Hole burning of long-chain molecular aggregates: homogeneous line broadening, spectral-diffusion broadening, and pressure broadening

We investigate broadening phenomena of spectral holes burned into delocalized states of molecular aggregates. We measured spectral-diffusion broadening, homogeneous line broadening, and pressure-induced line broadening. The behavior is quite different from that for localized states. Whereas homogeneous broadening is dominated by exciton–phonon scattering, spectral-diffusion broadening and pressure broadening are extremely small because of large motional narrowing effects.