Abstract

Biacetyl has been studied extensively in gas, solid, and liquid phases. As a result, much information is known about the kinetic behavior in these states. Little research has been done, however, on the behavior of biacetyl adsorbed on an alkali halide substrate. The focus of this research is into the kinetic profile of biacetyl. More specifically, it investigates the desorption kinetics of biacetyl, and its photoproducts, adsorbed on an alkali halide film, as well as its infrared spectrum.

Infrared spectra were utilized to determine the extent of desorption. Linear regression analyses of these data were used to determine kinetic profile, including activation energy, and the order of desorption (i.e., first order, second order, etc.). Additionally, analysis of the mode of adsorption was determined through use of Full Width Half Maximum (FWHM) data, frequency shifts and desorption parameters.

For these experiments, the desorption of biacetyl from the substrate follows first-order kinetics. Furthermore, the energy of activation for the desorption of biacetyl ranges between 38 and 43 kJ/mol. The desorption of biacetyl is not affected by irradiation. The activation energy for the desorption of the primary photoproduct, ketene, is comparable to that of the parent biacetyl.