CRITICAL COMPARISON OF PHOTON COUNTING AND DIRECT-CURRENT MEASUREMENT TECHNIQUES FOR QUANTITATIVE SPECTROMETRIC METHODS
CRITICAL COMPARISON OF PHOTON COUNTING AND DIRECT-CURRENT MEASUREMENT TECHNIQUES FOR QUANTITATIVE SPECTROMETRIC METHODS
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DOI：
10.1021/ac60312a020
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发表时间：
1972-01-01
影响因子：
7.4
通讯作者：
CROUCH, SR
中科院分区：
文献类型：
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作者：
INGLE, JD;CROUCH, SR
利用光子计数和直流技术对光谱测量的信噪比（SNR）表达式进行了比较，结果表明，在同等条件下，如果测量限制了散点噪声，光子计数技术的信噪比（SNR）可提高5%至22%。如果测量受到源或背景闪烁噪声的限制，两种技术都能提供等效的信噪比。然而，在光子计数中，直流电技术能够测量的光电平比没有脉冲堆积的情况下测量的光电平大几个数量级。讨论了分析光谱方法的实际意义，并提出了选择提供最高信噪比的检测技术的标准。光子计数已被提出作为一种测量技术用于几种分析光谱应用（1-5）。这就是为什么光子计数技术似乎比测量光强度的传统直流方法具有固有优势的几个原因。首先，以离散方式处理辐射通量信息，减少了获得与入射光电平相关的数字所需的域转换次数(6)。其次，数字电路对信息的处理使得光子计数检测不容易受到长期漂移和1//噪声的影响，而这些通常会限制模拟系统。该特性使光谱表能够利用比直流检测更长的平均时间，在直流检测中，低频噪声成分可以在狭窄的测量系统带宽下占主导地位。光子计数技术的其他优点包括能够区分源自dynode链的光电倍增管暗电流和虚拟消除可能限制模拟的读取误差
A comparison of signal-to-noise ratio (SNR) expressions for spectrometric measurements using photon counting and direct current techniques reveals that photon counting techniques provide SNR’s from 5 to 22% higher under equivalent conditions if measure-ments are shot noise limited. If measurements are limited by source or background flicker noise, both techniques provide equivalent SNR’s. However, dc techniques are capable of measuring light levels several orders of magnitude greater than can be measured without pulse pileup in photon counting. Practical implications for analytical spectrometric methods are discussed, and criteria are presented for choosing the detection technique providing the highest SNR.Photon counting has been proposed as a measurement tech-nique for several analytical spectrometric applications (1-5). These are several reasons why photon counting techniques appear to have inherent advantages over the conventional dc method of measuring light intensity. First, radiant flux in-formation is processed in a discrete manner, reducing the num-ber of domain conversions (6) necessary to obtain a number related to the incident light level. Second, the processing of information by digital circuity makes photon counting detec-tion less susceptible to long term drift and 1//noise which often limits analog systems. This feature enables the spectrome-trist to utilize much longer averaging times than would be feasible with dc detection where low frequency noise com-ponents can predominate at narrow measurement system bandwidths. Other advantages of the photon counting tech-nique include the ability to discriminate against photomulti-plier dark current originating down the dynode chain and the virtual elimination of the reading error which can limit analog