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1H NMR study of natural and partially deuterated ammonium hexachlorotellurate

✍ Scribed by T. Grabias; N. Piślewski

Publisher
Elsevier Science
Year
1998
Tongue
English
Weight
175 KB
Volume
12
Category
Article
ISSN
0926-2040

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✦ Synopsis

The proton spin-lattice relaxation times in natural and partially deuterated ammonium hexachlorotellurate have been Ž . measured. At high temperature above 50 K the relaxation curve reveals the classical, hindered reorientation of the ammonium ion with the same activation energy for all studied samples E s 5.6 kJrmol. Below 50 K, the minima which a appear in the T temperature dependencies are related to the level-crossing. The tunnelling splitting of the ground torsional 1 level in isotopic pure ammonium hexachlorotellurate is equal to 55 MHz and increases with increasing deuteron concentration, due to the phase transitions occurring in partially deuterated crystal. The lowest temperature minimum in Ž . isotopic pure NH TeCl can be interpreted as a result of the rigid ammonium ion's reorientation about the threefold 4 2 6 q w x crystallographic axis. The limited jumps of NH are characterised by the angle D s 48 between the NH bond and 111 4 direction.

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