The spectral-luminescence properties of the 4-cyano-4'-pentylbiphenyl CH 3 (CH 2 ) 4 (C 6 H 4 ) 2 CN (5CB) liquid crystal has been studied in the temperature range 4.2-297 K. It is shown that at increasing temperature the fluorescence spectra are shifted to the red side. The spectral long-wavelength shifts are also analyzed. A comparison of the temperature behaviour position of the emission of the band maxima l max and their half-widths Δl/2 in the fluorescence spectra and the results of the DSC-investigation show that phase transitions occur in 5CB liquid crystals at T ~ 230 and 260 K.

The spectroluminescence properties of 4cyano4'pentylbiphenyl CH 3 (CH 2 ) 4 (C 6 H 4 ) 2 CN (5CB) were studied in the temperature range 4.2–297 K. A red shift of the fluorescence spectrum was noted with increasing temperature. The long-wavelength shifts in these spectra were also analyzed. Comparison of the temperature dependence curves for the emission at the band maxima λ max and their halfwidths Δλ/2 in the fluorescence spectra and the results of a differential scanning calorimetry (DSC) study showed that phase transitions occur in the 5CB liquid crystals at ~230 and ~260 K.

We investigated the photoluminescent properties of nanocomposites based on the liquid crystal (LC) 5CB filled with dispersed inorganic particles, such as carbon nanotubes (CNT), montmorillonite mineral platelets (MMT) and titanium dioxide nanotubes TiO 2 (TNT), in the temperature range 4.2-300 K. The IR absorption spectra of these composites were studied in the spectral range 390-4000 cm - 1 at room temperature. The composite luminescent properties depending on the physical properties of the nanoparticles were considered. The long-wavelength shifts of the composites luminescence spectra according to the 5CB spectrum were defined by the magnitude of the nanoparticles specific surface. The spectral long-wavelength shifts at room and low temperatures were analyzed.

The concentration dependences of the electron spectra of impurity crystals of fluorobenzene in benzene and β-substituted naphthalenes in naphthalene are investigated (T = 4.2 K). Peculiarities of the energy spectra of clusters in the molecular crystals with non-dipole and dipole guest molecules are revealed. The energy and geometric conditions for D-cluster effect in the electron spectra of impurity crystals are determined.

The concentration dependence of the low-temperature (4.2 °K) electronic absorption and luminescence spectra is investigated for a β-naphthol impurity in a naphthalene crystal; this impurity forms substitutional solid solutions within definite concentration limits. The spectra are analyzed to obtain information on the modes of substitution and low-temperature distribution of impurity molecules without an inversion center in a solvent crystal with centrosymmetric molecules; the molecular interaction parameters are determined.