Laser-escitation spectroscopy of ultra-pure tetracene crystals
Abstract
We have measured the Raman and luminescence spectra of a set of tetracene crystals grown using a continuous, gas-flow sublimation technique. These crystals have impurity levels estimated to be 10**(-12), and injection devices made from them have produced lasing and superconductivity. We compare our results with those of other groups on crystals and powders made by other techniques. Interpretations from earlier groups include the possibility of exciton fission as indicated in the luminescence. We find that the luminescence is sensitive to the growth method, presumably because of impurity states, but is reproducible in our ultra-pure crystals, probably indicating intrinsic behavior. The results show that the background and the Raman lines change with excitation wavelength, because of resonance effects, and we emphasize studies at a laser wavelength of 830nm, which is below the principal electronic resonances
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARG18012T