Vibrational spectra of anhydrous lithium perchlorate in crystalline and molten states

Abstract

Anhydrous lithium perchlorate has been examined in the crystalline and molten state by infrared and Raman spectroscopy. In the crystalline phase all degenerate modes are split but the Raman and infrared spectra are essentially identical in the internal frequency region. In the molten state the spectra are more simple but no coincidences exist between infrared and Raman spectra. The spectra are interpreted in terms of a crystalline symmetry perturbation for both the solid and molten salts. The symmetry of the perturbing field is shown to change in going from the solid to the melt. An explanation of the melt spectra in terms of contact ion pairs is considered and dismissed. Observed vibrational frequencies and assignments are given.

FTIR spectroscopic investigations of supersaturated NaClO4 aerosols

“…The published data for alkali metal perchlorates usually indicate some splitting of the n 3 degeneracy into two or three bands separated by as much as 60 cm À1 , and the n 1 band was always visible through the anion distortion resulting from a low symmetry environment. 3,45,55,56 Therefore, both the Raman spectrum of the anhydrous NaClO 4 aerosols and the infrared spectrum of the anhydrous NaClO 4 /KBr pellet can be regarded as consistent with the previous reports.…”

Raman study of crystalline solvates between glymes CH3(OCH2CH2)nOCH3(n = 1, 2 and 3) and LiClO4

“…Our experimental data on LiClO 4 are in moderate agreement with those of Leong and James. 20 The n 1 vibration gives a single broad band situated at the highest frequency (964 cm À1 ) in the perchlorate series (Fig. 6(e)).…”

“…The Raman spectra of the pure LiClO 4 salt in the solid and melted states have previously been recorded before structural information was available. 20 More recently, the vibrational spectra of metal perchlorates MClO 4 (M ¼ K, Rb, Cs or Tl) have been investigated. 21,22 All of these compounds, including LiClO 4 , 11 crystallise in the Pnma-D 2h 16 (Z ¼ 4) space group.…”

Релаксация Колебательно-Возбужденных Состояний В Твердых Бинарных Системах Карбонат--Сульфат

“…При этом разность ν i − ν j частот колебаний карбонат-иона и сульфат-иона будет меньше, чем максимальная частота ν m фононного спектра системы и условие (4) окажется выполненным. Следовательно, возможна дис-сипация колебательной энергии ВМК карбонат-иона с последующим возбуждением соответствующего ВМК сульфат-иона и рождением решеточного фонона, так как разница в частотах указанных ВМК попадает в область достаточно высокой плотности состояний фононного спектра исследуемых кристаллов [24,25].…”