On the Temperature Assignments of Experimental Thermal Diffusion Coefficients

Brown, H. L.

doi:10.1103/physrev.58.661

Cited by 71 publications

(4 citation statements)

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“…This can be explained by the discrimination of two isotopologues due to thermal diffusion in a temperature gradient along the way to the cold trap 25. For instance, assuming that the temperature of the cold trap is 40 K and that the thermal diffusion factor at the effective temperature26 of 93 K between the cold trap and room air (300 K) is 0.19,25 we predict 466‰ enrichment at the cold end relative to the warm end (ambient temperature) by applying the thermal diffusion theory. For comparison, by using the enrichment of deuterium and the collection yield observed for 5 min of collection, one can calculate the δ D relative to the warm end as ∼490‰, similar to the value estimated by thermal diffusion theory.…”

Section: Resultsmentioning

confidence: 99%

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Rhee

Mak

Röckmann

et al. 2004

Rapid Comm Mass Spectrometry

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A convenient method is described for analyzing the deuterium/hydrogen (D/H) ratio of atmospheric molecular hydrogen (H(2)) based on mass spectrometric isotope-ratio monitoring. The method requires small amounts of air ( approximately 300 mL STP), is operated on-line, and comprises four steps: (1). the condensation of the air matrix at approximately 40 K; (2). the collection of the non-condensed components of the air sample (H(2), Ne, He, and traces of N(2)) in a 5 A molecular sieves pre-concentration trap at approximately 63 K; (3). gas chromatographic purification of H(2) in a flow of He; and (4) quantification of the D/H ratio in an isotope-ratio mass spectrometer. The precision of the determination of the D/H ratio is better than 2 per thousand, which is comparable to, or better than, that obtained by conventional duel-inlet off-line analysis. There are, however, discrepancies relative to the D/H ratios determined by conventional duel-inlet analysis. This is due to differences in peak shape between reference and sample air, depending on the amount of H(2) injected. Consequently, calibration runs are required. After the calibration of the system, we obtained an accuracy of 1.5 per thousand, so that the accumulated uncertainty is estimated to be less than 4 per thousand. The method also allows determination of the H(2) concentration, with an uncertainty estimated to be 2%.

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Section: Resultsmentioning

confidence: 99%

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Rhee

Mak

Röckmann

et al. 2004

Rapid Comm Mass Spectrometry

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“…Now since aT is linear in T over a temperature range of 50 K, the derivation of Brown [21,221 can be used to show that the value of aFp corresponds to a temperature given by f = ( t ' -T)/ln (r '/TI ('46) Thus, if we identify this temperature with the value in equation (Al), then d, in equation (A4) is always zero. In addition, by using experimental values of the variables in equation (AS), it can be shown that d2 is less than 0.1%.…”

Section: = -Abr2mentioning

confidence: 97%

Dimerisierung einiger organischer Säuren in der Gasphase

Büttner

Maurer

1983

Ber Bunsenges Phys Chem

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Experimental results for the compressibility factor of formic acid, acetic acid, and acrylic acid in the low pressure region at temperatures between 45 and 120°C were used to determine the dimerization constant (2 A -L AA) of these carboxylic acids in the vapour phase. The direct experimental results were evaluated applying three different models for the composition of the gas phase: besides monomers and dimers also the presence of trimers or tetramers was assumed. All three evaluations resulted only in small differences in the entropy and enthalpy of dimerization (maximum differences 6.3 and 5.7 per cent respectively for acetic acid). Assuming the existence of trimers or tetramers resulted in an essentially better agreement between calculated and measured compressibility factors only for formic and acetic acid, but not for acrylic acid. When only the formation of dimers is considered the following dimerization constants were obtained:Formic acid: In KAA = -18

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“…The thermal diffusion factor is also dependent on absolute temperature according to an approximate equation: 11,12,25 where a and b are arbitrary constants and 〈 T 〉 is the effective average temperature. This effective average temperature is given as 12 Although various equation forms have been proposed to describe the temperature dependence of α T , we favor eq 3 proposed from theoretical considerations in 1940 because of its simplicity and because it has been shown to adequately describe a high-precision thermal diffusion data set . The experimental value of the thermal diffusion factor of eq 2 is assigned to the effective average temperature of eq 4.…”

Section: Introductionmentioning

confidence: 99%

Determining the Thermal Diffusion Factor for ⁴⁰Ar/³⁶Ar in Air To Aid Paleoreconstruction of Abrupt Climate Change

Grachev

Severinghaus

2003

J. Phys. Chem. A

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The thermal diffusion factor (R T ) of 40 Ar/ 36 Ar in air has been measured in the laboratory for the first time. The mean values of R T × 10 3 that we find at -30.0 °C are 9.85 ( 0.04 for air and 11.25 ( 0.03 for pure argon. The latter value is more precise than the data found in the literature. The temperature dependence of the thermal diffusion factor in air in the range -60 to -10 °C can be described by an empirical equation R T × 10 3 ) 26.08 -3952/〈T 〉 ((1%), where 〈T 〉 is the effective average temperature. Results of this study are valuable for reconstruction of magnitudes of abrupt climate change events recorded in Greenland ice cores. For one abrupt warming event ∼15,000 years ago, near the end of the last glacial period, these results yield a warming of 11 ( 3 °C over several decades or less. Theoretical calculations are not yet able to provide the needed accuracy, and the experimental results for the thermal diffusion factor in air should be used for paleoenvironmental studies.

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On the Temperature Assignments of Experimental Thermal Diffusion Coefficients

Cited by 71 publications

References 4 publications

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Dimerisierung einiger organischer Säuren in der Gasphase

Determining the Thermal Diffusion Factor for ⁴⁰Ar/³⁶Ar in Air To Aid Paleoreconstruction of Abrupt Climate Change

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On the Temperature Assignments of Experimental Thermal Diffusion Coefficients

Cited by 71 publications

References 4 publications

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Continuous‐flow isotope analysis of the deuterium/hydrogen ratio in atmospheric hydrogen

Dimerisierung einiger organischer Säuren in der Gasphase

Determining the Thermal Diffusion Factor for 40Ar/36Ar in Air To Aid Paleoreconstruction of Abrupt Climate Change

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Determining the Thermal Diffusion Factor for ⁴⁰Ar/³⁶Ar in Air To Aid Paleoreconstruction of Abrupt Climate Change