ion decays in the nanosecond range (?30 ns), whereas in the
terbium ion it decays in the millisecond range. In [18] lifetime
measurements of the Ce 3þ emission glasses were performed
monitoring at 470 nm, after 337 nm pulsed laser excitation within
the Ce 3þ 4f-5d absorption transition. The cerium emission decay
follows a single-exponential decay with a lifetime value of
6572 ns. This very short decay time agrees with the electric
dipole allowed nature of the Ce 3þ 4f-5d transition. Lifetime
measurements of the 5D3 and
5 D 4
levels of Tb 3þ in zinc–sodium–
aluminosilicate glasses doped Ce 3þ /Tb 3þ were performed mon-
itoring the
5 D 3 - 7 F 4
(435 nm) and
5 D 4 - 7 F 5
(550 nm) emissions
with Ce 3þ excitation at 320 nm. The decay curves of these
emissions are non-exponential. The effective decay times of the
5 D 3
and
5 D 4
states are 2.570.2 ms and 4.170.3 ms, respectively.
The long decay time of the terbium emissions is typical for the f–f
transitions originating from
5 D 3
and
5 D 4
states. Our results show
that for in all the samples the decay kinetics of the luminescence
band at 436 nm (Fig. 6) a cannot be described by the monoexpo-
nential decay kinetics, and the kinetics can be divided into two
stages: the fast stage of decay with the relaxation time τ fast
?2372 ms and the slow component τ slow ?14074 ms. As the
concentration of cerium changes, the duration of both fast and
slow stages changes insignificantly (Fig. 6 a, inset). This means that
the processes of excitation and relaxation of the
5 D 3
level are
apparently not related directly to the presence of cerium ions in
the glass host
ion decays in the nanosecond range (?30 ns), whereas in theterbium ion it decays in the millisecond range. In [18] lifetimemeasurements of the Ce 3þ emission glasses were performedmonitoring at 470 nm, after 337 nm pulsed laser excitation withinthe Ce 3þ 4f-5d absorption transition. The cerium emission decayfollows a single-exponential decay with a lifetime value of6572 ns. This very short decay time agrees with the electricdipole allowed nature of the Ce 3þ 4f-5d transition. Lifetimemeasurements of the 5D3 and5 D 4levels of Tb 3þ in zinc–sodium–aluminosilicate glasses doped Ce 3þ /Tb 3þ were performed mon-itoring the5 D 3 - 7 F 4(435 nm) and5 D 4 - 7 F 5(550 nm) emissionswith Ce 3þ excitation at 320 nm. The decay curves of theseemissions are non-exponential. The effective decay times of the5 D 3and5 D 4states are 2.570.2 ms and 4.170.3 ms, respectively.The long decay time of the terbium emissions is typical for the f–ftransitions originating from5 D 3and5 D 4states. Our results showthat for in all the samples the decay kinetics of the luminescenceband at 436 nm (Fig. 6) a cannot be described by the monoexpo-nential decay kinetics, and the kinetics can be divided into twostages: the fast stage of decay with the relaxation time τ fast?2372 ms and the slow component τ slow ?14074 ms. As theconcentration of cerium changes, the duration of both fast andslow stages changes insignificantly (Fig. 6 a, inset). This means thatthe processes of excitation and relaxation of the5 D 3level areapparently not related directly to the presence of cerium ions inthe glass host
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