BI: v7

THE 4 “SENCES”:  Bioluminescence is a form of luminescence where living things give off light like a railroad worm or a firefly does.

THE 4 “SENCES”:  Fluorescent materials give off light instantly when atoms absorb energy.  When the energy source ceases, the molecules that are fluorescing light stop emitting light.  

THE 4 “SENCES”:  When you shine an infrared light on certain rocks, they fluoresce a different color. Then they abruptly stop when the light source is taken away. 

THE 4 “SENCES”:  Scientists have recently found many fish that fluoresce different colors when a red light is shined on them.

THE 4 “SENCES”:  Phosphorescence is when you shine an energy source like light on a material and it not only gives off light when you are shining a light on it, but the light radiated continues after the energy source is taken away.  Glow in the dark slime is an example of this.

THE 4 “SENCES”:  NASA has developed a phosphorescent metal oxide called strontium aluminate  that glows for 24 hours after it is exposed to light.  They use it to light emergency exits in the White House and escape routes in the Pentagon.

THE 4 “SENCES”:  Fluorescence is taking a high energy photon, interacting it with something and having a lower energy visible photon emitted.  A fluorescent light in the kitchen is an example of this!

THE 4 “SENCES”:  In a fluorescent light, the mercury vapor inside it is energized and emits short wave, high energy UV photons.  These encounter phosphorus atoms painted on the inside of the glass which change the invisible UV to light we can see.

THE 4 “SENCES”:  Some uses of fluorescence are surprising. Many washing detergents contain ingredients known as optical brighteners. As a result, when you look at freshly washed white clothes, you see brighter, slightly bluer reflected light produced by the optical brighteners.

THE 4 “SENCES”:   Optical brighteners make your clothes look cleaner and brighter.  This is why TV commercials used to talk about “bluey whiteness” and have featured smiling people holding their clothes up to a window where there’s more UV-rich sunlight.