Regime shifts in marine ecosystems: detection, prediction and management

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• 作者：Brad deYoung ; Manuel Barange ; Gregory Beaugr ; Roger Harris ; R. Ian Perry ; Marten Scheffer ; Francisco Werner
• 关键词：Laser heating ; Glass ceramic ; Tm³⁺ ; Yb³⁺
• 刊名：Trends in Ecology and Evolution
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：23
• 期：7
• 页码：402-409
• 全文大小：581 K

文摘

Desvitrification in a Tm³⁺ and Yb³⁺ codoped oxyfluoride glass has been obtained by exciting with a continuous Argon laser radiation increasing the average laser power from 144 to 2900 mW. Excitation spectra inside a locally damaged zone in a 1 mol % Tm³⁺ and 2.5 mol % Yb³⁺ codoped glass have been measured under excitation in the wavelength range 750–830 nm detecting the ²F_5/2 (Yb³⁺) level. This curve is the result of the contribution of two different kinds of centers, the fluoride nanocrystals and the glassy phase of the glass ceramic sample created due to the irradiation. The weight of the contributions of each of the centers depends on the excitation wavelength, and from the analysis of the decay of the luminescence it can be concluded that approximately 80 % of the Tm³⁺ ions are located in the nanocrystals and therefore less than 20 % in the glassy phase.