Determination of optical properties of slices of turbid media by diffuse CW laser light scattering profilometry

In this work we present a method for determining the optical parameters of turbid media, namely its absorption coefficient (μ_a) and its reduced scattering coefficient . It is based on the measurement of CW transmittance profiles and analysis of the experimental data by a theoretical model based on the diffusion approximation (DA) of the radiative transfer equation (RTE). The method developed has been investigated with solid polymer probes but it could be applied for liquid materials as well. Experimental results are presented and compared to those of other authors together with a discussion about the accuracy of measurements. In addition, measurements using integrating spheres as well as Monte Carlo simulations are also presented to validate these results.     

“Crowned” Univalent Indium Complexes as Donors? Experimental and Computational Insights on the Valence Isomers of EE′X4 Species

The use of the univalent indium reagent [In([18]crown-6)][OTf] as a donor is investigated by its reactions with acceptors including InX(3) (X=Cl, Br, I). The donor-acceptor complexes of the form [X([18]crown-6)In-InX(3)] obtained in this manner represent the first new isomeric form of indium(II) halides identified for at least five decades. The formation of such complexes appears to be particularly favorable and they are isolated as products in many reactions involving low-valent indium, a halide source, and [18]crown-6. A convenient solution-phase synthesis of In[ECl(4)] salts is reported. This facile and direct syntheses of In[ECl(4)] (E=Al, Ga, In) salts allows for the in situ preparation and isolation of crown-ether complexes of the form [In([18]crown-6)][ECl(4)], whose existence had been postulated but never confirmed. Solution-phase and solid-state NMR experiments reveal that these compounds can exist as either donor-acceptor complexes or ionic salts, depending on the phase of the system, the nature of the solvent employed, and the identity of the metalate anion involved. Similar investigations into the effect of a smaller crown ether allow for the isolations of salts containing the cation [In([15]crown-5)](+). Computational investigations into the nature of the crowned univalent indium donor fragments, and on the donor-acceptor complexes produced, demonstrate the influence of anionic substituents on the reactivity of lone pair of electrons of the In(I) center. Natural bond orbital (NBO) analysis of donor-acceptor models shows that the composition of the E-E bond MO should provide the ability to predict which models should form stable complexes.     

Resolution of conflicting views concerning frequency-response models for conducting materials with dispersive relaxation, and isomorphism of macroscopic and microscopic models

Possible errors in the widely used 1972–1973 macroscopic original-electric-modulus formalism are identified, corrected, and their consequences considered. These errors include misidentification of the high-frequency-limiting dielectric constant arising entirely from mobile charges, ε_C1∞, and the failure to treat properly the high-frequency-limiting dielectric constant associated with bulk dipolar and vibrionic effects, ε_D∞. It is shown that the corrected modulus formalism, which describes dispersed mobile-charge effects, is isomorphic in form with the 1973 microscopic continuous-time random-walk hopping model of Scher and Lax after a minor but significant correction is made to the latter's response function. This firmly established correction, which nevertheless could not be determined by Kronig–Kramers transformation, involved inversion of synthetic frequency-response data to determine a distribution of relaxation times and led to extension of the real part of the Scher–Lax dielectric response to higher frequencies by the inclusion of a nonzero limiting value. This isomorphism, along with excellent data fitting using the corrected modulus formalism, suggests that since the Scher–Lax stochastic model involves no explicit Coulomb interactions, cation motion in glasses is dominated by short-range interactions. Finally, two very-high-frequency processes, which each lead to a limiting plateau value of the real part of the conductivity at sufficiently high frequencies, are discussed in detail.     

On the Marzke-Wheeler and Desloge constructions

There is no indication of time dilation of clocks or of length contraction of rods in Marzke and Wheeler's clock or in Desloge's metrosphere.