CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

the samples, suggesting that Eu 3+ environment is not changing with increase in Eu 3+ content
in the medium. The relative intensity ratio of 5 D 0 → 7 F 2 (615 nm) to 5 D 0 → 7 F 1 (590 nm)
transition, known as the asymmetric ratio of luminescence, is found to be around 2.6 for all
the samples further confirming that the Eu 3+ environment is same in all the samples. The
excitation spectrum corresponding to 615 nm emission from these samples is shown in Fig.
27(left). The patterns essentially consist of sharp peaks characteristic of the intra 4f
transitions along with broad peaks centered ~ 265 and 360 nm. The peak at 265 nm arises due
to the Eu-O charge transfer process. This peak overlaps with that of host excitation peak
around 280 nm whereas the peak ~ 360 nm is due to excitation of electrons to the defect
levels present in GaOOH host as can be clearly seen in the excitation spectrum corresponding
to GaOOH nanorods prepared in the absence of Eu 3+ ions (Fig.26).
Normalised Intensity
1.0
0.5
0.0
1.0
0.5
0.0
5 7
D0 F1
5 7
D0 F2
5 7
D0 F3
5 7
D0 F4
(c)
(b)
1.0
0.5
(a)
0.0
500 550 600 650 700 750
Wavelength (nm)
Normalised intensity
0.9
0.6
0.3
0.0
0.9
0.6
0.3
0.0
0.9
0.6
0.3
(f)
(e)
(d)
0.0
200 250 300 350 400 450
Wavelength (nm)
7
F0
5
L6
Fig.27. Emission spectrum (left) obtained at 350 nm excitation and excitation spectrum
(right) corresponding to 615 nm emission from GaOOH nanorods prepared in the
presence of (a and d) 0.5 at % Eu 3+ , (b and e) 0.75 at % Eu 3+ , (c and f) 2 at % Eu 3+ .
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