10844
The presence of such weak molecular interactions in the solution state is convincingly established by one and two - dimensional ( 1 ) H , ( 19 ) F , and natural abundant ( 15 ) N NMR spectroscopic studies .
 ( 1 ) H, ( 19 ) F, ( 15 ) N
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 ( 1 ) H, ( 19 ) F, ( 15 ) N