Applicability of reaction rate in gas phase data to supercritical water region

气相数据反应速率对超临界水区域的适用性

• 批准号: 15560660
• 负责人: TAKAHASHI Kenji
• 金额: $ 2.37万
• 依托单位: Kanazawa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560660/
• 关键词: hydrated electron; Hydroxyl radical; solvation; dissociative electron attachment; electron affinity; electron transfer; supercritical water; pulse radiolysis; hydrated electron; Hydroxyl radical; solvation; dissociative electron attachment; electron affinity; electron transfer; supercritical water; pulse radiolysis

To study reaction rate of OH radical in high temperature water, the most direct method is to observe the transient absorption of OH radical itself. At room temperature there are a several demonstrations for such direct measurements, however, there are few example under high temperature conditions. In the direct UV absorption measurements, the absorption by sapphire windows prevents the measurement of OH signal. The actual absorption intensity due to OH radical was determined by subtraction of the sapphire window signals. The absorption spectra of OH radical in high temperature water shifted to blue. The absorption coefficient of OH radical at 250 nm decreased with increasing the temperature. At room temperature, the absorption coefficient of OH radical is known as to be 500. At 300 C, we found that the absorption coefficients decreased to 200.The temperature dependence of OH radical reaction rate was examined. The rates are followed by the Arrhenius temperature dependence up to 125 C. Above 125 C, however, the reaction rates are independent on the water temperature. The reaction rate at 125 C was 1x10^<10> M^<-1>s^<-1>.

为了研究高温水中OH自由基的反应速率，最直接的方法是观察OH基本本身的瞬时吸收。在室温下，有几次直接测量的演示，但是在高温条件下很少有例子。在直接的UV吸收测量值中，蓝宝石窗户的吸收可防止OH信号的测量。通过减去蓝宝石窗户信号确定了由于OH自由基引起的实际吸收强度。高温水中OH自由基的吸收光谱转移到蓝色。 OH自由基在250 nm时的吸收系数随温度的升高而降低。在室温下，OH自由基的吸收系数为500。在300C时，我们发现吸收系数降低到200。OH自由基反应速率的温度依赖性被检查。速率之后是Arrhenius温度依赖性高达125 C。但是，反应速率在水温下是独立的。 125 C时的反应速率为1x10^<10> m^<-1> s^<-1>。