How Glow-in-the-dark works

1. How Glow-in-the-dark works • All glow-in-the-dark products contain phosphors • A phosphor is a substance that radiates visible light after being energized. • Phosphors have three characteristics: • The type of energy they require to be energized • The color of the visible light that they produce • The length of time that they glow after being energized (Persistence) • Glow-in-the-dark objects are photoluminescent and phosphorescent • Steps involved in phosphorescence • Electrons are excited • Excitedelectrons drop to a lower, but still excited intermediate level (Most light emitted here) • Electrons drop to ground state Glow in the dark spectra Blue, Green and Red Phosphors

2. Glowing Pickle • Steps to make a pickle glow. • Large current flows through the pickle • Pickle quickly heats up near the electrodes due to current • At the electrodes water vaporizes. • The region near one end goes dry first, so the large current stops and all the voltage drops across this dry region. • In this dry region impact ionization now takes place. • e collides with Na, ionizing it etc.: e + Na → e + Na+ + e ... • Na+ relaxes emitting a photon: Na+ + e → Na* → Na + n • Just like in a Na vapor lamp! Glowing Pickle Specta • Lithium Chloride Pickle • We used a re-pickled pickle. • The pickle was “reconstituted” by soaking it in lithium chloride. • This caused there to be some red light in the spectrum along with the yellow light from the sodium. Wavelength (nm) Lithium Pickle peaks at 610nm, 670nm & 813nm Sodium pickle peaks at 589nm, 767nm & 770nm