Experimental proof of localized plasmon resonance was found in thin films containing either single-walled carbon nanotubes (SWNT) or SWNT bundles of different length. All samples were prepared by a simple technique that permitted the selection of different SWNT lengths in different samples without significant differences in electronic properties. Fourier-transform infrared spectroscopy showed that an optical-density peak, the same as a terahertz conductivity peak, shifts to higher frequencies as the SWNT lengths are reduced—in agreement with a similar tendency predicted for the localized plasmon resonance in finite-length SWNTs [Slepyan et al., Phys. Rev. B 81, 205423 (2010)].

Investigation results of dielectric and ultrasonic properties of layered CuInP₂S₆ crystals are presented. At low frequencies, dielectric spectra are highly influenced by the high ionic conductivity with the activation energy of 7357.4 K (0.635 eV). The high-frequency part of the spectra is determined by relaxational soft mode. The critical slowing down and Debye-type dispersion show the order–disorder type of the phase transition. The temperature dependence of the relaxational soft mode and dielectric contribution show a quasi-one-dimensional behaviour. Ultrasonic velocity exhibits critical slowing down which is accompanied by attenuation peaks in the phase transition region. Layered CuInP₂S₆ crystals have extremely large elastic nonlinearity in the direction perpendicular to layers. The nonlinear elastic parameters substantially increases at the PT temperature.

Dielectric spectra of several solid solutions of $\mathrm{Pb}{\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_3\text{−}\mathrm{Pb}{\mathrm{Sc}}_{1∕2}{\mathrm{Nb}}_{1∕2}{\mathrm{O}}_3\text{−}\mathrm{Pb}{\mathrm{Zn}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_3$ (PMN-PSN-PZN) relaxor ferroelectrics were investigated in a broad frequency range from $20\mathrm{Hz}$ up to $100\mathrm{THz}$ by a combination of dielectric spectroscopy $(20\mathrm{Hz}–53\mathrm{GHz})$, time-domain terahertz spectroscopy $(0.1–0.9\mathrm{THz})$, and infrared reflectivity ($20–3000{\mathrm{cm}}^{-1}$, $0.6–90\mathrm{THz}$). The very strong and broad dielectric relaxation observed below phonon frequencies was analyzed in terms of the distribution of relaxation times, using the Tichonov regularization method. This revealed slowing down of the longest and mean relaxation times obeying the Vogel-Fulcher law. The relaxation splits into two components near $T_m$ and the origin of both components is discussed. The formation of polar clusters below the Burns temperature $(700–800\mathrm{K})$ is manifested by the appearance of dielectric relaxation in the terahertz range and by splitting of the polar modes in the infrared spectra. On heating from low temperatures, the $A_1$ component of the strongly split ${\mathrm{TO}}_1$ mode softens toward the Burns temperature, but the softening ceases near $400\mathrm{K}$, which could be a signature of a polar cluster percolation temperature.