In the process of fluorescence, an atom ab-

sorbs a photon of ultraviolet light and emits
two or more photons of visible light.
Is the reverse process possible? (That is, is
it possible for an atom to absorb a photon of
visible light and emit photons of ultraviolet
light?)

1. Yes; ultraviolet photons have less energy
than visible light.
2. No; ultraviolet photons have more energy
than the visible light.
3. Yes; the energy is equal;
4. More information is needed.
5. None of these

Ultraviolet photons have more energy than visible photons. A single visible photon cannot excite the upper energy level needed to get ultraviolet light out.

At the very high intensities of some focused lasers, multiphoton absorption of visible light IS possible, with resulting ultraviolet emission, but it is not a common occurrence in nature.

They probably expect answer 2.

2. No; ultraviolet photons have more energy than visible light.

To determine if the reverse process is possible, we need to know whether ultraviolet photons have more or less energy than visible light photons. The energy of a photon is directly proportional to its frequency, and inversely proportional to its wavelength.

Option 1 suggests that ultraviolet photons have less energy than visible light photons, while option 2 suggests that ultraviolet photons have more energy. We need to determine which of these options is correct.

In reality, ultraviolet light has a higher frequency and shorter wavelength than visible light, which means it carries more energy per photon. Therefore, option 2 is the correct answer: "No, ultraviolet photons have more energy than visible light."

So, the reverse process is not possible because an atom cannot absorb a photon of lower energy (visible light) and emit a photon of higher energy (ultraviolet light).