The radiation chemistry of the terephthalate dosimeter.
The radiation chemistry of the terephthalate dosimeter.
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DOI：
10.2307/3575256
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发表时间：
1980-07
影响因子：
3.4
通讯作者：
R. W. Matthews
中科院分区：
文献类型：
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作者：
R. W. Matthews
(HTA)（G = 0.99 ± 0.01）、碳酸盐（G = 1.31 ± 0.08）和过氧化物（G = 2.84 ± 0.05）。0.04）。HTA和碳酸盐物质由羟基自由基攻击形成，占羟基自由基反应的约90%。邻-、Meta-和对-羟基苯甲酸（如果形成的话）的G值不能分别大于0.03、0.10和0.27;它们以对应于最大产率的浓度形成不会显著地贡献归因于HTA的荧光。氧必须存在的有效转化的羟自由基加合物的羟自由基，氧合增加G（羟自由基）以上的充气溶液值，但没有证据表明，羟自由基和CO2形成的初级辐射分解物种以外的羟基自由基。在pH 10的氢氧化钠溶液中，1 x 10-4和1 x 10-2 M之间的对苯二甲酸酯浓度变化不影响G（HTA），但如果溶液pH值降低，则会受到影响。在pH 6.85的磷酸盐缓冲溶液中，G（HTA）为0.93？0.01;溶液pH值的进一步降低产生较低的值。G（HTA）值的降低归因于羟基自由基产物和还原性自由基产物之间的重组反应。通过测量过氧化物产率的平行下降和观察G（HTA）的剂量率效应，获得了对重组假设的支持。加入溶质碳酸盐和碳酸氢盐的竞争动力学研究得到速率比k（OH + TA ~（2-））：k（OH + CO ~（2-））：k（OH + HCO ~（2-））= 1：0.106：0.0036。
(HTA) (G = 0.99 + 0.01), carbonate (G = 1.31 __ 0.08), and peroxides (G = 2.84 ? 0.04). The HTA and carbonate species are formed by hydroxyl radical attack and account for approximately 90% of hydroxyl radical reactions. The ortho-, meta-, and para-hydroxybenzoic acids, if formed at all, cannot have G values greater than 0.03, 0.10, and 0.27, respectively; their formation in concentrations corresponding to the maximum yields will not contribute significantly to the fluorescence attributed to the HTA. Oxygen must be present for efficient conversion of the terephthalate-OH radical adduct to HTA, and oxygenation increases G(HTA) above the aerated solution value; but no evidence was found for HTA and CO2 formation from primary radiolytic species other than the hydroxyl radical. G(HTA) is unaffected by changes in terephthalate concentration between 1 x 10-4 and 1 x 10-2 M in sodium hydroxide solutions at pH 10, but it is affected if the solution pH is decreased. In phosphate-buffered solutions at pH 6.85, G(HTA) is 0.93 ? 0.01; a further decrease in solution pH yields lower values. The lowering of the G(HTA) value is attributed to recombination reactions between the terephthalate-OH radical products and reducing radical products. Support for the recombination postulate was obtained from measurement of a parallel decrease in the peroxide yield and the observation of a dose-rate effect on G(HTA). Competition kinetic studies with added solutes carbonate and bicarbonate gave the rate ratios k(OH + TA2-):k(OH + CO2-):k(OH + HCO-) = 1:0.106:0.0036.