Triplet Excimer of Phenanthrene in Fluid Solution. Dynamic Analysis of Time-Resolved Phosphorescence

Abstract The excimer phosphorescence of phenanthrene in isooctane at temperatures over a range of 300–77 K has been studied by means of a photon-counting technique. At temperatures above the melting point of isooctane a broad emission spectrum with its intensity maximum at 525 nm was obtained, which is essentially different from the structured phosphorescence spectrum obtained in rigid media at 77 K. The time dependence of the spectral shape and intensity of the phosphorescence emission affords strong evidence that the broad emission spectrum originates from the triplet excimer. A scheme of the triplet excimer formation involving a self-quenching pathway of the triplet monomer is proposed to interpret the time and concentration dependence of the monomer and excimer phosphorescence.