Is phosphorescence radiative or nonradiative?

Phosphorescence usually occurs only with “heavier” molecules since the spin has to be reversed with the help of spin-orbit-coupling. Whether electromagnetic radiation is emitted at all, and with which wavelength, depends on how much energy can be released beforehand by non-radiative decay [6,7].

Is fluorescence or phosphorescence higher energy?

The reason phosphorescence lasts longer than fluorescence is because the excited electrons jump to a higher energy level than for fluorescence. The electrons have more energy to lose and may spend time at different energy levels between the excited state and the ground state.

Why phosphorescence is called delayed fluorescence?

Phosphorescence is a type of photoluminescence related tofluorescence. Unlikefluorescence, a phosphorescentmaterial 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.

What is the relationship between emission and fluorescence?

In fluorescence, the emission is basically immediate and therefore generally only visible, if the light source is continuously on (such as UV lights); while phosphorescent material can store the absorbed light energy for some time and release light later, resulting in an afterglow that persists after the light has been switched off.

What are examples of fluorescence?

Common materials that fluoresce Vitamin B2 fluoresces yellow. Tonic water fluoresces blue due to the presence of quinine. Highlighter ink is often fluorescent due to the presence of pyranine. Banknotes, postage stamps and credit cards often have fluorescent security features.

How does fluorescence occur?

The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can be seen only when exposed to UV light.

What is intrinsic protein fluorescence?

Therefore “Intrinsic Protein Fluorescence” usually refers to the fluorescence emission of the tryptophan amino acids. Intrinsic protein fluorescence is caused by exciting the protein with 280 nm ultraviolet light and observing at approximately 350 nm.