Nitrogen molecule near dissociation

The promoter action of adsorbed potassium has been attributed both to a stabilization of the molecular a-species as well as to an enhancement of the sticking coefficient for the formation of this a-species. On Fe(lll) the adsorption energy for a-N2 is increased locally in the vicinity of an adsorbed potassium atom from 31 to 44 kJ moP. Parallel to this increase in the adsorption energy for the precursor state its activation energy for dissociation is lowered, as becomes apparent from inspection of Fig. 3.10. Once the nitrogen molecule has become dissociated, the adsorbed N atoms formed near the K atoms diffuse away to the bare iron patches (when the temperature is above 400 K), so that finally the whole available surface is covered by Nad-... 

The absorption wavelengtlrs quoted here are for the complete dissociation of these molecules to the atoms in their ground state. The thermochemical data also show that a temperature of nearly 4000 K is requhed before the atomic oxygen concentration is equal to that of molecular oxygen, and almost 7000 K for the nitrogen atom population to be equal to the molecular nitrogen concentration, at one atmosphere pressure. 

Nitrogen dioxide is one of a few simple molecules in which the primary quantum yield near the dissociation limit (3980 A) has been measured nearly continuously as a function of incident wavelength. The energetics of photodissociation is given in Table VI- 5. The thcrmochcmical threshold at O K for the reaction, N02 - NO + O( P), corresponds to the incident wavelength 3978 A, which nearly coincides with the wavelength 3979 1 A below which... 

The photochemical decompositions of perfluoroazomethane - and per-fluoroazoethane closely resemble those of the parent azohydrocarbons. Thus perfluoroazomethane when irradiated in the near ultraviolet, decomposes to nitrogen and perfluoroethane via a primary dissociation step in which trifluoro-methyl radicals are formed. Quantum yields of about 0.25 in the gas phase at room temperature - may be the result of collisional deactivation of excited perfluoroazomethane molecules. 

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