The pseudopotential molecular-structure method has been used to calculate the $X^1$Σ and $a^3$Σ interaction potentials for the alkali-metal-atom–hydrogen-atom systems. These potentials were then used in a quantum-mechanical calculation to determine the spin-exchange cross sections in the energy range from 2.5×${10}^{\mathrm{-}4}$ eV to 2.5 eV. The cross sections follow the general form $Q^{1/2}$=a-b lnv. However, abundant structure on the cross sections is present due to orbiting resonances induced by the deeply bound well of the $X^1$Σ molecular state. The spin-exchange cross sections range from 17×${10}^{\mathrm{-}16}$ to 25×${10}^{\mathrm{-}16}$ ${\mathrm{cm}}^2$ at room temperature for H(F=1) transferring to H(F=0) in collision with unpolarized lithium and cesium, respectively.

• Received 12 October 1984

DOI:https://doi.org/10.1103/PhysRevA.31.2137