Interactions Between Light and Matter

Radio waves

• 1 mm to 100 m

• Excites spin of nucleus

• Used in MRI, AM, FM radio

Microwaves

• 100 cm to 100 um

• Excites spin of electrons

• Excites rotation of H2O and fats to cook food

Infrared

• 1000 nm to 800 nm

• Causes vibration in molecules

• Used in night vision goggles and measure intoxication

• Paschen series for H emission

Visible

• 800 nm to 300 nm

• Excites valence electrons to higher energy level

• Rays of detection for human eye

• Balmer series for H emission

UV

• 300 nm to 10 nm

• Excites valence electrons

• Causes sun burns

• Lyman series for H emission

X-rays

• 10 to 0.01 nm

• Excites core electrons

• Causes cell mutations

Gamma rays

• <0.01 nm

• Associated with decay of atom nucleus

• Emitted from stars