Dynode mass spectrometry

Mass spectrometry Ionization Accelerated ions Ionsensitive multiplier tubes, dynodes Spectrum Digitalized data... 

Figure 2.21. Schematic of (a) a photoplate detector (b) a Faraday cup (c) a discrete-dynode electron multiplier (EM) of Venetian blind type and (d) a continuous dynode EM. Parts (c) and (d) reprinted from A. Westman-Brinkmalm and G. Brinkmalm (2002). In Mass Spectrometry and Hyphenated Techniques in Neuropeptide Research, J. Silberring and R. Ekman (eds.) New York John Wiley Sons, 47-105. With permission of John Wiley Sons, Inc.

Linear trap with slots cut in two opposite rods. Sizes are 12 mm for sections A and C and 37 mm for B. Detectors D are placed off-line and ions are attracted by the conversion dynodes. The slots are 30 x 0.25 mm. Drawn according to the data from Schwartz J.C., Senko M.W. and Syka J.E.P., A Two-Dimensional Quadrupole Ion Trap Mass Spectrometer , Proceedings of the 50th ASMS Conference on Mass Spectrometry and Allied Topics, Orlando, Florida, 2002. 

Shaw LM, Edling-Owens J, Mattes R (1991) Ultrasensitive measurement of delta-9-tetra-hydrocannabinol with a high energy dynode detector and electron-capture negative chemical-ionization mass spectrometry. Clin Chem 37 2062-2068... 

FIGURE 11-2 (a) Oiscrete-dynode electron multiplier. Oynodes are kept at successively higher voltages via a multistage voltage divider, (b) Continuous-dynode electron multiplier. (Adapted from J, T. Watson. Introduction lo Mass Spectrometry, 3rd ed pp. 334-35, New Vork Raven Press. 1997. With permission.)... 

The secondary electron multiplier (SEM) detector is the key to the role of mass spectrometry as an extremely sensitive analytical technique with wide dynamic range and compatibility with on-line coupling to fast chromatographic separations. The SEM was a natural development from the invention of the photomultiplier (Zworkin 1936, 1939), in which photoelectrons produced by photons falling on a conversion dynode with a photo-sensitive surface are amplified in an avalanche fashion by accelerating the original (first strike) photoelectrons on to a... 

The IT-SIMS instruments were custom designed and fabricated in-house at the Idaho National Laboratory. All instruments were based on modifications of commercial gas chromatography/mass spectrometry (GC/ MS) instruments that were altered by removing the gas chromatography (GC) and inlet, and replacing it with a direct insertion probe, a modified conversion dynode and a Venetian blind electron multiplier, and a perrhenate primary ion gun. The primary ion gun and the direct insertion probe are located coaxial with the IT,... 

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