Atomic oxygen recombination on fused silica: experimental evidence of the surface state influence

The time post discharge of a low-pressure pulsed de discharge in pure oxyge n is used to investigate the atomic oxygen recombination on fused silica su rface. With the intention of studying this recombination for different surf ace states, we perform before each pulsed experiment a wall treatment by me ans of de discharges under different experimental conditions. Then, we moni tor the decrease of the atomic oxygen in time post discharge by time resolv ed VUV resonant absorption spectroscopy. We have shown that it is possible to obtain for a given wall treatment, a pulse after pulse variation of this decrease. We have attributed this variation to a filling of the chemisorpt ion sites. Finally, we have determined the surface reaction probability of atomic oxygen on fused silica surface and we have compared it to published values.