Describe how triboluminescence and fluorescence are produced.

Triboluminescence is a fascinating process rooted in the concept of excited molecules. When mechanical force is applied to certain substances—like crushing sugar in the dark—you may notice a spark of light. This occurs because the energy from the mechanical action excites the molecules within the substance. An excited molecule is simply a molecule that has absorbed energy, propelling its electrons to higher, less stable energy states.

As these excited molecules inevitably seek stability, they release the absorbed energy to sink back into their lower, more stable energy levels. This energy is emitted as visible light, providing a brief but spectacular display of triboluminescence. Hence, the light emitted from materials when they're scratched or crushed can be thought of as a molecular sigh of relief, as excited molecules return to their energy comfort zone. Understanding this concept helps us grasp why some substances light up when subjected to mechanical stress.

Electromagnetic radiation encompasses a wide range of energies, including the lights and radio waves that facilitate every day communication, to the more powerful, such as X-rays, that penetrate materials for medical imaging. Fluorescence comes into play when certain materials, known as fluorophores, interact with this radiation.

When fluorophores are exposed to electromagnetic radiation of a specific energy, typically ultraviolet (UV) light, they absorb some of this energy. The electrons within the fluorophores get excited, momentarily jumping to those higher electron energy levels before they can settle down. When they relax back to their original state, they emit photons of light at a longer wavelength than the absorbed radiation, which typically corresponds to visible light. This emitted light is what we observe as the glow of fluorescence—bright, otherworldly shades of color radiating from highlighters, glow sticks, and even biological markers used in scientific research.

The concept of electron energy levels is essential to understanding the inner workings of triboluminescence and fluorescence. An atom's electrons exist in specific energy levels or shells around the nucleus; these levels are akin to the rungs of a ladder, where electrons can move up or down. However, to move between these levels, an electron must either absorb or emit a precise amount of energy.

In the world of quantum mechanics, these jumps are not continuous but rather happen in discrete packets, or 'quanta', of energy. When mechanical pressure (triboluminescence) or electromagnetic radiation (fluorescence) provides the right amount of energy, electrons can leap to higher levels. Wielding energy like a currency, they subsequently 'spend' it as light when they return to their ground state. This exchange is the source of the light we see in triboluminescent events and the vivid colors of fluorescent materials. These fundamental interactions between electron energy levels and energy absorption or emission are not just fascinating; they underpin many technologies, including lasers, neon signs, and even the functionality of solar cells.