Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
Environ Sci Technol. 2010 Nov 1;44(21):8150-5. doi: 10.1021/es102218d.
Alkyl nitrites photolyze in air to yield alkoxy radicals and NO which, through secondary reactions, generate OH radicals. This photochemistry is important in the atmosphere and in laboratory studies where nitrites are often used as a source of OH. The overall quantum yield for hydroxyl radical formation from irradiation of isopropyl nitrite (i-C(3)H(7)ONO) between 300 and 425 nm in 1 atm air at 296 ± 2 K is reported for the first time. The OH radical was scavenged by reaction with CF(3)CF═CF(2) and the formation of CF(3)CFO and CF(2)O monitored as a function of time using Fourier transform infrared spectrometry. The quantum yield was found to be 0.54 ± 0.07 (2σ) and is independent of whether or not NO was added (up to 3 × 10(14) molecules cm(-3)) prior to photolysis to increase NO concentrations above those due to the photolysis of the nitrite. Ultraviolet-visible and infrared cross sections of i-C(3)H(7)ONO are also reported. These data on the OH quantum yields as well as the UV-visible and infrared cross sections for isopropyl nitrite are critical for quantitatively interpreting the results of laboratory studies where i-C(3)H(7)ONO is employed as an OH source as well as for assessing the role of alkyl nitrites in the chemistry of the troposphere.
亚硝酸酯在空气中光解生成烷氧基自由基和 NO，后者通过次级反应生成 OH 自由基。这种光化学反应在大气中和实验室研究中都很重要，因为亚硝酸酯通常被用作 OH 的来源。首次报道了在 1 大气压空气、296 ± 2 K 下，用 300 到 425nm 波长的辐射光解异丙基亚硝酸酯（i-C(3)H(7)ONO）时，生成 OH 自由基的总体量子产率。通过与 CF(3)CF═CF(2)反应捕获 OH 自由基，并使用傅里叶变换红外光谱法随时间监测 CF(3)CFO 和 CF(2)O 的形成，来研究 OH 自由基的形成。结果发现，量子产率为 0.54 ± 0.07（2σ），与是否在光解前添加 NO（高达 3×10(14)个分子 cm(-3))以增加 NO 浓度无关，因为亚硝酸酯的光解会导致 NO 浓度增加。还报道了 i-C(3)H(7)ONO 的紫外-可见和红外截面。这些关于 OH 量子产率以及异丙基亚硝酸酯的紫外-可见和红外截面的数据对于定量解释使用 i-C(3)H(7)ONO 作为 OH 源的实验室研究结果以及评估烷基亚硝酸酯在对流层化学中的作用至关重要。
