摘要:

The weak absorption system of crystalline naphthalene at 3200åhas been measured at 4°K in polarized light. Previous work at 20°K is supplemented by a number of newly recorded absorption lines, and by re-measurement of the frequencies of all lines at the lower temperature.

ISSN:0026-8976    

DOI:10.1080/00268976100100151

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The theory of intermolecular resonance effects in the spectra of molecular crystals is extended to very weak systems in which the pure electronic transitions are either forbidden (as in the benzene 2600åsystem) or comparable in intensity with accompanying vibrationally induced transitions (as in the naphthalene 3200åsystem). For the pure electronic transitions the intermolecular coupling is through transition octupole moments, giving splittings and intensity transfers of the same type, though smaller, as those familiar in the stronger, dipole-coupled, systems. Values of octupole-octupole and octupole-dipole interactions sums are reported for naphthalene and the crystal spectrum calculated. For vibration-induced transitions it is shown that the intermolecular effects are due only to the small component of ‘stolen’ character, thus allowing the lack of splitting and intensity transfer to be understood. The nature of such bands as arising from localized excitation can thus be explained in the framework of the simple rigid-lattice excition theory.

ISSN:0026-8976    

DOI:10.1080/00268976100100161

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The ‘wide-line’ proton magnetic resonance spectra ofn-tridecane andn-hexadecane and their urea adducts have been examined from 77°K to 298°K. The results show that the enclosed component is capable of a considerable degree of molecular motion. Estimates of the energy barriers involved support the idea that the interaction between the urea cage and the adducted hydrocarbon is only slight.

ISSN:0026-8976    

DOI:10.1080/00268976100100171

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Analysis of the electron spin resonance spectrum shows that CO−2radical ions are trapped in sodium formate at room temperature after irradiation of the crystal with high energyγ-rays. This radical is bent with an angle of about 134° and has a2A1ground state. From the experimental values of the13C coupling coefficients and thegvalues, coefficients are derived for the mixing of atomic orbitals in the half-filled 4a1molecular orbital which appears to be 14 per cent carbon 2s, 66 per cent carbon 2pzand 11 per cent of each oxygen 2pz. There is also coupling to the sodium nucleus in an adjacent cation.

ISSN:0026-8976    

DOI:10.1080/00268976100100181

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

A calculation of the field due to the ring current in the porphyrin system is given and shown to account for the observed chemical shifts of the protons in porphyrins. Also variations of the ring current are shown to account for the observed variations in the proton chemical shifts of different porphyrin molecules.

ISSN:0026-8976    

DOI:10.1080/00268976100100191

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Measurements have been made of the heat capacityCpfrom ∼14 to 300°kof three clathrates of krypton andβ-quinol, in which 24·2, 47·9 and 79·5 per cent of the cavities were occupied by krypton.Cpwas found to be a linear function of composition. These results together with those previously obtained for the argon clathrate make it possible to fix within comparatively narrow limits a distance parameter characteristic of the quinol lattice (in effect a measure of the thickness of the wall of the cavity). This should make it possible to carry out a reliable analysis of the contribution made to the heat capacity of quinol clathrates by diatomic and polyatomic molecules.

ISSN:0026-8976    

DOI:10.1080/00268976100100201

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The intermolecular charge-transfer spectrum of the crystalline anthracene-TNB complex has been measured, using polarized light. The crystal spectrum differs from that of the solution to a much greater degree than is the case for ordinary aromatic systems. The transition is polarized along the intermolecular axis and is blue-shifted with respect to the solution. There is pronounced vibrational structure, including a prominent 250 cm-1interval. A Davydov splitting of approximately 200 cm-1is observed, and this is shown to be in reasonable agreement with the known crystal structure and with the symmetry assignment of the transition, which isA′ ←A′ for the complex in solution andA←Ain the crystal.

ISSN:0026-8976    

DOI:10.1080/00268976100100211

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

It is concluded from electron spin resonance spectra that the radical (CO2H)CH2ĊH2CH(CO2H) remains trapped in a glutaric acid crystal afterγ-irradiation. This radical is found in two different conformations. Approximate hyperfine coupling constants are given for each, although exact interpretation is hindered by the overlapping of spectra. Reasons for the formation of the two forms of the radical are discussed.

ISSN:0026-8976    

DOI:10.1080/00268976100100221

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

All possible two-centre Coulomb integrals between 2pπand 3pπatomic orbitals with equal orbital exponentαhave been evaluated analytically and tabulated forα= 1·00 (0·25) 10·00.

ISSN:0026-8976    

DOI:10.1080/00268976100100231

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The theory of optical absorption assisted by states of charge transfer is extended to inter-system (spin-change) transitions. The transition probabilities are calculated. By some very special choice of the overlap integrals agreement is obtained between the theory and the experiments on hydrated manganous ions.

ISSN:0026-8976    

DOI:10.1080/00268976100100241

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor