Difference between fluorescence and phosphorescence


The key distinction between light and fluorescence is that light stops as before long as we have a tendency to subtract the sunshine supply whereas fluorescence tends to remain very little longer even once the irradiating source of illumination is removed.

When a molecule or atom absorbs energy, it will endure varied changes. Light and fluorescence square measure two such processes. Additionally to the on top of key distinction, there square measure another variation between the two terms like the energy discharged within the light method is beyond that within the fluorescence.

Comparison in tabular form:

comparison fluorescence phosphorescence
definition The emission of light by a substance that has absorbed light or other electromagnetic radiation The light emitted by a substance do not have combustion or perceptible heat.
time It take away the light source. Tends to stay little longer even after we remove the irradiating light source
mechanism Take place when excited energy is released and the molecule comes back to the ground state from the singlet-excited stage. Takes place when a molecule is coming back to the ground state form excited state.
Energy released It higher than that in the phosphorescence Is lower than that in the fluorescence
Relationship between the absorbed and released energy The absorbed amount of energy is released back. Released energy is lower that what is absorbed


What is Fluorescence?

Electrons in Associate in Nursing atom or a molecule will absorb the energy within the radiation Associate in nursing thereby excite to a higher energy level. This higher energy level is unstable; so, lepton likes to come back to the bottom state. Once returning, it emits the absorbed wavelength. During this relaxation method, they emit excess energy as photons. We have a tendency to decision this relaxation method as visible radiation. Visible radiation takes place rather more quickly. Generally, it completes in regarding 10-5 seconds or less time from the time of excitation.

When gasified atoms endure visible radiation, atomic visible radiation takes place once exposed to radiation with a wavelength that precisely matches one in every of the absorption lines of the part. As an example, gasified metallic element atoms absorb and excite by engrossing 589 nm radiations. Relaxation takes place when this by reemission of fluorescent radiation of the identical wavelength. Owing to this, we are able to use visible radiation to spot completely different components. Once excitation and reemission wavelengths are constant, we have a tendency to decision the ensuing emission as resonance visible radiation.

What is Phosphorescence?

When molecules absorb light-weight and move to the excited state they need 2 choices. They either unleash energy and are available back to the bottom state forthwith or endure different non-radioactive processes. If the excited molecule undergoes a non-radioactive method, it emits some energy and is available to a triplet state wherever the energy is somewhat lesser than the energy of the exited state; however it’s more than the bottom state energy. Molecules will keep a small amount longer during this less energy triplet state.

We decision this state because the stability state. Then stability state (triplet state) will slowly decay by emitting photons, and are available back to the bottom state (singlet state). Once this happens we have a tendency to decision it fluorescence.

Key difference:

There are different mechanisms by that Associate in nursing excited atom or molecule will surrender its excess energy and relax to its state. Non-radioactive relaxation and visible radiation emissions are two such necessary mechanisms. Owing to several mechanisms, the life of Associate in nursing excited state is transient.

The relative variety of molecules that glow is little as a result of this development needs structural options that slow the speed of the non-radioactive relaxation and enhance the speed of visible radiation. In most molecules, these options aren’t there; so, they endure non-irradiative relaxation, and visible radiation doesn’t occur. Molecular visible radiation bands are consisting of an oversized variety of closely spaced lines; so, sometimes it’s laborious to resolve.