7381
The sensitive structural dependence of the optical properties of single - walled carbon nanotubes , which are dominated by excitons and tunable by changing diameter and chirality , makes them excellent candidates for optical devices .
 Chemical: carbon
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: carbon 
Answer:
 Chemical: carbon