A laser-based O atom beam source together with state-resolved detection techniques are used to characterize the energy transfer dynamics of ground (P-3) and electronically excited (D-1) state O atoms interacting with a fused silica surface. Time-of-flight spectra of the incident beam and scattered O atoms are measured, and provide detailed information regarding state-resolved angular and velocity distributions. We find a significant degree of "thermalization" (angular, fine structure state, and velocity distributions) in the scattered O(P-3) atoms. The survival probability of O(D-1) is determined to be less than or equal to0.01, and the probability for O(D-1) quenching to "super-elastic" O(P-3) is 0.05. Given that the measured probability for radiative quenching of D-1 is not significant (less than or equal to0.001), these results indicate that the majority of the available energy in the incident O atoms (both P-3 and D-1) is transferred to the substrate. The implications of the scattering/energy transfer dynamics with respect to the O atom/fused silica surface interactions are discussed.