Dynamic-range extension of MAES multichannel analyzers based on BLPP-2000 and BLPP 4000 photodetector arrays

One trend in the development of integral atomic emission spectral analysis with low spectral background excitation sources, such as inductively coupled or microwave plasma, is to increase the dynamic range of spectrum recording systems based on photodetector arrays. To achieve low detection limits, it is necessary to use photodetector arrays with low reading noise. The dynamic range of a single readout of such photodetector arrays usually does not exceed four orders of magnitude. The dynamic range increase due to the accumulation of spectra from multiple acquisition leads to a quadratic increase in the measurement time. This method does not allow one to cover the entire dynamic range of spectral line intensities of inductively coupled or microwave plasma (which can reach seven orders of magnitude) while maintaining an acceptable total measurement time of a sample spectrum. As an alternative, it is proposed to increase the dynamic range toward higher line intensities by using two different alternating accumulation times during measurement. The objective of this study is to implement the proposed recording mode in MAES analyzers based on BLPP-2000 and BLPP-4000 photodetector arrays in order to increase the dynamic range of recorded spectral lines. Dependences of the signal-to-noise ratio and the dynamic range of spectral lines recorded in integral atomic emission spectrometry on the accumulation time, the total measurement time, the spectral background level, and the photodetector array parameters are obtained. It is shown theoretically that the use of the recording mode with alternating different accumulation times should increase the dynamic range of BLPP-2000 and BLPP-4000 photodetector arrays by two orders of magnitude. The dynamic range of spectral line intensities of a hollow-cathode lamp is shown experimentally to increase by two orders of magnitude (to five orders of magnitude).