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Relative to previous larger structures from top - down electron - beam lithography , the single crystallinity and atomically smooth surfaces of these self - assembled plasmonic structures result in 50 % narrower resonances , and the small gaps with associated strong coupling enable observation of multiple dark and bright modes .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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