19501
The C2 - D band is a very weak infrared absorber , so this vibration is not expected to be useful in infrared transmission experiments for proteins .
 Chemical: C2 - D
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: C2 - D 
Answer:
 Chemical: C2 - D