Manifestation of Unforeseen Superradiance Phenomenon from Phenanthrene and Chrysene Nanoaggregates

摘要

The thin film and nanocomposite forms of polyacene and their derivatives have attracted extensive research attention in the recent few years. However, the thin film or nanostructure forms of nonlinearly attached polyaromatic compounds remain unattractive toward the scientific community, until now. Herein, the detail photophysical investigations have been presented for nanoaggregates of two nonlinearly attached polyaromatic molecules, namely, phenanthrene and chrysene. Upon aggregate formation, these materials shows 4-6 times enhancement in the extinction coefficient associated with the lowest energy transition. This is governed by a stronger transition dipole appearing through the correlated interaction of the transition dipole associated with the adjacent molecules present in the aggregates. The stronger transition dipoles also consequence significantly higher emission yield by promoting the faster radiative decay, as compared to that of the monomeric form. The enhanced radiative decay rate and its dependence upon sample temperature certify the presence of the superradiance property of these materials. Most importantly, this is the first report to detect the superradiant property of these nonlinearly attached polyaromatic molecular systems in any physical form and thus deserves remarkable research interest of the scientific community in the near future.