Electro-optical ion detectors

Electro-Optical Ion Detectors in Mass Spectrometry Simultaneous Monitoring of All Ions over Wide Mass Ranges... 

Figure 8. Schematic presentation of an electro-optical ion detector for spector...

Analytical research applications of mass spectrometers fitted with electro-optical ion detectors are carried out at the present time at JPL and the FOM Institute. These involve" (1) at JPL a 1" EOID on sector type mass spectrometer (CEC type 21-490) in conjunction with an API (armospheric pressure ionization) source for the development of an automated assay procedure for amino acid derivatives produced by a novel Edman type sequenator (23), and (2) at the FOM Institute a 1" EOID on a sector mass spectrometer,fitted with magnetic and electrostatic quadruple "Zoom" lenses, permitting variation of dispersion for focusing a greater number of masses on the 1" detector (24,25). 

The electro-optical ion detector (EOID) combines ion and photon detection devices. This type of detector operates by converting ions to electrons and then to photons. The most common electro-optical ion detector is called the Daly detector. As shown in Figure 3.7, this type of detector is made up of two conversion dynodes, a scintillation or phosphorescent screen and a photomultiplier. This device allows the detection of both positive and negative ions. As for the electron multipliers, ions from the analyser strike a dynode. In the positive mode, ions are accelerated towards the dynode that carries a negative potential, whereas in the negative mode, ions are accelerated towards the positive dynode. Secondary electrons... 

Another electro-optical ion detector, which is called the electro-optical array detector, allows the simultaneous measurement of ions spatially separated along the focal plane of the mass spectrometer. It combines the microchannel plate and Daly detector. The ions are converted in a microchannel plate into electrons that are amplified. The released secondary electrons finally strike a phosphorescent screen that emits photons. These photons are then detected with a photodiode array or CCD detector. This array detector acts as electronic photoplates. 

Electro-optical ion detector an ion-to-photon detector that combines an ion and photon detection device. This type of detector operates by converting ions to electrons and then to photons. Ions strike a conversion dynode to produce electrons that in turn strike a phosphor and the resulting photons are detected by a photomultiplier. 

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