Spectrometer magnetic mass analyzer

Fig. 2. Mass spectrometer with photoionization 1—built-in hydrogen lamp 2—vacuum monochromator filled with hydrogen 3—LiF window 4—ionic source container 5—photoionization space with the accelerating grids 6—fluorescent layer for intensity calibration of the incident u.v. light 7—photomultiplier 8—magnetic mass analyzer 9—electron multiplier.

In the geometric separation method, ions having different m/e ratios are separated according to their geometric position at the collecting spot. The magnetic mass analyzer, the quadrupole mass analyzer, and the ion trap are based on these principles of operation. The magnetic mass spectrometer will not be discussed in this chapter as it has not been used for the detection of explosives. 

Magnetic deflection mass analyzer Double focusing sector spectrometer Quadrapole mass analyzer Triple quadrapole analyzer... 

The major components of the mass spectrometer are a gas-handling manifold that enables the gas to be transferred from the ovens to the ion source, the ion source that consists of an electron impact source, magnetic mass analyzer with gap field of 6500 G, four different EM detectors, and an ion pump to ensure low pressure for the EMs. The gas handling system also included a controlled leak valve that could obtain Martian gas and feed the gas directly into the mass spectrometer for analysis. All the tubes in the gas handling system were heated to 35 C to ensure that there is no condensation of water and other volatile vapors on the hardware. 

The cross section measurements were made with an apparatus described previously (1). The instrument consists of a primary mass spectrometer (PMST in tandem with a secondary mass spectrometer (SMS). The PMS is a 1 cm radius of curvature 2500 G permanent magnet mass analyzer. The SMS is a 60° magnetic sector instrument with an 8 in. radius of curvature. The detection of product ions was made by counting ions with a 17 stage electron multiplier. The gas pressure in the reaction cell was measured with an MKS Baratron differential pressure gauge. 

By combining a magnetic-sector mass analyzer with an electrostatic analyzer (often termed a double-sector or double-focusing mass spectrometer), a significant improvement in resolution is realized. Such a double-focusing instrument can achieve a resolution of the order of 100,OOO.The double-focusing magnetic mass analyzer utilizes two independent sectors. In addition to the... 

Separation of ions according to their m/z values can be effected by magnetic and/or electric fields used as mass analyzers, which are described in Chapters 24 through 27. However, apart from measurement of m/z values, there is often a need to be able to transmit ions as efficiently as possible from one part of a mass spectrometer to another without any mass separation. 

Rapid scanning mass spectrometers providing unit resolution are routinely used as chroaatographic detectors. Ion separation is accomplished using either a magnetic sector, quadrupole filter or ion trap device. Ions can also be separated by time-of-flight or ion cyclotron resonance mass analyzers but these devices are not widely used with chromatograidiic inlets and will not be discussed here [20]. 

Because there is so little mass bias in the mass analyzer, a discussion of ion transfer optics and collectors is not presented. The ion transfer optics of the magnetic sector mass analyzer, and the collectors used for isotope ratio measurements are critical design elements in all isotope ratio mass spectrometers and recent reviews of these items can be found in Habfast... 

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