Ametek Dycor Dymaxion Mass Spectrometer, Руководство пользователя

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1-2 | Dycor Dymnaxion Mass Spectrometer
Mass Spectrometer Theory
The mass spectrometer allows you to identify the masses of individual atoms and
molecules that have been converted to ions from a given sample. This technique
is unique in that it provides a fingerprint identification for the structural and
chemical properties of these molecules. The quadrupole mass spectrometer is one
of a specialized subset of mass spectrometers that measure background gases in
an existing vacuum chamber.
A mass spectrometer consists of the following components:
• Sampling System
• Mass Spectrometer Hardware
• Data System
Sampling System
The Sampling System serves as a connection between the outside sample envi-
ronment and the vacuum environment that the mass spectrometer requires. The
Dycor Dymaxion can be equipped with a variety of inlet systems. All of these
systems are configured to bring the required number of sample streams into the
Dymaxion at the specified pressure, while maintaining the high vacuum neces-
sary for proper mass spectrometry operation.
Mass Spectrometer Hardware
Once the sample reaches the mass spectrometer hardware, three processes take
place:
• Ionization
• Separation
• Detection
Ionization
During ionization, sample molecules are turned into ions which are then focused
towards the quadrupole to be detected. The process occurs in the ionizer which
consists of a filament, filament electron repeller, ionizer body, ion volume and
two focusing lenses. See Figure 1-1.
The filament produces electrons. As current flows through the filament, it is elec-
trically heated to incandescence and emits free electrons. Once the electrons are
free, they are accelerated towards the ionizer body by the potential difference
between the filament and the ionizer body. As a cloud of electrons accelerates
towards the ionizer body, the electrons collide with the sample in the center of the