Nanoforum - Nanotech Regulatory Document Archive

Figure 17: Sample of Nanotehcnology in Lithuania
• Investigation of principles of spatial organisation of J-aggregates and determination
of the size and shape of these nano-structures by non-linear spectroscopic methods
and atomic force microscopy (AFM).
The energy relaxation kinetics and structure of the J-aggregates formed by water-soluble
TPPS4 molecules were investigated in aqueous media by means of steady state and
time-resolved fluorescence and absorption spectroscopy. The spatial structure of J-
aggregates and deposited on silicon and several glass substrates can be analysed by
atomic force microscopy (AFM) and modelled theoretically.
Figure 18: Sample of J-aggregated nano-structures
• Investigation of modification of nano-structures under the influence of optical
irradiation, interaction with biologically active molecules, deposition on different
substrates and incorporation to the polymer matrix.
J-aggregates being deposited on the hard substrate retain their structure. The AFM
experiments indicated the presence of stick-like J-aggregate structures on all surfaces.
The size of the sticks ranged from 0,05-3 nm in length, 25-45 nm in width (depending on
substrate), and 4-5 nm in thickness (cross-sectional profiles). Investigation of
spectroscopic properties of J-aggregates incorporated in thin layers of organic polymers
has revealed that TPPS4 does self-associate in polyvinyl alcohol at acidic pH forming
molecular nano-structures with slightly different spectroscopic features in comparison
with aqueous media.
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