The physics of spin–rotation interaction in roughly spherical perfluorinated gas molecules has been studied extensively. But, it is difficult to calculate a spin–lattice relaxation time constant T1 for any given temperature and pressure using the published literature. We give a unified parameterization that makes use of the Clausius equation of state, Lennard-Jones collision dynamics, and a formulaic temperature dependence for collision cross section for rotational change. The model fits T1s for SF6, CF4, C2F6, and c-C4F8 for temperatures from 180 to 360 K and pressures from 2 to 210 kPa and in mixtures with other common gases to within our limits of measurement. It also fits previous data tabulated according to known number densities. Given a pressure, temperature, and mixture composition, one can now calculate T1s for common laboratory conditions with a known accuracy, typically 0.5%. Given the success of the model’s formulaic structure, it is likely to apply to even broader ranges of physical conditions and to other gases that relax by spin–rotation interaction.
%0 Journal Article
%1 kuethe2005inert
%A Kuethe, Dean O.
%A Pietraß, Tanja
%A Behr, Volker C.
%D 2005
%J J. Magn. Reson.
%K mri peer
%N 2
%P 212-220
%R 10.1016/j.jmr.2005.07.022
%T Inert fluorinated gas T1 calculator
%V 177
%X The physics of spin–rotation interaction in roughly spherical perfluorinated gas molecules has been studied extensively. But, it is difficult to calculate a spin–lattice relaxation time constant T1 for any given temperature and pressure using the published literature. We give a unified parameterization that makes use of the Clausius equation of state, Lennard-Jones collision dynamics, and a formulaic temperature dependence for collision cross section for rotational change. The model fits T1s for SF6, CF4, C2F6, and c-C4F8 for temperatures from 180 to 360 K and pressures from 2 to 210 kPa and in mixtures with other common gases to within our limits of measurement. It also fits previous data tabulated according to known number densities. Given a pressure, temperature, and mixture composition, one can now calculate T1s for common laboratory conditions with a known accuracy, typically 0.5%. Given the success of the model’s formulaic structure, it is likely to apply to even broader ranges of physical conditions and to other gases that relax by spin–rotation interaction.
@article{kuethe2005inert,
abstract = {The physics of spin–rotation interaction in roughly spherical perfluorinated gas molecules has been studied extensively. But, it is difficult to calculate a spin–lattice relaxation time constant T1 for any given temperature and pressure using the published literature. We give a unified parameterization that makes use of the Clausius equation of state, Lennard-Jones collision dynamics, and a formulaic temperature dependence for collision cross section for rotational change. The model fits T1s for SF6, CF4, C2F6, and c-C4F8 for temperatures from 180 to 360 K and pressures from 2 to 210 kPa and in mixtures with other common gases to within our limits of measurement. It also fits previous data tabulated according to known number densities. Given a pressure, temperature, and mixture composition, one can now calculate T1s for common laboratory conditions with a known accuracy, typically 0.5%. Given the success of the model’s formulaic structure, it is likely to apply to even broader ranges of physical conditions and to other gases that relax by spin–rotation interaction.},
added-at = {2018-01-19T14:49:20.000+0100},
author = {Kuethe, Dean O. and Pietraß, Tanja and Behr, Volker C.},
biburl = {https://www.bibsonomy.org/bibtex/2459533e2942a4d8abc7b9f976de1de1e/vrbehr},
doi = {10.1016/j.jmr.2005.07.022},
interhash = {9ed629d701913655b9491d90991d85e7},
intrahash = {459533e2942a4d8abc7b9f976de1de1e},
journal = {J. Magn. Reson.},
keywords = {mri peer},
month = {12},
number = 2,
pages = {212-220},
timestamp = {2018-01-19T14:49:20.000+0100},
title = {Inert fluorinated gas T1 calculator},
volume = 177,
year = 2005
}