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The rotational spectrum of nitrogen - protonated nitrous oxide ( HNNO ( + ) ) , an isomer whose existence was first inferred from kinetic studies more than 30 years ago , has now been detected by Fourier transform microwave spectroscopy , guided by new high - level coupled - cluster calculations of its molecular structure .
 Chemical: nitrogen; Chemical: protonated nitrous oxide; Chemical: HNNO ( + )
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: nitrogen; Chemical: protonated nitrous oxide; Chemical: HNNO ( + )