afterglow vs crepusculum

afterglow

noun
  • The glow seen in the sky after sunset. 

  • The mildly euphoric feeling experienced after a pleasurable experience, especially after an orgasm or drug-induced high. 

  • An afterparty. 

  • The light emitted by an incandescent object while cooling. 

  • The light emitted by a phosphor after excitation. 

crepusculum

noun
  • crepuscule; twilight; dusk 

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