diffusion vs dispersal

diffusion

noun
  • The act of diffusing or dispersing something, or the property of being diffused or dispersed; dispersion. 

  • The gradual spread and adoption of goods or services. 

  • Exchange of airborne media between regions in space in an apparently random motion of a small scale. 

  • The spread of cultural or linguistic practices, or social institutions, in one or more communities. 

  • The scattering of light by reflection from a rough surface, or by passage through a translucent medium. 

  • The movement of water vapor from regions of high concentration (high water vapor pressure) toward regions of lower concentration. 

  • The intermingling of the molecules of a fluid due to random thermal agitation. 

dispersal

noun
  • The act or result of dispersing or scattering; dispersion. 

  • A dispersal prison. 

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