title: Enhancement of the photoluminescence of CdSe quantum dots during long-term UV-irradiation: privilege or fault in life science research?
abstract: The present study describes an impressive enhancement of the photoluminescence (PL) intensity of low-temperature synthesized CdSe nanocrystals (75 degrees C) during long-term UV-irradiation. The integrated PL-intensity of CdSe core and CdSe/ZnS core/shell nanocrystals, dispersed in chloroform, enhanced about 3 and 6 times, respectively, during 9 h exposure to UV-light, without any significant changes in the characteristic absorbance spectra and shifting of PL-spectra. After termination of the irradiation a comparatively slow photobleaching was detected with tau(1/2) = 6 h for CdSe core and tau(1/2) = 14 h for CdSe/ZnS core/shell nanocrystals. The most impressive was the effect of UV-irradiation on the photoluminescence of water-soluble CdSe nanocrystals. The integrated PL-intensity enhanced about 10 times during 11 h exposure to UV-light and the improved PL-intensity was preserved during 3 days after termination of the irradiation without any significant photobleaching. The results are discussed in the context of application of CdSe nanocrystals as novel fluorophores in life science experiments.
authors.affiliation: Natural-Substance Composed Materials Group, National Institute for Advanced Industrial Science and Technology, AIST-Kyushu, Tosu, Saga-ken, Japan.
authors.forename: Zhivko
authors.initials: Z
authors.lastname: Zhelev
authors.forename: Rajan
authors.initials: R
authors.lastname: Jose
authors.forename: Toshimi
authors.initials: T
authors.lastname: Nagase
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohba
authors.forename: Rumiana
authors.initials: R
authors.lastname: Bakalova
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Baba
mesh_terms: D001690:Biological Science Disciplines; D019187:Cadmium Compounds / Q000737:chemistry / Q000528:radiation effects*; D003460:Crystallization; D049449:Luminescence; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry / Q000528:radiation effects*; D013050:Spectrometry, Fluorescence; D014466:Ultraviolet Rays
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide