We report high-resolution measurements of the differential cross section for scattering Na in its $3S_{\frac{1}{2}}$ and $3P_{\frac{3}{2}}$ states from Ne. A new scheme is used to maintain a high fraction (∼20%) of an atomic beam of Na in the excited state for many radiative lifetimes using a single-mode cw dye laser. The differential cross sections are interpreted to yield interatomic potential curves for both the $X\Sigma$ and $A\Pi$ states of the NaNe molecule which seriously disagree with recent pseudopotential calculations.

• Received 24 July 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.1144