摘要：

The photochemical cis → trans and trans → cis isomerizations of azobenzene solutions in isoöctane have been studied. Quantum yields for both processes have been determined with precisions of from 5 to 10% over wide ranges of wave length, concentration and light intensity. The quantum yield depends only on wave length and is approximately constant throughout a single absorption band. The average quantum yields are as follows: for the ultraviolet band, cis → trans 0.42 ± 0.04, trans → cis 0.11 ± 0.01; for the visible band, cis → trans 0.48 ± 0.05, trans → cis 0.24 ± 0.02. The results suggest that the isomerization takes place as an ordinary thermal reaction of an electronic excited state.

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