An electro-optical ion detector for spark source mass spectrometry

A novel ion detection system for spark source mass spectrometry has been developed. It utilizes a channel electron multiplier array with phosphor screen readout and is capable of simultaneously detecting several mass resolved ion species.

The design, construction, and initial optimization of this detector are described. Various optical detectors were used in conjunction with the device, including a silicon vidicon Tv camera, a linear diode array and a photomultiplier tube. In addition, a signal averager was used to accumulate the data and to provide a convenient means of background subtraction, thus increasing the signal-to-noise ratio.

Quantitative data were obtained for three systems, showing different ways in which this detector might be used for chemical analysis. A study of isotope dilution, using the element indium, was performed. Also, fly ash was analyzed for six elements using a method in which separated isotopes were used as internal standards. Finally, the Zirconium-Hafnium system was studied to show whether inter-element measurements would be feasible with this detection system.

The results of these studies revealed that the channel electron multiplier array can be used to obtain data with precision and accuracy equal to that of existing detectors. However, due to its nonlinear response characteristics, more work needs to be done in the fabrication of the channel plates themselves.