Inficon Transpector MPS, Руководство по эксплуатации

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Transpector MPS Operating Manual
The analyzer factor, A
b
, depends on the transmission and detection characteristics
of the analyzer, the Electron Multiplier gain (if the analyzer is so equipped), and the
basic sensitivity, as indicated in
equation [4] :
[4]
Here,
TF
b
is the transmission factor of the mass filter at mass
b
. The transmission
factor is the fraction of ions at mass
b
which pass through the mass filter, relative
to nitrogen ions at mass 28. Nominally, the transmission factor is equal to 28
divided by the mass of the ion,
b
.
The detection factor, DF
ab
, is equal to 1 for a Faraday Cup detector. For an Electron
Multiplier, the detection factor is a function of the mass of the ion and its chemical
nature, and is measured relative to that of a reference gas, typically nitrogen.
In general, as the mass ion increases, the Electron Multiplier detection factor
decreases.
The gain of the Electron Multiplier, G , measured at mass 28 for nitrogen, is the
Electron Multiplier output current divided by the Faraday mode output current,
under otherwise identical conditions. The multiplier gain is a strong function of the
high voltage applied.
The sensitivity of the instrument, S , is the ratio of Faraday mode ion current for a
given pressure of pure nitrogen measured at mass 28, and is typically expressed
in amps/Torr.
cyclohexane C
6
H
12
6.4 propane C
3
H
8
3.7
deuterium D
2
0.35 silver perchlorate AgClO
4
3.6
dichlorodifluormethane CCl
2
F
2
2.7 stannic iodide Snl
4
6.7
dichloromethane CH
2
Cl
2
7.8 sulfur dioxide SO
2
2.1
dintrobenzene C
6
H
4
(NO
2
)
2
7.8 sulfur hexafluoride SF
6
2.3
ethane C
2
H
6
2.6 toluene C
6
H
5
CH
3
6.8
ethanol C
2
H
5
OH 3.6 trinitrobenzene C
6
H
3
(NO
2
)
3
9.0
ethylene oxide (CH
2
)
2
O 2.5 water H
2
O 1.0
helium He 0.14 xenon Xe 3.0
hexane C
6
H
14
6.6 xylene C
6
H
4
(CH
3
)
2
7.8
hydrogen H
2
0.44
Table 4-5 Ionization Probabilities for some Common Substances (continued)
Substance Formula
Relative
Ionization
Gauge
Sensitivity
substance Formula
Relative
Ionization
Gauge
Sensitivity
A
a
1
TF
b
DF
ab

G

S

-------------------------------------------------- =