19503
Raman spectra at varying concentrations of Cu ( 2 + ) also show the C2 - D band ' s sensitivity to metal coordination , with differences due to changes in the coordination environment .
 Cu ( 2 + ), C2 - D
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Cu ( 2 + ), C2 - D