Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review Letters

Enhanced Cooling of Hydrogen Atoms by Lithium Atoms

Robin Côté, Michael J. Jamieson, Z-C. Yan, Neri Geum, Gwang‐Hi Jeung, A. Dalgarno

Published Mar 27, 2000• 51 citations
Publisher

Abstract

We present calculated scattering lengths for collisions between various isotopic forms of lithium and hydrogen atoms interacting via singlet and triplet molecular states of LiH. We demonstrate that one bound triplet level is supported for each isotopomer 7LiH, 6LiH, 7LiD, and 6LiD. We obtain large calculated triplet scattering lengths that are stable against uncertainties in the potential. We present elastic and momentum transfer cross sections, and the corresponding rate coefficients, for hydrogen atoms colliding with 7Li atoms. We suggest that enhanced cooling of trapped atomic hydrogen by 7Li atoms is feasible.

DOI
10.1103/physrevlett.84.2806

Related papers

Accurate calculation of the elastic scattering properties of 7 Li atoms at ultralow temperatures

Sun Jin-Feng, Zhang Ji-Cai, Jiemin Wang

The elastic scattering properties for collisions between two 7 Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X 1 ∑ g + and triplet a 3 ∑ u + ground states of the Li 2 . Our calculated values for the scattering lengths a and the effective ranges r e are compared with previous ones and found them to be in good agreement. The scattering lengths are 34.6 a 0 for the singlet state and −27.6 a 0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X 1 ∑ g + and a 3 ∑ u + states.

Chinese Physics•Mar 1, 2006•19 citations

Elastic scattering of hydrogen atoms at low temperatures

Michael J. Jamieson, A. Dalgarno, John N. Yukich

The elastic scattering of two hydrogen atoms interacting at very small energies is explored numerically using the most accurate potential-energy curves available for the X $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ and $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ states of ${\mathrm{H}}_{2}$. The scattering lengths and low-temperature-averaged cross sections are determined and compared with previous calculations. The scattering lengths are 0.41${\mathit{a}}_{0}$ for the singlet case and 1.91${\mathit{a}}_{0}$ for the triplet. The predicted total triplet cross section at 2 K is 5.5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{cm}}^{2}$ but it could be lower, at 4.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{cm}}^{2}$, with a different fit to the triplet potential between 12${\mathit{a}}_{0}$ and 15${\mathit{a}}_{0}$. A more accurate triplet-state potential is needed at these separations.

Physical Review A•Dec 1, 1992•53 citations

A new path to ultracold hydrogen

Robert deCarvalho, Nathan Brahms, Bonna K. Newman +3 more

Ultracold hydrogen offers unique possibilities for precision spectroscopy, studies of atomic interactions, and the creation of quantum fluids containing mixtures of hydrogen and deuterium. Current techniques for trapping and cooling hydrogen have produced large condensates with N ∼ 109 atoms, but suffer from a variety of experimental limitations. Among these are the slow evaporative cooling rate due to the small H–H elastic-scattering cross section, the need for a superfluid helium film in the initial thermalization process, a geometry that severely limits detection efficiency, and the inability to trap deuterium. We are constructing a new apparatus based on buffer-gas cooling that will overcome these problems. To accelerate evaporative cooling, the thermalization rate is increased by simultaneously loading lithium and hydrogen into a 4.2 T anti-Helmholtz trap. Lithium accelerates evaporative cooling because the Li–H elastic-scattering cross section is ∼1200 times larger than that of H–H. Hydrogen and lithium will be produced by laser ablation of solid LiH in a 3He buffer gas held at temperatures of ∼350 mK. Because no wall collisions are needed for initial thermalization, ablating a solid sample of LiD should enable studies of deuterium. The apparatus is in the final stages of construction. We report on results of initial tests and discuss the new scientific opportunities made possible by this approach.PACS No.: 32.80.Pj

Canadian Journal of Physics•Apr 1, 2005•13 citations

Sympathetic cooling of Li6 atoms

Frank A. van Abeelen, BOUDEWIJN J. VERHAAR, A. J. Moerdijk

We use recently measured cold photoassociation and two-photon data to extract the singlet and triplet accumulated radial phases of interacting ground-state lithium atoms. Using the resulting values we predict scattering lengths, Feshbach resonances, and exchange decay rates for cold collisions between $^{7}\mathrm{Li}$ and $^{6}\mathrm{Li}$ atoms that are of interest for the possibility of sympathetic cooling of $^{6}\mathrm{Li}$ and for the coexistence of the bosonic and fermionic quantum-degenerate phases of $^{7}\mathrm{Li}$ and $^{6}\mathrm{Li}$. In addition, we calculate scattering lengths and exchange decay rates for cold collisions between identical lithium isotopes in different hyperfine states. These quantities are used to examine the possibilities of coexisting $^{7}\mathrm{Li}$ Bose condensates and of evaporatively cooling coexisting $^{6}\mathrm{Li}$ subsystems.

Physical Review A•Jun 1, 1997•46 citations

Elastic scattering of two Li7 atoms

Robin Côté, A. Dalgarno, Michael J. Jamieson

Interaction potentials for the X $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ and a $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ states of ${\mathrm{Li}}_{2}$ are constructed and used in calculations of the elastic scattering of two $^{7}\mathrm{Li}$ atoms at ultralow temperatures. The extreme sensitivity of the cross sections to the details of the interaction potentials is demonstrated. The calculated elastic and spin-change cross sections are very large, of the order of ${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{2}$ at zero temperature. The predicted scattering length for the triplet state is negative with a value of -17.2${\mathit{a}}_{0}$. Pronounced shape resonances appear at energies of 4.9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}8}$ a.u. in the singlet scattering and 5.5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$ a.u. in the triplet scattering.

Physical Review A•Jul 1, 1994•90 citations

Potential Scattering and Spin-Exchange Cross Sections in Atomic Hydrogen at Very Low Energies

Naoto Koyama, James C. Baird

Potential scattering and spin-exchange scattering cross sections in the energy range from 10 -3 cm -1 to 100 cm -1 have been calculated numerically for hydrogen atoms in collision based on the most accurate Kołos-Woniewicz adiabatic potentials available at present. The scattering lengths for the singlet and triplet states are calculated to be a 0 s =0.595 a.u. and a 0 t =1.34 a.u., respectively. The quasi-bound state with ν=14 and l =4 is found to be at E =1.675 cm -1 above the dissociation limit. The thermally averaged spin-exchange cross section has the low temperature limit \barσ ex (0 K)=0.982 A 2 with a minimum \barσ ex (2.5 K)=0.329 A 2 .

Journal of the Physical Society of Japan•Mar 15, 1986•16 citations
We present calculated scattering lengths for collisions between various isotopic forms of lithium and hydrogen atoms interacting via singlet and triplet molecular states of LiH. We demonstrate that one bound triplet level is supported for each isotopomer 7LiH, 6LiH, 7LiD, and 6LiD. We obtain large calculated triplet scattering lengths that are stable against uncertainties in the potential. We present elastic and momentum transfer cross sections, and the corresponding rate coefficients, for hydrogen atoms colliding with 7Li atoms. We suggest that enhanced cooling of trapped atomic hydrogen by 7Li atoms is feasible.
The elastic scattering properties for collisions between two 7 Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X 1 ∑ g + and triplet a 3 ∑ u + ground states of the Li 2 . Our calculated values for the scattering lengths a and the effective ranges r e are compared with previous ones and found them to be in good agreement. The scattering lengths are 34.6 a 0 for the singlet state and −27.6 a 0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X 1 ∑ g + and a 3 ∑ u + states.
The elastic scattering of two hydrogen atoms interacting at very small energies is explored numerically using the most accurate potential-energy curves available for the X $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ and $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ states of H2{\mathrm{H}}_{2}H2​. The scattering lengths and low-temperature-averaged cross sections are determined and compared with previous calculations. The scattering lengths are 0.41a0{\mathit{a}}_{0}a0​ for the singlet case and 1.91a0{\mathit{a}}_{0}a0​ for the triplet. The predicted total triplet cross section at 2 K is 5.5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ cm2{\mathrm{cm}}^{2}cm2 but it could be lower, at 4.8\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ cm2{\mathrm{cm}}^{2}cm2, with a different fit to the triplet potential between 12a0{\mathit{a}}_{0}a0​ and 15a0{\mathit{a}}_{0}a0​. A more accurate triplet-state potential is needed at these separations.
Ultracold hydrogen offers unique possibilities for precision spectroscopy, studies of atomic interactions, and the creation of quantum fluids containing mixtures of hydrogen and deuterium. Current techniques for trapping and cooling hydrogen have produced large condensates with N ∼ 109 atoms, but suffer from a variety of experimental limitations. Among these are the slow evaporative cooling rate due to the small H–H elastic-scattering cross section, the need for a superfluid helium film in the initial thermalization process, a geometry that severely limits detection efficiency, and the inability to trap deuterium. We are constructing a new apparatus based on buffer-gas cooling that will overcome these problems. To accelerate evaporative cooling, the thermalization rate is increased by simultaneously loading lithium and hydrogen into a 4.2 T anti-Helmholtz trap. Lithium accelerates evaporative cooling because the Li–H elastic-scattering cross section is ∼1200 times larger than that of H–H. Hydrogen and lithium will be produced by laser ablation of solid LiH in a 3He buffer gas held at temperatures of ∼350 mK. Because no wall collisions are needed for initial thermalization, ablating a solid sample of LiD should enable studies of deuterium. The apparatus is in the final stages of construction. We report on results of initial tests and discuss the new scientific opportunities made possible by this approach.PACS No.: 32.80.Pj
We use recently measured cold photoassociation and two-photon data to extract the singlet and triplet accumulated radial phases of interacting ground-state lithium atoms. Using the resulting values we predict scattering lengths, Feshbach resonances, and exchange decay rates for cold collisions between 7Li^{7}\mathrm{Li}7Li and 6Li^{6}\mathrm{Li}6Li atoms that are of interest for the possibility of sympathetic cooling of 6Li^{6}\mathrm{Li}6Li and for the coexistence of the bosonic and fermionic quantum-degenerate phases of 7Li^{7}\mathrm{Li}7Li and 6Li^{6}\mathrm{Li}6Li. In addition, we calculate scattering lengths and exchange decay rates for cold collisions between identical lithium isotopes in different hyperfine states. These quantities are used to examine the possibilities of coexisting 7Li^{7}\mathrm{Li}7Li Bose condensates and of evaporatively cooling coexisting 6Li^{6}\mathrm{Li}6Li subsystems.
Interaction potentials for the X $^{1}\mathrm{\ensuremath{\Sigma}}_{\mathrm{g}}^{+}$ and a $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{+}$ states of Li2{\mathrm{Li}}_{2}Li2​ are constructed and used in calculations of the elastic scattering of two 7Li^{7}\mathrm{Li}7Li atoms at ultralow temperatures. The extreme sensitivity of the cross sections to the details of the interaction potentials is demonstrated. The calculated elastic and spin-change cross sections are very large, of the order of ${10}^{\mathrm{\ensuremath{-}}13}$ cm2{\mathrm{cm}}^{2}cm2 at zero temperature. The predicted scattering length for the triplet state is negative with a value of -17.2a0{\mathit{a}}_{0}a0​. Pronounced shape resonances appear at energies of 4.9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}8}$ a.u. in the singlet scattering and 5.5\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}7}$ a.u. in the triplet scattering.
Potential scattering and spin-exchange scattering cross sections in the energy range from 10 -3 cm -1 to 100 cm -1 have been calculated numerically for hydrogen atoms in collision based on the most accurate Kołos-Woniewicz adiabatic potentials available at present. The scattering lengths for the singlet and triplet states are calculated to be a 0 s =0.595 a.u. and a 0 t =1.34 a.u., respectively. The quasi-bound state with ν=14 and l =4 is found to be at E =1.675 cm -1 above the dissociation limit. The thermally averaged spin-exchange cross section has the low temperature limit \barσ ex (0 K)=0.982 A 2 with a minimum \barσ ex (2.5 K)=0.329 A 2 .