摘要:

The photochemistry of atmospheric constituents in the cold atmospheres of Jupiter, Saturn and Titan is reviewed: H2, CH4, NH3, PH3, H20, N2, etc. A detailed discussion of major dissociation paths and essential chemical reactions is given with the emphasis on a first-order description of the concentrations of simple molecules in the photochemical regions of these atmospheres. The composition as measured by Voyager spacecraft instruments, IUE and ground-based telescopes is compared with the predictions of aeronomical models and generally acceptable agreement is found for Jupiter, provided the C2H6mixing ratio is ∼ 1 × 10−6. More complex molecules do not exceed ppb mixing ratios as a consequence of large H-atom concentrations and the efficiency of H-atom cracking reactions. Even on Titan with lower H-atom concentrations these reactions are apparently effective in suppressing the concentrations of C4H2, C3H4, HC3N, and C2N2.

ISSN:0144-235X    

DOI:10.1080/01442358309353342

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The transition metal dichalcogenides form a group of layered, highly anisotropic compounds which exhibit interesting and unusual physical properties. Compounds formed from the Group Iv, Group V and Group VI transition metals and from sulphur or selenium have been the subject of a great deal of interest in the past few years because of the possibility of introducing foreign species between the layers and causing many of the properties of the host lattice to change in a predictable way, consistent with the rigid band model. The most common intercalate complexes are those formed from alkali metals, Lewis bases and transition and post-transition metals. In this review a number of these compounds are discussed, with special emphasis on those which provide new information about the host material, or where some new, interesting property of the complex has been demonstrated.

ISSN:0144-235X    

DOI:10.1080/01442358309353343

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The development of the conception of handedness in the physical world is outlined, culminating with the views of Pasteur on the role of chiral structures and dissymmetric forces in nature. The evolution is traced of the general conclusion that steric congruence dominates chiral discrimination in biochemical enantioselection, asymmetric organic synthesis, the crystal structures of enantiomers and racemates, and the distinction between homochiral and heterochiral interactions in the fluid state. The significance of the unification of the electromagnetic with the weak interaction is discussed with reference to the proposed universality of optical activity, and of the particular terrestrial enantioselection observed in natural products.

ISSN:0144-235X    

DOI:10.1080/01442358309353344

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

L.E. Reichl and W.C. Schieve (Editors).Instabilities, Bifurcations and Fluctuations in Chemical Systems. Austin: University of Texas Press. £26.25. ISBN 292 738293.

ISSN:0144-235X    

DOI:10.1080/01442358309353345

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor