Energy- and time-resolved IR emission spectra of NO trapped in Kr and Xe matrixes following excitation by an ArF laser were recorded. In Kr matrixes, the ground-state levels are predominantly populated by radiative decay from the a 4P state. The Xe matrixes ground-state v - v - 2 IR emission bands were obsd. for v = 22-3, confirming that in the NO/Xe system most of the excited-state energy is dissipated nonradiatively into the ground state. The IR bands show typical radiative decay times in the ms range but in Xe for all measured levels (v = 22-15), the rise time is ?1 ms. The nonradiative decay of the excited states to the ground state of NO in Xe matrixes is highly nonresonant. [on SciFinder (R)]