Product quantum yields for the 305-nm photodecomposition of nitrate in aqueous solution
Product quantum yields for the 305-nm photodecomposition of nitrate in aqueous solution
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DOI：
10.1021/j100333a022
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发表时间：
1988-11
期刊：
影响因子：
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通讯作者：
P. Warneck;C. Wurzinger
中科院分区：
文献类型：
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作者：
P. Warneck;C. Wurzinger
采用自由基清除技术和产物分析来确定两个主要过程的量子产率：(1) NO/sub 3//sup -/ + hv = NO/sub 2//sup -/ + O 和 (2) NO/sub 3//sup -/ + H/sup +/ hv = NO/sub 2/ + OH 在空气饱和的硝酸钠稀溶液中。通过氧原子与环戊烯的反应和乙烯的生成来检测氧原子。发现的量子产率为 /phi/(O) = (1.1 /plus minus/ 0.1) x 10/sup -3/。通过与苯反应生成苯酚和与2-丙醇反应生成丙酮，证实了OH自由基的产生。第二个反应用于确定 OH 量子产率 /phi/(OH) = (9.2 /plus minus/ 0.4) x 10/sup -3/。在 pH 值 5-12 范围内，亚硝酸盐的生成量相似，而在 pH 值较低时，生成量下降。甲酸盐作为清除剂将 OH 自由基转化为 O/sub 2//sup -//HO/sub 2/ 自由基，从而产生 H/sub 2/O/sub 2/。 pH 5.6 时 H/sub 2/O/sub 2/ 的产量低于预期，而 NO/sub 2//sup -/ 的产量较高。假设反应可以解释这一观察结果以及亚硝酸盐形成的 pH 依赖性。
The radical scavenging technique with product analysis was employed to determine quantum yields for the two main processes (1) NO/sub 3//sup -/ + hv = NO/sub 2//sup -/ + O and (2) NO/sub 3//sup -/ + H/sup +/ hv = NO/sub 2/ + OH in dilute, air-saturated solutions of sodium nitrate. Oxygen atoms were detected by their reaction with cyclopentene and the production of ethene. The quantum yield found was /phi/(O) = (1.1 /plus minus/ 0.1) x 10/sup -3/. The generation of OH radicals was confirmed by their reactions with benzene to give phenol and with 2-propanol to produce acetone. The second reaction was used to establish an OH quantum yield of /phi/(OH) = (9.2 /plus minus/ 0.4) x 10/sup -3/. Nitrite was formed with a similar yield in the pH region 5-12, whereas at lower pH the yield declined. Formate as a scavenger converts OH radicals toward O/sub 2//sup -//HO/sub 2/ radicals which produce H/sub 2/O/sub 2/. The yield of H/sub 2/O/sub 2/ at pH 5.6 was lower than expected whereas that of NO/sub 2//sup -/ was higher. Reactions are postulated to explain this observation as well as the pH dependence of nitrite formation.