Broad-band capture

On the other hand, the defect states such as oxygen vacancies in the ZnO nanorods also capture electrons, and generate a broad band green emission centered at 525 nm. Due to the spectral overlap between the defect-related emission of ZnO and the absorption band of Fo D2 transition at 465 nm of Eu ions, an efficient energy transfer also occurs. Thus,... 

M-center consists of two electrons captured by F anion vacancies in fluorite. It is characterized by red luminescence peaking at 725 nm and excited in 370 and 530 nm spectral ranges (Tarshchan 1978). This center is characterized by long decay time and is detected with relatively broad gate width. Vk-center is a hole center, which is formed by F ions which loses its electron. It is characterized by UV luminescence band peaking at approximately at 290 nm with very short decay time (Fig. 5.106). 

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