Absolute isotope amount ratio measurements on gases

Absolute isotope ratios of carbon dioxide – a feasibility study

“…It has been shown that, in the case of a true molecular gas ow into the ionization chamber, the logarithm of the two ratios R m 45 and R m 46 should linearly increase over time during the measurement. 35,[37][38][39][40]46,51 This is due to the kinetic gas theory, which explains this with the faster effusion of the lighter CO 2 species of mass 44. Therefore, the gas remaining in the gas reservoir becomes enriched in the heavier species, so that the measured ratios also increase.…”

“…33,34 Also, in the case of carbon dioxide, this approach has already been tested at the Institute for Reference Materials and Measurements (IRMM), Geel, Belgium, to calibrate a mass spectrometer with gravimetrically prepared mixtures. 17,[35][36][37][38][39][40][41] This publication presents a potential approach showing how the gravimetric mixture method can be adapted for carbon dioxide and how the isotopic equilibrium is considered in the calculation of the K-factors. The rst experiments testing our new approach, preparing binary mixtures from isotopically enriched parent materials, are presented.…”

Estimation of Mass Discrimination Factor for a Wide Range of m/z by Argon Artificial Isotope Mixtures and NF3Gas

“…When isotopes with different masses effuse from the gas reservoir through μm-size orifice with molecular flow, lighter isotopes travel with a higher speed governed by the kinetic gas theory. 18,19,22 In the ionization chamber maintained a high vacuum (less than 1 × 10 −4 Pa), neutral molecules which avoid to be any ions by electron impact immediately evacuated by the turbo molecular pump. Under our experimental condition, the estimated ionization efficiency (the number of Ar ions arrived at the detector relative to the number of injected molecules) reached only less than 0.01 %.…”

“…It was proven with numerous reports from IRMM researchers that mass discrimination effect during the effusion process in the gas/MS agrees well with the theoretical projection by gas kinetics. [22][23][24] The gas/MS used in this work (located at Korea Research Institute of Standards and Science, KRISS) shows the same characteristic with IRMM's instrument.…”

Uncertainty assessment of Si molar mass measurements

“…The basic model is given in [16]; in the present paper, a proportional relationship is assumed. To compensate for source noise and drift, measurements are performed by using a single Faraday cup in peak jumping mode.…”