Primary hydrogen isotope effects on simple bond cleavage

1 Primary hydrogen isotope effects on simple bond cleavage 

From consideration of peak heights in the El mass spectrum of a mixture of HzO, HOD and DzO, the intramolecular isotope effect, /H//D. on the loss of a hydrogen atom from (HOD) was found to be constant at 2.1 over a range of electron energies from 23 to 500 eV. At lower electron energies, the ratio decreased, i.e. more (OH)+ was formed [297]. The abundance of Of formed from (H20)f was 1.38 times greater than that of Of from either (HOD)f or (D20)f [298], The nature of the reaction forming Of is uncertain for these source reactions. 

In the same type of experiment with hydrogen sulphide, the intramolecular isotope effect was found to be 2.8 [296] (see also ref. 247). The intermolecular isotope effect on the abundance of (HS)+ from H2S and of (DS)+ from D2S was 1.08, and that with Sf from H2S and D2S was 1.3 [247, 296]. 

Isotope effects upon the dissociative electron attachment of water and hydrogen sulphide have been reported [195]. The processes investigated were 

An intermolecular isotope effect, /h//d °f 200 has been reported [741, 742] for dissociative electron attachment of H2 and D2. The intermolecular deuterium isotope effects on dissociative electron attachment in hydrogen chloride, hydrogen bromide and hydrogen iodide have been determined as 1.41,1.45 and 1.66, respectively [168] 

In an early study of metastable ions following El, the decomposition (CD4)t (CD3f+ D- 

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