The phenomenon of collision-induced electronic energy transfer in selectively excited diatomic radicals has been investigated experimentally. Direct laser excitation of initial rovibronic states and dispersed, temporally-resolved fluorescence analysis of both parent and collisionally populated levels has allowed the collisional encounter to be quantified at a state-specific level. Theoretical modelling of these results allows the form of the potential energy surfaces which control the dynamics to be established. In an extended series of experiments, collision-induced C²Δ-B²Σ⁺ transfer in the SiF radical has been investigated. It was observed that the product B²Σ⁺ state vibrational distributions were well correlated with the Frank-Condon overlap between vibronic wavefunctions of the two states. Dominant channels were found to involve Δv=0, which corresponds to the energy defect of ~5000 cm^-1. Rotationally resolved investigation of the C²Δ, v=0→B²Σ⁺, v'=0 channel revealed a significant fraction of this energy to be released as product state rotation. A limiting impulsive model of the energy release reproduced the main features of the observed behaviour. Polarisation resolved investigation of the transfer event revealed significant depolarisation of the product B²Σ⁺ state compared to the initial C²Δ state. This observation was rationalised within two dynamically distinct models of rotational energy transfer. It is believed that all these observations may be explained by the valence-Rydberg nature of the electronic states involved. In a related set of experiments, novel measurements of collision-induced transfer between the A²Δ and B²Σ^- states of the CH radical have been obtained.