Nier-design

In 1935 A.O. Nier designed a relatively simple but accurate mass spectrometer employing the principle of double focussing. The essential features are the same as described above but some improvements have been made which are ... 

Electron ionization (El) was introduced in 1921 by Dempster, who used it to measure lithium and magnesium isotopes [31]. Modern El sources are, however, based on the design by Bleakney [32] and Nier [33, 34], who both worked in Prof. J. T. Tate s laboratory. In El ions are produced by directing an electron beam into a low pressure vapor of analyte molecules. 

Following the pioneer work of Aston and Dempster, there were rather limited advances made in the field of isotopic abundance measurements until 1935 when A. 0. Nier (85) introduced a number of improvements to mass spectrometer design. Since then, many more refinements have been made, particularly with regard to more efficient ion sources and to more sensitive ion detectors, so much so, that the mass spectrometer has become an extremely sensitive instrument for the detection of practically all of the elements, and its sensitivity remains second only to that of radioactive counting techniques. 

Figure 16.7. Schematic diagrams of the two most commonly used double-focusing mass spectrometers. The Nier-Johnson is really a modified design capable of resolution <7/150,000 because of the cuMed hexapole lenses. From S. Evans and R. Graham, Advan. Mass Spectrom., 6, 429 (1974), by permission of Applied Science Publishers, Ripple Road, Barking, Essex, England.

FIGURE 20-14 Nier-Johnson design of a double-focusing mass spectrometer. 

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