11896
Photoinduced formation mechanism of the thymine - thymine ( 6 - 4 ) adduct .
 Chemical: thymine - thymine ( 6 - 4 )
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: thymine - thymine ( 6 - 4 )