On charge carrier photogeneration mechanisms in organic molecular crystals

Photogeneration of charges in poly(N-vinylcarbazole) doped with lutetium bisphthalocyanines and lutetium bisnaphthalocyanines

Lutetium bisphthalocyanines and bisnaphthalocyanines, sandwich complexes having interesting electronic properties were studied as electron-acceptors associated with the donor polyvinylcarbazole ( PVCz ) in single-layer photoconductors. It is known, from their redox properties, that these lanthanide complexes are potential electron-acceptors as well as electron-donors; moreover, they strongly absorb light from the near-UV to the near-IR. The xerographic spectra recorded between 400 and 900 nm show that the polymeric phases doped with the lutetium bisphthalocyanines are photoconductive. These new photoconducting phases are active in the near IR domain which is promising with regard to their potential applications.

Vacuum UV--photophysics and photochemistry of biomolecules

The vacuum UV radiation absorbed by biomolecules may initiate luminescence, photodestruction and photoionization processes which lead to distortions or damage of the molecular structure. To explain the mechanisms of the processes in question and the role of different molecular fragments, it is necessary to analyse the absorption spectra. The accurate determination of the photoproducts is necessary when discussing the possible scission of molecular bonds. A knowledge of the quantum yields of vacuum UV-induced processes provides information on the relative effectiveness of different processes. In particular, the most efficient destruction of purine-pyrimidine bases, nucleotides and DNA is caused by irradiation of aqueous solutions rather than solid compounds. Additional information on molecular damage mechanisms may be obtained by comparison of data obtained using ionizing UV and UV laser irradiation.