Electromagnetic Spectrum Wavelength (A) Energy Molecular effects higher frequency cm kcal/mol shorter wavelength 10-9 gamma rays 106 10-7 X rays 104 ionization vacuum UV 102 10-5 near UV electronic transitions 10-4 visible 10 infrared 10-3 1 molecular vibrations (IR) 10-2 10-1 microwave 10-4 rotational motion 102 lower frequency radio 10-6 104 nuclear spin transitions longer wavelength Electromagnetic Spectrum