CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

asymmetric band at 280 nm. The broad band is a combination of host absorption and Eu-O
charge transfer transition whereas the sharp peaks are characteristic f-f transitions of Eu 3+ ion.
The decay corresponding to the 5 D 0 level of Eu 3+ in the sample is shown in the Fig.104 (c). It
is bi-exponential in nature with lifetime components 200 ms (45%) and 526 ms (55%). The
faster and slower components are due to surface and bulk Eu 3+ ions, respectively present in
ZnGa 2 O 4 nanoparticles.
5.5.3 Tb 3+ doped ZnGa 1.5 In 0.5 O 4 nanoparticles: Emission spectrum of Tb 3+ doped
ZnGa 1.5 In 0.5 O 4 nanoparticles excited at 280 nm is shown in Fig.105 (a). The spectrum
consists of a broad band at 460 nm along with sharp peaks at 490, 545, 585 and 620 nm. This
broad band is the characteristic of the host emission and the sharp peaks are due to 5 D 4 → 7 F 6 ,
5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 and 5 D 4 → 7 F 3 transitions of Tb 3+ , respectively. 5 D 4 decay profile of Tb 3+
(Fig.105 (b)) is a single exponential with lifetime of 1.39 ms.
0.8
0.6
0.4
0.2
Normalised intensity1.0
λ exc
= 280 nm
7
F6
5 D 4
7
F4
5
D4
7 F 5
5
D4
7
F3
5
D4
Intensity(arb.units)
1000
100
10
λ exc
= 280nm, λ em
= 545 nm
0.0
350 400 450 500 550 600 650
Wavelength (nm)
(a)
0 2 4 6 8 10
Time (ms)
(b)
Fig.105. (a) Emission spectrum and (b) 5 D 4 decay profile of Tb 3+ , from Tb 3+ doped
ZnGa 1.5 In 0.5 O 4 nanoparticles. The excitation and emission wavelengths are 280 and
545 nm, respectively.
164