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In
the frame of Frontier Science Research Conferences the meeting named
“Luminescent Materials-2002” took place in La Jolla,
California and was organized by La Jolla International School of
Science and The Institute for advanced Physics Studies, divisions
of the Stefan University. About
twenty presentations from different countries covered practically
all hot areas of the modern luminescence.
The
advantages of material science and fundamental physics were
demonstrated by various techniques and with different organic,
inorganic and hybrid substances. Some theoretical approaches were
demonstrated in connection with luminescent properties of systems.
Few
reports (Dr.E.Antic-Fidancev, Dr.P.Dorenbos, Dr.A.Florez ,
Dr.D.Jaque and Dr.Morita) were devoted by high luminescent
materials based on lanthanides. The new developments in Ln3+
doped laser give a possibility to spread the range of laser
application from the UV to the IR. Absorption/emission lines of an
isostructural family exhibit a linear relation with ionic radii of
the Ln3+ ions along the lanthanide series. On the basis
of the evolution of Stark components of some crystal field levels
the phase existence limit is demonstrated. The preparation and
photoluminescence of rare earth complexes embedded in xerogel
Participants
of Conference paid many attentions to inorganic nanostructures
(Dr. L.Carlos, Dr.A.Ivanov, Dr.K.Hino) and organic ones (Dr.P.Reineker,
Dr.A.Vitukhnovsky). There is growing interest in the full color
emitting materials that combine good mechanical, thermal and
chemical stability in air with high room temperature emission
quantum yield. From this aspect, the main interest of the
organic/inorganic hybrid concept basically derives from
possibility of tailoring the properties of novel multifunctional
advanced materials through the combination at the nanosize level
of the organic and inorganic components in a single material.
Review of resent results on the emission properties of stable
sol-gel derived nanohybrids and lanthanide-based di-uresil
nanocomposites is presented. The excellent report about theory of
the quantum dots
interfaces and quasi-two dimensional optics of the
semiconductor nanostructures was done by Dr.A.Ivanov.
The
non-adiabatic treatment of optical properties of quantum dots
proposed in Devreese’e presentation to provide an explanation
for remarkably high intensity of phonon satellities observed in
the photoluminescence and Raman spectra of quantum-dot structures.
Minami et al present the experimental result showing that the
spectral width of optical transitions, especially of exciton
transition, is narrow enough in GaAs quantum dots, because of the
phonon bottleneck effect, and the coherence created by laser light
maintains ~ 1ns. Quantum interference between continua and a
discrete level embedded in the former gives rise to a pronounced
asymmetric spectral profile having a peak-and-dip structure know
as a Fano resonance. This phenomenon is investigated by Dr.Hino.
The new theoretical approaches show generation of quite rich
fine-structures of Fano resonance states ascribable to VB mixing
as well as Coulomb coupling.
Two
presentations are connected with organic nanoobjects –
dendrimers. Dendrimers are new class of engineered macromolecules
showing a branching pattern on a nanometer scale. Reineker with
coauthors focused on optical absorption and energy transfer of
dendrimers taking into account vibrational degrees of freedom.
They applied the Frenkel exciton model and describe the dephasing
according to Haken, Strobl and Reineker theory to the three lowest
dendrimer D4, D10 and D22. Vitukhnovsky gave the description of
experimental results for exciton relaxation in J-aggregates of
thiacarbocyanine dyes (THIATS and TDC) and energy transfer from
multiple the dendrimer peripheries to lanthanide ions used as
dendrimer core.
Some
other aspects of luminescent materials were represented on
Conference: new materials for medical applications, doped
insulators and electron processes inside them, application of
surface plasmon excitation of photofunctional molecules on gold
surface and many others topics.
We
believe that such type of meeting is fruitful and has some
advantages against traditional conferences.
Prof.
Alexei Vitukhnovsky
Head of Vavilov Luminescence Department
P.N. Lebedev Institute of Physics, Russian Academy of Sciences
Moscow 119991 Russia
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