Application of photoconductivity measurements to photodynamic processes investigation in LiYF4:Ce3+ and LiLuF4:Ce3+ crystals
✍ Scribed by L. Nurtdinova; V. Semashko; Y. Guyot; S. Korableva; M.-F. Joubert; A. Nizamutdinov
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 417 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0925-3467
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✦ Synopsis
Photoconductivity measurements are applied to the studies of photodynamic processes in LiYF 4 :Ce 3+ and LiLuF 4 :Ce 3+ crystals undergoing ultraviolet irradiation. Photoconductivity spectra were registered by means of microwave technique under irradiation at 220-320 nm at the room temperature. Photoconductivity signal appeared at $300 nm and monotonically increased with the shortening of wavelength. Pumping energy dependencies of photoconductivity within 225-305 nm spectral range were registered and revealed the change of the dependence degree from quadratic at longer wavelengths through linear to saturation-like at shorter ones. Numerical simulation based on four-level model of photodynamic processes was performed. Values and spectral distributions of probabilities of different types of photodynamic processes for 225-295 nm were estimated. Ce 3+ ions excited-state photoionization cross-section spectra in both investigated materials revealed a band with a peak around 270 nm most probably corresponding to 5d-6s transition of Ce 3+ . Recombination cross-section in Ce:LiLuF 4 appeared to be two orders of magnitude higher than in Ce:LiYF 4 . A complete energy level diagram of ''Ce 3+ ion-LiYF 4 crystal'' system has been proposed.