Abstract
We present a comprehensive experimental and theoretical study of the optical properties of matrix-isolated molecules of the two perylene derivatives -dimethylperylene-3,4,9,10-dicarboximide (MePTCDI) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA). A solid solution of the dyes in an matrix exhibits monomer-like behavior. Transient absorption pump-probe spectroscopy in the range has been performed on an ultrafast time scale. The differential transmittance reveals contributions from ground-state bleaching, stimulated emission, and excited-state absorption. Both systems exhibit broad excited-state absorption features below with a clear peak around . The spectra can be consistently explained by the results of quantum-chemical calculations. We have applied both the coupled cluster singles and doubles (CCSD) model and the multireference-determinant single and double configuration-interaction (MRD-CI) technique on the basis of the intermediate neglect of differential overlap (INDO) Hamiltonian. The results are insensitive to whether the geometry is optimized for the electronic ground state or first excited state. The experimental polarization anisotropies for the two major transitions are in agreement with the calculated polarizations.
- Received 25 November 2005
DOI:https://doi.org/10.1103/PhysRevB.73.245216
©2006 American Physical Society