8437
After the addition of salts , a strong signal was observed from hollow gold with a LSPR of 650 nm and a weaker , yet observable , signal from HGNs with a LSPR of 775 nm .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None