8181
The samples were characterized before and after exposure to NO ( 2 ) by X - ray diffraction , scanning electron microscopy , N ( 2 ) - adsorption at 77 K , thermal analysis , and infrared spectroscopy .
 Chemical: NO ( 2 ); Chemical: N ( 2 )
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: NO ( 2 ); Chemical: N ( 2 )