Vibrational Cooling in Large Molecular Systems: Pentacene in Naphthalene

摘要

In condensed matter systems comprised of complex molecules, vibrational relaxation (VR) is an ultrafast process. Molecular crystals are a natural system to use to study VR because that bath states into which the excess vibrational energy flows are particularly well characterized. These are the phonon modes of a perfect crystal. The density of states (DOS) and dispersion relations have been accurately measured for many such systems. The model pure crystal systems in which VR has been studied, either via ultrafast spectroscopy, or by infrared or Raman line shape analysis, include pure crystal of benzene, naphthalene, anthracene, and durene. Binary mixed crystals have also been used to investigate vibrational energy transfer (VET) between unlike molecules. The model binary systems which have been investigated include isotopic pairs such as C6- benzene C5- C1-benzene, benzene/d6-benzene, naphthalene/d10-naphthalene, naphthalene/d1-naphthalene, and heteromolecular pairs such as pentacene/naphthalene, naphthalene/durene, and anthracene/naphthalene. Organic chemistry. Reprints. (jes)