Abstract 1,3-cyclohexadiene was isolated in solid parahydrogen, and its photochemical reactions were studied via irradiation with 193 nm photons from an ArF excimer laser. Photoproducts were identified using Fourier-transform infrared spectroscopy supported by density functional theory calculations. Photolysis with 193 nm light caused the formation of two well-characterized conformers of 1,3,5-hexatriene, tZt-1,3,5-hexatriene and tEt-1,3,5-hexatriene. A third initial photoproduct was identified as the conformer cZc-1,3,5-hexatriene, and its infrared spectrum was characterized for the first time. In addition, the bicyclo[2.2.0]hex‑2-ene and 1-methyl-bicyclo[2.1.0]pent‑2-ene were also found to be a minor products from photo-induced ring-closure reactions, where the latter further converts to 2-methyl-cyclopentadiene. The reaction mechanisms and stability of these products are discussed using infrared spectroscopy and density functional theory calculations.

中文翻译：

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在固体仲氢中分离的 1,3-环己二烯的紫外光化学

摘要 在固体仲氢中分离出 1,3-环己二烯，并通过 ArF 准分子激光器产生的 193 nm 光子照射研究其光化学反应。使用由密度泛函理论计算支持的傅立叶变换红外光谱识别光产物。193 nm 光的光解导致 1,3,5-己三烯、tZt-1,3,5-己三烯和 tEt-1,3,5-己三烯的两种充分表征的构象异构体的形成。第三个初始光产物被鉴定为构象异构体 cZc-1,3,5-己三烯，其红外光谱首次被表征。此外，还发现双环[2.2.0]己-2-烯和1-甲基-双环[2.1.0]戊-2-烯是光致闭环反应的次要产物，其中后者进一步转化为 2-甲基-环戊二烯。