The Dual-Stage Reflectron

I pnc recalls the equation that was used to determine the space-focus plane for a duai- istage extraction system  

Chapter 3 Reflectrons and Other Energy-Focusing Devices 

FIGURE 3.6 Experimental relative variations of AT/T of the peak centroid of Csjl formed by PDMS as a function of variations AU/U of the accelerating voltage. is the total voltage applied to the reflectron. (Reprinted with permission from reference 10). 

FIGURE 3.7 A linear reflectron with transparent ion source. (Reprinted with permission from reference 12). 

Dual-channelplate detectors that have a small, centered hole through which the incoming ion beam can be transmitted are now available commercially, and have 

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FIGURE3.il Electrical potential diagrams of (a) a single-stage reflectron, (b) a dual-stage reflectron, (c) a quadratic reflectron, and (d) the gridless reflectron described by Wollnik and co-workers, " generated by SIMION. 

Post-Source Decay Spectra Using a Dual-Stage Reflectron. The discussion on coincidence techniques above suggests that the opportunities for recording product ion spectra on a reflectron instrument and the necessity for obtaining spectra at different reflectron voltages have been appreciated for some time. Nevertheless, the currendy popular technique known as post-source decay (PSD) is based upon an... 

Mass calibration for instruments using dual-stage reflectrons is, of course, similar if one utilizes only those portions of the post-source decay spectra that are linear. 

FIGURE 9.8 MALDI mass spectra of a-cyano-4-hydroxy-cinnamic acid recorded on the dual-stage reflec-tron tandem mass spectrometer, (a) Normal mass spectrum obtained through both reflectron analyzers, (b) mass spectrum after gating of the molecular ion, and (c) product-ion mass spectrum after activating the pulsed valve. (Reprinted with permission from reference 6). 

Second-order solutions are also possible for the dual-stage source (Figure 10.3c), and they result in a much shorter optimal drift length. This configuration is rarely used in a simple linear spectrometer, but can be used to form an intermediate virtual point source for a reflectron (see below). A shorter, higher-order focal plane has also been used in the development of instruments of compact size. 

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