the desorption rate[mol/(cm2 s)], order of desorption, surface coverage, pre-exponential factor [Hz], activation energy of desorption [kJ/mol], gas constant, temperature [K]. Using the before mentioned Redhead method (a method less precise as the "complete analysis" or the "leading edge" method) and the temperature maximum one can determine the activation energy: (equation 5) for n=1 (equation 6) for n=2 M. Ehasi and K. Christmann described a simple method to determine the activation energy of the second order. Equation 6 can be changed into: (equation 6a) where: is the surface area of a TDS or TPD peak. A graph of versus results in a straight line with a slope equal to . Thus in a first-order reaction the is independent of the surface coverage. Changing the surface coverage one can determine . Usually a fixed value of the pre-exponential factor is used and is known, with these values one can derive the iteratively from . See also Temperature-programmed reduction References External links Temperature programmed desorption @ the Surface Science Laboratory Thermal desorption of large adsorbates Mass spectrometry Analytical chemistry Surface science