摘要
A photon avalanche phenomenon was observed in Er^3＋ and Li^ ＋ eodoped ZnO nanocrystals at room temperature under excitation around 976 nm. When the excitation power was over 120 mW/mm^2 , we found that the upconversion of red emission was generated by a four-photon absorption process and might be caused by intense interaction between neighboring Er^3 ＋ ions ： ^4 F7/2 ＋ ^4 I11/2 → 2^4 F9/2. When the excitation power was over the threshold of 240 mW/mm^2, the green emission avalanche upconversion was generated through an excitedstate absorption process ： ^4 F9/2 ＋ photon →^2 H9/2. The study extends the knowledge of this ion to a wider range of upconversion application.
A photon avalanche phenomenon was observed in Er3+ and Li+codoped ZnO nanocrystals at room temperature under excitation around 976 nm.When the excitation power was over 120 mW/mm2,we found that the upconversion of red emission was generated by a four-photon absorption process and might be caused by intense interaction between neighboring Er3+ ions:4F7/2+4I11/2→ 24F9/2.When the excitation power was over the threshold of 240 mW/mm2,the green emission avalanche upconversion was generated through an excited-state absorption process:4F9/2+photon → 2H9/2.The study extends the knowledge of this ion to a wider range of upconversion application.
