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Electron-phonon coupling in oligo(para-phenylene)s is addressed in terms of the off-resonance Raman intensities of two distinct modes at 1220 and 1280 cm(-1). On the basis of Albrecht's theory, vibrational coupling and Raman intensities are calculated from first-principles quantum-chemical methods. A few-state model is used to evaluate the dependence of the mode intensities on oligomer length, planarity, and excitation wavelength. The link between electron delocalizationconjugation and Raman intensities is highlighted. Extending on prior studies, the present work focuses on providing an in-depth understanding of the origin of this correlation in addition to reproducing experimental findings. The model applied here allows us to interpret the results on a microscopic, quantum-mechanical basis and to relate the observed trends to the molecular orbital structure and nature of the excited states in this class of materials. We find quantitative agreement between the results of the calculations and those of measurements performed on oligo(para-phenylene)s of various chain lengths in the solid state and in solution.

We report on the morphological aspects of thin films prepared from a blue–green light‐emitting conjugated polymer, (methyl‐substituted ladder‐type poly(p‐phenylene, mLPPP)), blended with a solid‐state electrolyte composed either by a crown ether, dicyclohexano‐18‐crown‐6 (DCH18C6), or a high‐molecular‐weight poly(ethylene oxide) (HMWPEO), and a Li salt, lithium trifluoromethanesulfonate (LiCF3SO3, Li triflate (LiTf)), as they have been successfully applied in light‐emitting electrochemical cells (LECs). The surface morphologies of the blend layers were investigated using atomic force microscopy (AFM) in tapping mode, and the ion distribution was probed using X‐ray analysis by means of energy‐dispersive X‐ray spectrometry (EDXS) in the scanning electron microscope (SEM). We show that the two different phase‐separation processes, the complexation tendencies of the ionic species as well as the ionic transport numbers, have tremendous influence on the performances of the corresponding LECs, revealing either rectifying or symmetric optoelectronic characteristics in forward and reverse bias directions. This opens up new possibilities for tuning the optoelectronic properties of ion‐supported organic electronic devices.

In this work, we clarify the nature of a previously not precisely identified Fermi dyad in the frequency range around 1600 cm−1 in oligo( para-phenylenes). To this end, we deploy a novel method to calculate third order anharmonic coupling effects in molecules. This Fermi dyad is shown to yield important information on the structural properties of the investigated materials. The nature of all vibrations contributing to this quantum mechanical resonance phenomenon is explained on the basis of a detailed normal coordinate analysis. The anharmonic coupling is then closely investigated by applying our theoretical model. In particular, we discuss the intensity redistribution among the two components of the Fermi doublet as well as their energetic separation. Subsequently, we establish a relation between these features and the structural conformation of the molecules. We show, how oligomer length and planarity of these systems can be determined from experimental Raman spectra by extracting the positions and relative intensities of the two components of the Fermi doublet. Furthermore, this Fermi resonance is shown to be sensitive to chemical modification on the molecules such as deuteration or substitution. Finally, we extend our model to electronically excited states in this class of molecules, as well as to charged species.

The conventional optical multichannel technique (MT) has improved optical spectroscopy, in comparison to single-channel methods, by at least an order of magnitude in measurement time at the same signal-to-noise ratio. In this work we show that some disadvantages (e.g., limited range of the recorded spectra, different noise and sensitivity of each detection element, and fixed spectral distance of the detection elements) can be excluded by using what we call the scanning multichannel technique (SMT). A calculation of the measurement time for characteristic single-channel and multichannel detectors results in the fact that SMT is, like MT, an order of magnitude faster than the single-channel technique (SCT). In some particular cases SMT results in measurement times shorter than those for MT. We conclude that SMT combines the advantages of MT and SCT. Moreover, measurements of sharp spectral lines made it evident that SMT also improves the reproducibility of the spectrometer used and increases the accuracy of the recorded spectra. The SMT method is not only restricted to optical spectroscopy but can be universally applied to all spectroscopic methods where multichannel detection is used.

A novel ternary phase, SnyNi4Sb12−xSnx, has been characterized and found to exhibit a wide range of homogeneity (at 250 °C, 2.4 ≤ x ≤ 5.6, 0 ≤ y ≤ 0.31; at 350 °C, 2.7 ≤ x ≤ 5.0, 0 ≤ y ≤ 0.27). SnyNi4Sb12−xSnx crystallizes in a skutterudite-based structure in which Sn atoms are found to occupy two crystallographically inequivalent sites: (a) Sn and Sb atoms randomly share the 24g site; and (b) a small fraction of Sn atoms occupy the 2a (0, 0, 0) position, with an anomalously large isotropic atomic displacement parameter. Eu0.8Ni4Sb5.8Sn6.2, Yb0.6Ni4Sb6.7Sn5.3 and Ni4As9.1Ge2.9 are isotypic skutterudites. Depending on the particular composition, metallic as well as semiconducting states appear. The crossover from semiconducting to metallic behaviour is discussed in terms of a temperature-dependent carrier concentration employing a simple model density of states with the Fermi energy slightly below a narrow energy gap. This model accounts for the peculiar temperature-dependent electrical resistivity. These skutterudites are characterized by a number of lattice vibrations, which were elucidated by Raman measurements and compared to the specific heat data. The Eu-containing compound exhibits long-range magnetic order at Tmag ≈ 6 K, arising from the Eu2+ ground state.