State-to-State Differential Cross Sections by Velocity Mapping for Rotational Excitation of CO by Ne

State-to-state differential cross sections for rotational excitation of CO by Ne were determined in a crossed beam experiment at 511 cm -1 . Scattered CO molecules were ionized with 2+1 resonance enhanced multiphoton ionization and detected with velocity mapping. Cross sections were determined for most of the energetically allowed final states of CO. The results were compared with predictions from two Ne−CO ab initio potential surfaces. The CCSD(T) surface of McBane and Cybulski [ J . Chem . Phys . 1999, 110, 11734] predicts the positions of the rotational rainbow maxima more accurately than does the surface of Moszynski et al. [ J . Phys . Chem . A 1997, 101, 4690].