cool off vs intensify

cool off

verb
  • To cause to decrease in temperature, activity or temper. 

  • To decrease in temperature, activity, or temper. 

intensify

verb
  • To render more intense 

  • To become intense, or more intense; to act with increasing power or energy. 

How often have the words cool off and intensify occurred in a corpus of books? (source: Google Ngram Viewer )