"Activated and Intermittent Photoluminescence in Thin CdSe Quantum Dot Films" A. Javier, G.F. Strouse, Phys. Rev. B, submitted 7/03
"Photothermal Melting and Energy Migration in Conjugated Oligomer Films with CdSe Quantum Dots" A. Javier, R.W. Meulenberg, C.S. Yun, G.F. Strouse J. Phys. Chem. B., (2005). [view article-PDF]
"Nanometal Surface Energy Transfer in Optical Rulers, Breaking the FRET Barrier" C.S. Yun, A. Javier, T. Jennings, M. Fisher, S. Hira, S. Peterson, B. Hopkins, N.O. Reich, and G.F. Strouse, J. Am. Chem. Soc.127(9), 3115-3119 (2005). [view article-PDF]
"Quantum Dot-Organic
Oligomer Nanostructures: Electronic Excitation Migration
and Optical Memory Design" A.
Javier, C. S. Yun, Geoffrey F. Strouse*,
Mat. Res. Soc. Symp. Proc,
Vol. 776, Q2.1.1 [ view
article - PDF ]
"Nanosecond Exciton Recombination
Dynamics in Colloidal CdSe Quantum Dots Under Ambient
Conditions" A. Javier,
D. Magana, T. Jennings and G.F. Strouse, Applied
Physics Letters, 83, 1423
[ view article
- PDF ]
"Synthesis and Characterization
of a 1:6 Au-CdSe Nanocomposite."
Cumberland, S. L.; Berrettini,
M. G.; Javier, A.; Strouse, G. F.; Chem.
Mater., 15(5); 1047-1056
(2003). [ view
article - PDF ]
"Energy Transport
in CdSe Nanocrystals Assembled with Molecular Wires."
Javier, A.; Yun, C.S.;
Sorena, J.; Strouse, G.F.
J. Phys. Chem. B, 107,
435-442 (2003).
[ view article
- PDF ]
"Inorganic Clusters
as Single Source Precursors for Preparation of CdSe,
ZnSe, CdSe/ZnS Nanomaterials."
Cumberland, S.L.; Hanif, K.M.; Javier, A.; Khitrov,
G.A.; Strouse, G.F.; Woessner, S.M.; Yun, C.S.
Chem. Mater., 14, 1576-1584
(2002).
[ view article
- PDF ]
The
research effort on 2-dimensional self-assembled nano-crystalline
films is achieved via ‘evaporative assembly’;
similar to efforts in other groups on Ag and Au nano-dots.
The nano-crystalline CdSe materials can be surface exchanged
with hexadecylamines or hexadecyl thiols, producing materials
that readily assemble into hexagonally packed regions
in the 2-d films, as illustrated in the TEM image. We
are currently probing the assembly dynamics of these materials
and have begun to investigate energy transfer between
large and small nano-crystals imbedded in the evaporated
film. A recent effort that shows promise is the assembly
of these materials using electrostatic interactions. Capping
of a 4.0 nm CdSe nano-crystal with an acid terminated
alkyl thiol and a 6.0 nm CdSe nano-crystal with amine
functionality has produced very regular films. We are
currently using TEM imaging to probe the structure of
the assembled films. The investigation of charge transport
in these assembled films is ongoing.
In a recent study in our lab, we have initiated a study
of organic polymers as molecular scaffolding for CdSe
nano-composites. These polymer based nanocomposites exhibit
efficient energy transfer from the organc oligomers to
the nanomaterial. Energy transfer appears to be dominated
by a dipole-dipole exchange mechanism in which the size
dependent nature of this energy transfer process is clearly
evident in the loss of quantum efficiency for transfer
above 5 nm. The quenching of the polymer by appended nanoscale
CdSe via directed energy transfer proceeds with near unit
quantum efficiency in the region where the spectral overlap
<J-integral> is favorable. At 5 nm the nature of
the directed energy transfer from the polymer to CdSe
can be modulated by photolysis. The observation of a photo-initiated
switch in the efficiency of energy transfer coupled to
recent crystal structures of the oligomers suggest that
structural reorientation of the composite may lead to
the opening of transverse optical energy transfer along
a pi-pi stacking direction. We are developing a series
of oligomerically linked (n = 1, 3, 5) systems based on
PAO, phenylethynylene, appended to CdSe. The PAO is linked
to the CdSe through a benzylic thiol bond. The size dependent
nature of energy transfer allows fine control over energy
transport from the surface of the CdSe.
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