摘要:

A group of fairly weak phosphorescences of platinum phthalocyanine (PtPc) whose intensities become comparable with those from the3(ππ*) states at liquid helium temperatures, were found to lie lower than the3(ππ*) states. This observation is unique among the many metal phthalocyanine (MPc) phosphorescences observed to date. The Zeeman effect on these emissions was investigated in order to establish their spectroscopic origin. The results showed that they cannot be π-π*, nor any metal-related (CT andd-d) transitions. The only remaining possibility is that they are tripletn-π* transitions which confirmed our previous assignment. We propose a molecular structure for PtPc which explains the present observations, as well as other unusual spectral and dynamic properties of this complex studied both in the presence and absence of magnetic fields in the past.

ISSN:0026-8976    

DOI:10.1080/00268978700102391

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The velocities of bismuth clusters produced by the inert gas condensation technique have been measured by the time of flight spectrometer. A large velocity slip has been observed between the helium carrier gas and the clusters. The translational temperature of helium has been also measured. Although the fragmentation phenomena associated with electron impact ionization precludes a precise determination of the temperature of the clusters, this temperature can be roughly estimated and our results show that a partial mass selection of neutral clusters by a velocity selector is possible.

ISSN:0026-8976    

DOI:10.1080/00268978700102401

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A study of three smectic liquid crystal systems is made through a comparison of the high field and zero field N.M.R. spectra of probe molecules. The motional averaging of the proton dipolar interaction of a CH2Cl2solute molecule reflects the local symmetry of SmecticA, BandEphases. In the SmecticEsystem, the onset of the biaxiality of the phase is clearly evident even in an unaligned sample.

ISSN:0026-8976    

DOI:10.1080/00268978700102411

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We use a mean field theory for non-uniform molecular fluids to study the interfacial properties of theABliquid-liquid interface of model ternary mixtures (A, B, C) with one amphiphilic component (C). We calculate the surface tension, adsorption and density-orientational profiles at the interface as a function of the bulk composition ofCin the two liquid phase region. The latter terminates at a plait, tricritical or triple point depending on the values of the external fields (temperature and pressure) and on the parameters characterizing the intermolecular interactions. The surface tension of theABinterface decreases rapidly with the bulk concentration ofCand vanishes at the plait and tricritical points. Under conditions of three phase equilibria theABinterface is characterized, in general, by low surface tensions and may undergo a wetting transition.

ISSN:0026-8976    

DOI:10.1080/00268978700102421

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Magnetizability (χ) and carbon-13 shielding (σ) surfaces have been calculated for the methane molecule using a Hartree-Fock wave-function. Correlation corrections to the diamagnetic parts of the surfaces have been calculated using a CAS SCF wavefunction. The results show that the properties are very sensitive to bond stretching with |χ| increasing and σ decreasing with increasing bond length. They are less sensitive to change of interbond angle. The surfaces are given in terms of the coefficients of Taylor series expansions about equilibrium geometry with respect to both symmetry coordinates and valence coordinates.

ISSN:0026-8976    

DOI:10.1080/00268978700102431

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper reports results from isothermal-isobaric molecular dynamics simulations of binary mixtures of Lennard-Jones fluids. The simulations were performed at several component size ratios in the range 1 ˇ- σBB/σAAˇ- 2 and at three pressures. The principal results reported here are excess Gibbs free energiesgE, excess volumesvE, and excess enthalpieshE. These new results do not coincide with previous Lennard-Jones simulations because of the extensive size and pressure ranges studied and because of the accuracy attained in the values forgE. The simulation data are used to test a recent revision of thermodynamic perturbation theory based on hard-sphere mixtures.

ISSN:0026-8976    

DOI:10.1080/00268978700102441

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Bands in theÃ-[Xtilde]emission spectrum of N2O+photographed under high resolution which involve all four spin-vibronic levels ν2= 1 of the[Xtilde]2Π manifold have been analysed. The vibronic splitting due to Renner-Teller and Herzberg-Teller interactions is interpreted in terms of an effective Renner parameter εeffwhose value is determined to be -0·176. The relative intensity of the forbidden 201transition can be accounted for by Herzberg-Teller coupling between the[Xtilde]2Π andÃ2Σ+states.

ISSN:0026-8976    

DOI:10.1080/00268978700102451

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The theory for collision induced rotational absorption between nonpolar molecules is extended to near-symmetric top molecules using Wigner rotational matrices to represent the field and polarizability in the induced dipole moment. The resulting theory is applied to the collision induced spectrum of ethylene-ethylene. This spectrum is shown to be dominated by absorption due to the off-diagonal quadrupole moment in spherical coordinates,Q¯22. Fitting the calculated to observed absorption coefficient at 140 cm-1leads to an accurate value of the quadrupole moment difference,Q¯xx-Q¯yy= -4·33 × 10-26esu·cm2in molecule fixed cartesian coordinates.

ISSN:0026-8976    

DOI:10.1080/00268978700102461

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Rotational collision-induced absorbance has been observed in the far I.R. spectra of cyclopropane samples and cyclopropane-argon mixtures. The part of the spectrum due to the polarizability and quadrupolar and octapolar field is calculated using the literature values of the molecular properties for this oblate symmetric top. Prolate and oblate top molecules are shown to have excess observed absorbance at different frequencies. The excess absorbance is analysed in terms of violations of the multipolar selection rule, ΔK= 0, which is caused by asymmetrical interactions during collisions.

ISSN:0026-8976    

DOI:10.1080/00268978700102471

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Raman spectra of liquid H2S and D2S at various temperatures are analysed. The band profiles have a rotational origin and are compared with those calculated by theJextended diffusion model for an asymmetric rotor. The values obtained for the angular momentum correlation time correspond to a large angle rotational diffusion. The rotational motion is discussed in terms of the Chandler model for translational diffusion.

ISSN:0026-8976    

DOI:10.1080/00268978700102481

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor