Effect of pressure on the first singlet exciton in crystalline anthracene

Abstract

The first singlet exciton state of anthracene single crystals has been studied by optical reflection spectroscopy under hydrostatic pressures up to 30 kbar. The Davydov splittings of the 0–0, 0–1, and 0–2 vibrational bands increase much faster than expected on the basis of first order dipolar resonance interaction. The average pressure coefficients are 16.6, 13.6, and 9.0 cm−1/kbar for the 0–0, 0–1, and 0–2 bands, respectively. The pressure effect on the exciton shift is small compared to the strong pressure dependence of the Davydov splitting. The pressure induced shifts of the excitonic transition energies are discussed in terms of molecular exciton theory.