The NO release following 266 nm photolysis of ortho and meta isomers of nitrophenol and nitroaniline shows a bimodal translational energy distribution, wherein the slow and fast components originate from dynamics in the S₀ and T₁ states, respectively. The translational energy distribution profiles for any NO product state show a higher slow-to-fast (s/f) branching ratio for the ortho isomer in comparison with the meta isomer. The observed variation in the s/f branching ratio vis-à-vis the ortho and meta isomers is attributed to the presence of intramolecular hydrogen bonding between the ortho substituent and NO₂ moiety, which favours the roaming mechanism.

中文翻译：

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NO 释放的机制差异：硝基苯酚和硝基苯胺的邻位异构体与间位异构体

硝基苯酚和硝基苯胺的邻位异构体和间位异构体在266 nm光解后释放的NO显示出双峰平移能量分布，其中慢分量和快分量分别源自S ₀和T ₁态的动力学。任何 NO 产物状态的平移能量分布曲线显示，与间位异构体相比，邻位异构体具有更高的慢到快 (s/f) 支化比。观察到的邻位和间位异构体的s/f支化比的变化归因于邻位取代基和NO ₂部分之间存在分子内氢键，这有利于漫游机制。