Quantitative extraction of continuous distributions of energy states and pre-exponential factors from thermal desorption spectra

Abstract In many adsorption systems of practical interest, such as polycrystalline surfaces, desorption occurs from a continuous distribution f ( E ) of energy states. The quantitative inversion of temperature programmed desorption (TPD) spectra to obtain f ( E ) has heretofore proven quite difficult. In this paper, a method is presented in which f ( E ) may be calculated from a single spectrum for any reaction order if the pre-exponential factor ν 0 is known. If ν 0 is not known a priori, it is shown how a conventional heating rate study may be used to determine the magnitude of ν 0 and any energy dependence it may have. Some aspects of the coverage dependence of the desorption parameters may be determined as well.

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