Excitonic photoluminescence spectra of C₆₀ single crystals grown by different techniques

Dipartimento di Fisica dell'Università di Bari and Istituto Nazionale di Fisica della Materia, Via Amendola 173, 70126 Bari, Italy

Corresponding author: vito.capozzi@ba.infn.it

Received: 7 April 2000
Revised: 11 January 2001
Accepted: 24 January 2001
Published online: 15 April 2001

Abstract

We report photoluminescence spectra of C₆₀ single crystals grown by vapor phase transport method using either the sealed ampoule technique or the open tube technique. The spectra for both types of samples show similar features, but different line resolution related to the two different growth techniques. An analysis of temperature and excitation intensity dependencies of the luminescence spectra is reported. The main structures of the spectra have been interpreted according to a model involving intramolecular polaron-exciton recombinations. In particular, emissions due to purely electronic transitions of singlet and triplet or the exciton and related vibronic recombinations have been resolved. At low temperature, emission bands due to X-traps have been observed on the high-energy side of the excitonic singlet purely electronic transition.