Charge-transfer biexciton spectra of molecular crystals

✍ Scribed by C. Mavroyannis

• Publisher: Springer US
• Year: 1975
• Tongue: English
• Weight: 610 KB
• Volume: 18
• Category: Article
• ISSN: 0022-2291
• DOI: 10.1007/bf00116141

✦ Synopsis

A self-consistent theory is presented to account for the possibility of coherent pairing between Mott and a Frenkel exciton at low temperatures in a two-level system of an organic solid. It is shown that a charge-transfer (CT) biexciton state can exist at low temperatures provided that certain conditions are satisfied. The physical process for the formation of a CT biexciton can be attributed to the stabilization of the Mott exciton through its interaction with the polarization waves of the medium. The excitation spectrum of the biexciton state is of the excitonic insulator type and therefore no superfluid properties are expected to occur due to tJ)e condensation of the exciton pairs. The scattering amplitude arising from the exciton pairing is calculated at zero temperature and the parameters involved are discussed. Expressions are derived for the absorption coefficient describing optical transitions to CT biexciton states.