Time -Resolved Emission Spectroscopy of Pyrene Derivatives

An improved model of the picosecond time-resolved spectrofluorimeter equipped with an optical Kerr shutter was designed and constructed. The instrument was applied for measurements of time-resolved fluorescence (TRF) spectra of 4_-(pyrenyl-1-yl)acetophenone (Py-BK) and 4_-(pyrenyl-1-yl)benzonitrile (Py-BN). The experimental results indicate that both molecules relax after excitation by mutual twisting of two subunits towards a more planar geometry. In the case of Py-BK the kinetics of creation of excited state hydrogen-bonded complexes was discussed in detail.