What is phosphorescence and how is it different from flourescence?
- Phosphorescence and fluorescence both involve the absorption of photons of light by electrons. In the case of fluorescence the electrons, which have jumped to a higher orbit, re-emit that photon of light immediately after reaching orbit, thus allowing the electron to descend to its former orbit. Phosphorescence, however, involves electrons jumping to higher orbits and being unable to descend to their former orbit immediately due to lack of opportunity. They thus retain their photon until they find an opportunity to descend, at which time they release the photon of light and then drop back down to their former position. The emission of light therefore occurs over an extended period of time, the length of time depends firstly on the substance and then on the environmental factors.
Examples of substances that phosphoresce:
- Molybdenum Disulfide and Molybdenum amalgams:
- Qualities of Molybdenum (Mo): a transition element (number 42); silvery white metal; has a high melting point and is used as a high-temperature lubricant; combined as an alloy with other metals to increase strength and hardness; has high electrical conductivity; resists corrosion; used as a pigment; as a trace element in soil it improves cauliflower growth. It is also found in organisms in an enzyme form (compound form), especially those involved in nitrogen fixation but also in the gut of beetles and in the bodies of humans. In a compound form (as Molybdenum Disulfide [MoS2]), and in some amalgam forms, it is phosphorescent.
- Strontium Aluminate (doped with Europium)
- Zinc Sulphide
For how long do substances phosphoresce?
- Some phosphorescent substances incorporated into manufactured items can now phosphoresce in darkness for 10 hours after being placed in sunlight. This means that phosphorescent solar energy can be available for nearly an entire day. By using the technology of harvesting in combination with the technology of storage Phosolar approaches a round-the-clock phenomenon, although in a very weak form. This potentially puts it into the same competitive field as coal-fired power stations. However, the technology of phosphescent solar energy has yet to be built and tested. The real power of phosphorescent solar energy is during the daytime with the intense power of the Sun directly activating the phosphorescent compound. The night-time potential, however, should not be overlooked and should be continually improved.