How was Ronald George Wreyford Norrish awarded the Noble Prize?

Name: Ronald George Wreyford Norrish. 
Country: American.
Date of Birth: 9 November 1897.
Date of Death: 7 June 1978.
The subject of Study: Chemical reaction, flash photolysis, reaction mechanism, reaction rate..
Noble Prize Year: Nobel Prize for Chemistry in 1967 for his research on extremely fast chemical reactions.