Van der Waals complexes of perylene with rare-gas atoms

✍ Scribed by John C. Kettley; T. Frank Palmer; John P. Simons

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 633 KB
• Volume: 115
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(85)80098-1

✦ Synopsis

Fluorescence exatntion specua of weaNy bound complexes between perylene (P) and rare-gas atoms (R) have been ob-served_ Model ealculatlons of potentul surfers of vdW complexes conslslrng of perylene and rare-gas atoms show that geometrzcal re-orgnnisation IS Important and that thermal population of mtermolecular P-R nbraUona1 states may account in part for unresolved broadening at moderate stagnation pressures. 1. introduction In recent years there has been considerable experlmental work directed towards the study of large van der Waals (vdW) complexes of aromatic molecules such as s-tetrazine [ 13, anthracene [2J], tetracene 14-71 and pentacene [8,9] with rare-gas atoms and small solvent molecules. Seeding of the aromatic vapour into a high stagnation pressure of the rare gas, followed by free jet supersonic expansion from the high-pressure regron through a nozzle mto a vacuum chamber, results in considerable vibrational and rotational cooiing and weakly bound species formed during expansion can be stabihsed. These vdW molecules represent microscopically well-defined solute-solvent complexes and ave rise to electronic spectra largely free from sequence congestion and thermal inhomogeneous broadening effects. The elucidation of the ground-state structures and energetlcs of very large vdW molecules is of crucial irnportance tn the development of a microscopic approach to the effect of "so!vents" on electronic spectroscopy in the condensed phase [IO--141. Model calculations of the nuclear potential energy surfaces of tetracenel rare-gas vdW complexes [ 151 have yielded information on binding energes, equdibrium configurations, low-Frequency nuclear motion and existence of isoenergetic chemical isomers, wtuch are consistent ~nth the expertmental observations. In this paper we present experimental observations and model calculations of