ANOMALOUS RECOILLESS FRACTION OF 30-ANGSTROM-DIAMETER FEOOH PARTICLES

Investigation of a 30-Angstrom iron oxyhydroxide catalyst by Mossbauer spectroscopy revealed that the recoilless fraction decreased dramatic ally with increasing temperature, becoming effectively zero at 50 K. T his effect is explained on the basis of a combined effect of the recoi l of the particle and the particle motion due to thermal agitation. Th e mean-square amplitude of particle motion is derived as a function of temperature. Application of uniaxial pressure to the sample or freezi ng the sample in carnuba wax increased the recoilless fraction markedl y by enhancing the interparticle contact forces.