1. Institute for Solid State Physics, University of Tokyo, Roppongi, Tokyo 106 September 7, 1989 <p class="abstrast"> Time-resolved optically detected magnetic resonance experiments were carried out in a-Si:H, using CW Ar+ laser light pulsed by an acousto-optic modulator. Detection condition was chosen to be suitable for measuring the long delay time region of ∼µs. Using this technique, we could concentrate on the behaviors of quenching signals and conclude that there exist two nonradiative...