How the phosphorus chains impact on the vibrational properties of diphosphides ZnP₂ and CdP₂ at low temperatures

The temperature dependence of the vibrational modes in the diphosphides ZnP₂ and CdP₂ has been studied by employing IR reflectance spectroscopy within the 4…300 K temperature range in the polarized radiation. It has been demonstrated that decreasing the bond distance in the phosphorus chain at low temperatures causes an additional amount of anharmonicity of the corresponding modes, which is manifested in more pronounced temperature dependences of their frequencies and damping coefficients

The boson peak and the first sharp diffraction peak in (As2S3)x(GeS2)1–x glasses

The parameters of the boson peak (BP) and the first sharp diffraction peak (FSDP) in (As2S3)x(GeS2)1x glasses measured using high-resolution Raman spectroscopy and high-energy synchrotron X-ray diffraction measurements are examined as a function of x. It has been found that there is no correlation between the positions of BP and FSDP. The BP position shows a nonlinear composition behavior with a maximum at about x = 0.4, whereas the FSDP position changes virtually linearly with x. The intensities of both BP and FSDP show nonlinear composition dependences with the slope changes at x = 0.4, although there is no direct proportionality. Analysis of the partial structure factors for the glasses with x = 0.2, 0.4 and 0.6 obtained in another study has shown that the cation-cation atomic pairs of Ge–Ge, Ge–As and As–As make the largest contribution to FSDP, where the Ge–Ge and Ge–As pairs are dominant

Reststrahlen spectroscopy of MgAl₂O₄ spinel

Using IR reflectance spectroscopy and surface polariton spectroscopy in the reststrahlen region, we investigated Czochralski-grown MgAl₂O₄ spinel. The computer analysis of variance made for spectra enabled us to get a mathematical model for reflection spectra of spinel. In our calculations we used consistent data for optical parameters (zero- and high-frequency permittivities, transverse optical phonon frequencies and corresponding damping coefficients) of spinel single crystals that have been obtained from comparison between the measured and calculated spectra. These data were used when studying attenuated total reflection spectra and dispersion curves for surface polaritons in MgAl₂O₄ spinel