Question

Difference between the fluorescence and phosphorescence

Answer 1

$\huge{\mathbf{\underline{\underline{Answer:-}}}}$

$\star$ Fluorescence and phosphorescence both are photoluminescence process which means the phenomena of absorption and subsequent emission of light by a substance.

$\star$ Difference between Fluorescence and Phosphorescence:-

➡️ When light is supplied to a sample of Molecules, we immediately see the Fluorescence. Fluorescence stops as soon as we take away the light source. But Phosphorescence tends to stay little longer even after the irradiating light source is removed.

➡️ Fluorescence take place when the Molecules come back to the ground state from the singlet-excited stage, so the decay period is very low. In Phosphorescence molecules goes to singlet exited state, it first dissipate its energy and then transit to triplet state. Then form triplet state molecule jump back to ground. So, the decay period is longer.

➡️ The energy released in the Fluorescence process is higher than that in the Phosphorescence.

➡️ Example of fluorescent material are crude oil, anthracene

➡️ Example of phosphorescent materials are the glow in the dark toys, paint and clock dials.

Answer 2

$\huge{\mathcal{\red{\underline{\underline{Question}}}}}$

$<font colour="black"><b>$Difference between the fluorescence and phosphorescence?

$\huge{\mathcal{\blue{\underline{\underline{Answer}}}}}$

$<font colour="black"><b>$The difference between fluorescence and phosphorescence are as follows:-

$\huge{\star{\bold{\green{\underline{Fluorescence}}}}}$

✴Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation.

✴It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation.

✴Generally molecules that fluoresce are conjugated systems.

✴Fluorescence occurs when an atom or molecules relaxes through vibrational relaxation to its ground state after being electrically excited.

✴The specific frequencies of excitation and emission are dependent on the molecule or atom.

$\huge{\star{\bold{\green{\underline{Phosphorescence}}}}}$

✴Phosphorescence is a type of photoluminescence related to fluorescence.

✴Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs.

✴The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum mechanics.

✴This phosphorescence is usually caused by algae suspended in the water.

✴Much like fireflies flitting through the air, the algae (of a wide variety of species) emit a glow whenever they are jostled. Sometimes that's caused by the tides rolling in and out.
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