摘要:

The proton magnetic resonance spectrum of biphenyl has been observed in dilute solution withd-chloroform and tetramethylsilane as the solvents. Theoretical analyses of these spectra were carried out with the aid of additional data provided by several deuterated biphenyls. A limited amount of data was also obtained forp-terphenyl and fluorene to assist in the interpretation. Estimates of the additional anisotropy contributions at each position from the second ring were calculated as a function of the dihedral angle of biphenyl. The results obtained are interpreted assuming a freely rotating model with weak interaction between phenyl rings.

ISSN:0026-8976    

DOI:10.1080/00268976600100411

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The zero-field splitting parameters of the triplet state,D,EandD*, have been calculated in the two configuration approximation for the hydrocarbons pyrene and 1,12-benzperylene, and the results compared with the experiment. For calculations on molecules of this size it is a reasonable approximation to neglect two centre dipolar interaction integrals betweenπ-electron centres more than 12 Bohr radii apart. Results in a one configuration approximation for the naphthalene molecule using open shell-SCF-MO's are also compared with other calculations and experiment.

ISSN:0026-8976    

DOI:10.1080/00268976600100421

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The electron spin resonance spectrum of the radical ĊH(NH3+)CO2-, I, trapped in irradiated glycine has been re-examined at 77°kand the hyperfine couplings obtained when the -NH3+ceases to rotate. The individual hydrogens are clearly identified by reference to the x-ray structure. Improved values are obtained for the room temperature couplings of this radical. There is also, after irradiation at 77°k, a spectrum consisting of two broad lines tentatively attributed to one of the molecular ions; the species giving rise to this spectrum changes irreversibly into I on warming above 77°k.

ISSN:0026-8976    

DOI:10.1080/00268976600100431

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The principal molecular susceptibilities of bisdehydro[14]annulene, determined from measurement of the diamagnetic anisotropy of a single crystal, are -20, -24 and -358 (× 10-6c.g.s. e.m.u.). The results are in agreement with a London calculation of the π-electron contribution to the molecular anisotropy.

ISSN:0026-8976    

DOI:10.1080/00268976600100441

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The non-additive contribution to the long-range interaction energy of three atoms A, B and C at large distancesRab,RbcandRcaapart may be writtenE(ABC)=γ(ABC)(1 + 3 cos ϑacos ϑbcos ϑc)/(RabRacRbc)e, where ϑa, ϑband ϑcare the internal angles of triangle ABC. The values of γ(ABC) for triads selected from hydrogen and helium atoms are calculated. In atomic units they are respectively 21·64, 8·12, 3·80 and 1·49 for the mixtures H-H-H, H-H-He, H-He-He and He-He-He.

ISSN:0026-8976    

DOI:10.1080/00268976600100451

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The temperature and isotope effects which have been observed in the electron resonance spectrum of the methyl radical are quantitatively correlated by attributing both to the out-of-plane vibration. An attempt is made to explain the temperature dependence of the benzene anion spectrum in terms of the same effect. The attempt fails, but some predictions are made.

ISSN:0026-8976    

DOI:10.1080/00268976600100461

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Group theory has been used to factorize the secular determinants of a number of eight spin systems belonging to the classificationAA′A″A…' XX′X″X…'withTd,D2h,D4,D2dandC2hsymmetry as a first step toward breaking down the problems in search of characteristic sub-patterns of energy levels. Examples of the method are given.

ISSN:0026-8976    

DOI:10.1080/00268976600100471

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The patterns of energy levels within each symmetry species in each problem considered in part I have been further reduced in complexity using theXapproximation. Recognizable sub-patterns of energy levels have been investigated using the principles of sub-spectral transformations. Contradictions arise between sub-spectral parameter values derived from invariants of the systems considered except in the wing-spectra. The implications are discussed.

ISSN:0026-8976    

DOI:10.1080/00268976600100481

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

It is shown that the use of the symmetry group of a non-rigid molecule leads to the same results for the statistical weights and symmetry number as do more conventional methods.

ISSN:0026-8976    

DOI:10.1080/00268976600100491

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Little [1] has proposed that high temperature superconductivity should be possible in long substituted polyenes, with electronic virtual excitations in the substituents providing a mechanism for attractive forces between polyene electrons. This proposal is examined in detail, and in particular the question of screening of the coulomb interaction between elections under these circumstances is discussed. Reasons are given why screening should not be taken into account. Explicit calculations for a number of substituted polyenes lead to the conclusion that the criterion for superconductivity is not satisfied in these systems.

ISSN:0026-8976    

DOI:10.1080/00268976600100501

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor