A Test of the Radiation Hypothesis of Chemical Reaction

Citation

Ure, William (1928) A Test of the Radiation Hypothesis of Chemical Reaction. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/CDKJ-6283. https://resolver.caltech.edu/CaltechETD:etd-02282005-092521

Abstract

The viewpoint that thermal unimolecular reactions are to be considered as photochemical reactions with the activating frequencies lying in the infra-red region should be susceptible of experimental test by subjecting a system to radiation from an outside source, and determining whether or not the thermal reaction rate is thereby increased. The difficulties in such an experiment arise from two sources. First, there is the necessity of obtaining a high intensity of infra-red radiation, without at the same time raising the temperature of the reacting substance to such a point that the normal thermal rate is the preponderating effect. In the second place, the extreme opacity of almost all substances to all but the shortest of infra-red rays makes it difficult to find a window that will permit a high intensity over the wide range of frequencies which may be important in activating the molecules. For, since we do not know in what part of the infra-red spectrum the activating frequencies might lie, a conclusive test of the hypothesis should involve the use of all frequencies which are present to an appreciable extent in a hohlraum at the thermal reacting temperature.

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