Hi guys,

Thank you very much for your suggestions. Unfortunately, this was not the 
thing I meant, I have to admit my question was not very precise.
 I thought about the pressure dependence while measuring it using a gas 
mass spectrometer. I found some literature 
about noble gases, like.

[1] M. Honda, I. McDougall, D. B. Patterson, A. Doulgeris, and D. A. 
Clague, “Noble gases in
submarine pillow basalt glasses from Loihi and Kilauea, Hawaii: A solar 
component in the
Earth,” Geochimica et Cosmochimica Acta, vol. 57, no. 4, pp. 859‐874, 

[2] F. K. A. Burnard P. G., “Calibration of pressure‐dependent 
sensitivity and discrimination in
Nier‐type noble gas ion sources,” Geochemistry, Geophysics, Geosystems, 
vol. 1, no. 7.

In these the authors describe, that the ionization efficiency dependes on 
the gas pressure. Unfortunately, there are no
reasons given why it depends on the pressure. 

Maybe some of you knows why or where to find a reasnoble explanation.


Lukas Flierl
Physikalisch-Technische Bundesanstalt PTB
Metrology in Chemistry, 3.11
Bundesallee 100
38116 Braunschweig, Germany
Tel. +49-531-592-3318
e-mail: [log in to unmask]