ELECTRONIC-ENERGY TRANSFER IN SUPERSONIC JET EXPANDED NAPHTHALENE-(CH2)(N)-ANTHRACENE BICHROMOPHORIC MOLECULES

A study of intramolecular electronic energy transfer (Intra-EET) has p rovided evidence, for the first time, of a dramatic difference in Intr a-EET efficiency results obtained under jet cooled and room temperatur e solution conditions. This was observed with anthracene-(CH2)(n)-naph thalene bichromophoric molecules, A1N (n = 1) and A3N (n = 3). The ric h fluorescence excitation spectrum of the naphthalene moiety in A1N in dicates an inefficient EET process whose rate constant is substantiall y slower than that of the naphthalene moiety fluorescence. It was show n that the EET rate depends on a specific vibronic excitation that aff ects the molecular conformation, and was found to be at least two orde rs of magnitude slower in A1N molecule compared to A3N.