Dipole orientation correlation parameter

A different measure for the structuredness of solvents in terms of order, relevant to polar solvents only, is their dipole orientation correlation parameter (see Chapter 3) ... 

In addition to Trouton s rule, some other parameters for measuring the structuredness of solvents have been recommended, for example a solvent dipole orientation correlation parameter [175, 200], the solvent s heat capacity density [175, 200], and a so-called Ap parameter derived from the solvent s enthalpy of vapourization minus EPD/ EPA and van der Waals interactions [201], According to these parameters, solvents can be classified as highly structured e.g. water, formamide), weakly structured e.g. DMSO, DMF), and practically non-structured e.g. -hexane and other hydrocarbons) [200, 201]. 

Another measure for order in a liquid is the Kirkwood dipole orientation correlation parameter (KDOCP) g, but this pertains only to dipolar liquids ... 

The conformational characteristics of dimethyl esters of dicarboxylic acids are studies by the NMR and dipole moment method. Conformational energies of the internal CH2-CH2 bonds are determined from the observed 1H-1H vicinal coupling constants. Preferred conformations around the C-C bond are elucidated from the RIS analysis of dipble moments. With the RIS parameters thus established, the orientational correlation between the terminal ester groups is examined. The analysis provides the reason why the odd-even effect in the dipole moment is moderate, and attenuates rapidly with n in the ct.co-diester series. 

Kirkwood dipole orientation parameter Pair correlation function Enthalpy, molar (kJ moP )... 

Of course, the achievable polarization anisotropy is limited by the degree of orientational order of polymer backbones (Equations (2.7a) and (2.7b)), and by the degree of alignment of the optical transition dipole moments (Equation (2.8)). For instance, polarized Raman microscopy is an especially powerful tool to evaluate the order of molecules within single nanofibers. By this method values of the orientational order parameter (Section 2.1.5) up to 0.75 have been found for poly(ethylene terephthalate) (PET) electrospun nanofibers. In addition, interesting correlations can be drawn between the orientational order of molecules and fiber fabrication parameters, used solvents, etc. The investigation of electrospun poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(l,4-benzo- 2,T-3 -thiadiazole)] nanofibers shows that more ordered molecular chains, without nanoscale aggregates, are obtained when the nanostructures are produced from THF solutions rather than from mixtures of THF and dimethyl sulfoxide (DMSO). ... 

An elegant molecular-beam study of the photofragmentation of aryl halides and methyl iodide has permitted extraction of excited-state lifetimes from a measured anisotropy parameter which depends upon the lifetime of excited state, the rotational correlation time of the molecule, and the orientation of the electronic transition dipole with respect to the —X bond.38 The lifetimes obtained were methyl iodide 0.07 ps, iodobenzene 0.5 ps, a-iodonaphthalene 0.9 ps, and 4-iodobiphenyl 0.6 ps, from which it was concluded that, whereas methyl iodide dissociates directly, the aryl halides predissociate. A crossed-beam experiment using electron-beam excitation has yielded the results for the Si Tt intersystem-crossing relaxation time in benzene, [sHe]benzene, fluorobenzene, and... 

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