The infrared spectra of zinc formate dihydrate are presented for the region 1000 to 400 cm−1 along with the laser-excited Raman spectra. With the use of the corresponding IR and Raman spectra for the deuterated and anhydrous samples and their temperature dependence (between 300 to 90 K), two sets of bands for the in-plane bending mode of formate ion and all the three librations of water have been identified corresponding to two types of formate and water in the unit cell. The large shift of the formate ν3 mode in going from the hydrate to the deuterate has been attributed to a dynamic interaction of this mode with the close-lying H2O rocking mode.
Evans holes have been identified in OH(OD) stretching regions in the ir spectra of M(HCOO)2•2X2O (M = Mn, Co, Ni and Zn; X = H, D) and attributed to Fermi interaction between the stretching mode and an overtone of the bending mode of water.
The Raman spectra (30–3300 cm−1) of a single crystal and of polycrystalline forms of NH4SCN are presented in the temperature range 135 to −175 °C. The polarization behavior of the Raman bands reveals the antipolar arrangements of SCN− ions in the room temperature phase. Above 86.5 °C the spectra do not show polarization behavior due to the formation of polycrystalline domains. Other changes observed in the entire spectrum at this phase transition are attributed to reorientation of SCN− ions between two equivalent configurations. At the next phase transition around 112 °C the lattice modes of SCN− ions are affected. The characteristics are those of a second-order displacive phase transition. A new phase transition observed at −70 °C is characterized by the strengthening of the hydrogen-bond networks in the lattice.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.