Physical Review Letters

Spin-Rotation Interaction of Noble-Gas Alkali-Metal Atom Pairs

Z. Wu, Thad G Walker, W. Happer

Published Apr 29, 1985• 50 citations

Abstract

Recent experimental data show that the spin-rotation coupling for alkali-metal-noble-gas van der Waals molecules is mainly due to the spin-orbit interaction of the alkali-metal valence electron within the core of the noble gas. We present a simple formula which accounts very well for the systematic variation of the spin-rotation interaction with different noble-gas or alkali-metal atoms.

DOI: 10.1103/physrevlett.54.1921

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Physical Review Letters

Spin-Rotation Interaction of Noble-Gas Alkali-Metal Atom Pairs

Z. Wu, Thad G Walker, W. Happer

Published Apr 29, 1985• 50 citations

Publisher

Abstract

DOI: 10.1103/physrevlett.54.1921

Related papers

Experimental determination of the spin-rotation coupling in Na-Xe molecules

M. Hou, B. Feng, J. Zhang +3 more

A theory for calculating the spin–rotation coupling coefficient in alkali-metal–noble-gas van der Waals molecules was recently presented.1 It assumes the spin–rotation interaction in alkali-metal–noble-gas molecules to be mainly due to the spin–orbit interaction of the alkali-metal valence electron within the core of the noble gas, and predicts that the spin–rotation constant γ should depend on the spin–orbit interaction in the noble gas and be almost independent of the spin–orbit interaction of the alkali-metal atom. Experimentally, only a few of the possible pairs of the different alkali-metal atoms with different noble-gas atoms have been investigated. By measuring the sodium spin relaxation rate as a function of the helium buffer-gas pressure and the width of the sodium magnetic slowing-down curve, we report in this paper our experimentally determined value of the spin–rotation interaction constant in Na–Xe molecules γ = (1.1 ± 0.3)MHz. The measured value is nearly the same as was measured in K–Xe, Rb–Xe, and Cs–Xe.1 This result shows a reasonable agreement with the theoretical prediction.A theory for calculating the spin–rotation coupling coefficient in alkali-metal–noble-gas van der Waals molecules was recently presented.1 It assumes the spin–rotation interaction in alkali-metal–noble-gas molecules to be mainly due to the spin–orbit interaction of the alkali-metal valence electron within the core of the noble gas, and predicts that the spin–rotation constant γ should depend on the spin–orbit interaction in the noble gas and be almost independent of the spin–orbit interaction of the alkali-metal atom. Experimentally, only a few of the possible pairs of the different alkali-metal atoms with different noble-gas atoms have been investigated. By measuring the sodium spin relaxation rate as a function of the helium buffer-gas pressure and the width of the sodium magnetic slowing-down curve, we report in this paper our experimentally determined value of the spin–rotation interaction constant in Na–Xe molecules γ = (1.1 ± 0.3)MHz. The measured value is nearly the same as was measured in K–Xe, Rb–Xe, and Cs–Xe.1 This result shows a reasonable agreement with the theoretical prediction.

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Physical Review AJun 1, 1989155 citations

K

and for the nuclear spin

I

of the alkali-metal atom are assumed. Precise formal expressions for spin transfer coefficients are given along with convenient approximations based on a perturbation expansion in powers of ${(\frac{\ensuremath{\alpha}}{\ensuremath{\gamma}N})}^{2}$, a quantity which has been shown to be small by experiment.

By analyzing the measured spin-relaxation transients of

^{129}\mathrm{Xe}

nuclear spins and alkali-metal-atomic spins in mixtures of alkali-metal-atom vapors, Xe gas, and larger amounts of

{\mathrm{N}}_{2}

gas, we have determined the three-body formation rates and the spin-transfer probabilities for alkali- metal--noble-gas van der Waals molecules. Three parameters, in addition to the spin quantum numbers of the alkali-metal and noble-gas nuclei, are needed to predict the spin-transfer rates. These parameters, which we have determined from experimental measurements, are x=\ensuremath{\gamma}N/\ensuremath{\alpha}, the ratio of the spin-rotation interaction \ensuremath{\gamma}N to the spin-exchange interaction \ensuremath{\alpha};

{p}_{0}

, the third-body pressure for which the molecular breakup rate ${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}1}$ is equal to the spin-rotation frequency \ensuremath{\gamma}N/h; and Z, the three-body rate constant for forming van der Waals molecules.

^{83}\mathrm{Kr}

and

^{129}\mathrm{Xe}

were measured in a vapor of spin-polarized alkali-metal atoms oriented parallel and antiparallel to the external magnetic field. The shift in the EPR frequency of the alkali-metal vapor due to the polarized noble-gas nuclei was measured simultaneously, thus providing a measurement of the absolute noble-gas nuclear polarization. The frequency shifts can be used as a convenient way to measure the absolute nuclear spin polarization of noble gases.