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However there is great interest in understanding the properties of graphene plasmons across the infrared spectrum , especially at energies exceeding the graphene optical phonon energy .
 Chemical: graphene; Chemical: graphene
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: graphene, graphene 
Answer:
 Chemical: graphene; Chemical: graphene