The Thionine System

The problem with thionine as a constituent of a photogalvanic cell is that, although its rate constant k-2 has a satisfactory value of 500 dm mol l its 

Thus it is impossible, using thionine, to achieve the necessary condition of egn (3) (X 0 10.  

We therefore decided that the right aporoach must be to synthesise modified thiazine dyes by attaching sulphonate groups to the thiazine nucleus. 

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