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A Minicomputer-Based Emission Spectrographic Analysis System Dependent on Scanning Microphotometry

Volume 33, Number 6 (Dec. 1979) Page 604-612

Thomas, Catharine P.


A minicomputer-based, semiquantitative, emission spectrographic system was designed to perform survey analyses (64 elements per sample), on a wide variety of geologic materials rapidly (9 s per determination). The system can analyze as many as 40 000 samples per year, while maintaining long-term consistency of results, and can provide archival storage capability (photoplate, microfiche, data bank). The minicomputer's partitioned memory allows simultaneous execution of programs to acquire 92 000 sequential, digitized, transmittance-readings per spectrum from a precision scanning microphotometer in 70 s, and to reduce these data to the peak and background transmittances, the location, and a profile code of as many as 500 analytical lines. The plate emulsion is calibrated in 10 equal segments between 2300 and 4700 Å. Intensities and preliminary concentrations based on prestored analytical curve coefficients are calculated for each line. Corrections for spectral interferences are made, and final results are selected according to a predetermined priority scheme. A report form for every 10 samples is printed within 5 min after a plate is recorded. All the preliminary data are stored on magnetic tape for production of microfiche within 24 h. Spectra on a second plate can be scanned while analysis of the first plate is being performed.