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He also studied the propagation of monochromatic light waves and their interaction with acoustic waves , i.e. , scattering of light with a frequency change , which became known as Brillouin scattering .
 person: Brillouin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Brillouin