EuCl3.6H2O中Eu^3＋的^5D0—^7F0跃迁的“反常”温度效应及其跃迁机制研究

Studies on “Abnormal” Temperature Effect and Transition Mechanism of  5D 0 - 5F 0  Transition of Eu 3+ in EuCl 3·6H 2O

研究了ＥｕＣｌ３·６Ｈ２Ｏ中Ｅｕ３＋的５Ｄ０－７Ｆ０“禁戒”跃迁的机制及其“反常”温度效应。通过比较不同温度下荧光光谱中５Ｄ０－７Ｆ０跃迁和５Ｄ０－７Ｆ２跃迁第一条谱线的强度比，发现由于晶格振动，７Ｆ２态（主要是最低的一个次能级）通过四个频率为２４５ｃｍ－１的声子与７Ｆ０态耦合，使７Ｆ０态成为混合态，因而使５Ｄ０－７Ｆ０的跃迁成为可能，并且其振子强度随温度的变化而变化。从而很好地解释了ＥｕＣｌ３·６Ｈ２Ｏ中这一“禁戒”跃迁的机制及其跃迁振子强度随温度的变化关系。

The transition mechanism and “abnormal” temperature effect of  5D 0 - 7F 0  transition of Eu 3+ in EuCl 3·6H 2O are studied. By analysing the intensity ratios of the  5D 0 - 7F 0  transition to the lowest energy level line of the  5D 0 - 7F 2  transition of fluorescence spectra at different tempertures, it is found that  7F 2  state (mainly the lowest energy level) can couple with  7F 0  state by four 245 cm -1 phonons. The  7F 0  state becomes a mixed state, so the “forbidden”  5D 0 - 7F 0  transition can be allowed and its oscillator strength varies with temperature. Therefore, the transition mechanism and the relationship between the oscillator strength of  5D 0 - 7F 0  transition in EuCl 3·6H 2O and temperature are well explained.