摘要:

The triplet lifetime has been used as a monitor to follow the progress of purification during the zone-refining of natural and synthetic anthracene. Chromatography has been found to be a satisfactory initial purification process if a highly pure solvent, e.g. benzene, is used.

ISSN:0369-1152    

DOI:10.1080/15421406808082928

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This bibliography is the seventh in a series. Earlier issues were listed in the preceding issue (VI), which appeared inMolec. Cryst.3, 1–101 (1967). An outline of the energy transfer process and remarks on the scope of the bibliographies were given in issue IV. Copies of earlier issues are available.

ISSN:0369-1152    

DOI:10.1080/15421406808082929

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The investigation of optically generated triplet excitons in anthracene crystals began in 19633with the discovery that red light from a ruby laser can generate detectable concentrations of triplet excitons in spite of the low probability for this transition. Following this discovery, experimental and theoretical studies of triplet excitons became a much more active area of research in teh field of the organic sold state. Anthracene has been chosen as the organic solid state. Anthracene has been chosen as the model system by the vast majority of the investigators. For this reason this review deals with anthracene almost exclusively. We, furthermore, emphasize the work at room temperature where the triplet excitons are essentially free and where understanding of their properties has progressed the farthest. Only brief mention will be made of low temperature experiments where complicated trapping effects play an essential role, and a great deal of additional research is necessary for gaining a clearer understanding of what is goind on. Although the literature was surveyed to the end of 1967, a few 1968 papers are included. In keeping with our own interests, we will stress dynamical properties in this paper.

ISSN:0369-1152    

DOI:10.1080/15421406808082930

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Nuclear magnetic resonance line-widths of23Na have been determined at several compositions in two isotropic solution phases and five mesomorphous phases in the sodium caprylate-decanol-water system. The results obtained demonstrate that the rate of nuclear magnetic relaxation of23Na+ is primarily determined by the number of water molecules per sodium ion. this indicates that in all the phases investigated, the sodium ions are predominantly coupled to water molecules. A comparison with81Br nuclear magnetic relaxation data shows that the bonding of sodium ions is markedly different from that of bromide ions in systems containing association colloids and water. This diversity is found to be due to differences in ion-water coupling.

ISSN:0369-1152    

DOI:10.1080/15421406808082931

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Polymorphism of the methylchloromethane compounds, (CH3)nCCI4-n, where n varies from 0 to 4, has been studied using low-temperature X-ray diffraction techniques. Single crystals of both high and low-temperature phases were grown and crystal data were obtained for the various phases. The crystal structure of the phase of t-butyl chloride which is stable between −54 and −90° was determined. On the basis of the present investigation, the conclusion is reached that the high-temperature modifications are dynamically disordered, in agreement with the results of n.m.r. and dielectric studies.

ISSN:0369-1152    

DOI:10.1080/15421406808082932

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Theoretical calculations are presented for the splittings, caused by intermolecular forces, of vibrational spectroscopic transitions in crystalline benzene and naphthalene. Semi-empirical potential functions for the interactions between pairs of molecules are assumed. The interaction between two molecules is further assumed to be composed of central forces acting between pairs of atoms, one on each molecule.

ISSN:0369-1152    

DOI:10.1080/15421406808082933

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Since the successful recording of the transient absorption spectrum of the hydrated electron by Keene1and Hart and Boag2using pulse radiolysis, an enormous amount of experimental and theoretical data3has been presented confirming the existence of the hydrated electron in water (at room temperature). In comparison, however, teh solvated electron inpureice was identified only recently by Eiben and Taub.4They irradiated pure ice samples at 77°K with60Co gamma radiation, recorded and analyzed the absorption spectra of the irradiated samples, and subsequently assigned the observed absorption maximum at 6400 Å (1.9 eV) to the hydrated electron. The observed absorption was thermally stable at 77°K and could be photobleached using visible radiation. Working withpureice samples in the temperature range of 200°K to 260°K, V. N. Shubinet al.5employed the techniques of pulse radiolysis to map the absorption spectra of short-lived species (typical lifetimes of 10−3-10−5sec) in ice, and they attributed the observed transient absorption centered around 6400 Å to the hydrated electron.

ISSN:0369-1152    

DOI:10.1080/15421406808082934

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Recently Blum, Mattern, Arndt, and Damask1reported the production of both optically absorbing and paramagnetic species in the gamma radiolysis of crystals of anthracene. They found no such behavior on exposure of this material of 50 Ke V X-rays.

ISSN:0369-1152    

DOI:10.1080/15421406808082935

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0369-1152    

DOI:10.1080/15421406808082927

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor