9

There are two potential questions here: one is why is dimming a slow drawn-out process (incoherent, unlike a "switch"). The second question is why different stars may appear to lose their intensity at a different rate. The light-emission process behind your stars involves phosphorescence. The process involves relaxation of an electronically excited system ...


7

Fluorescent lamps do primarily work by fluorescence. According to this Wikipedia article: "The inner surface of the lamp is coated with a fluorescent (and often slightly phosphorescent) coating..." First off, an electric current excites the outer electrons of gas atoms (typically mercury) within the lamp to a higher energy state. When the atoms relax ...


7

The human eye is most sensitive in green wavelengths. Therefore, if one were to put the same amount of light energy into different wavelengths, the green portion of the spectrum would appear brightest, though it contained no more energy than the rest. If a phosphor or glow-stick manufacturer is seeking the "greatest bang for the buck", i.e. the most light ...


6

There are two things going on here. You have conflated with "forbidden" with unfavorable. In many systems, the first excited triplet is lower in energy than the first excited singlet. Hence, the order of energies excited singlet > triplet > ground state singlet is correct and sensible. If your question is "why is this the order?" that should be a separate ...


4

Source of light I imagine that the cause of the stars becoming dimmer is that some electrons are relaxing down before others. This statement could be interpreted in two different ways, one incorrect and one correct. It could mean that electrons have an "on" state where they continuously emit light. That is not the case. Instead, they emit light once ...


3

The after-glow is called phosphorescence. Fluorescence stops immediately the moment light is turned off because the process is ultrafast! Phosphorescence on the other hand requires a change in the spin of the electron in a molecule, such transitions are forbidden, this is why it is slow. You can check the Jablonski diagram to understand this better, see here ...


2

Although the previous answers correctly explain the different mechanisms of fluorescence and phosphorescence, they do not really touch upon why the light is not emitted all at once. Even in the very fast fluorescence, not all light is emitted in one burst (although one needs fast detectors to see this). The reason for the slow de-excitation of the molecules ...


2

Phosphorescence is driven by the slow loss of energy from excited electron states Firstly, the phenomenon you describe is phosphorescence not fluorescence: they have different mechanisms. Fluorescence happens (to simplify a little) when light kicks electrons from their normal orbitals in some molecules to a higher excited state orbital (often via a multi-...


1

To answer why the energy is not emitted as a burst we have consider the chance of a photon being emitted. To match experimental data we have to assume that each event (photon emission) is randomly occurring and is independent of all others and that each occurs in a non-overlapping time interval (i.e. its own). This means that in a time interval $\delta t$ (a)...


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