Positron Annihilation Studies of Mesoporous Silica MCM-41
Positron annihilation has been used to study the mesoporous silica MCM-41. Lifetime spectra of evacuated MCM-41 indicate a significant contribution from 3γ annihilation events with τ4 116 ns and I4 24.5 %. This is supported by measurements of the full energy distribution, where MCM-41 shows enhanced...
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| Veröffentlicht in: | Journal of physics. Conference series 2013-01, Vol.443 (1), p.12063-4 |
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| container_title | Journal of physics. Conference series |
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| creator | Williams, J F Guagliardo, P Sudarshan, K Ranganathaiah, C Koutsantonis, G Hondow, N Samarin, S |
| description | Positron annihilation has been used to study the mesoporous silica MCM-41. Lifetime spectra of evacuated MCM-41 indicate a significant contribution from 3γ annihilation events with τ4 116 ns and I4 24.5 %. This is supported by measurements of the full energy distribution, where MCM-41 shows enhanced counts in the low energy region (below 511 keV) relative to a pure 2γ sample. MCM-41 was also studied under air and oxygen atmospheres. The presence of atmosphere has a significant effect on both the lifetime and Doppler patterns, with both the lifetime data (τ4 and I4) and the 3γ-fraction decreasing with increasing oxygen concentration. This is indicative of paramagnetic quenching of o-Ps by oxygen. |
| doi_str_mv | 10.1088/1742-6596/443/1/012063 |
| format | Article |
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| subjects | Atmospheres Counting Doppler Doppler effect Energy distribution Evacuation Oxygen Physics Positron annihilation Quenching Silicon dioxide Spectra |
| title | Positron Annihilation Studies of Mesoporous Silica MCM-41 |
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