The infrared spectrum of biacetyl is well characterized in the liquid, gas and solid phases. Its behavior has been investigated on different substrates as well as in matrices. This study focuses on the infrared spectrum and desorption kinetics of deuterated biacetyl and its major photoproduct, ketene-d2, on alkali halide films.
Analysis of the infrared spectra of biacetyl-d6 suggests that this compound adsorbs parallel or almost parallel to the surface of the substrate. The use of Full Width at Half Maximum and peak shift analysis suggests that there is hindrance of torsional motion, which indicates that all or most of the functional groups are in contact with the substrate surface.
Desorption of biacetyl-d6 and its photoproduct follows a mixture of first-order and zero-order kinetics. This suggests that biacetyl-d6 may adsorb in a way so that there are islands of solid on the surface, and not only in a monolayer film. Both species have similar energy of activation ranges, which suggests that ketene-d2 is possibly trapped within the bulk solid biacetyl-d6.
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