The effect of Si dangling bonds (Pb center) upon the broad luminescence band, at about 1.1eV, of porous samples was examined on the basis of transient wave-form measurements of optically detected magnetic resonance. The observed wave-form was compatible with the non-geminate shunt path scheme, and the characteristic time constant of this non-radiative process was deduced to be equal to 15s at 1.6K. The competing radiative channel had a decay time of 3s. It was concluded that Pb centers were unlikely to be involved as a radiative state in the infra-red luminescence.

Y.Mochizuki, M.Mizuta: Applied Physics Letters, 1995, 67[10], 1396-8