23491
This prominent red - shift is attributed to the interaction of Sn ( ii ) 5s orbitals with the TiO2 decreasing the band gap of TiO2 by raising its valence band .
 Chemical: Sn ( ii ); Chemical: TiO2; Chemical: TiO2
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: Sn ( ii ); Chemical: TiO2; Chemical: TiO2