the thin layer of the inner cone of the flame and in an ellipsoid beyond the cone. C_2 was generated via pyrolysis and then agglomerated to form carbon particles. CH was produced from the reaction of small hydrocarbon radicals with oxygen and/or oxides in flame.
1987, 3(02): 141-145
doi: 10.3866/PKU.WHXB19870207
Abstract:
Infrared and Raman spectra of W_6O_(19)~(2-) were measured, and the normal coordi- nate analysis was performed for the W_6O_(19)~(2-) anion by using general valence force field (GVFF), Urey-Bradley force field (UBFF) and modified Urey-Bradley force field (MUBFF). The later is the best one,and the result is given. The sym- metrical coordinates consisted of 132 internal coordinates were used, in order to split the secular equations into blocks and assign the symmetrical species of the vibrations. For the terminal oxygen exhibit stronger electric negativity, repulsive forces among them were considered in MUBFF, and an improved result was obtained at high wavenumbers. Although the central oxygen atom exhibits ion character, the contributions of the internal coordinates associated with it should not be ignored. However, these coordinates only show an effect on IR active bands, and so Raman active bands 230 cm~(-1) (A_(1g)) and 122 cm~(-1) (E_g) can′t be assigned as W-O_c stretching. Moreover, the Raman band 122 cm~(-1) assigned as F_(2g) was found following the prediction of the calculation.
Infrared and Raman spectra of W_6O_(19)~(2-) were measured, and the normal coordi- nate analysis was performed for the W_6O_(19)~(2-) anion by using general valence force field (GVFF), Urey-Bradley force field (UBFF) and modified Urey-Bradley force field (MUBFF). The later is the best one,and the result is given. The sym- metrical coordinates consisted of 132 internal coordinates were used, in order to split the secular equations into blocks and assign the symmetrical species of the vibrations. For the terminal oxygen exhibit stronger electric negativity, repulsive forces among them were considered in MUBFF, and an improved result was obtained at high wavenumbers. Although the central oxygen atom exhibits ion character, the contributions of the internal coordinates associated with it should not be ignored. However, these coordinates only show an effect on IR active bands, and so Raman active bands 230 cm~(-1) (A_(1g)) and 122 cm~(-1) (E_g) can′t be assigned as W-O_c stretching. Moreover, the Raman band 122 cm~(-1) assigned as F_(2g) was found following the prediction of the calculation.
1987, 3(02): 146-154
doi: 10.3866/PKU.WHXB19870208
Abstract:
The solubilities of o, m, p-xylene in water as well as in the aqueous salt solution were determined at 25 ℃ by spectrophotometer. The activity coefficient (f) of each of the xylenes has also been calculated. The salts used are LiCl, NaCl, KCl, SrCl_2, BaCl_2, LiBr, NaBr and KBr.
The salt concentrations (c_s) used are 0-1 mol L~(-1). When logf were ploted vs. c_s for eight salts, the obtained results are all straight lines. On comparison of the slopes of these 24 lines, the salting-out order is BaCl_2>SrCl_2>NaCl>KCl>NaBr≈LiCl>KBr>LiBr for each of the xylenes.
The salt effect constant k_s can be expressed in terms of the sum of k_+ and k_-. The values of k_ decreases with the increase of the dipole moment of the xylene molecule.
The salting-out constants of these xylenes in eight aqueous salt solutions have been calculated respectively by the formulas of (1) Debye-McAulay, (2) Conway-Desnoyers-Smith, (3) McDevit-Long and (4) modified internal pressure theory.
Some assumtions were made for the modified equation of the internal pressure theory. When the distance between ion and nonelectrolyte molecule in aqueous salt solution was calculated, Latimer′s radii are used instead of the Pauling′s radii of ions. For larger nonelectrolyte molecules, equation of the modified internal pressure theory (4) given results in better agreement with the experiment than those of (1), (2) and (3).
The solubilities of o, m, p-xylene in water as well as in the aqueous salt solution were determined at 25 ℃ by spectrophotometer. The activity coefficient (f) of each of the xylenes has also been calculated. The salts used are LiCl, NaCl, KCl, SrCl_2, BaCl_2, LiBr, NaBr and KBr.
The salt concentrations (c_s) used are 0-1 mol L~(-1). When logf were ploted vs. c_s for eight salts, the obtained results are all straight lines. On comparison of the slopes of these 24 lines, the salting-out order is BaCl_2>SrCl_2>NaCl>KCl>NaBr≈LiCl>KBr>LiBr for each of the xylenes.
The salt effect constant k_s can be expressed in terms of the sum of k_+ and k_-. The values of k_ decreases with the increase of the dipole moment of the xylene molecule.
The salting-out constants of these xylenes in eight aqueous salt solutions have been calculated respectively by the formulas of (1) Debye-McAulay, (2) Conway-Desnoyers-Smith, (3) McDevit-Long and (4) modified internal pressure theory.
Some assumtions were made for the modified equation of the internal pressure theory. When the distance between ion and nonelectrolyte molecule in aqueous salt solution was calculated, Latimer′s radii are used instead of the Pauling′s radii of ions. For larger nonelectrolyte molecules, equation of the modified internal pressure theory (4) given results in better agreement with the experiment than those of (1), (2) and (3).
1987, 3(02): 155-161
doi: 10.3866/PKU.WHXB19870209
Abstract:
The reactions of F atoms with C_2H_I, C_2F_5I, and C_3H_5I has been studied by the crossed beam laser-induced fluorescence technique within the 570-620 nm wa- velength region. The vibrational and rotational excitation spectra of the reaction product IF were measured. The relative vibrational population densities of v=3, 4, and 5 vibrational levels, and some of the relative fine vibrational rate con- stants, the rotational temperatures, and the mean fractions of rotational energy in individual vibrational states of the reaction product IF were obtained.
The experimental results show that the vibrational state distributions for the products of the reactions F+C_2H_5I and F+C_2F_5I among the v=3, 4 and 5 levels are essentially statistical. This indicates that mechanism of indirect reaction exists in the reactions of F atoms with iodides of saturated or fluorinated polyatomic radicals. The vibrational state distributions for the product of the reaction F+C_3H_5I exhibits population inversion among the v=3, 4 and 5 leveles. This indicates that mechanism of direct reaction exists in the reactions of F atoms with iodides of unsaturated polyatomic radicals.
The reactions of F atoms with C_2H_I, C_2F_5I, and C_3H_5I has been studied by the crossed beam laser-induced fluorescence technique within the 570-620 nm wa- velength region. The vibrational and rotational excitation spectra of the reaction product IF were measured. The relative vibrational population densities of v=3, 4, and 5 vibrational levels, and some of the relative fine vibrational rate con- stants, the rotational temperatures, and the mean fractions of rotational energy in individual vibrational states of the reaction product IF were obtained.
The experimental results show that the vibrational state distributions for the products of the reactions F+C_2H_5I and F+C_2F_5I among the v=3, 4 and 5 levels are essentially statistical. This indicates that mechanism of indirect reaction exists in the reactions of F atoms with iodides of saturated or fluorinated polyatomic radicals. The vibrational state distributions for the product of the reaction F+C_3H_5I exhibits population inversion among the v=3, 4 and 5 leveles. This indicates that mechanism of direct reaction exists in the reactions of F atoms with iodides of unsaturated polyatomic radicals.
1987, 3(02): 162-169
doi: 10.3866/PKU.WHXB19870210
Abstract:
The state population distributions of the nascent products for Ca+NF_3→CaF+ NF_2 and Ca+CHF_3→-CaF+CHF_2 reactions were studied by means of LIF in a beam- gas arrangement. From the LIF spectra of CaF and the computer simulations, the CaF vibrational distributions for both reactions were found to be similar to the Boltzmann distribution and the internal energy disposal of CaF was determined quantitatively.The results of the spectral simulation and the information theory computation indicate that NF_2 and CHF_2 radicals were vibrationally and rotationally excited. These two reactions are thought to be direct collision reactions with the “late” exoergicity on potential surface.
The state population distributions of the nascent products for Ca+NF_3→CaF+ NF_2 and Ca+CHF_3→-CaF+CHF_2 reactions were studied by means of LIF in a beam- gas arrangement. From the LIF spectra of CaF and the computer simulations, the CaF vibrational distributions for both reactions were found to be similar to the Boltzmann distribution and the internal energy disposal of CaF was determined quantitatively.The results of the spectral simulation and the information theory computation indicate that NF_2 and CHF_2 radicals were vibrationally and rotationally excited. These two reactions are thought to be direct collision reactions with the “late” exoergicity on potential surface.
1987, 3(02): 170-177
doi: 10.3866/PKU.WHXB19870211
Abstract:
This paper reports our study on thermodynamic properties of HCl+NaCl+ 2-propanol+H_2O system by means of emf measurements of the cells without liquid junction,
Pt, H_2(1atm)|HCl(m), 2-propanol(x), H_2O(1-x)|AgCl-Ag (A)
Pt, H_2(1atm)|HCl(m_A), NaCl(m_B), 2-propanol(x), H_2O(1-x)|AgCl-Ag (B)
at constant total ionic strenths I=0.5, 1.0, 2.0 and 3.0 mol kg~(-1), from 5 to 45 ℃, where m_A and m_B are the molalities of HCl and NaCl, respectively, x is the mo- lar fraction of 2-propanol in the mixed solvent, which is 0.05 during all measurements.
The standard electrode potential of Ag-AgCl in mixed solvent have been determined from equation (1) and using emf data of the cell (A) in table 1. The transfer properties of HCl have been calculated and listed in table 2. Using emf of cell (B), the activity coefficients of HCl, γ_A, in the system have determined according to equation (16).
The results show that HCl obeyes Harned Rule up to I=3.0 mol kg~(-1) over a range 15—45 ℃ (Fig.1). Under the condition of constant components of mixture, the logarithm of HCl activity coefficients, logγ_A are a linear function for reciprocal of temperatures equation (17). The primary, secondary and total medium effect of HCl have been calculated and discused (see table 5).
This paper reports our study on thermodynamic properties of HCl+NaCl+ 2-propanol+H_2O system by means of emf measurements of the cells without liquid junction,
Pt, H_2(1atm)|HCl(m), 2-propanol(x), H_2O(1-x)|AgCl-Ag (A)
Pt, H_2(1atm)|HCl(m_A), NaCl(m_B), 2-propanol(x), H_2O(1-x)|AgCl-Ag (B)
at constant total ionic strenths I=0.5, 1.0, 2.0 and 3.0 mol kg~(-1), from 5 to 45 ℃, where m_A and m_B are the molalities of HCl and NaCl, respectively, x is the mo- lar fraction of 2-propanol in the mixed solvent, which is 0.05 during all measurements.
The standard electrode potential of Ag-AgCl in mixed solvent have been determined from equation (1) and using emf data of the cell (A) in table 1. The transfer properties of HCl have been calculated and listed in table 2. Using emf of cell (B), the activity coefficients of HCl, γ_A, in the system have determined according to equation (16).
The results show that HCl obeyes Harned Rule up to I=3.0 mol kg~(-1) over a range 15—45 ℃ (Fig.1). Under the condition of constant components of mixture, the logarithm of HCl activity coefficients, logγ_A are a linear function for reciprocal of temperatures equation (17). The primary, secondary and total medium effect of HCl have been calculated and discused (see table 5).
1987, 3(02): 178-184
doi: 10.3866/PKU.WHXB19870212
Abstract:
The SERS spectra of ammonia adsorbed on Ag electrode were obtained when the electrodes were treated by cyclic electrochemical oxidation and reduction in 0.1 mol L~(-1) NH_3+0.1 mol L~(-1) NH_4Cl solutions. The enhancement factor was estimated as high s 1.2×10~5. In order to observe the intense SERS spectra, the bulk con- centration of ammonia should be lower, but the high concentration of Cl~- is favo- rable. It was found that, in the non-Faradaic region, the SERS intensity decreases irreversibly and the position of band shifts toward loward lower wavenumber with the electrode potential made negative.
It can be seen that SERS spectrum of the adsorbed ammonia is similar to the normal Raman spectrum of Ag(NH_3)_2NO_3, which implies that Ag(δ+)—NH_3 surface complex is likely to exist on the Ag electrode and bring about the SERS effect.
The possible schemes of Ag(δ+)—NH_3 surface complex is given. The orientation of the adsorbed NH_3 is perpendicular to surface rather than inclined.
The SERS spectra of ammonia adsorbed on Ag electrode were obtained when the electrodes were treated by cyclic electrochemical oxidation and reduction in 0.1 mol L~(-1) NH_3+0.1 mol L~(-1) NH_4Cl solutions. The enhancement factor was estimated as high s 1.2×10~5. In order to observe the intense SERS spectra, the bulk con- centration of ammonia should be lower, but the high concentration of Cl~- is favo- rable. It was found that, in the non-Faradaic region, the SERS intensity decreases irreversibly and the position of band shifts toward loward lower wavenumber with the electrode potential made negative.
It can be seen that SERS spectrum of the adsorbed ammonia is similar to the normal Raman spectrum of Ag(NH_3)_2NO_3, which implies that Ag(δ+)—NH_3 surface complex is likely to exist on the Ag electrode and bring about the SERS effect.
The possible schemes of Ag(δ+)—NH_3 surface complex is given. The orientation of the adsorbed NH_3 is perpendicular to surface rather than inclined.
1987, 3(02): 185-191
doi: 10.3866/PKU.WHXB19870213
Abstract:
A computing model is presented for the calculation of the transient population distribution of polyatomic molecules excited by an IR laser pulse, SF_6 has been used as an example. This model allows the calculation of the vibrational energy distributions from the observed IR fluorescence or absorption spectrum, and vice versa. The thermal vibrational distribution calculated by this model from the mea- sured spectrum of SF_6 at 300 K is in od agreement with the Boltzmann distribu- tion (Table 1). The present model has a few advantages over an earlier study~[1], such as higher precision of computation, accurate generation of the vibrational transition matrix and being capable of calculating the transient vibrational population distribution at any instant after laser excitation. Using this model a rotationally resolved spectrum of SF_6 at 20 K has been obtained for the first time.
A computing model is presented for the calculation of the transient population distribution of polyatomic molecules excited by an IR laser pulse, SF_6 has been used as an example. This model allows the calculation of the vibrational energy distributions from the observed IR fluorescence or absorption spectrum, and vice versa. The thermal vibrational distribution calculated by this model from the mea- sured spectrum of SF_6 at 300 K is in od agreement with the Boltzmann distribu- tion (Table 1). The present model has a few advantages over an earlier study~[1], such as higher precision of computation, accurate generation of the vibrational transition matrix and being capable of calculating the transient vibrational population distribution at any instant after laser excitation. Using this model a rotationally resolved spectrum of SF_6 at 20 K has been obtained for the first time.
1987, 3(02): 192-196
doi: 10.3866/PKU.WHXB19870214
Abstract:
In this paper, properties of molecular graphs with partly identical topological spectra has been discussed in detail. The concept of pseudo-reflection plane has been described and illustrated by a few examples. The molecular graph G which does not contain the plane of symmetry is said to have a pseudo-reflection plane σ_p if there exists a symmetry plane in a deleting graph G_a′. The G is partitioned into two parts G_(A1)(σ_p), G_(A2)(σ_p) by the plane σ_p. The conjugated species G_(A1)(σ_p)、 G_(A2)(σ_p) are isospectral or partly isospectral molecules if the construction of G_(A1)(σ_p)、G_(A2)(σ_p) are not identical.
In this present article a straight chain containing three vertices has been studied. This graph stands for a general result result of the deletion of numerous partly isospectral molecules.
In this paper, properties of molecular graphs with partly identical topological spectra has been discussed in detail. The concept of pseudo-reflection plane has been described and illustrated by a few examples. The molecular graph G which does not contain the plane of symmetry is said to have a pseudo-reflection plane σ_p if there exists a symmetry plane in a deleting graph G_a′. The G is partitioned into two parts G_(A1)(σ_p), G_(A2)(σ_p) by the plane σ_p. The conjugated species G_(A1)(σ_p)、 G_(A2)(σ_p) are isospectral or partly isospectral molecules if the construction of G_(A1)(σ_p)、G_(A2)(σ_p) are not identical.
In this present article a straight chain containing three vertices has been studied. This graph stands for a general result result of the deletion of numerous partly isospectral molecules.
1987, 3(02): 197-203
doi: 10.3866/PKU.WHXB19870215
Abstract:
The vibrational energy transfer in SF_6-UF_6 system has been investigated using a pulsed TEA CO_2 laser for excitation of SF_6 and SF_6~* is employed as a sensitizer to excite UF_6 molecule. The transient changes in UV absorption of the vibration- ally excited UF_6 molecules in 220-320 nm region have been observed. For 2.0 Torr SF_6+2.0 Torr UF_6 system, three different kinds of vibrationally excited UF_6 have been found and their V-V intermolecular energy transfer times are 6.8, 9.0 and 26 μs, the V-T energy relaxation times are 42, 8.0 and 1 ms respectively. The vibrational energy transfer mechanism of SF_6-UF_6 system has been discussed.
The vibrational energy transfer in SF_6-UF_6 system has been investigated using a pulsed TEA CO_2 laser for excitation of SF_6 and SF_6~* is employed as a sensitizer to excite UF_6 molecule. The transient changes in UV absorption of the vibration- ally excited UF_6 molecules in 220-320 nm region have been observed. For 2.0 Torr SF_6+2.0 Torr UF_6 system, three different kinds of vibrationally excited UF_6 have been found and their V-V intermolecular energy transfer times are 6.8, 9.0 and 26 μs, the V-T energy relaxation times are 42, 8.0 and 1 ms respectively. The vibrational energy transfer mechanism of SF_6-UF_6 system has been discussed.
1987, 3(02): 204-208
doi: 10.3866/PKU.WHXB19870216
Abstract:
The adsorption heats on h-mordenite (HM) have been investigated by flow-DTA adsorptive calorimetric technique. Plots of differential absorption heats. (Q_d) of ammonia, pyridine, benzene, toluene and p-xylene at 200 ℃ against varying adsorption amounts (A) were given respectively. There appears a turning point on the plot of Q_d of ammonia vs. A, which shows that there are two kinds of acid sites on HM, one is strong with the adsorption heat of ammonia in the range of 120-155 kJ mol~(-1), and the other weak in the range of 70—85 kJ mol~(-1). For the purpose of getting the information about the adsorption of aromatic compounds on different adsorption regions containing different kinds of acid sites. the adsorption heat of benzene and toluene on HM partly and totaly poisoned by ammonia were respectively measured. The results dempstrate that the non-physical adsorption of aromatic compounds only occurs on the regions containing acid sites, nevertheless, the adsorption strength of aromatic compounds is different from that of ammonia on each region.
The adsorption heats on h-mordenite (HM) have been investigated by flow-DTA adsorptive calorimetric technique. Plots of differential absorption heats. (Q_d) of ammonia, pyridine, benzene, toluene and p-xylene at 200 ℃ against varying adsorption amounts (A) were given respectively. There appears a turning point on the plot of Q_d of ammonia vs. A, which shows that there are two kinds of acid sites on HM, one is strong with the adsorption heat of ammonia in the range of 120-155 kJ mol~(-1), and the other weak in the range of 70—85 kJ mol~(-1). For the purpose of getting the information about the adsorption of aromatic compounds on different adsorption regions containing different kinds of acid sites. the adsorption heat of benzene and toluene on HM partly and totaly poisoned by ammonia were respectively measured. The results dempstrate that the non-physical adsorption of aromatic compounds only occurs on the regions containing acid sites, nevertheless, the adsorption strength of aromatic compounds is different from that of ammonia on each region.
1987, 3(02): 209-212
doi: 10.3866/PKU.WHXB19870217
Abstract:
An analytic approximation wave function of free ion Ni~(2+) is obtained from Watson′s SCF-3d orbit. Crystal field energy levels in the ZnWO_4 : Ni~(2+) crystal are then calculated with this wave function using ligand theory. The calculation are based on real C_2 symmetry of the crystal and according to the descending symmetry devided in two steps. O_h C_(2v) and C_(2v) C_2. Sometimes it is difficult to determine the numerous parameters from spectral data in case of lower symmetry crystal. We try to overcome this difficulty. The theoretical calculations are in od agreement with the experimental results.
An analytic approximation wave function of free ion Ni~(2+) is obtained from Watson′s SCF-3d orbit. Crystal field energy levels in the ZnWO_4 : Ni~(2+) crystal are then calculated with this wave function using ligand theory. The calculation are based on real C_2 symmetry of the crystal and according to the descending symmetry devided in two steps. O_h C_(2v) and C_(2v) C_2. Sometimes it is difficult to determine the numerous parameters from spectral data in case of lower symmetry crystal. We try to overcome this difficulty. The theoretical calculations are in od agreement with the experimental results.
1987, 3(02): 213-217
doi: 10.3866/PKU.WHXB19870218
Abstract:
In the present paper, preliminary application of NMR to phase diagram study was reported. A multinuclear NMR quantitative method was developed. NaCl- NH_4Cl-H_2O system was studied by ~(23)Na and ~(14)N NMR. It has been shown that the multinuclear NMR quantitative method has its advantages when studying systems of multi-components.
In the present paper, preliminary application of NMR to phase diagram study was reported. A multinuclear NMR quantitative method was developed. NaCl- NH_4Cl-H_2O system was studied by ~(23)Na and ~(14)N NMR. It has been shown that the multinuclear NMR quantitative method has its advantages when studying systems of multi-components.
1987, 3(02): 218-221
doi: 10.3866/PKU.WHXB19870219
Abstract:
The crystal of potassium terbium metaphosphate KTb(PO_3)_4 belongs to the monoclinic space group P2_1 with unit cell parameters a=0.7239(1) nm, b=0.8325(2) nm, c=0.7896(1) nm, β=91.82(1)°, V=0.4756 nm, Z=2. The structure was solved by heavy-atom method and the final R=0.034 after refining by block-dia nal least-squares method. The structure contains helical ribbons, (PO_3)_n, formed by cornersharing tetrahedra of PO_4. The coordination of the terbium by oxygen atoms is eight-fold with the geometry of dodecahedra. The shortest Tb—Tb distance is 0.6544 nm.
The crystal of potassium terbium metaphosphate KTb(PO_3)_4 belongs to the monoclinic space group P2_1 with unit cell parameters a=0.7239(1) nm, b=0.8325(2) nm, c=0.7896(1) nm, β=91.82(1)°, V=0.4756 nm, Z=2. The structure was solved by heavy-atom method and the final R=0.034 after refining by block-dia nal least-squares method. The structure contains helical ribbons, (PO_3)_n, formed by cornersharing tetrahedra of PO_4. The coordination of the terbium by oxygen atoms is eight-fold with the geometry of dodecahedra. The shortest Tb—Tb distance is 0.6544 nm.
1987, 3(02): 222-224
doi: 10.3866/PKU.WHXB19870220
Abstract:
The exchange currents of Ag/AgNO_3-NH_3 electrode systems were measured by using radiotrcer method.The magnitude of exchange currents was obtained to be of the order 10~(-7) A. cm~(-2) in solutions with various concentrations of Ag~+(Ⅰ). The data show that the exchange currents decrease with reduction in Ag~+ (Ⅰ) concen- trations.However the difference of exchange currents is not significant.It is in coincidance with the assumption that in very low overpotential region the surface diffusion of adatom is the rate determining step.
The experimental conditions that must be fulfilled in order to ensure successful application of this method were also discussed.
The exchange currents of Ag/AgNO_3-NH_3 electrode systems were measured by using radiotrcer method.The magnitude of exchange currents was obtained to be of the order 10~(-7) A. cm~(-2) in solutions with various concentrations of Ag~+(Ⅰ). The data show that the exchange currents decrease with reduction in Ag~+ (Ⅰ) concen- trations.However the difference of exchange currents is not significant.It is in coincidance with the assumption that in very low overpotential region the surface diffusion of adatom is the rate determining step.
The experimental conditions that must be fulfilled in order to ensure successful application of this method were also discussed.
