ShO₂上の吸着酸素のESR

抄録

The ESR measurement of oxygen adsorbed on SnO₂ revealed that adsorption of oxygen resulted in the formation of three paramagnetic centers and one diamagnetic center. These centers may be attributed to O₂^- (g₁=2.002, g₂=2.009, g₃=2.026 and 2.035), O^- (g₁=2.0015, g₂=2.028, g₃=2.030), neutral-O₂ (g₁=1.993, g₂=2.003, g₂=2.023) and O^2- (diamagnetic) respectively. Only the O₂^- species appeared at the early stage of adsorption at room temper-ature and then it dissociated into the O²- species. Neutral-O₂ Species always coexisted with the O₂^- species and was easily desorbed by evacuation at room temperature. Although the O^- species appeared between room temperature and 200°C its adsorption amount was much less than that of the O^2- species. The relative amount of adsorbed oxygen species was dis-cussed in connection with the relation between the fermi level and the lowest empty energy level of the adsorbed species.