We present crossed-beam scattering results for reaction of ground state O(P-3) and electronically excited O(D-1) with n-pentane at a collision energy of 13 kcal/mol. The results were obtained using velocity map imaging with 157 nm single-photon ionization of the products. Using this probe, the only reaction channel observed was that producing the hydrocarbon radical and OH. The results show dramatically contrasting dynamics, with backward-sideways scattering dominating the ground state triplet reaction and isotropic/forward scattering for the singlet reaction. (C) 2003 Published by Elsevier B.V.