Can i find references describing these two types of luminescence? Thank you
I am including the following links.
a) http://krishikosh.egranth.ac.in/bitstream/1/2037133/1/12720.pdf
b) http://www.ep2-bayreuth.de/wp-content/publications/2002%20enginMat%204%20fluorescence%20and%20phosphorescence%20in%20organic%20materials%20-%20Review%20article.pdf
c) https://books.google.co.in/books?hl=en&lr=&id=7eI3AVl4dDsC&oi=fnd&pg=PR5&dq=Fluorescence+and+Phosphorescence&ots=0cUHJMBVc-&sig=mGobrBTTXgEP-bmzxZDDtRFqTNU
d) https://www.osapublishing.org/abstract.cfm?uri=josa-54-2-183
e) https://books.google.co.in/books?hl=en&lr=&id=j9o_DQAAQBAJ&oi=fnd&pg=PP1&dq=Fluorescence+and+Phosphorescence&ots=Tb4IBYALoP&sig=dtOM41MWT7UpEgZcsZnG0RcRD2U
Regards,
RB
Hello Ahmed Hijazi !
Fluorescence Versus Phosphorescence
Fluorescence and phosphorescence are two mechanisms that emit light or examples of photoluminescence. However, the two terms don't mean the same thing and don't occur the same way. In both fluorescence and phosphorescence, molecules absorb light and emit photons with less energy (longer wavelength), but fluorescence occurs much more quickly than phosphorescence and does not change the spin direction of the electrons. Here's how photoluminescence works and a look at the processes of fluorescence and phosphorescence, with familiar examples of each type of light emission.
Photoluminescence Basics
Photoluminescence occurs when molecules absorb energy. If the light causes electronic excitation, the molecules are called excited. If light causes vibrational excitation, the molecules are called hot. Molecules may become excited by absorbing different types of energy, such as physical energy (light), chemical energy, or mechanical energy (e.g., friction or pressure). Absorbing light or photons may cause molecules to become both hot and excited. When excited, the electrons are raised to a higher energy level. As they return to a lower and more stable energy level, photons are released. The photons are perceived as photoluminescence. The two types of photoluminescence ad fluorescence and phosphorescence.
Examples of Fluorescence
Fluorescent lights and neon signs are examples of fluorescence, as are materials that glow under a black light, but stop glowing once the ultraviolet light is turned off. Some scorpions will fluoresce. They glow as long as an ultraviolet light provides energy, however, the exoskeleton of the animal does not protect it very well from the radiation, so you shouldn't keep a black light on for very long to see a scorpion glow. Some corals and fungi are fluorescent. Many highlighter pens are also fluorescent.
References:
https://www.thoughtco.com/fluorescence-versus-phosphorescence-4063769
http://www.phys.ubbcluj.ro/~dana.maniu/OS/BS_7.pdf
https://www.physics.uoguelph.ca/~garrettp/teaching/PHY-1070/lecture-24.pdf
Basics and principle of Fluorescence & Phosphorescence measurement | Learn under 5 min | AI 06.
Image: https://www.youtube.com/watch?v=CcN8NnGGPhs
Thank you, dear colleagues, for your valuable comments. They were really useful to me .
When excited, electrons rise to a higher energy level. In this time deliveried photoluminescence transfer electrons to a high level of energy, which are termal relaxation. Anothers photons are perceived as photoluminescence.
Check this link
Chapter Fluorescence and Phosphorescence Spectroscopy
regards
these links are useful
Chapter Fluorescence and Phosphorescence Spectroscopy
https://link.springer.com/chapter/10.1007/978-1-4684-1521-6_7
https://www.researchgate.net/.../231268649_A_Brief_History_of_Flu...
https://en.wikipedia.org/wiki/Phosphorescence
regards
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