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wypward(金币+3):欢迎新虫，谢谢你的参与 2010-05-30 09:30:11
xiangshang(金币+7, 翻译EPI+1): 2010-05-30 09:47:49
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The Photoluminescence (PL) spectroscopy is a method to measure the optical properties of semiconductors. Generated by recombination of free charge carriers, PL spectra reveal the separation effect of charge carriers. This is to say, the more intense the PL signal, the more charge carriers recombined. Figure 2-8 shows the PL spectra of Ba0.7Sr0.3TiO3 and BaTiO3 under the excitation wavelength of 270nm. As can be seen, the samples display intense and broad luminescence signals in the range of 400～450 nm. Ba0.7Sr0.3TiO3 and BaTiO3 have similar shape with their PL spectra, indicating that the doping of Sr did not produce new signals. However, Ba0.7Sr0.3TiO3 has much more intense signals than pure BaTiO3, meaning the electrons and holes are easier to recombine in Ba0.7Sr0.3TiO3. Figure 2-9 shows the results of photocatalytic degradation of Methylene Blue by Ba0.7Sr0.3TiO3 and BaTiO3. According to the principles of photocatalysis, only when the photon energy is large than or equal to the bandgap of semiconductors (hv≥Eg), the semiconductors could be excited by absorbing the photons, generating electron-hole pairs with strong redox abilities and degrading the targets by oxidation. |
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