Overtone Spectroscopy of the OH and OD Stretch Modes in LiNbO₃

Abstract

absorption bands due to the fundamental and the overtone of OH and OD stretch modes are investigated in undoped, Mg-doped, and benzoic acid treated LiNbO,. The different bands are interpreted using an anharmonic oscillator model. Spectroscopic parameters determined from the isotope shift and the overtone frequencies are in good agreement. The anharmonicity found is comparable t o that of OH in other ABO, compounds and in alkali halides.Es werden die infraroten Absorptionsbanden der Grund-und Obertone der OH-und OD-Streckschwingungen in reinem, dotiertem (Magnesium) und mit Benzoesiure behandelten LiNbO, untersucht. Die verschiedenen Banden werden mittels eines anharmonischen Oszillatormodells interpretiert. Spektroskopische Parameter, die aus der Isotopieverschiebung und den Obertonfrequenzen abgeleitet werden, stimmen gut iiberein. Die gefundene Anharmonizitit ist mit der fur OH in anderen AB0,-Verbindungen und Alkalihalogeniden vergleichbar.

New concepts in low‐temperature catalytic hydrogenation and their implications for process intensification

“…The ability of activated H atoms to migrate from Ru metal particles toward the alumina support was confirmed via H/D isotopic exchange (Figure ) and in situ DRIFTS analyses (Figure ). Characteristic stretching vibrations of OH and OD groups appeared with an isotope ratio of ν OH/ ν OD 1.356, very similar to the theoretical ratio (∼1.37), which confirms that H atoms activated on Ru nanoparticles can be actually transferred to alumina and move along the surface via exchange with the hydrogen atoms from hydroxyl groups. The rate of exchange was found to be higher on surfaces containing large Ru nanoparticles, and a synergy in hydrogen diffusivity resulted in mechanical mixtures of catalysts containing Ru nanoparticles with different sizes.…”

FTIR Spectroscopy to Monitor OH‐Impurity Interactions in Insulating Crystals

“…For OH" interacting with trivalent cations, as Ti 3+ in LiF, x e is slightly higher than that related to divalent cations, as Mg 2+ (see Table 1). As a general remark, the anharmonicity parameter for noninteracting OH" in oxides [6,15] is larger than that in alkali halides and perovskites (see Table 1). As a rule, x e for OH", perturbed by impurity-related defects, increases slightly by increasing the temperature.…”

Comparative study on three highly sensitive absorption measurement techniques characterizing lithium niobate over its entire transparent spectral range

“…From the successful calibration of the PAS measurement it can be concluded that the ratio of the band intensities of fundamental and overtone OH − vibrations has indeed in undoped lithium niobate a value of about 175. This number was originally taken from studies with proton exchanged lithium niobate by Förster et al [12].…”

“…The excitation of the first overtone of the OH − vibration leads to an absorption band at 1470 nm. The ratio of the band intensities between fundamental and overtone excitations was determined by Förster et al in proton exchanged lithium niobate to a value of 175 [12]. In undoped LiNbO 3 the absorption band of the overtone is difficult to measure with standard transmission spectrometers, but can be observed with the PAS.…”