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1.
The opto-acoustic spectrum of I2 in the presence of various quenching gases — NO, O2, CH3I, SO2, C3HS, N2, and He — has been studied. Of these, the I2/O2 spectrum is quite different due to the near-resonant energy transfer I(2P12) + O2(3Σ) → I(2P32) + O2(IΔ), wherein the resistance of the O2((IΔ) species to collisional relaxation severely distorts the acoustic signal. The photochemical production of excited 2P12 iodine atoms commences at wavelengths considerably longer than the dissociation limit of the I2B? state.  相似文献   

2.
Photoionization mass spectrometer techniques have been employed to study the charge transfer reactions: Xe+ + O2 → O+2 + Xe and O+2 + Xe → Xe+ + O2. The results show the reaction of Xe+(2P32) ions with O2 molecules is much more efficient than the reaction of Xe+(2P12) ions with O2 molecules. The charge transfer reaction of O+2 ions with Xe atoms was detected for O+2 ions in the a 4Πu state.  相似文献   

3.
The crystal structure of Na7Mg4.5(P2O7)4 has been solved by direct methods from the three-dimensional X-ray data. The space group is P1. The crystal structure consists of Mg2+, Na+, and P2O4?7 ions. One magnesium atom at symmetry center (0,0,0) and two sodium atoms at ±(?0.0421, ?0.0596, 0.2230) display occupation factors 0.5 each. A short interatomic distance between these Na+ and Mg2+ ions (1.80 ± 0.01 Å) excludes the occupation of both sites in the same unit cell. The crystal structure of Na7Mg4.5(P2O7)4 consists of unit cells containing Na8Mg4(P2O7)4 or Na6Mg5(P2O7)4 with a statistical occurrence 1:1.Each Mg2+ ion is octahedrally coordinated by six O2? ions at distances 1.979 – 2.270 Å. The coordination polyhedra around the Na+ ions are ill-defined. The bond angles POP in the P2O4?7 groups are 126.6 and 133.6° (±0.3°). The final reliability factor R is 7.1%.  相似文献   

4.
Three-dimensional classical trajectory calculations have been carried out for the quenching of Br*(2P1/2) by collision with ground-state H2, using an approach that describes the electronic as well as heavy-particle (i.e. transition, rotation, vibration) degrees of freedom by classical mechanics. We find a sizeable quenching cross section (≈12 Å2), with essentially all of the collision products having H2 vibrationally excited to υ = 1, i.e. near-resonant EV transfer dominates the non-resonant ET,R processes. This is in agreement with experimental results.  相似文献   

5.
The phase equilibria and the thermodynamics of coexisting phases in the PrFeO system have been studied using static and dynamic methods for attaining equilibrium with subsequent annealing and identification of the condensed phases by X-ray analysis. Equilibrium phase diagrams have been constructed to define the changes that take place in the PrFeO system on variation of the partial oxygen pressure, the temperature, and the composition of the initial mixture of oxides. An isothermal cross section at 1300°K and equilibrium diagrams of the type PO2 = f(composition) with T = constant, PO2 = f(1T) with one composition parameter fixed and T = f(composition) with PO2 = constant have been constructed. It has been shown in the PrFeO system that only one ternary compound with perovskite structure, PrFeO3, is formed, and furthermore, it is stable no matter how high the partial oxygen pressure.  相似文献   

6.
Photoacoustic measurements are described giving branching ratios for the I(2P12) and I(2P32) atom production following vapour-phase photolysis of CH3I. A range of excitation wavelengths are used from the long wavelength tail up to 248 nm. The presence of three bands is shown within the σ* ← n continuum; in the strong-coupling model these are E ← A1(⊥), A*1 ← A1(||) and E ← A1(⊥) with only the A*1 ← A1 transition giving excited iodine atoms.  相似文献   

7.
Emission spectra resulting from reaction of “clean” N2(A3 Σu+) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N2(A,v') + Cu(2S12) → N2(X, v) + Cu* , and that the transfer is most efficient for N2(A,v') → N2(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.  相似文献   

8.
Deactivation rate constants of spin-orbital excited Br atoms in the reactions Br(2P12) + O2 → Br(2P32) + O2 (k1), and Br(2P12) + NO → Br(2P32) + NO (k4) have been measured with a photodissociative IBr laser on the electronic transition 2P12?2P32 in the Br atom (λ = 2.7 μm). The values obtained are (6.4 ± 1.8) × 10?14 cm3 s?1 and (1.9 ± 0.6) × 10?12 cm3 s?1, respectively. Comparison with published data leads to the conclusion that, contrary to a widely accepted point of view, the high rate constants for the quenching of excited halogen atoms are due to resonant energy transfer processes and not to the paramagnetic nature of the quencher.  相似文献   

9.
The concentration and temperature dependence of J(199HgC19F) for solutions of CF3HgX (X = Cl, I, OCOCF3) in various solvents shows that in inert solvents these molecules exist mainly as non-solvent dimers (X = I or OCOCF3) or as monomers (X = Cl). In strongly coordinated solvents 12 complexes are largely formed from CF3HgX and the electron-donating solvent molecules. In pyridine solution an equilibrium exists between the 11 and 12 complexes. Complexes of the type CF3HgX·D are T-shaped and have a higher relative content of s-electrons in the HgCF group compared with tetrahedral CF3HgX·2D complexes.  相似文献   

10.
11.
The chemiluminescence produced by the Ba + Cl2 reaction was recorded as a function of He and N2 pressure. A modified Stern-Volmer treatment of competitive electronic quenching of BaCl* and BaCl*2 emission yielded upper limits to the half pressures p12(He) ? 9.0 ± 3 mtorr and p12 (N2) ? 1.1 ± 0.2 mtorr for quenching of BaCl*2 by helium and nitrogen, respectively. A lower limit of the BaCl*2 radiative lifetime is placed at τR ? 100 μ.  相似文献   

12.
From measurements of the heats of iodination of CH3Mn(CO)5 and CH3Re(CO)5 at elevated temperatures using the ‘drop’ microcalorimeter method, values were determined for the standard enthalpies of formation at 25° of the crystalline compounds: ΔHof[CH3Mn(CO)5, c] = ?189.0 ± 2 kcal mol?1 (?790.8 ± 8 kJ mol?1), ΔHof[Ch3Re(CO)5,c] = ?198.0 ± kcal mol?1 (?828.4 ± 8 kJ mo?1). In conjunction with available enthalpies of sublimation, and with literature values for the dissociation energies of MnMn and ReRe bonds in Mn2(CO)10 and Re2(CO)10, values are derived for the dissociation energies: D(CH3Mn(CO)5) = 27.9 ± 2.3 or 30.9 ± 2.3 kcal mol?1 and D(CH3Re(CO)5) = 53.2 ± 2.5 kcal mol?1. In general, irrespective of the value accepted for D(MM) in M2(CO)10, the present results require that, D(CH3Mn) = 12D(MnMn) + 18.5 kcal mol?1 and D(CH3Re) = 12D(ReRe) + 30.8 kcal mol?1.  相似文献   

13.
Room temperature experiments have measured the rate of electronic-to-vibrational energy transfer between spin—orbit excited Br(42P12) and HF. The Br* + HF quenching rate is very fast, (1.1 ± 0.2) × 106 s?1 torr?1, due to a near resonance between the spin—orbit splitting and the vibrational spacing. The majority of the Br* spin—orbit energy goes directly into HF vibration.  相似文献   

14.
Reactions of ketenes (R1R2CCO) with (η5-C5H5)Ni(PPh3)CCR (I) and (η5-C5H5)Fe(CO)(L)CCR (III, L = CO and PPh3) give σ-cyclobut-1-en-3-onyl complexes, {(η5-C5H5)Ni(PPh3)CC(R)COC}R1R2 (VI) and (η5-C5H5)Fe(CO)(L)CC(R)COCR1R2 (IX)}, (2 + 2) cycloaddition products, in good yields. The σ-cyclobutenonyl complexes also can be prepared by the reaction of I and III with acyl chlorides in the presence of triethylamine.  相似文献   

15.
The structural and magnetic properties of the Pr1?xMn1+xO3 perovskites were studied. The increase of x (i.e., PrMn < 1) leads to the decrease of the orthorhombic deformation and of the Néel temperature and, simultaneously, to an increase of the ferromagnetic contribution. The latter effect is explained from the suggested distribution of the cations (Pr3+1?xMn2+x)A(Mn3+1?xMn4+x)O2?3 by the double exchange of Mn3+Mn4+ pairs at the B—sublattice.  相似文献   

16.
CH3Br is photodissociated in the first continuum. Dissociation takes place into ground state CH3 and Br [ = Br(2P32] or Br* [ = Br(*P12)]. Time of flight and angular distributions of the CH3 fragments are measured. The Br*/Br ratios upon excitation at 222 and 193 nm are found to be 1.00 and 0.20 respectively. The anisotropy parameters at these wavelengths are β = 0.28±0.04 and β = ?0.23±0.02, respectively. The total absorption cross section is decomposed into partial absorption cross sections of the 1Q, 3Q0 and 3Q1 states. It appears that excitation at 222 nm takes place to the 3Q0 and 3Q 1 states whereas at 193 nm the 1Q and 3Q0 states are excited. Contrary to CH3I, the adiabatic curve crossing between the 3Q0 and the 1Q states in Ch3Br is not important. The dissociation energy of the CBr bond is determined to be D0(CH3Br) = 2.87±0.02 eV.  相似文献   

17.
18.
The cross section for the process BaCl(C2Π32, ν = 0) + Ar → BaCl(C2Π12, ν = 0, 1, 2) + Ar was measured by a laser induced fluorescence technique and found to be 16(7) Å2. This cross section is much larger than the intermultiplet energy transfer cross sections in the alkalis based on a comparison of the fine structure splitting. It is concluded that in the molecular case coupling of internal degrees of freedom plays an important role.  相似文献   

19.
The rate coefficients for the collisional deactivation of Tl(62P32) by several gases has been determined at 300°K. This data is compared with that previously obtained at higher temperatures and the Arrhenius parameters calculated. Both the overall rate coefficients and temperature effects display trends similar to those observed for 1(52P12) relaxation. The deactivation of Tl(62P32) by O2 is shown to proceed by a process involving an equilibrium with Tl(62P12) and electronically excited oxygen, probably O2(1Δg).  相似文献   

20.
The vibrational distribution of CO produced from the following two electronic-to-vibrational energy transfer reactions:
have been determined by means of infrared resonance absorption measurements employing a cw CO laser. The CO molecules formed in both reactions were found to be vibrationally excited up to the limits of available electronic energies carried by the excited atoms. A similar result was also observed in the Br(42P12) + CO reaction, in which absorption occurred only in the 1 → 2 band. For the O* + CO reaction the efficiency of E → V energy transfer was determined to be 16%. Our present results were found to be inconsistent with the impulsive (half-collision) model.  相似文献   

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