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小磊磊爱无机

银虫 (小有名气)

[求助] 求助几个关于光谱检测器的问题

我有几道分析化学习题,是关于光谱检测器的,恳求这方面的大神帮忙解答一下,能解释的尽量简单解释一下,中文或英文回答均可以,谢谢~~
1. For the common spectroscopic detectors, do the detectors directly provide information that can be used for qualitative information, quantitative information, or both? Explain.

2. Explain how a PMT (光电倍增管??) operates.
a. What portion of the PMT is the transducing element? amplifier?
b. What is the physical process that produces the transduction in a PMT?
c. What is (are) the quantity that must be input into the PMT? If you increase this quantity, what characteristics of the detector are changed?

3. What determines the lower limit of the linear dynamic range of the detector? (two quantities)
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leefadisky

木虫 (小有名气)

【答案】应助回帖

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费姚永芬: 金币+1, 欢迎常来分析版交流 2013-10-10 06:24:31
小磊磊爱无机: 金币+6, ★★★★★最佳答案, 很感谢 2013-10-10 19:11:36
1. For the common spectroscopic detectors, do the detectors directly provide information that can be used for qualitative information, quantitative information, or both? Explain.
光电探测器接收光信号直接用于定性分析,必须在满足一定操作规范和相应样品时才可用于定量分析
2. Explain how a PMT (光电倍增管??) operates.
a. What portion of the PMT is the transducing element? amplifier?
PMT既是传感器件同时也是放大器
b. What is the physical process that produces the transduction in a PMT?
入射光子轰击阴极,向真空中激发出光电子,然后经聚焦极电场进入倍增系统,并通过进一步的二次发射得到的倍增放大。然后把放大后的电子用阳极收集
作为信号输出。因此PMT用于弱光探测。
c. What is (are) the quantity that must be input into the PMT? If you increase this quantity, what characteristics of the detector are changed?
入射光信号和工作电压。1如果入射光信号过大则PMT饱和2工作电压过大则系统暗电流增加影响弱光探测效果

3. What determines the lower limit of the linear dynamic range of the detector? (two quantities)
PMT输出光电流i=kI+q,I对应于产生光电流i的入射光强度,k为比例系数,q为暗电流。则在一定范围内保持线性相应关系。1入射光强过大则饱和,所以线性响应范围的大小与光阴极
的材料有关2暗电流均随工作电压升高而急剧增加,使光电倍增管工作不稳定,所以线性响应范围的大小与最高工作电压相关
2楼2013-10-09 21:52:17
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