摘要:

Es wird gezeigt, dass der Dichte-Operator einer generalisierten Gesamtheit gewisse Bedingungen erfüllen muss, wenn sie die Gleichungen der Thermodynamik und korrekte Schwankungsgleichungen ergeben soll. Die von Byers Brown vorgeschlagene Druckgesamtheit erfüllt die Bedingungen für die Gültigkeit der Thermodynamik, führt aber auf unrichtige Schwankungsgleichungen. Insbesondere ergibt sich eine falsche Formel für die Lichtstreuung eines Einkomponentensystems. Dies beruht darauf, dass in der Gesamtheit von Byers Brown die Schwankungen von vornherein teilweise unterdrückt werden.

ISSN:0026-8976    

DOI:10.1080/00268975900100011

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

It is shown that the partition functions relating to statistical ensembles can be classified as cumulative, distributive or differential with regard to any of the extensive thermodynamic variables. The Laplace transforms involved in the general formulation of transformed partition functions, when extensive parameters are replaced by their conjugate intensive variables, are two-sided and appear in different forms according to the classification mentioned.

ISSN:0026-8976    

DOI:10.1080/00268975900100021

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

This theory, which is based upon McMillan and Mayer's cluster expansion of the grand partition function, is extended to include all of the components of the potentials of average force between sets of solute molecules or ions in the solvent at infinite dilution. The resulting cluster integral sum, which is a sum of integrals over an infinite number of infinite series of Mayer prototype graphs, is transformed into the sum of a single infinite series of integrals on graphs involving new types of bonds. These bonds are defined in a way first suggested by Meeron. There results a compact expression for the cluster integral sum.

ISSN:0026-8976    

DOI:10.1080/00268975900100031

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

It is shown that the differences in the thermodynamic properties of HT and D2is due to the fact that, for the same total mass, the distribution of mass between the two atoms is not the same. This fact introduces for the heteronuclear molecules a correlation between translational and rotational degrees of freedom. This is a pure quantal effect. A quantum-mechanical perturbation calculation shows that the energy of the ground state is higher for assemblies of heteronuclear molecules than for assemblies of homonuclear ones. On account of this the equation of state of heteronuclear hydrogen molecules is different from that of homonuclear hydrogen molecules. This permits an understanding, for example, of the higher vapour pressure of HT compared to D2and the anomalous behaviour of HD.

ISSN:0026-8976    

DOI:10.1080/00268975900100041

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

The optical reflectivity of shock fronts in A, N2, O2, CO, CO2, N2O, CH4, Cl2and HCl have been studied. The thickness of shock fronts in A up to the Mach numberM= 1·55 is in agreement with the theory of Gilbarg and Paolucci. The rotational relaxation time is about 5·5 collisions in N2and equal to or less than that in the other gases. However, for stronger shocks N2does not appear to reach rotational equilibrium in the shock front and a qualitative theoretical discussion of this phenomenon is presented. In HCl there appears to be over-excitation of rotation in the shock front. There is no vibrational excitation of any of the gases.

ISSN:0026-8976    

DOI:10.1080/00268975900100051

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

The proton shielding constants of the hydrogen halides have been calculated employing a molecular wave function built from gauge-invariant atomic orbitals. Each of the molecular wave functions contains a single parameter which is determined from the observed dipole moment. Calculated and experimental values of the shielding constants for HF, HCl, HBr and HI agree to within approximately 10 per cent.

ISSN:0026-8976    

DOI:10.1080/00268975900100061

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

Chemical shifts of the thallium nuclear resonance have been measured in solutions of thallous hydroxide, fluoride, acetate, formate, nitrate, and perchlorate of varying concentrations and in the presence of added substances. At low concentrations the chemical shift varies non-linearly with concentration of anion and can be correlated with the formation of ion-pairs. In stronger solutions the variation of chemical shift becomes linear, and is attributed to interactions between the ion-pairs and the added substances.

ISSN:0026-8976    

DOI:10.1080/00268975900100071

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

A comparison is made between the π-electron transitions in the benzene molecule and its mono- and di-valent ions following thea.s.m.o.-treatment of Pariser and Parr. Starting from this theoretical treatment the experimental spectra of the molecules and negative ions of coronene and triphenylene have been interpreted. The locations of the absorption bands are in good agreement with the theoretical expectations; the intensity rules, however, are strongly violated. This divergence between theory and experiment is probably due to a Jahn-Teller distortion.

ISSN:0026-8976    

DOI:10.1080/00268975900100081

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor

摘要:

From the energy levels of the gaseous ions Ac++, Th+++, and Th++, it can safely be extrapolated that the ground electron configuration of all actinide ions with ionic charges at least + 3 contains only 5f-electrons outside the emanation shells. This is further supported by the 5fn→ 5fn-16d transitions observed in Pa(IV), U(III), Np(III) (though their wave numbers are too high to be measured in U(IV) and Np(IV)). The configuration f2has a very characteristic distribution of energy levels between3H4and3P2with1S0as much higher, isolated level. The absorption spectra of U(IV) complexes and of PuF6suggest interelectronic repulsion parameters ∼60 per cent of the values in the corresponding lanthanides, while the Landé factors are about twice as large. This would also explain the recent measurements of Cm(III) complexes, compared to Gd(III). The larger average radius of the 5f-shell causes larger perturbation effects from the ligands than in the lanthanides. TheJ-values will therefore be distributed between several adjacent, observed energy levels without making the general treatment of the fn-configurations impossible. The variation with oxidation numbers in isoelectronic series are discussed, e.g. U(III) and Np(IV); Pu(III) and AmF4; and Am(III) and CmF4. Band positions are predicted in Bk(III) and BkF4. Finally, the chemical properties of the actinide elements are discussed, and it is emphasized that no necessary connections exist between the presence of f-electrons and constant trivalency.

ISSN:0026-8976    

DOI:10.1080/00268975900100091

出版商:Taylor & Francis Group    

年代:1959

数据来源: Taylor