Excitation dynamics in polyacene molecules on rare-gas clusters

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Condensed Matter Physics

Background:

• Polycyclic aromatic hydrocarbons like anthracene, tetracene, and pentacene are studied for their photophysical properties.
• Solid rare gas clusters (argon, neon) serve as weakly interacting matrices for molecular studies.
• Understanding excitation decay dynamics is crucial for molecular electronics and photonics.

Purpose of the Study:

• To investigate the laser-induced fluorescence spectra and excitation lifetimes of anthracene, tetracene, and pentacene on solid argon clusters.
• To compare these properties with previous findings on neon clusters.
• To elucidate the influence of cluster material and dopant density on excitation decay mechanisms.

Main Methods:

• Laser-induced fluorescence spectroscopy was employed.
• Excitation lifetimes were measured.
• Experiments were conducted on argon clusters of varying sizes, molecular densities, and excitation densities.

Main Results:

• Significant differences in excitation decay dynamics were observed between argon and neon clusters for the studied acenes.
• The lifetime behavior of anthracene showed a notable contrast between argon and neon cluster environments.
• Qualitative differences in the dependence on dopant density were identified.

Conclusions:

• The material of the rare gas cluster (argon vs. neon) significantly influences the excitation decay dynamics of acenes, despite both being weakly interacting.
• Previous assignments of collective radiative and non-radiative decay mechanisms require re-evaluation in light of these findings.
• The observed differences suggest complex interactions between the acenes and the cluster environment.