Kinetics of iodine dissociation on silica surfaces between 800-1000 K

Abstract

The heterogeneously activated atomization of I_2 was studied by modulated beam mass spectrometry in a fused silica molecular flow reactor between 800-1000 K. Experimental dissociation rates at 1000 K are about 10^(3.9) times faster than those estimated for the decomposition of fully equilibrated gas-phase iodine molecules at the same collision frequency and the associated activation energy, E = 24.5 kcal/mol, is considerably smaller than D_O (I_2). Both effects can be ascribed to a chemical reaction involving physisorbed species rather than to direct interfacial energy transfer or reactive gas-solid interactions.

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