Room-temperature lasing from fluorene thin-film crystals densely doped with anthracene.
The potential for room-temperature lasing in densely doped organic crystals has been examined using (fluorene)0.8-(anthracene)0.2 thin crystals fabricated in a narrow gap between two quartz plates. An excitation-intensity dependence study confirms that the system shows spectral line narrowing, a super linear increase of the narrow line above threshold excitation intensity, and laser cavity modes. These results indicate that lasing has been observed in the densely doped organic crystal, which contains in-plane cavities with a length of approximately 100 μm.
Electroluminescence of anthracene with powdered graphite electrodes and ambient gas effects on the electrodes
Double‐injection electroluminescence of anthracene with a special electrode has been studied. The electrode was efficiently capable of injecting both electrons and holes into anthracene. Both current and electroluminescence intensity were markedly enhanced by a factor of about 30 when the ambient gas of the cathode was changed from air to nitrogen. The emitted light which peaked at 4440 A was generated with an external quantum efficiency ranging from 4 to 6%.
One hundred percent tumor induction in mouse skin after repeated beta irradiation in a limited dose range.
Repeated beta irradiation of the backs of mice three times a week with radiation doses of 250 to 1180 cGy per exposure induced 100% incidence of tumors. The incidence of skin tumors appeared to be determined by the total number of repeated exposures in this dose range. An abrupt delay in tumor emergence was observed when the radiation dose was reduced from 250 to 150 cGy per exposure, indicating the existence of a critical threshold. Mouse skin resembles human skin rather than rat skin in its response to radiation.