lasers in chemistry

Today’s post was written by Guest Professor Austin, a chemical engineering student who also wrote Darkrai and Rotom! If you’d like more information on how to write for us as a Guest Professor, please send us an ask!

In this article, we will be discussing Genesect, the legendary steel bug pokemon.  Team Plasma revived Genesect from a fossil, and decided the only way to make this prehistoric bug pokemon cooler was to strap a giant laser cannon to its back. When different drives are equipped, the cannon attached to its back can fire a variety of different types and colors of lasers. For example, the burn drive fires a red laser that is fire-type, and the Shock Drive fires a yellow laser that does electric-type damage. Different colors are created by different wavelengths of light, but how does a laser work?

In basic chemistry, you know that electrons orbit the nucleus of an atom in specific shells, or energy levels. When you give an electron energy, typically by absorbing a photon, the electron will jump from a lower shell to an higher shell, called an excited state. If you excite it with too much energy, the electron leaves the atom entirely. But if the electron is still bound to the atom, it will eventually de-excite and go back to ground state. To do this, it must release some of its excess energy, which it does by creating a photon. The amount of energy that it gives off determines the wavelength, and therefore color, of the light. Purple photons have higher energy than red photons.

This is the same atomic process that glow in the dark toys and many other things use to emit light. What makes lasers different is that this light is then focused. A typical laser consists of several parts: a flash lamp, a medium to excite, a reflector, and an output coupler. The medium determines the color of light. For example, many green lasers use Helium-Neon gas as the medium to produce green light. The first ever laser used ruby, and emitted red light. This is where Genesect’s drives come in. Different drives produce different colors and types of attack, so therefore the different drives represent different mediums.

(From top to bottom: InGaAlP (first two), HeNe, DPSS, and InGaN (bottom two) lasers)

The flash lamp is used to give the medium the initial energy it needs, exciting the electrons inside the medium. The electrons will release photons through the emission process discussed above, and that will start a chain reaction, causing other photons of the exact same properties (same direction, wavelength, frequency, photon energy, polarization) to be emitted while the flash lamp is being pulsed. More and more photons team up together in this way, amplifying the total signal.

(A poorly drawn diagram of photon amplification during stimulated emission)

The reflector and the output coupler are on opposite sides of the laser. The reflector, as you might have guessed, simply reflects the photons towards the output coupler. Every single photon reflects off of the reflector: it is 100% reflective. The output coupler is what focuses the beam itself. It is not as reflective, and only allows a portion of the photons to be escape in one direction: a beam. The photons that do not escape bounce back to the reflector, and keep going back and forth until they do manage to escape in the right direction allowed by the output coupler, creating a single focused beam of light.

Lasers have tons of applications, including surgery, dentistry, targeting and radar systems, astronomy, laser printers, acne treatment, fingerprint scanners, thermometers, and metal cutting. Metal-cutting lasers actually heat up and melt the metal in a very focused line, to cut it.

Larger destructive weaponized lasers like Genesect’s canon are largely still in development, but they work in similar ways. However, instead of a steady beam of laser, it emits in very fast pulses. The repetitive rapid change between laser and no laser, heat and cool, evaporation and expansion creates a shockwave throughout the target, ultimately damaging them.

Genesect’s laser canon excites electrons in different mediums that emit light, depending on which drive is installed.  The light is then reflected and bounced around inside the canon, allowing the light to escape in only one direction, creating a damaging beam.