Local Structure and Tunneling Kinetics of Ammonium Aluminum Alum by Infrared Hole-Burning

Abstract

The title compound, crystallized with a few percent of deuterium, contains some NH(3)D(+) and HOD. At low temperatures, five N-D stretch bands are observed. These belong to two ammonium sites with apparent C(s) symmetry in the low-temperature phase. The N-D bands can be hole-burned with an infrared laser. Burning bands belonging to the A-sites transforms some of them to the higher-energy B-sites. The A- and B-sites probably differ from each other by the arrangement of water and sulfate about the ammonium.

Infrared Study of Weakly Bound Hydrogen Bonds in Crystalline Sodium Sulfanilate Dihydrate

“…Infrared spectra were measured at lower temperatures in the 4000−2000 cm -1 region using a Nicolet 850 FT-IR with an InSb detector with the sample loaded into a closed-cycle helium cryostat (CTI-Cryogenics SC 21). The details of this setup have been described previously . Line shifts and widths were obtained using second derivative, peak finder, and Fourier self-deconvolution programs…”

Dielectric properties of ammonium iron sulphate-dodecahydrate alum crystal

“…Roberts and Sambles [7] have studied the spin relaxation phenomena in AFeSD-alum crystal using Mossbauer spectroscopy, which explained that anomalous variations in linewidth with temperature should not be directly correlated with the polar phase transformation at 88 K. Lou and Yu [8] studied the dimorphism in methylammonium aluminum alum by X-ray diffraction and electron paramagnetic resonance. Cha and Strauss [9] have obtained the local structure and tunnelling energy of ammonium aluminum alum crystal by hole burning. Lui et al [10] have studied morphology and compositional preparation of Al 2 O 3 powders by spray pyrolysis of ammonium alum crystal.…”