Molecular aggregates are mesoscopic clusters of molecules

with intermediate sizes between crystals and isolated molecules.Molecular aggregates belong to the group of nanostructure materials

which are presently at the heart of scientific fashion.In particular the unique optical properties of these materials receive much attention.An important difference between aggregates and most other nanostructures is the absence of electron delocalization

which makes its optical response easier to model.The red shift and narrowing for J-band were observed from the absorption spectrum of molecular aggregates PIG-I in this paper.The number of monomers in the chain N≈3

or chain length L=0.3nm×3=0.9nm were calculated

and vibration mode 1368cm

-1

was derived from the experimental data.Com-paring the fluorescence spectrum with the absorption spectrum it is found that the emission band 572.5nm and absorption band 572.5nm is resonance.Raman spectra(100~1800cm

-1

) of molecular aggregates PIC-I were systematically investigated.