The emission spectra of Eu(C
2F
5COO)
3·Phen was shown in Fig. 3, which composed of narrow and well-resolved characteristic emission peaks of Eu
3+ arising from the transition
5D
0→
7F
0 (580 nm),
5D
0→
7F
1 (592 nm),
5D
0→
7F
2 (613 and 619 nm), respectively. A relevant feature that may be noted for the complex is the high intensity of the
5D
0→
7F
2 transition, relative to the
5D
0→
7F
1 lines, indicating that the Eu
3+ ion coordinated in a local site without an inversion center. Further, the emission spectra of the complex was chacterized only one peak for
5D
0→
7F
0 transition, suggesting the presence of a single chemical environment around the Eu
3+ ion and also showing that the Eu
3+ ion occupies a low-symmetry site. The lifetime value (
τobs) of the
5D
0 level was determined from the luminescence decay profile for Eu(C
2F
5COO)
3·Phen at room temperature. And the lifetime value of the complex was fitting by bi-exponential function with the fast and slow decay lifetimes 2970 and 820 μs. The data presented suggested that two kind of symmetrical sites of Eu
3+ ions exist in this composite. The lifetime value is longer than many fluorinated europium complexes [
12,
13]. Considering the long lifetime, the multiphonon relaxation by coupling to O–H and C–H vibrations are reduced.