摘要:

Semi-classical analysis is applied to vibrationally and rotationally inelastic molecular collisions. The deflection angles for weak transitions are shown to be simply related to the classical deflection angles for elastic scattering under the initial and final conditions. The position of the crossing-point, at which the transition can occur without change of radial momentum, plays an important role in the discussion and expressions are derived for these points for systems undergoing rotational transitions. Finally it is shown that markedly inelastic behaviour recently observed in collisions between K and HBr is unlikely to arise from rotational transitions.

ISSN:0026-8976    

DOI:10.1080/00268976400100581

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

An exact formal integral equation is derived for the solute radial distribution functions in a multi-component solution of ions interacting with a Coulomb potential plus a short-range potential. The equation resembles, in a certain sense defined by the use of a diagram formalism, the recent exact equation of the theory of fluids but involves the Debye-Hückel potential of average force (i.e. a shielded Coulomb potential plus the short-range potential) instead of the total direct potential. Well-defined approximations yield equations which are analogues of the hypernetted chain and Percus-Yevick equations. The possible usefulness of the equations for ionic solutions and defects in ionic crystals is indicated.

ISSN:0026-8976    

DOI:10.1080/00268976400100591

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Calculations have been carried out using alternant molecular orbitals (AMO) for the electrons in theπ-system of planar C(CH2)3++, C(CH2)3+and C(CH2)3. The results are compared with those that have been previously obtained using other approximation methods and the complete configuration interaction treatment. Because lower energies are obtained using improved AMO's, these improved AMO calculations have also been carried out for the allyl cation, radical and anion, which were treated in an earlier paper.

ISSN:0026-8976    

DOI:10.1080/00268976400100601

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

A model is proposed for liquid and solid argon, in which the repulsive forces are represented by rigid cores and the attractive forces by a uniform background potential which depends on density but not on temperature. Thermodynamic consistency implies the equation of state:

ISSN:0026-8976    

DOI:10.1080/00268976400100611

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

Isopropyl-t-butyl nitroxide has been prepared by the reaction oft-butyl magnesium chloride on 2-nitropropane. Its E.P.R. spectrum is essentially a triplet of doublets (interaction with the nitrogen atom and the iopropyl proton). The hyperfine splittings are solvent dependent and, in water:aN= 16,83 gauss,aH= 1,80 gauss. A system of satellites is attributed toC13in natural abundance. These data are discussed by comparation to the isoelectronic pentamethylacetone radical-ion.

ISSN:0026-8976    

DOI:10.1080/00268976400100621

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The temperature dependence of the nuclear magnetic resonance, N.M.R., spectra ofdnoctahedral complexes has been calculated for all the ground-state configurations. This function is similar to the comparable temperature dependent expression for the magnetic susceptibility of these molecules.

ISSN:0026-8976    

DOI:10.1080/00268976400100631

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The magnitudes and some of the relative signs of the15N-H and H-H couplings in N-methylformamide-15N and formamide-15N have been determined. The15N-H couplings through one bond in these amides and in ammonia, ammonium ion and pyridinium ion are apparently dominated by the Fermi contact term, pyrrole being exceptional. Other couplings are quite successfully accounted for by the theory worked out for molecules with exclusively carbon frameworks.

ISSN:0026-8976    

DOI:10.1080/00268976400100641

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

We show that the decreased light absorption and the anomalous optical rotatory dispersion in helical polynucleotides and polypeptides may be interpreted purely as a local field effect. The electric field of the incident light wave is screened off from each residue by the induced electric dipoles in the others. Quantum-mechanical calculations based on time-dependent Hartree theory and this local field picture correspond precisely with the formulae derived in Tinoco's, Rhodes's, and Moffitt's exciton theories, provided that the Coulomb interactions are small. The degenerate exciton waves in our theory correspond to normal modes of a set of coupled oscillators, and the rotational strengths and oscillator strengths are conserved. There is no conflict between Tinoco's theory of hypochromism and the ones proposed by Bolton and Weiss and by Nesbet. One new conclusion is that the energy shifts accompanying hypochromism should not vary much when the exciton coupling changes from the strong to the weak coupling limits.

ISSN:0026-8976    

DOI:10.1080/00268976400100651

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The quantum yields of naphthalene vapour fluorescence at 225°cand of phenanthrene vapour fluorescence at 365°cexcited by the Hg 313μline are independent of concentration up to 0·014 and 0·007 moles/l. respectively; this is attributed to fast dissociation relaxation of the excimer at these temperatures.

ISSN:0026-8976    

DOI:10.1080/00268976400100661

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor

摘要:

The proton spin-lattice relaxation time,T1, has been measured for aqueous solutions of sodium, potassium, rubidium and magnesium chlorides up to a concentration of about 4Nat 25°c. The sodium and the magnesium chloride solutions were also measured at 60°cand 100°c. The variation of 1/T1isnotlinear with concentration, at least above about ¼N, in contrast with previous reports [1, 2]. The behaviour depends markedly on the nature of the salt and on the temperature. It is shown that almost the whole of the variation ofT1as compared with that of water can be directly and simply related to the corresponding changes in the shear viscosity of the solutions. It is noted that the viscosity correction is better the higher the temperature of the solution.

ISSN:0026-8976    

DOI:10.1080/00268976400100671

出版商:Taylor & Francis Group    

年代:1964

数据来源: Taylor