Drift rates, modulators

Figure 7.33 and Fig. 7.34 show the eount-rate dependent timing drift of the IRF for an XP2020 linear-focused PMT and an H5773-20 photosensor module. The eurves were reeorded with a BHL-600 diode laser of 40 ps pulse width and 650 nm wavelength, and an SPC-140 TCSPC module (both Beeker Hiekl, Berlin). The... 

A remarkable adaptation of technology borrowed from another analytical method was demonstrated for an electrospray ionization (ESI) IMS instrument ion injection to a drift tube was achieved through modulation with a mechanical chopper as found in atomic absorption spectrometry. The chopper was a disk with a small hole that would align with the source and drift tube and would operate as an ion injector. The disk had a second window that was used with optical sensors to synchronize ion injection and drift time, and ion injections were made at pulse rates of 5 to 200 Hz with pulse widths of 200 to 500 ps. 

FIGURE 6.11 Diagram of a commercial modulated TCD that uses only one filament cell. The anal5dical and reference gas flows are switched at a rate of 10 Hz. This design results in a detector with very low drift. This assembly is further insulated on all sides mounted in a metal enclosure. (Reprinted with permission from previous edition. Copyright 1995 John Wiley and Sons, Inc.)... 

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