Estimating the Triple-Point Isotope Effect and the Corresponding Uncertainties for Cryogenic Fixed Points

The phase diagram of natural neon has been calculated for temperatures in the range of 17-50 K and pressures between 10(-2) and 2 x 10(3) bar. The phase coexistence between solid, liquid, and gas phases has been determined by the calculation of the separate free energy of each phase as a function of temperature. Thus, for a given pressure, the coexistence temperature was obtained by the condition of equal free energy of coexisting phases. The free energy was calculated by using nonequilibrium techniques such as adiabatic switching and reversible scaling. The phase diagram obtained by classical Monte Carlo simulations has been compared to that obtained by quantum path-integral simulations. Quantum effects related to the finite mass of neon cause that coexistence lines are shifted toward lower temperatures when compared to the classical limit. The shift found in the triple point amounts to 1.5 K, i.e., about 6% of the triple-point temperature. The triple-point isotope effect has been determined for (20)Ne, (21)Ne, (22)Ne, and natural neon. The simulation data show satisfactory agreement to previous experimental results, which report a shift of about 0.15 K between triple-point temperatures of (20)Ne and (22)Ne. The vapor pressure isotope effect has been calculated for both solid and liquid phases at triple-point conditions. The quantum simulations predict that this isotope effect is larger in the solid than in the liquid phase, and the calculated values show nearly quantitative agreement to available experimental data.

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“…V). 10,47 Our simulations correctly reproduce that the VPIE is larger in the solid than in the liquid phase.…”

Section: Vapor Pressure Isotope Effectsupporting

confidence: 60%

Quantum path-integral study of the phase diagram and isotope effects of neon

Ramı́rez

Herrero

2008

The Journal of Chemical Physics

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“…There were no experimental VPIE data for Xe until 1942 when Clusisus tried a direct measurement of the vapour pressure which failed somehow [1]. There was distillation [3]work done by Grigor'ev.…”

Section: Need For Vpie Pressure Differences For Different Isotopesmentioning

confidence: 99%

“…In that distillation measurement the accuracy was very small as compared to differential pressure VPIE values. There are two different theoretical calculations discussed by [1]. Both calculated the ln( / ) for Xe where f is reduced partition function ratio for condensed phase "C" and vapor phase "V".…”

Section: Need For Vpie Pressure Differences For Different Isotopesmentioning

confidence: 99%

“…The isotopic dependence of vapour pressure of Xenon has not been studied a lot, although there are a significant publication record and data available for other noble elements. Indeed, for Xenon, earlier studies gave much smaller results than the theoretical value [1,2]. In [3] where the measurement was based on distillation, they obtained a value of vapour pressure with zero dependencies.…”

Section: Chapter 1: Introductionmentioning

confidence: 99%

“…In [3] where the measurement was based on distillation, they obtained a value of vapour pressure with zero dependencies. A review of the available data for this study is given by Tew [1].…”

Section: Chapter 1: Introductionmentioning

confidence: 99%

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A Study Of The Xenon Vapour Pressure Isotope Effect

Alamre¹

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The goal of this research was to study the xenon vapour pressure isotope effect (VPIE) and this was done to explore the feasibility of doing the Xe enrichment, using a 1.83 m high, cryogenic distillation column at Carleton University. One of the famous isotopes for the 0vββ decay detection is 136 Xe which is not easily available in pure form, and it is available from the Centrifuge systems in Russia. Therefore, the VPIE of xenon isotopes were needed which have not been measured to date. The VPIE from this work would be 5.28 x 10-5 while the theoretical value reported by Tew is 5.17 x10-5 per mass unit. Thus, the experimental and theoretical values agree with the accuracy of the present slope measurement. Moreover, the data demonstrate for the first time the linear dependence of the VPIE across a range of isotopes, and this is consistent with the theoretical predictions.

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Isotopic Dependence of Vapor Pressure in Xenon

et al. 2020

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The vapor pressure isotopic effect (VPIE) of xenon has been measured using cryogenic distillation. The still is calibrated with argon and krypton and yields a measurement of ln(p 130/p 136) ≃ (0.26 ± 0.04) × 10–3, where p 130 and p 136 are the vapor pressures of 130Xe and 136Xe at the nominal boiling point, respectively. The dependence of the VPIE across the isotopes for the three elements is found to be approximately linear with atomic mass, and all values are consistent with theoretical expectations.

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Estimating the Triple-Point Isotope Effect and the Corresponding Uncertainties for Cryogenic Fixed Points

Cited by 9 publications

References 35 publications

Quantum path-integral study of the phase diagram and isotope effects of neon

Quantum path-integral study of the phase diagram and isotope effects of neon

A Study Of The Xenon Vapour Pressure Isotope Effect

Isotopic Dependence of Vapor Pressure in Xenon

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