![]() With the addition of copper dopant and intermediate bandgap of 220kJ/mol (2.28 eV) provides an intermediate level. This large gap would normally produce very few electrons and holes due to autoionization. ZnS has an energy band gap of 350 kJ/mol( 3.6ev). The glow in the dark paper is a common zinc doped copper sulphide (ZnS:Cu). Phosphorescent decay can last minutes to hours until all the excited electron states are exhausted. Despite being forbidden they do still occur but at a significantly slower time scale. In certain materials there is an intersystem crossing in which the absorbed photon energy can be trapped in a triplet state in which is forbidden (by the rules of quantum mechanics) to decay directly to the ground state. In fluorescent materials the emission is a very rapid, on the order of 10-nanoseconds. In an excited material a population of electrons and holes is formed. Many materials exhibit fluorescence when they are excited by a sufficiently energetic light source. What affect will temperature have on the phosphorescent decay pattern? Background: What reaction order do you predict the phosphorescent emission from glow in the dark paper will follow? This provides an insight into reaction order and methods for studying emissive processes. Then the data is transferred to Excel to find the best fit curve and its equation. ![]() In this activity you will measure the phosphorescence over time of a glow-in-the-dark paint following excitation by a flash of light.
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