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Calibration of pressure-dependent sensitivity and discrimination in Nier-type noble gas ion sources

Burnard, P. G. and Farley, K. A. (2000) Calibration of pressure-dependent sensitivity and discrimination in Nier-type noble gas ion sources. Geochemistry, Geophysics, Geosystems, 1 (7). 2000GC000038. ISSN 1525-2027. https://resolver.caltech.edu/CaltechAUTHORS:BURggg00

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Abstract

The efficiency of many noble gas mass spectrometers to ionize gas species is known to be a function of the pressure of gas in the spectrometer. This work shows how the half plate voltage for maximum He or Ar signal depends on the spectrometer pressure and shows that the half plate voltage for maximum 4He sensitivity does not coincide with the half plate voltage for maximum 3He sensitivity. In addition, half plate voltage has a greater control on sensitivity at higher spectrometer pressures. Variations in He and Ar sensitivity and isotopic discrimination as a function of pressure are due, at least in part, to these variations in the position of maximum sensitivity with respect to half plate voltage. The maximum sensitivity settings shift to lower half plate voltage at high spectrometer pressures, irrespective of if the pressure increase is due to the gas being investigated or a different species. Therefore noble gas mass spectrometers should always be tuned at the maximum possible pressure; measurements at higher pressures should be avoided. Significant errors in the spectrometer sensitivity and discrimination can result from improper tuning and calibration of noble gas mass spectrometers.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2000GC000038DOIUNSPECIFIED
ORCID:
AuthorORCID
Farley, K. A.0000-0002-7846-7546
Additional Information:Copyright 2000 by the American Geophysical Union. Received January 8, 2000; Revised May 25, 2000; Accepted June 17, 2000; Published July 18, 2000. P.B. was funded under the Caltech postdoctoral fellowships program. E.V. Nenow is thanked for technical assistance in automating the half plate voltages. Two anonymous reviewers are thanked for their constructive comments.
Subject Keywords:Mass spectrometer; noble gases; Instruments and techniques; isotopic composition/chemistry; geochronology
Issue or Number:7
Record Number:CaltechAUTHORS:BURggg00
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:BURggg00
Official Citation:Burnard, P. G., and K. A. Farley, 2000. Calibration of pressure-dependent sensitivity and discrimination in Nier-type noble gas ion sources. Geochem. Geophys. Geosyst., vol. 1, Paper number 2000GC000038
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1102
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:19 Dec 2005
Last Modified:03 Mar 2020 13:01

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