24510
Here we show that the QYs of Yb ( 3 + ) sensitized two - photon upconversion emissions can be well characterized by the balancing power density , at which the ETU rate and the linear decay rate have equal contributions , and its corresponding QY .
 Chemical: Yb ( 3 + )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
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Answer:
 Chemical: Yb ( 3 + )