Hexathiophene single crystals: luminescence and magnetic resonance

We employed the absorption and photoluminescence (PL) spectroscopies, PL ex citation dependence and PL-detected magnetic resonance (PLDMR), to study th e steady state photophysics of ultrapure cr-GT single crystals. Whereas the lowest lying absorption band has only very little oscillator strength, nev ertheless we found strong PL emission. From this and the symbatic PL excita tion spectrum we conjecture that the PL emission is intrinsic. The PLDMR sp ectra show several discrete lines showing the contributions of two similar triplets located at two different crystal locations.