7079
Here we report the spectroscopic identification in a monolayer MoS ( 2 ) field - effect transistor of tightly bound negative trions , a quasiparticle composed of two electrons and a hole .
 Chemical: MoS ( 2 )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: MoS ( 2 )