The authors investigate the dynamics of a series of room temperature ionic liquids, based on the same 1-butyl-3-methylimidazolium cation with different anions, by means of broadband (10(-6)-10(9) Hz) dielectric spectroscopy and depolarized light scattering in the temperature range from 400 K down to 35 K. Typical ionic conductivity is observed above the glass transition temperature Tg. Below Tg the authors detect relaxation processes that exhibit characteristics of secondary relaxations, as typically observed in molecular glasses. At high temperatures, the characteristic times of cation reorientation, deduced from the light scattering data, are approximately equal to the electric modulus relaxation times related to ionic conductivity. In the supercooled regime and close to Tg, the authors observe decoupling of conductivity from structural relaxation. Overall, room temperature ionic liquids exhibit typical glass transition dynamics, apparently unaltered by Coulomb interactions.

Precursor dynamics of a cubic to tetragonal ferroelectric phase transition in BaTiO3 is studied by the accurate measurement of the second harmonic generation (SHG) integral intensities. A finite signal holds for the SHG integrated intensity above the ferroelectric Curie temperature T(c)=403  K. Above the Burn's temperature T(d)≈580  K, the power law with the exponent γ=1 shows normal SHG nature originating from the hyper-Raman scattering by dynamical polar excitations, while, below T(d), a SHG signal from polar nanoregions becomes dominant with the larger exponent γ=2. Such a crossover of the power law exponent near T(d) is discussed on the basis of the effective Hamiltonian method and Monte Carlo simulation.

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Low-frequency light scattering spectra of As2S3 glass former have been investigated over a temperature range of 300–712 K. Using the model of a damped oscillator, the parameters of the intensities of the boson peak and of the fast relaxation as well as the boson peak position and the relaxational time are extracted as a function of temperature. The temperature increase of the fast relaxation becomes more sharp above Tg and stabilizes at T = 600 K. By analogy with other glass formers it is suggested that the critical temperature Tc within the framework of the mode-coupling theory should be near 600 K for As2S3. It was found that the damping parameter at Tc is the same for As2S3 and B2O3; an explanation of this coincidence is suggested. The boson peak is found to be present up to 712 K with almost the same strength as at low temperatures.