Studies of the phosphorescent state of tetraphenyl group IV compounds

Abstract

Detailed studies of the phosphorescent of tetraphynyl Group IV compounds are presented. Analysis of high resolution emission spectra of mixed crystal systems at 4.2 K indicates the following: 1. The internal heavy atom effect arises through both electronic and vibronic interactions while the external heavy atom effect appears largely through electronic interaction. 2. Both excition—trap interactions and dispersive forces are responsible for the mixed crystal solvent effects which produce spectral shifts up to ∼ 80 cm −1. 3. Translationally equivalent interactions control triplet energy transfer. 4. The T 1 ↔ Sσ origin of tetraphynlmethane has been located at 27474 cm −1 by impurity-induced emission. EPR studies of the phosphorescent state of tetraphenylmethane dispersed in tetraphenyltin show that the magnitudes ofthe spin dipolar interactions and the inter-ring interactions are comparable (∼0.1 cm −1.