Control of electron-phonon dynamics by quantum confinement in
isolated Y2SiO5:Pr3+ nanocrystal
Yu.V. Malyukin, A.A. Masalov, P.N. Zhmurin
Institute for Scintillation Materials, NAS of Ukraine, 60 Lenin Ave., 61001 Kharkov, Ukraine
I(t)
The search of fundamental principles to control luminescent characteristics of
solids could provide a strategy for creation of new scintillation materials. For
instance, quantum-size effect allows zone, electronic and vibrational states of
nanocrystal to be changed at the expense of nanocrystal size variation at a constant
chemical composition. The direct observation of the size confinement effect on
electronic states of doped ions is impossible, because the localization of electronic
wave functions is less than a lattice constant. However, the luminescent dynamics of
activated nanocrystals could be modified by changing the doped ion electron-phonon
interaction. This phenomenon was demonstrated in isolated Y2SiO5:Pr3+ nanocrystals
using Single Molecule Spectroscopy technique [1,2]. Linear and quadratic electronphonon interactions of doped ions were shown to be changed dramatically in such
systems [1,2].
a) Linear electron phonon interaction. The fast electron relaxation rate within Jmultiplets of rare earth doped ions is shown to be
0
suppressed in the nanosized Y2SiO5:Pr3+crystal
which has a week coupling with an environment.
-1
For the excited Stark components of 1D2
-2
multiplet, the electron relaxation appears to be
more than 104 times suppressed, while an average
-3
splitting of the 1D2 multiplet by the crystal field
-4
of ligands is 200 cm–1. It leads to strong
fluorescence from the high 1D2 crystal field
-5
components. The curves of luminescence decay
from the excited 1D2 components well fit by the
1
2
3
4
algebraic low t-1/2 that is evidence of Rabbi
t-1/2,s-1/2
oscillations in doped ion–isolated nanocrystal
The curve of luminescence decay from
system.
the excited Stark component of the 1D2
b) Quadratic electron-phonon interaction. It was
term of the Pr3+ ion.
shown that the temperature broadening of the
spectral line that corresponds to the 3H41D2 resonance optical transition of doped
Pr3+ ions in Y2SiO5:Pr3+ nanocrystals is much weaker as compared to that in the bulk
crystals [1,2].
All effects observed are very sensitive to cluster environment interaction. For
example, the coupling between the nanocrystal and the polymeric matrix is enough to
provide the fast electronic relaxation within the 1D2 manifold similar to that in the
crystal.
* corresponding author e-mail: malyukin@isc.kharkov.com
References
1. Yu.V. Malyukin, A.A. Masalov, P.N. Zhmurin, Opt. Commun. 239, 409 (2004).
2. Yu.V. Malyukin, A.A. Masalov, P.N. Zhmurin, Phys. Lett. A. 316, 147 (2003).