Скачать с ютуб Explain the principle of Fluorescence and Phosphorescence. | Analytical Chemistry в хорошем качестве

Explain the principle of Fluorescence and Phosphorescence. | Analytical Chemistry

Many compounds absorb ultraviolet or visible light and undergo an electronic transition from low electronic energy levels to high electronic, energy levels. This Absorption of light requires 10-15 sec. The instant re-emission of the absorbed energy is called Fluorescence. While delayed re-emission of the absorbed energy is called Phosphorescence. For most molecules, the electrons are paired in the ground state i.e. pair of electrons have opposite spins this is called singlet state. As the spin is paired up, they do not show any magnetic moment. But if the electrons have the same spin the magnetic moment of both the electrons gets combined and they behave like a tiny magnet. This state where the electron pair is having the same spin is called as triplet state. In a molecule, there are several electronic energy levels and electrons are present at the ground state in the singlet state i.e. with opposite spins. When a molecule absorbs U.V. or Visible light, one electron from ground state undergoes to an excited state. Now the excited state is also having several vibrational levels, so the excited electron loses its energy by intermolecular collision and it comes to the lowest vibrational level of the excited state. Finally, the electron from the lowest vibrational level of excited state returns to the ground state by emitting the radiation or light of lower energy or higher wavelength. This overall process of absorption, intermolecular collision, and emission take 10-4 to 10-8 sec which is very small thus it looks like instant re-emission of light. But the energy of radiation emitted is always less than the energy of radiation absorbed. Or in other words, the wavelength of emitted radiation will be always higher than the wavelength of radiation absorbed. This is Fluorescence phenomenon. Analytical Reasoning    • Solve Problems Related To Ages With T...   English Grammar    • Making Sense With Tense #1 - English ...   Interview Skills    • Questions You May Be Asked During an ...   Managerial Economics    • MCQ #1 of Managerial Economics   Royalty Free Stock Footage    • Flowers - Royalty free footage   Chemical Thermodynamics - Physical Chemistry    • State and Explain first law of thermo...   Ionic Equilibria - Physical Chemistry    • Derive expression for Ostwald’s Dilut...   Electrochemistry - Physical Chemistry    • What are different types of Reversibl...   Solid State - Physical Chemistry    • Explain the following terms | Solid S...   Gaseous State - Physical Chemistry    • Postulates of Kinetic Molecular Theor...   Colloidal States - Physical Chemistry    • What is Colloidal Solution? | Colloid...   Stereochemistry - Organic Chemistry    • Explain Configuration and Conformatio...   Nanomaterials - Engineering Chemistry    • Compare top down with bottom up Proce...   Water and Its Treatment - Engineering Chemistry    • Explain why hard water gives out a cu...   Electrochemistry - Engineering Chemistry    • Distinguish between metallic and elec...   Environmental Studies    • MCQ on Environmental Studies Part 8   Optics - Applied Physics    • What are cartesian sign conventions f...   For Details Visit http://cepekmedia.co.nf http://cepek.hol.es/ http://edmerls.66Ghz.com/ http://edmerls.tk/