Atomic species as intermediates in heterogeneous

Adsorbed Atomic Species as Intermediates in Heterogeneous Catalysis Carl Wagner... 

C. Wagner, Adsorbed Atomic Species as Intermediates in Heterogeneous Catalysis, in Adv. Catal., (1970), pp. 323-381. 

In looking for the mechanism, many intermediates are assumed. Some of these are stable molecules in pure form but very active in reacting systems. Other intermediates are in very low concentration and can be identified only by special analytical methods, like mass spectrometry (the atomic species of hydrogen and halogens, for example). These are at times referred to as active centers. Others are in transition states that the reacting cheimicals form with atoms or radicals these rarely can be isolated. In heterogeneous catalytic reaction, the absorbed reactant can... 

In heterogeneous catalysts, the notion has been put forward that the energy of reaction to form a surface intermediate can be trapped in that intermediate. Such an intermediate is referred to as unaccommodated, meaning that it has not achieved thermal equilibration with the surrounding medium and therefore can be considered hot or energized. The reactivity pathways of the unaccommodated species (for example, alkyl radicals or H atoms) can be significantly different from those of their thermally equilibrated analogues [35-40],... 

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