Optical spectroscopy of disorder in molecular chains (<b> <i>J</i> </b>-aggregates)

Abstract

The form of the exciton absorption band for 1D molecular chains and their luminescence are investigated in glass matrices of various composition and in Langmuir–Blodgett (LB) films under selective excitation. It is shown that the exciton absorption band for 1D chains is always asymmetric. The shape of the low-frequency edge of their absorption band changes from the Gaussian to the Lorentzian depending on the method of obtaining of 1D chains due to a change in the diagonal and off-diagonal disorder in molecular chains. Under selective excitation of 1D molecular chains, the effect of considerable luminescence band narrowing is not observed. This is associated with statistical properties of the exciton absorption band and with relaxation processes in the materials under investigation in the excited state.