Makrides, C.
, Barker, D.
, Fedchak, J.
, Scherschligt, J.
, Eckel, S.
and Tiesinga, E.
(2020),
Collisions of room temperature helium with ultra-cold lithium and the van-der-Waals bound state of HeLi, Physical Review A, [online], https://doi.org/10.1103/PhysRevA.101.012702, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928390
(Accessed October 16, 2025)
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Collisions of room temperature helium with ultra-cold lithium and the van-der-Waals bound state of HeLi
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Author(s)
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Abstract
We have computed the thermally-averaged total, elastic rate coefficient for the collision of a room-temperature helium atom with an ultra-cold lithium atom. This rate coefficient has been computed as part of the characterization of a cold atom vacuum sensor based on laser-cooled Li atoms that will operate in the Ultra-High-Vacuum (UHV, p < 10^-6 Pa) and Extreme- High-Vacuum (XHV, p < 10^-10 Pa) regimes. The analysis involves computing the X HeLi Born-Oppenheimer potential followed by the numerical solution of the relevant radial Schrodinger equation. The potential is computed using a multi-reference-coupled-cluster electronic-structure method with basis sets of different completeness in order to characterize our uncertainty budget. We predict that the rate coefficient for a 300 K helium gas and a 1 microK Li gas is 1.467(13)×10^-9 cm^3 /s for ^4He+^6Li and 1.471(13) × 10^-9 cm^3 /s for ^4He+^7Li, where the numbers in parenthesis are the one-standard-deviation uncertainties in the last two significant digits. We quantify the temperature dependence as well. Finally, we evaluate the binding of the single van-der-Waals bound state of HeLi. We predict that this weakly-bound level has a binding energy of -0.0064(43) x hc cm^-1 and -0.0122(67) x hc cm^-1 for ^4He^6Li and ^4He^7Li, respectively.Citation
Physical Review A
Volume
101
Pub Type
Journals
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Keywords
pressure sensor, ultracold atoms, van-der-Waals molecules, interatomic potentials, UHV
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Created January 5, 2020, Updated October 12, 2021