摘要:

Areas of particular current interest in the field of unimolecular reactions are reviewed. New developments and experimental applications of the theory of thermal unimolecular reactions are discussed, with particular stress on simple descriptions of both the low and high-pressure limiting ranges and the intermediate fall-off. Recent experimental studies of elementary steps in unimolecular reactions after optical (one photon) and molecular beam (chemical) activation are reviewed in relation to theory. The kinetic and mechanistic aspects of the new field of unimolecular reactions induced by monochromatic infrared radiation (URIMIR, with multiphoton excitation) are developed in some detail. Experiments in this area are summarized and their role for the interpretation ofURIMIRis discussed.

ISSN:0144-235X    

DOI:10.1080/01442358109353318

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0144-235X    

DOI:10.1080/01442358109353319

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Rapid specimen rotation about an axis inclined at the magic angle of 54° 44′ to the direction of the applied magnetic field can remove many sources of broadening from the NMR spectrum of a solid and enable finer features to be revealed.

ISSN:0144-235X    

DOI:10.1080/01442358109353320

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The electron configurations (in spite of being a debatable approximation to the wavefunction) predict correctly the number of levels with givenJvalue, and in the case of reasonably valid Russell-Saunders coupling, their bunching together in (S,L) terms. The similarity with the energy levels in condensed matter attenuates from the 4f to the 5f group, and in d-group compounds (like those outside the transition groups) usually only 5 remains a good quantum number. Recent experimental results, such as the Judd-Ofelt treatment of absorption and fluorescence transition probabilities (of importance for lasers), photoelectron and Auger spectra, antiferromagnetic coupling through anion bridges (allowing excitation of two transition-group ions by the same photon) and arguments for definite spectroscopic and conditional oxidation states, are connected with a general analysis of non-totally symmetric states. It is shown that the less frequent occurrence of positive S values in compounds of elements lighter than calcium, distort many opinions about chemical bonding.

ISSN:0144-235X    

DOI:10.1080/01442358109353321

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Differences in equilibrium properties of hydrogen- and deuterium-bonded systems are considered. The potential energy surface is assumed to be independent of the isotopic species and the differences attributed to vibrational motion. A useful understanding of the problem can be gained by considering a hydrogen-bonded species as if it were a linear triatomic molecule AH … B with three significant vibrational modes—the A—H stretching mode and the doubly degenerate H-bond bend. Differences in the stabilities of H- and D-bonded species are related to differences in the zero-point energies of these vibrations.

ISSN:0144-235X    

DOI:10.1080/01442358109353322

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor