30061
Rotational spectra of OH and its isotopologues have been precisely measured using high efficiency Terahertz ( THz ) sources .
 Chemical: OH
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: OH 
Answer:
 Chemical: OH