Noble gas mass spectrometry with a compressor driven recycling system for improved sensitivity

Abstract

In order to increase the sensitivity of static-mode noble gas mass spectroscopic analysis, we have developed and tested a gas re-circulation system, which uses a commercially available turbo molecular pump (TMP). During the analysis, the sample gases are directed from the collector end towards the ionization source part of the flight tube. Our preliminary results indicate that the apparent sensitivity of krypton and xenon can be increased by a factor of about 20 and 50, respectively. We also found that the gain factor of helium was somewhat smaller and was approximately 2. Such mass-dependence is quite consistent with the compressibility of TMP which is larger for the heavier molecules.

EGT—A sensitive time‐of‐flight mass spectrometer for multielement isotope gas analysis

“…The latter is pumping to a reservoir (RES1), which is evacuated from time to time (if p > 10 −2 mbar) by a turbomolecular pump, which is connected to a four‐chamber membrane pump (RVTMP). Because the system is designed for low gas amounts, the EGT is not actively pumped during measurements (static mode) . After a measurement, the remaining gas is evacuated by TMP1 to prevent contamination of IG1.…”

“…Especially in the field of noble gas (He, Ne, Ar, Kr, Xe) mass spectrometry, instruments having a high detection sensitivity and ionisation efficiency are mandatory as the investigated solid samples are typically highly depleted in these gases. Since the introduction of the concept of measuring in static operational mode that allows to measure small quantities of a gas (introduced by Reynolds and Aldrich and Nier around the 1950s), there is a continuous request for instrumentation with improved figures of merit and measurement capabilities . To date, various systems were designed and developed in noble gas mass spectrometry with the goal to improve measurement capabilities, ranging from quadrupole mass spectrometers, resonant ionisation mass spectrometers, mass spectrometer that are coupled to a compressor, among others.…”

“…Since the introduction of the concept of measuring in static operational mode that allows to measure small quantities of a gas (introduced by Reynolds 8 and Aldrich and Nier 9 around the 1950s), there is a continuous request for instrumentation with improved figures of merit and measurement capabilities. [10][11][12][13][14] To date, various systems were designed and developed in noble gas mass spectrometry with the goal to improve measurement capabilities, ranging from quadrupole mass spectrometers, 15 resonant ionisation mass spectrometers, [16][17][18] mass spectrometer that are coupled to a compressor, 12 among others. Sector field mass spectrometers coupled to multicollector systems are today's state-of-the-art laboratory techniques used in noble gas mass spectrometry as they provide the most accurate isotope ratio analysis.…”

Gas Source Isotope Ratio Mass Spectrometry for the Analysis of Noble Gases

“…Another group tested this design with a commercially available turbopump, which resulted in increased levels of isobaric interferences, presumably due to pump oil and viton sealings in the turbo pump. 58 The signal gain was found to be smaller and mass dependent, from B2 for He, to B22 Kr and B50 for Xe. Sensitivity and instrumental isotopic fractionation of the Nier-type sources depend on the gas pressure in the source (i.e.…”

The preparation of non-radioactive glassy surrogate nuclear explosion debris (SNED) loaded with isotopically altered Xe

“…before measurement in a single or multicollector gas mass spectrometer. Isotope ratio measurements can be performed on quantities down to 10 5 atoms [8].…”