J. R. Fernandes

Infrared spectroscopic study of the phase transitions in CsNO3, RbNO3 and NH4NO3

Phase transitions of CsNO3 (II-I), RbNO3 (IV-III-II) and NH4NO3 (V-IV-III-II-I) have been studied by i.r. spectroscopy. The study has provided useful information on the changes in the dispositions of the ions during the phase transitions.

A Raman and infrared spectroscopic study of the ferroelectric phase transition of (CH3NH3)5Bi2Br11

The Phase transition of (CH 3 NH 3 ) 5 Bi 2 Br 11 from a ferroelectric to a paraelectric state has been followed by infrared and Raman spectroscopy. The libration mode of the (CH 3 NH 3 ) + cation shows changes in the Raman spectrum probably due to order-disorder processes.

An infrared spectroscopic study of the low-spin-high-spin transition in FexMn1-x(Phen)2(NCS)2: A composition-induced change in the order of the spin-state transition☆

Infrared spectroscopy provides a valuable tool to investigate the spin-state transition in Fe(II) complexes of the type Fe(Phen)2(NCS)2. With progressive substitution of Fe by Mn, the first-order transition changes over to a second-order transition, with a high residual population of the high-spin state even at very low temperatures

Calorimetric, infrared and ESR studies of the plastically crystalline state of organic compounds

Enthalpy changes of the crystal-plastic and plastic-liquid transitions are related to the temperature range of stability of the plastic phase. Thermodynamics of the plastic state of binary mixtures have been examined. Infrared correlation times, τc, and activation energies have been measured for a few molecules in the plastic state. Molecular tumbling times, τt, have also been measured employing ESR spectra of a spin-probe. Plots of log τc(τt) 1/T are continuous through the plastic-liquid transition. Activation energies for molecular motion seem to vary in the same direction as the ΔH of the plastic-crystal transition. Infrared correlation times of solute molecules in binary solutions in the plastic and the liquid states show interesting variations with solute concentration.

PHASE TRANSITIONS IN KLISO4 AND RBLISO4+ : AN INFRARED SPECTROSCOPIC INVESTIGATION

Infrared spectroscopy shows the occurrence of a transition to a phase of lower symmetry on cooling KLiSO 4 below 170K, but there appears to be no change in the point group symmetry of the SO 4 2− ion across the C 6 6 -C 4 3v transition around 200K. Infrared spectra characteristic of the various phases (I-V) of RbLiSO 4 have been obtained. True monoclinic order in RbLiSO 4 seems to be present only in the room-temperature phase (V). Bands due to the LiO 4 units in both these solids have been studied through the phase transitions.

Raman and infrared spectroscopic studies of the low- and high-temperature forms of octahalo cyclic phosphazene tetramers, P4N4Cl8 and P4N4F8

Based on a study of the Raman and infrared spectra, normal vibrations of the low-temperature skew-tub

Infrared and nuclear quadrupole resonance studies of the phase transitions of para-dichlorobenzene

(S_4)

FTIR SPECTRA OF YBa2Cu3O7−δ AND RELATED OXIDES

and high-temperature

Infrared spectra of superconducting La2−xSrxCuO4 and YBa2Cu3O7−δ

C_i

Phase transitions in KLiSO 4 and RbLiSO 4+ : an infrared spectroscopic investigation

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