Collisional quenching of electronically excited OH A(2)Sigma(+) radicals by molecular hydrogen introduces nonradiative pathways that rapidly remove OH population from the excited state, and result in a significantly decreased fluorescence lifetime. One of these pathways is shown to lead to ground state OH X-2 Pi products with similar to 1 eV of internal excitation in both highly excited rotational levels of v = 1 and the lowest rotational levels of v = 2. This highly nonstatistical OH X-2 Pi product distribution reflects the passage of the HO-H, system through the conical intersection regions that couple the ground and excited state surfaces. (c) 2006 Elsevier B.V. All rights reserved.