摘要:

Triplet-triplet (T-T) absorption, E.S.R., and phosphorescence spectra were observed for tetrachlorophthalic anhydride and phthalic anhydride complexes with methyl substituted benzenes. T-T absorption bands characteristic of electron donor-acceptor interaction, in addition to those pertinent to the component molecules, were found for the tetrachlorophthalic anhydride complexes. The observed T-T absorption spectra can be understood systematically by considering the interaction among zero-order charge-transfer triplet states and zero-order locally (within the acceptor) excited triplet states. From the analysis of the results of E.S.R. spectra, the CT characters of the lowest triplet states were obtained to be 80, 46, 37, and 26 per cent for the tetrachlorophthalic anhydride complexes with durene, mesitylene, toluene, and benzene, respectively, while the lowest triplet states of complexes of phthalic anhydride with mesitylene and toluene were found to have the character of local excitation within the acceptor.

ISSN:0026-8976    

DOI:10.1080/00268977500100121

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The thermoneutral alkali atom-alkali dimer exchange reaction Li+Li2→ Li2+ Li has been studied on a LEPS surface, having a potential well of depth 8·30 kcal mole-1, using classical trajectory methods. The total reaction cross section, collision lifetime, differential reaction cross section and product energy disposal were calculated for seven initial collisional energies. Comparison with the results from statistical theories shows good agreement for energies up to a quarter of the well depth in the case of the energy disposal and for energies about equal to the well depth in the case of the angular scattering. At low collisional energies the reaction is found to proceed via a long-lived complex which is non-linear and non-rigid. About 50–60 per cent of the total available energy goes into internal motion of the product molecule and is partitioned almost equally between vibration and rotation at low energies with rotation being slightly favoured at higher energies. The calculated total reaction cross sections and energy disposal are similar to the results obtained from recent molecular beam studies of some alkali atom-alkali dimer exchange reactions.

ISSN:0026-8976    

DOI:10.1080/00268977500100131

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The spectral distribution of Rayleigh and Raman anisotropy scattering has been measured for ten simple organic liquids at 20°C and the interpretation in terms of reorientational motions is discussed. All spectra approximated closely to a Lorentzian form. In most cases the spectral linewidths derived from Raman bands were greater (by up to 150 per cent) than those derived from Rayleigh measurements. Furthermore, the linewidths of Raman anisotropy scattering from different totally symmetric vibrations of the same molecule were found to differ by as much as 100 per cent. The Rayleigh-Raman linewidth differences correlate strongly with the Raman vibrational linewidths and it is suggested that there are significant interactions between rotational and vibrational energies as a result of molecular interactions in the liquids. These observations obscure any interpretation of linewidth differences in terms of cooperative reorientational motions in these liquids. Anisotropy linewidths were also studied as a function of concentration for solutions of nitrobenzene and methyl cyanide in carbon tetrachloride. The data are discussed in the light of the above conclusions.

ISSN:0026-8976    

DOI:10.1080/00268977500100141

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A general procedure for calculating N.M.R. bandshapes of spin-1/2 nuclei in spin systems containing quadrupolar nuclei is discussed. A computer programme, QUADREDOCOS, which utilizes this procedure, is described. Some results for the2A2B3X system are presented. Calculations for the [2A3X]2system ofcis-N2F2produced spectra comparable to those published; the effects ofJNN',T1Nand the correlation of relaxation at the two nitrogen nuclei are discussed. It is probable that1JNN'and3JFF'have opposite signs.

ISSN:0026-8976    

DOI:10.1080/00268977500100151

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Further experimental results on level anticrossing and cross-relaxation effects in phosphorescent benzophenone and 4,4′-dibromobenzophenone crystals are reported. In addition to level anticrossing lines, and triplet-triplet and triplet-radical cross-relaxation lines, the spectra of 4,4′-dibromobezophenone show strong cross-relaxation with the bromine nuclear quadrupole states.

ISSN:0026-8976    

DOI:10.1080/00268977500100161

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Recent measurements of deuterium quadrupole coupling in the gas phase are reviewed. Most of the results presented were obtained using molecular beam maser spectrometers and this type of apparatus is discussed briefly. Variations in the quadrupole coupling strength for changes in the adjacent atom and bond order are discussed. The relation between electric field gradients and stretching force constants is examined in terms of the experimental data.

ISSN:0026-8976    

DOI:10.1080/00268977500100171

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

In molecular beam experiments the preferred spatial orientation orpolarizationof the rotational angular momentum of reactively scattered molecules can be determined by deflection in an inhomogeneous electric field. The apparatus, experimental method, and analysis procedure are described and illustrated with data obtained for the K + HBr, Cs + HBr, and Cs + HI reactions. The experiments employ a new field design which eliminates the non-adiabatic change of quantization axis that handicapped a previous polarization study. A simple normalization procedure provides ‘reduced deflection profiles’ which are very insensitive to substantial variations in the experimental parameters, including the deflection field strength, beam position in the field, collimating slit widths, dipole moment, and distributions of rotational and translational energy. These reduced profiles yield <cos2x> and <cos4x>, the first two moments of the probability distribution of polarization, wherexis the angle between the rotational angular momentum and the initial relative velocity vector. The experimental results indicate marked polarization, corresponding to <cos2x> < 0·10, and agree well with theoretical moments calculated from a statistical phase-space treatment.

ISSN:0026-8976    

DOI:10.1080/00268977500100181

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A detailed study of the low temperature absorption spectra of some 16 molecular crystals containing Ni(H2O)6++has allowed us to identify the electronic and vibrational origins of the ‘red’ absorption band. A complete band contour analysis has been performed, which makes possible a discussion of the crossing of the1Γ3and3Γ3levels.

ISSN:0026-8976    

DOI:10.1080/00268977500100191

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268977500100201

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268977500100211

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor