INFICON Composer Elite Gas Concentration Monitor - Manual (Page 137)

9 - 3
PN
07
4-
56
6-
P1
B
Composer Elite Operating Manual
Where f and f
2
are the resonant frequencies of the mixture and pure gas,
respectively.
Combining 12, 13 and 14:
[15]
Simplifying leads to,
[16]
where,
[17]
[18]
[19]
Since the equation is quadratic, the solutions are of the following form,
[20]
Since x1,2 represents the Mole Fraction of the gases, acceptable solutions are,
[21]
The general result of this analysis is that the technique is most sensitive to
composition changes when the Molecular Weight difference between the carrier
gas and the precursor is the greatest. See
Figure 9-1 .
Figure 9-1 Mole fraction of trimethylindium in H
2
vs. instrument’s frequency
 1 m 1 –  x +  
g h –   1 h –    
x 1 g –   g h –   +  
------------------------------------------------ h + =
Ax
2
Bx C + + 0 =
A  m 1 –   1 g –   =
B m g h –    1 2g – h +   h 1 g –   – + =
C  1 –   g h –   =
x
1,2
B – B
2
4AC – 
2A
------------------------------------------- =
0 x
1,2
1  
Frequency (Hz)
Mole-Fraction (%)
5
4
3
0
2
1
2000 2500 3000 3500 1500 4000