Photoluminescence spectral change in layered titanate oxide intercalated with hydrated Eu3+
Photoluminescence spectral change in layered titanate oxide intercalated with hydrated Eu3+
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DOI：
10.1021/jp063412o
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发表时间：
2006-11-30
影响因子：
3.3
通讯作者：
Matsumoto, Yasumichi
中科院分区：
文献类型：
--
作者：
Ida, Shintaro;Unal, Ugur;Matsumoto, Yasumichi
钛酸盐层状氧化物与水合Eu3+的插层具有许多有趣的光致发光性质。在紫外光照射下，Eu3+的光致发光强度随时间急剧下降，紫外光的能量高于基质Ti1.81O4层的带隙能量。这可能是由于Eu3+周围的水分子的水合状态发生了变化，从而减少了从宿主TiO层到Eu3+的能量转移，这是由TiO价带中产生的空穴引起的。停止照射后，发射强度逐渐恢复。通过热处理去除中间层中的水分，可延长恢复时间。这表明层间水的状态在辐照过程中发生了变化，并在停止辐照后恢复到初始状态。在紫外光照射下，激发光谱在任意波长都发生了剧烈的变化。比较辐照前后的激发光谱发现，与光谱烧孔的情况一样，只有辐照波长附近的激发峰在辐照后有所降低。Eu3+周围的水分子的水合状态可能随照射波长的不同而变化，导致上述光谱变化的原因是Eu/TiO膜具有超晶格结构，产生不同能量的空穴。
A number of interesting photoluminescence properties of titanate layered oxide intercalated with hydrated Eu3+ have been demonstrated. Photoluminescence intensity of Eu3+ decreased rapidly with time during irradiation by UV light having energy higher than the band gap energy of the host TiO (Ti1.81O4) layer. This is presumably due to the decrease in energy transfer from the host TiO layer to Eu3+ as a result of the change in the hydration state of water molecules surrounding Eu3+, which is caused by the hole produced in the TiO valence band. When irradiation was discontinued, the emission intensity gradually recovered. The recovery time increased when the water in the interlayer is removed by heat treatment. This indicates that the state of interlayer water changes during irradiation and returns to its initial state after discontinuation of irradiation. The excitation spectra changed drastically at any given wavelength upon irradiation with UV light. A comparison of the excitation spectra before and after irradiation reveals that only the excitation peak at around the irradiation wavelength decreased upon irradiation, as in the case of spectral hole burning. The hydration state of water molecules surrounding Eu3+ presumably changes depending on the irradiation wavelength, leading to the above spectral change because the Eu/TiO film has a superlattice structure producing holes with different energies.