DATA-PROCESSING TECHNIQUES FOR IMPROVED SPECTROCHEMICAL MEASUREMENTS WITH PHOTODIODE ARRAY SPECTROMETERS

A number of data processing and data acquisition methods are presented that enhance the performance of a photodiode array (PDA) spectrometer. Zero-filling or Fourier-domain interpolation is used to interpolate peak shapes. This improves the accuracy and precision of spectral peak height and position measurements and can be used to overcome spectral line/diode registry effects. A procedure is presented for the automated calibration and recalibration of the wavelength window measured with a photodiode array spectrometer. This method is based, in part, on cross-correlation of spectral patterns. Finally it is shown that by programming of the integration time, several spectra can be combined into a single wide-dynamic-range spectrum. Taken as a whole, these data processing and acquisition techniques improve the accuracy, precision, and dynamic range of spectrochemical data acquired with a PDA spectrometer. This is illustrated by using the system for the rapid measurement of excitation temperatures of plasma sources.