摘要:

A possible applicatory scope of linear dichroism in solution chemistry is outlined together with some recent measuring and interpretation methods. The possibility to obtain structural information is stressed. The applications are illustrated by experimental results.

ISSN:0038-7010    

DOI:10.1080/00387017708065494

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The form of the distribution function of a solute in uniaxially stretched polyethylene is discussed. Conditions and formulas are given for the determination of independent (reduced) absorption spectra of chromophores with absorption polarized in three mutually perpendicular directions, and an experimental result is presented. The ”orientation triangle” is defined, and its usefulness in studies of linear dichroism is emphasized.

ISSN:0038-7010    

DOI:10.1080/00387017708065495

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A model of light polarization measurement given by a general algorithm formed at the aim of coherency matrix formalism of electromagnetic wave is reported. There are shown the operations needed for measurement of any polarization state and control of measurement process at determination of physical quantities by means of polarization parameters.

ISSN:0038-7010    

DOI:10.1080/00387017708065496

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Different methods for the interpretation of linear dichroic spectra of molecules incorporated in uniaxial matrices are discussed. A method based on the combination of both polarized absorption and emission measurements is described for the resolution of absorption and emission spectra into their different polarized components, and for the investigation of molecular distributions in the oriented matrix. The distributions of some planar molecules of different shapes incorporated in stretched polyethylene films are presented.

ISSN:0038-7010    

DOI:10.1080/00387017708065497

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Pyrene and three azapyrenes have been studied by means of linear and magnetic circular dichroic spectroscopy. As a result, an improved understanding of the lower excited states has been reached, and a simple relation has been found between structure and MCD sign of the first two transitions in the azapyrenes.

ISSN:0038-7010    

DOI:10.1080/00387017708065498

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The study shows that aromatic molecules are caught efficiently from vapour phase by stretched polyethylene film and are bonded inside the film showing orientational dichroism. The saturation time is dependent on vapour pressure, degree of vacuum, and temperature. Compared with the usual solution phase method the application of vapour phase offers the following advantages: the film can be more saturated with molecules and micro-samples can be applied with little waste.

ISSN:0038-7010    

DOI:10.1080/00387017708065499

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Legrand-Grosjean circular dichroism spectrometers are easily converted to detect electric dichroism (ELD), i.e. anisotropic absorption due to an external electric field. The sensitivity enables the studying of small molecules with dipole moments or anisotropic polarisabilities. The observed ELD is in part due to the orientation of the absorbing transition dipole (the orientational distribution being given by the interaction between the dipole and the electric field) but contributions due to perturbations (type Stark) may generally not be neglected. The method is predicted to become an important complement to LD studies in oriented matrix, to evaluate directions of transitions moments, but other applications are also possible. The experimental qualifications are demonstrated on two different species, nitrobenzene and Cu(II) ethylenediamine (acetylacetone)2.

ISSN:0038-7010    

DOI:10.1080/00387017708065500

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The existence of anisotropic local field perturbation on electronic absorption is proved by non-zero linear dichroism of isotropic chromophores (Mo(CO)6) in anisotropic environment. Two sources of such effects are possible: a) perturbation of the electronic energy levels in the chromophore by the static electric solvent field (= Stark effect) or, in case of anisotropic polarizable or dipolar molecules, similar effects involving molecular orientation, and b) dielectric effects on the effective radiation field. The latter effect was considered by various models: The Lorentz field model predicts an effect with wrong sign, it also yields too large a magitude if the anisotropy of the field is considered. If no local field correction is made and the anisotropy only operates in the radiation intensity a result more in agreement with experiment is obtained. By using the Onsager-Böttcher model one may take into account specific properties of the absorbing molecule, like anisotropy in α/r3where α is its polarizability and r its Onsager radius.

ISSN:0038-7010    

DOI:10.1080/00387017708065501

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Optical calculi for anisotropic media are reviewed and extended for use in phasemodulation spectroscopy.

ISSN:0038-7010    

DOI:10.1080/00387017708065502

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Attention is called to an artifact in linear dichroism (LD), so called absorption statistics, which leads to reduced LD intensity in regions of high absorption. The reduction factor is larger than that governing the corresponding reduction in absorption, when LD is measured by using a Legrand-Grosjean circular dichroism spectrophotometer. In the case of infinite fibres at perfect order it coincides with the absorption statistical reduction factor of optical activity. The artifact was observed for β-carothene solubilized in lecithin liposomes oriented at flow.

ISSN:0038-7010    

DOI:10.1080/00387017708065503

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor