Abstract An advanced data-processing method using a fast Fourier transform (FFT) analyzer, associated with a modulation of DC voltage applied to a plasma excitation source, is suggested in glow discharge optical emission spectrometry (GD-OES). A pulsation of the DC voltage can be employed effectively for analysis of several specified samples, such as a ultra-thin layer to suppress the sputtering rate; however, it might worsen the analytical performance due to a decrease in the emission intensity. The FFT analyzer has an ability to disperse electronic signals by frequency to yield a power spectrum, and it is thus employed to select the component at a particular frequency. In pulsed GD-OES, data analysis based on FFT algorism enabled the signal component of an analyte emission line to be separated at a pulse frequency from the overall emission signal having any other frequencies, when the pulsed discharge voltage could control the sampling and excitation processes of the analyte in the plasma. The power spectrum of a Cu I emission line strongly depended on the duty ratio of the pulsed DC voltage, because each signal component at higher-order overtone frequencies contributed to the spectrum in a different manner. At a duty ratio of 20%, a summation of the FFT components from the fundamental frequency to higher-order harmonic frequencies could be effective to obtain larger signal intensities with smaller variances. The FFT component of the Cu I signal summed up to the eighth harmonic frequency was 3.8-times as large as the component of the fundamental frequency, whereas the RSD was improved from 2.32% to 0.20%.

中文翻译：

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占空比对方波脉冲辉光放电等离子体激发发射信号FFT功率谱的影响

摘要 在辉光放电发射光谱法 (GD-OES) 中提出了一种使用快速傅立叶变换 (FFT) 分析仪的高级数据处理方法，该方法与施加到等离子体激发源的直流电压调制相关联。可以有效地利用直流电压的脉动来分析几种特定的样品，例如超薄层以抑制溅射速率；然而，由于发射强度的降低，它可能会恶化分析性能。FFT 分析仪能够按频率分散电子信号以产生功率谱，因此可用于选择特定频率下的组件。在脉冲 GD-OES 中，基于 FFT 算法的数据分析使得分析物发射谱线的信号成分能够以脉冲频率与具有任何其他频率的整体发射信号分离，此时脉冲放电电压可以控制等离子体中分析物的采样和激发过程. Cu I 发射线的功率谱强烈依赖于脉冲直流电压的占空比，因为高阶泛音频率处的每个信号分量以不同的方式对谱做出贡献。在 20% 的占空比下，从基频到高次谐波频率的 FFT 分量的总和可以有效地获得更大的信号强度和更小的方差。Cu I 信号的 FFT 分量加起来为八次谐波频率为 3。